Aiming at mercury and dioxin in fire coal gas as research objects,nonthermal plasma(NTP)catalytic technology was used to investigate the degradation effect of operating condition parameters on mixed pollutants in mixe...Aiming at mercury and dioxin in fire coal gas as research objects,nonthermal plasma(NTP)catalytic technology was used to investigate the degradation effect of operating condition parameters on mixed pollutants in mixed flue gas condition,and to explore the synergistic degradation of Hg0and TCB(1,2,3-trichlorobenzene,TCB)under mixed flue gas conditions.The research results showed that the conversion efficiency of mercury and TCB increased with the additional output of voltage,and decreased with the increase of the gas flow rate.Under optimal reaction conditions:voltage=17 k V,frequency=300 Hz,gas flow rate=21 min^(-1),the conversion efficiency of Hg^(0)and TCB reached the highest 91.4%and 84.98%,respectively.In the NTP catalytic system,active free radicals played an important role in the synergistic conversion of mercury and TCB,which have a competitive effect,to make the conversion efficiency of mixed pollutants lower than a single substance.In the mixed flue gas condition,the mixed gas has an inhibitory effect on the synergistic conversion of mercury and TCB.Kinetic modeling of NTP catalytic synergistic reaction was established.Under three conditions of TCB,mercury and TCB,mixed simulated flue gas,the NTP catalytic technology showed a quasi-firstorder kinetic reaction for the degradation of TCB.According to the synergistic effect of NTP and composites,the transformation and degradation of TCB mainly included two processes:TCB and ring opening,and Hg^(0)was finally oxidized to Hg^(2+).展开更多
To evaluate the ability of the Predicted Particle Properties(P3)scheme in the Weather Research and Forecasting(WRF)model,we simulated a stratiform rainfall event over northern China on 22 May 2017.WRF simulations with...To evaluate the ability of the Predicted Particle Properties(P3)scheme in the Weather Research and Forecasting(WRF)model,we simulated a stratiform rainfall event over northern China on 22 May 2017.WRF simulations with two P3 versions,P3-nc and P3-2ice,were evaluated against rain gauge,radar,and aircraft observations.A series of sensitivity experiments were conducted with different collection efficiencies between ice and cloud droplets.The comparison of the precipitation evolution between P3-nc and P3-2ice suggested that both P3 versions overpredicted surface precipitation along the Taihang Mountains but underpredicted precipitation in the localized region on the leeward side.P3-2ice had slightly lower peak precipitation rates and smaller total precipitation amounts than P3-nc,which were closer to the observations.P3-2ice also more realistically reproduced the overall reflectivity structures than P3-nc.A comparison of ice concentrations with observations indicated that P3-nc underestimated aggregation,whereas P3-2ice produced more active aggregation from the self-collection of ice and ice-ice collisions between categories.Efficient aggregation in P3-2ice resulted in lower ice concentrations at heights between 4 and 6 km,which was closer to the observations.In this case,the total precipitation and precipitation pattern were not sensitive to riming.Riming was important in reproducing the location and strength of the embedded convective region through its impact on ice mass flux above the melting level.展开更多
Post-processing correction is an effective way to improve the model forecasting result. Especially, the machine learning methods have played increasingly important roles in recent years. Taking the meteorological obse...Post-processing correction is an effective way to improve the model forecasting result. Especially, the machine learning methods have played increasingly important roles in recent years. Taking the meteorological observational data in a period of two years as the reference, the maximum and minimum temperature predictions of Shenyang station from the European Center for Medium-Range Weather Forecasts (ECMWF) and national intelligent grid forecasts are objectively corrected by using wavelet analysis, sliding training and other technologies. The evaluation results show that the sliding training time window of the maximum temperature is smaller than that of the minimum temperature, and their difference is the largest in August, with a difference of 2.6 days. The objective correction product of maximum temperature shows a good performance in spring, while that of minimum temperature performs well throughout the whole year, with an accuracy improvement of 97% to 186%. The correction effect in the central plains is better than in the regions with complex terrain. As for the national intelligent grid forecasts, the objective correction products have shown positive skills in predicting the maximum temperatures in spring (the skill-score reaches 0.59) and in predicting the minimum temperature at most times of the year (the skill-score reaches 0.68).展开更多
Carbon capture,utilization and storage(CCUS) is widely recognized as a vital strategy for mitigating the impact of human induced climate change.Among various CO_(2) adsorbents,intermediate-temperature solid adsorbents...Carbon capture,utilization and storage(CCUS) is widely recognized as a vital strategy for mitigating the impact of human induced climate change.Among various CO_(2) adsorbents,intermediate-temperature solid adsorbents have garnered significant attention due to their potential applications in hydrogen utilization,specifically in the water gas shift,steam reforming and gasification processes.These processes are crucial for achieving carbon neutrality.While laboratory-level studies have showcased the high adsorption capacity of these materials via various synthesis and modification methods,their practical application in complex industrial environments remains challenging,impeding the commercialization process.This review aims to critically summarize the recent research progress made in intermediatetemperature(200-400℃) solid CO_(2) adsorbents,particularly focusing on indicators such as cyclability,gas selectivity,and formability,which play vital roles in industrial application scenarios.Additionally,we provide an overview of laboratory-level advanced technologies specifically tailored for industrial applications.Furthermore,we highlight several industrial-ready advanced technologies that can pave the way for overcoming the challenges associated with large-scale implementation.The insights provided by this review aim to assist researchers in identifying the most relevant research directions for industrial applications.By promoting advances in the application of solid adsorbents,we strive to facilitate the ultimate goal of achieving carbon neutrality.展开更多
Human activities have altered weather patterns by causing an increase in greenhouse gas. The effects of climate change have been studied, including effects on some ecosystems throughout the world. There are many studi...Human activities have altered weather patterns by causing an increase in greenhouse gas. The effects of climate change have been studied, including effects on some ecosystems throughout the world. There are many studies on changes in the soil due to climate change, but much of them did not extend their research to soil enzyme that integrates information on soil microbial status and soil physical-chemical conditions. Meanwhile, there are lots of experimental fields established to study effects of long-term fertilization on soil enzyme activities, but many did not compare the difference of soil enzyme activities and did not analyze the effect of climatic factors on soil enzyme activities with long-term fertilization under different hydrothermal conditions. In this study, we compared soil enzyme activities of three long-fertilization stations which had different hydrothermal conditions in Northeast China, and analyzed the relationship of hydrothermal condition, soil chemical properties with soil enzyme activities. Hydrothermal conditions (annual temperature and total rainfall) decreased in order of Gongzhuling (Jilin Province, China ) > Harbin (Heilongjiang Province, China) > Heihe (Heilongjiang Province, China) over the course of the long-term fertilization experiment. Sunshine hours showed the longest in Gongzhuling, the second in Heihe, and the last in Harbin. However, the order of soil enzymes was not in agreement with hydrothermal conditions. Overall, the order of soil enzymes for the same treatment among three stations was consistent in 2008 with in 2009. Correlation analysis demonstrated that different soil enzymes achieved the different affected levels by climatic factors under different fertilization treatments. Urease activity showed a significant relationship with sunshine hours in no fertilizer (CK) treatment (R=-0.91, P<0.01) and relative humidity in mineral fertilizers plus manure (MNPK) treatment (R=0.82, P<0.05). Phosphatase activity exhibited a negative correlation with annual mean temperature, annual mean maximum temperature and annual mean minimum temperature, and their correlation coefficients were separately -0.83, -0.79, and -0.83 at P<0.05 in CK treatment. Invertase activity was highly and positively correlated with sunshine hours in CK treatment (R=0.94, P<0.01). Catalase activity showed significant negative correlations with minimum relative humidity in CK treatment (R=-0.81, P<0.05), and positive correlations with sunshine hours in M treatment (R=0.83, P<0.05). There were no climatic factors which strongly affected on dehydrogenase in all treatments. Soil enzyme activities were closely related to the soil chemical properties. Soil urease activity was positively correlated with available P (P<0.05). With exception of correlation between invertase and total P at P<0.05, phosphase, invertase, catalase, and dehydrogenase showed significant positive correlations with soil chemical properties (P<0.01). It was a comprehensive process that biologic and abiotic factors were effect on soil enzyme activities under different fertilization treatments. To sum up, the variation of hydrothermal conditions in different climate zones and soil chemical properties affect integrally metabolic activity and metabolic finger print of microbial communities in black soil.展开更多
This paper reviews the studies and research on climate change impacts on the forest ecosystems in Northeast China.The results show that in the context of global and regional warming,the growing season of coniferous fo...This paper reviews the studies and research on climate change impacts on the forest ecosystems in Northeast China.The results show that in the context of global and regional warming,the growing season of coniferous forests has been increasing at an average rate of 3.9 d per decade.Regional warming favors the growth of temperate broad-leaved forests and has a detrimental efect on the growth of boreal coniferous forests.Over the past hundred years,the forest edge of the cool temperate zone in the southern Daxing’anling region has retreated 140 km northward.From 1896 to 1986,the northern boundary of broad-leaved forests in Heilongjiang province has extended northwestward about 290 km.Future climatic changes(until 2060)may lead to the northern deciduous needle forests moving out of China’s territory altogether.The occurrence cycles of pests and diseases have shortened;their distribution ranges have expanded.The life cycle of tent caterpillars(Malacosoma neustria testacea Motschulsky)has shortened from 14–15 years in the past to8–10 years now.The pine caterpillar(Dendrolimus tabulaeformis Tsai et Liu),which has spread within western Liaoning province and the nearby areas,can now be found in the north and west.Lightning fires in the Daxing’anling region have significantly increased since 1987,and August has become the month when lightning fires occur most frequently.Overall,the net primary productivity(NPP)of forest in Northeast China has increased.The NPP in 1981 was around 0.27 Pg C,and increased to approximately 0.40 Pg C in 2002.With the current climate,the broad-leaved Korean pine forest ecosystem acts as a carbon sink,with a carbon sink capacity of 2.7 Mg C hm 2.Although the carbon sink capacity of the forest ecosystems in Northeast China has been weakened since 2003,the total carbon absorption will still increase.The forest ecosystems in Northeast China are likely to remain a significant carbon sink,and will play a positive role in the mitigation of climate change.展开更多
Characteristics of air pollution in Northeast China(NEC) received less research attention in the past comparing to other heavily polluted regions in China.Spatiotemporal variations of six criteria air pollutants(PM10,...Characteristics of air pollution in Northeast China(NEC) received less research attention in the past comparing to other heavily polluted regions in China.Spatiotemporal variations of six criteria air pollutants(PM10, PM2.5, SO2, NO2, O3 and CO) in Central Liaoning Urban Agglomeration(CLUA) and Harbin-Changchun Urban Agglomeration(HCUA) in NEC Plain were analyzed in this study based on three-year hourly observations of air pollutants and meteorological variables from 2015 to 2017.The results indicated that the annual mean concentrations of air pollutants are generally higher in the middle and southern regions in NEC Plain and lower in the northern region.Megacities such as Shenyang, Harbin and Changchun experience severe air pollution, with a three-year averaged air quality index(AQI) larger than 80, far exceeding the daily AQI standard at the first-level of 50 in China.The annual mean PM and SO2 concentrations decrease most significantly in NEC urban agglomerations from 2015 to 2017, followed by CO and NO2, while O3 shows a slight increasing trend.All the six pollutants exhibit obvious seasonal and diurnal variations, and these variations are dictated by local emission and meteorological conditions.PM2.5 and O3 concentrations in NEC urban agglomerations strongly depend on wind conditions.High O3 concentrations at different cities usually occur in presence of strong winds but are independent on wind direction(WD), while high PM2.5 is usually accompanied by weak winds and poor dispersion condition, and sometimes also occur when the northerly or southerly winds are strong.Regional transport of air pollutants between NEC urban agglomerations is common.A severe haze event on November 1–4, 2017 is examined to demonstrate the role of regional transport on pollution.展开更多
By using,summer temperature data in 26 stations from 1951 to 2003, the variation characteristics of summer temperature in Northeast China (NET) were analyzed based on the background of climate warming. The results sho...By using,summer temperature data in 26 stations from 1951 to 2003, the variation characteristics of summer temperature in Northeast China (NET) were analyzed based on the background of climate warming. The results showed that the warming in summer was 0.15℃/10a in Northeast China, which was higher than that on the global, Northern Hemisphere or Northeast Asia scale in the recent 50 years. The responses of NET to global warming were shown in 3 aspects mainly. Firstly, it became warm and the average temperature increased in summer; secondly, the temperature variability increased, which displayed the increase of climatic instability; thirdly, the disaster of low temperature decreased and high temperature damage increased obviously, but the disaster of low temperature still existed in some areas under global warming background, which would be worthy of notice further.展开更多
The classification of the Northeast China Cold Vortex(NCCV)activity paths is an important way to analyze its characteristics in detail.Based on the daily precipitation data of the northeastern China(NEC)region,and the...The classification of the Northeast China Cold Vortex(NCCV)activity paths is an important way to analyze its characteristics in detail.Based on the daily precipitation data of the northeastern China(NEC)region,and the atmospheric circulation field and temperature field data of ERA-Interim for every six hours,the NCCV processes during the early summer(June)seasons from 1979 to 2018 were objectively identified.Then,the NCCV processes were classified using a machine learning method(k-means)according to the characteristic parameters of the activity path information.The rationality of the classification results was verified from two aspects,as follows:(1)the atmospheric circulation configuration of the NCCV on various paths;and(2)its influences on the climate conditions in the NEC.The obtained results showed that the activity paths of the NCCV could be divided into four types according to such characteristics as the generation origin,movement direction,and movement velocity of the NCCV.These included the generation-eastward movement type in the east of the Mongolia Plateau(eastward movement type or type A);generation-southeast longdistance movement type in the upstream of the Lena River(southeast long-distance movement type or type B);generationeastward less-movement type near Lake Baikal(eastward less-movement type or type C);and the generation-southward less-movement type in eastern Siberia(southward less-movement type or type D).There were obvious differences observed in the atmospheric circulation configuration and the climate impact of the NCCV on the four above-mentioned types of paths,which indicated that the classification results were reasonable.展开更多
The presence of embedded convection in stratiform clouds strongly affects ice microphysical properties and precipitation formation.In situ aircraft measurements,including upward and downward spirals and horizontal pen...The presence of embedded convection in stratiform clouds strongly affects ice microphysical properties and precipitation formation.In situ aircraft measurements,including upward and downward spirals and horizontal penetrations,were performed within both embedded convective cells and stratiform regions of a mixedphase stratiform cloud system on 22 May 2017.Supercooled liquid water measurements,particle size distributions,and particle habits in different cloud regions were discussed with the intent of characterizing the riming process and determining how particle size distributions vary from convective to stratiform regions.Significant amounts of supercooled liquid water,with maxima up to 0.6 g m−3,were observed between−3℃ and−6℃ in the embedded convective cells while the peak liquid water content was generally less than 0.1 g m−3 in the stratiform regions.There are two distinct differences in particle size distributions between convective and stratiform regions.One difference is the significant shift toward larger particles from upper−15℃ to lower−10℃ in the convective region,with the maximum particle dimensions increasing from less than 6000μm to over 1 cm.The particles larger than 1 cm at−10℃ are composed of dendrites and their aggregates.The other difference is the large concentrations of small particles(25–205μm)at temperatures between−3℃ and−5℃ in the convective region,where rimed ice particles and needles coexist.Needle regions are observed from three of the five spirals,but only the cloud conditions within the convective region fit into the Hallett-Mossop criteria.展开更多
Meteorological conditions,particularly the vertical wind field structure,have a direct influence on the PM2.5 concentrations over the Pearl River Delta(PRD).In October 2012,an exceptional air pollution event occurred ...Meteorological conditions,particularly the vertical wind field structure,have a direct influence on the PM2.5 concentrations over the Pearl River Delta(PRD).In October 2012,an exceptional air pollution event occurred in the PRD,and a high concentration of PM2.5 was registered at some stations.During days with PM2.5 air pollution,the wind speed was less than 3 m s-1 at the surface,and the vertical wind field featured a weak wind layer(WWL)with a thickness of approximately 1000 m.The mean atmospheric boundary layer height was less than 500 m during pollution days,but it was greater than 1400 m during non-pollution days.A strong negative correlation was detected between the PM2.5 concentration and the ventilation index(VI).The VI was less than 2000 m2 s-1 during PM2.5 air pollution days.Because of the weak wind,sea-land breezes occurred frequently,the recirculation factor(RF)values were small at a height of 800 m during pollution days,and the zones with the lowest RF values always occurred between the heights of 300 and 600 m.The RF values during PM2.5 pollution days were approximately 0.4 to 0.6 below a height of 800 m,reducing the transportation capacity of the wind field to only 40%to 60%.The RF and wind profile characteristics indicated that sealand breezes were highly important in the accumulation of PM2.5 air pollution in the PRD.The sea breezes may transport pollutants back inland and may result in the peak PM2.5 concentrations at night.展开更多
In this study,the clear sky hourly global and net solar irradiances at the surface determined using SUNFLUX,a simple parameterization scheme,for three stations(Gaize,Naqu,and Lhasa) on the Tibetan Plateau were evaluat...In this study,the clear sky hourly global and net solar irradiances at the surface determined using SUNFLUX,a simple parameterization scheme,for three stations(Gaize,Naqu,and Lhasa) on the Tibetan Plateau were evaluated against observation data.Our modeled results agree well with observations.The correlation coefficients between modeled and observed values were > 0.99 for all three stations.The relative error of modeled results,in average was < 7%,and the root-mean-square variance was < 27 W m 2.The solar irradiances in the radiation model were slightly overestimated compared with observation data;there were at least two likely causes.First,the radiative effects of aerosols were not included in the radiation model.Second,solar irradiances determined by thermopile pyranometers include a thermal offset error that causes solar radiation to be slightly underestimated.The solar radiation absorbed by the ozone and water vapor was estimated.The results show that monthly mean solar radiation absorbed by the ozone is < 2% of the global solar radiation(< 14 W m 2).Solar radiation absorbed by water vapor is stronger in summer than in winter.The maximum amount of monthly mean solar radiation absorbed by water vapor can be up to 13% of the global solar radiation(95 W m 2).This indicates that water vapor measurements with high precision are very important for precise determination of solar radiation.展开更多
Background:Biogenic volatile organic compounds(BVOCs)play an essential role in tropospheric atmospheric chemical reactions.There are few studies conducted on BVOCs emission of dominant forest species in the Jing-Jin-J...Background:Biogenic volatile organic compounds(BVOCs)play an essential role in tropospheric atmospheric chemical reactions.There are few studies conducted on BVOCs emission of dominant forest species in the Jing-Jin-Ji area of China.Based on the field survey,forest resources data and the measured standard emission factors,the Guenther model developed in 1993(G93)was applied in this paper to estimate the emission of BVOCs from several dominant forest species(Platycladus orientalis,Quercus variabilis,Betula platyphylla,Populus tomentosa,Pinus tabuliformis,Robinia pseudoacacia,Ulmus pumila,Salix babylonica and Larix gmelinii)in the Jing-Jin-Ji area in 2017.Then the spatiotemporal emission characteristics and atmospheric chemical reactivity of these species were extensively evaluated.Results:The results showed that the total annual BVOCs emission was estimated to be 70.8 Gg C·year^(−1),consisting 40.5%(28.7 Gg C·year^(−1))of isoprene,36.0%(25.5 Gg C·year^(−1))of monoterpenes and 23.4%(16.6 Gg C·year^(−1))of other VOCs.The emissions from Platycladus orientalis,Quercus variabilis,Populus tomentosa and Pinus tabulaeformis contributed 56.1%,41.2%,36.0% and 31.1%,respectively.The total BVOCs emission from the Jing-Jin-Ji area accounted for 61.9% and 1.8%in summer and winter,respectively.Up to 28.8% of emission was detected from Chengde followed by Beijing with 24.9%,that mainly distributed in the Taihang Mountains and the Yanshan Mountains.Additionally,the Robinia pseudoacacia,Populus tomentosa,Quercus variabilis,and Pinus tabulaeformis contributed mainly to BVOCs reaction activity.Conclusions:The BVOCs emission peaked in summer(June,July,and August)and bottomed out in winter(December,January,and February).Chengde contributed the most,followed by Beijing.Platycladus orientalis,Quercus variabilis,Populus tomentosa,Pinus tabulaeformis and Robinia pseudoacacia represent the primary contributors to BVOCs emission and atmospheric reactivity,hence the planting of these species should be reduced.展开更多
The optical and microphysical properties of aerosols remain one of the greatest uncertainties associated with evaluating the climate forcing attributed to aerosols.Although the trends in aerosol optical depth(AOD)at g...The optical and microphysical properties of aerosols remain one of the greatest uncertainties associated with evaluating the climate forcing attributed to aerosols.Although the trends in aerosol optical depth(AOD)at global and regional scales have been widely examined,little attention has been paid to the trends in type-dependent AODs related to aerosol particle properties.Here,using the aerosol optical component dataset from the Multi-angle Imaging SpectroRadiometer(MISR)instrument,we investigate decadal-scale trends in total aerosol loading as well as AODs for five aerosol components by particle size and morphology during 2003–2018 over land.Relationships between the total AOD(TAOD)trends and type-dependent AOD changes were examined,and the relative contribution of each type-dependent AOD to the overall TAOD trends was quantified.By dividing the TAOD values into four different aerosol pollution levels(APLs)with splits at 0.15,0.40,and 0.80,we further explored the relationships between TAOD changes and interannual variations in the frequency-of-occurrences(FoOs)of these APLs.Long-term trends in FoOs in the different APLs show that there was a significant improvement in air quality between 2003 and 2018 in most land areas,except South Asia,corresponding to a shift from lightly polluted to clean conditions.However,the effects of different APLs on TAOD changes are regionally dependent and their extent of correlation varied spatially.Moreover,we observed that the annual mean TAOD has decreased by 0.47%.a^(-1)over land since 2003(P<0.05).This significant reduction was mainly attributed to the continued reduction in small-sized(<0.7 mm diameter)AOD(SAOD)(-0.74%.a^(-1))and spherical AOD(SPAOD)(-0.46%.a^(-1)).Statistical analysis shows that SAOD and SPAOD respectively accounted for 57.5%and 89.6%of the TAOD,but contributed 82.6%and 90.4%of the trend in TAOD.Our study suggests that small-sized and spherical aerosols composed of sulfate,organic matter,and black carbon play a dominant role in determining interannual variability in land TAOD.展开更多
SUNFLUX is a fast parameterization scheme for determination of the solar radiation at the Earth's surface.In this paper,SUNFLUX is further modified in the treatment of aerosols.A new aerosol parameterization schem...SUNFLUX is a fast parameterization scheme for determination of the solar radiation at the Earth's surface.In this paper,SUNFLUX is further modified in the treatment of aerosols.A new aerosol parameterization scheme is developed for five aerosol species.Observational data from Baseline Surface Radiation Network(BSRN),Surface Radiation Budget Network(SURFRAD) and Aerosol Robotic Network(AERONET) stations are used to evaluate the accuracy of the original and modified SUNFLUX schemes.General meteorological data are available at SURFRAD stations,but not at BSRN stations.Therefore,the total precipitable water content and aerosol data are obtained from AERONET stations.Fourteen stations are selected from both BSRN and AERONET.Cloud fraction data from MODIS are further used to screen the cloud.Ten-year average aerosol mixing ratios simulated by the CAM-chem system are used to calculate the fractions of aerosol optical depth for each aerosol species,and these fractions are further used to convert the observed total aerosol optical depth into the components of individual species for use in the evaluations.The proper treatment of multiple aerosol types in the model is discussed.The evaluation results using SUNFLUX with the new aerosol scheme,in terms of the BSRN dataset,are better than those using the original aerosol scheme under clear-sky conditions.However,the results using the SURFRAD dataset are slightly worse,attributable to the differences in the input water vapor and aerosol optical depth.Sensitivity tests are conducted to investigate the error response of the SUNFLUX scheme to the errors in the input variables.展开更多
This study investigates diurnal variations of precipitation during May–August, 1998–2012, over the steep slopes of the Himalayas and adjacent regions(flat Gangetic Plains–FGP, foothills of the Himalayas–FHH, the s...This study investigates diurnal variations of precipitation during May–August, 1998–2012, over the steep slopes of the Himalayas and adjacent regions(flat Gangetic Plains–FGP, foothills of the Himalayas–FHH, the steep slope of the southern Himalayas–SSSH, and the Himalayas-Tibetan Plateau tableland–HTPT). Diurnal variations are analyzed at the pixel level utilizing collocated TRMM precipitation radar and visible infrared data. The results indicate that rain parameters(including rain frequency, rain rate, and storm top altitude) are predominantly characterized by afternoon maxima and morning minima at HTPT and FGP, whereas, maximum rain parameters at FHH typically occur in the early morning. Rain parameters at SSSH are characterized by double peaks;one in the afternoon and one at midnight. Over HTPT and FGP,convective activity is strongest in the afternoon with the thickest crystallization layer. Over FHH, the vertical structure of precipitation develops most vigorously in the early morning when the most intense collision and growth of precipitation particles occurs. Over SSSH, moist convection is stronger in the afternoon and at midnight with strong mixing of ice and water particles. The results of harmonic analysis show that rain bands move southward from lower elevation of SSSH to FHH with apparent southward propagation of the harmonic phase from midnight to early morning. Moreover, the strongest diurnal harmonic is located at HTPT, having a diurnal harmonic percentage variance of up to 90%. Large-scale atmospheric circulation patterns exhibit obvious diurnal variability and correspond well to the distribution of precipitation.展开更多
The paper discusses the core parameters of the 3 D and 4 D variational merging based on L1 norm regularization,namely optimization characteristic correlation length of background error covariance matrix and regulariza...The paper discusses the core parameters of the 3 D and 4 D variational merging based on L1 norm regularization,namely optimization characteristic correlation length of background error covariance matrix and regularization parameter. Classical 3 D/4 D variational merging is based on the theory that error follows Gaussian distribution. It involves the solution of the objective functional gradient in minimization iteration,which requires the data to have continuity and differentiability. Classic 3 D/4 D-dimensional variational merging method was extended,and L1 norm was used as the constraint coupling to the classical variational merged model. Experiment was carried out by using linear advection-diffusion equation as four-dimensional prediction model,and parameter optimization of this method is discussed. Considering the strong temporal and spatial variation of water vapor,this method is further applied to the precipitable water vapor( PWV) merging by calculating reanalysis data and GNSS retrieval.Parameters were adjusted gradually to analyze the influence of background field on the merging result,and the experiment results show that the mathematical algorithm adopted in this paper is feasible.展开更多
Different from other domestic and foreign research in which the optimum interpolation(OI) merging algorithm is commonly used,this paper constructs the non-Gaussian model for generalized variational precipitation data ...Different from other domestic and foreign research in which the optimum interpolation(OI) merging algorithm is commonly used,this paper constructs the non-Gaussian model for generalized variational precipitation data merging research based on the non-Gaussianity of precipitation data. For CMORPH data correction,the probability density function( PDF) matching method is adopted,during which the GAMMA function fitting is utilized,and the generalized variational merging based on non-Gaussian model is used to merge corrected CMORPH precipitation data and station ground observation precipitation data. Meanwhile,we carry out an experiment on CMORPH precipitation data correction and the merging of multisource precipitation data based on non-Gaussian model. By measuring the structural similarity between the merged field and the reference field,we get a merging method that can better retain useful " outliers" which represent weather phenomena. The experimental results accord with our expectations.展开更多
The presented work reports the selective catalytic reduction(SCR)of NO_(x) assisted by dielectric barrier discharge plasma via simulating marine diesel engine exhaust,and the experimental results demonstrate that the ...The presented work reports the selective catalytic reduction(SCR)of NO_(x) assisted by dielectric barrier discharge plasma via simulating marine diesel engine exhaust,and the experimental results demonstrate that the low-temperature activity of NH_(3)-SCR assisted by non-thermal plasma is enhanced significantly,particularly in the presence of a C_(3)H_(6) additive.Simultaneously,CeMnZrO_(x)@TiO_(2) exhibits strong tolerance to SO_(2) poisoning and superior catalytic stability.It is worthwhile to explore a new approach to remove NO_(x) from marine diesel engine exhaust,which is of vital significance for both academic research and practical applications.展开更多
基金supported by National Natural Science Foundation of China(No.52270114)。
文摘Aiming at mercury and dioxin in fire coal gas as research objects,nonthermal plasma(NTP)catalytic technology was used to investigate the degradation effect of operating condition parameters on mixed pollutants in mixed flue gas condition,and to explore the synergistic degradation of Hg0and TCB(1,2,3-trichlorobenzene,TCB)under mixed flue gas conditions.The research results showed that the conversion efficiency of mercury and TCB increased with the additional output of voltage,and decreased with the increase of the gas flow rate.Under optimal reaction conditions:voltage=17 k V,frequency=300 Hz,gas flow rate=21 min^(-1),the conversion efficiency of Hg^(0)and TCB reached the highest 91.4%and 84.98%,respectively.In the NTP catalytic system,active free radicals played an important role in the synergistic conversion of mercury and TCB,which have a competitive effect,to make the conversion efficiency of mixed pollutants lower than a single substance.In the mixed flue gas condition,the mixed gas has an inhibitory effect on the synergistic conversion of mercury and TCB.Kinetic modeling of NTP catalytic synergistic reaction was established.Under three conditions of TCB,mercury and TCB,mixed simulated flue gas,the NTP catalytic technology showed a quasi-firstorder kinetic reaction for the degradation of TCB.According to the synergistic effect of NTP and composites,the transformation and degradation of TCB mainly included two processes:TCB and ring opening,and Hg^(0)was finally oxidized to Hg^(2+).
基金supported by the National Key R&D Program of China(2019YFC1510305)the National Natural Science Foundation of China(Grant Nos.41705119 and 41575131)+2 种基金Baojun CHEN also acknowledges support from the CMA Key Innovation Team(CMA2022ZD10)Qiujuan FENG was supported by the General Project of Natural Science Research in Shanxi Province(20210302123358)the Key Projects of Shanxi Meteorological Bureau(SXKZDDW20217104).
文摘To evaluate the ability of the Predicted Particle Properties(P3)scheme in the Weather Research and Forecasting(WRF)model,we simulated a stratiform rainfall event over northern China on 22 May 2017.WRF simulations with two P3 versions,P3-nc and P3-2ice,were evaluated against rain gauge,radar,and aircraft observations.A series of sensitivity experiments were conducted with different collection efficiencies between ice and cloud droplets.The comparison of the precipitation evolution between P3-nc and P3-2ice suggested that both P3 versions overpredicted surface precipitation along the Taihang Mountains but underpredicted precipitation in the localized region on the leeward side.P3-2ice had slightly lower peak precipitation rates and smaller total precipitation amounts than P3-nc,which were closer to the observations.P3-2ice also more realistically reproduced the overall reflectivity structures than P3-nc.A comparison of ice concentrations with observations indicated that P3-nc underestimated aggregation,whereas P3-2ice produced more active aggregation from the self-collection of ice and ice-ice collisions between categories.Efficient aggregation in P3-2ice resulted in lower ice concentrations at heights between 4 and 6 km,which was closer to the observations.In this case,the total precipitation and precipitation pattern were not sensitive to riming.Riming was important in reproducing the location and strength of the embedded convective region through its impact on ice mass flux above the melting level.
文摘Post-processing correction is an effective way to improve the model forecasting result. Especially, the machine learning methods have played increasingly important roles in recent years. Taking the meteorological observational data in a period of two years as the reference, the maximum and minimum temperature predictions of Shenyang station from the European Center for Medium-Range Weather Forecasts (ECMWF) and national intelligent grid forecasts are objectively corrected by using wavelet analysis, sliding training and other technologies. The evaluation results show that the sliding training time window of the maximum temperature is smaller than that of the minimum temperature, and their difference is the largest in August, with a difference of 2.6 days. The objective correction product of maximum temperature shows a good performance in spring, while that of minimum temperature performs well throughout the whole year, with an accuracy improvement of 97% to 186%. The correction effect in the central plains is better than in the regions with complex terrain. As for the national intelligent grid forecasts, the objective correction products have shown positive skills in predicting the maximum temperatures in spring (the skill-score reaches 0.59) and in predicting the minimum temperature at most times of the year (the skill-score reaches 0.68).
基金funded by the National Key R&D Program of China(2022YFB4101702)the National Natural Science Foundation of China(52106072 and 52225003)the Fundamental Research Funds for Central Universities(2019JQ03015)。
文摘Carbon capture,utilization and storage(CCUS) is widely recognized as a vital strategy for mitigating the impact of human induced climate change.Among various CO_(2) adsorbents,intermediate-temperature solid adsorbents have garnered significant attention due to their potential applications in hydrogen utilization,specifically in the water gas shift,steam reforming and gasification processes.These processes are crucial for achieving carbon neutrality.While laboratory-level studies have showcased the high adsorption capacity of these materials via various synthesis and modification methods,their practical application in complex industrial environments remains challenging,impeding the commercialization process.This review aims to critically summarize the recent research progress made in intermediatetemperature(200-400℃) solid CO_(2) adsorbents,particularly focusing on indicators such as cyclability,gas selectivity,and formability,which play vital roles in industrial application scenarios.Additionally,we provide an overview of laboratory-level advanced technologies specifically tailored for industrial applications.Furthermore,we highlight several industrial-ready advanced technologies that can pave the way for overcoming the challenges associated with large-scale implementation.The insights provided by this review aim to assist researchers in identifying the most relevant research directions for industrial applications.By promoting advances in the application of solid adsorbents,we strive to facilitate the ultimate goal of achieving carbon neutrality.
基金supported by the grants of the National Natural Science Foundation of China(40901147, 31070399, and 41071171)the International Cooperation Project of Heilongjiang Province,China (WB09B105)
文摘Human activities have altered weather patterns by causing an increase in greenhouse gas. The effects of climate change have been studied, including effects on some ecosystems throughout the world. There are many studies on changes in the soil due to climate change, but much of them did not extend their research to soil enzyme that integrates information on soil microbial status and soil physical-chemical conditions. Meanwhile, there are lots of experimental fields established to study effects of long-term fertilization on soil enzyme activities, but many did not compare the difference of soil enzyme activities and did not analyze the effect of climatic factors on soil enzyme activities with long-term fertilization under different hydrothermal conditions. In this study, we compared soil enzyme activities of three long-fertilization stations which had different hydrothermal conditions in Northeast China, and analyzed the relationship of hydrothermal condition, soil chemical properties with soil enzyme activities. Hydrothermal conditions (annual temperature and total rainfall) decreased in order of Gongzhuling (Jilin Province, China ) > Harbin (Heilongjiang Province, China) > Heihe (Heilongjiang Province, China) over the course of the long-term fertilization experiment. Sunshine hours showed the longest in Gongzhuling, the second in Heihe, and the last in Harbin. However, the order of soil enzymes was not in agreement with hydrothermal conditions. Overall, the order of soil enzymes for the same treatment among three stations was consistent in 2008 with in 2009. Correlation analysis demonstrated that different soil enzymes achieved the different affected levels by climatic factors under different fertilization treatments. Urease activity showed a significant relationship with sunshine hours in no fertilizer (CK) treatment (R=-0.91, P<0.01) and relative humidity in mineral fertilizers plus manure (MNPK) treatment (R=0.82, P<0.05). Phosphatase activity exhibited a negative correlation with annual mean temperature, annual mean maximum temperature and annual mean minimum temperature, and their correlation coefficients were separately -0.83, -0.79, and -0.83 at P<0.05 in CK treatment. Invertase activity was highly and positively correlated with sunshine hours in CK treatment (R=0.94, P<0.01). Catalase activity showed significant negative correlations with minimum relative humidity in CK treatment (R=-0.81, P<0.05), and positive correlations with sunshine hours in M treatment (R=0.83, P<0.05). There were no climatic factors which strongly affected on dehydrogenase in all treatments. Soil enzyme activities were closely related to the soil chemical properties. Soil urease activity was positively correlated with available P (P<0.05). With exception of correlation between invertase and total P at P<0.05, phosphase, invertase, catalase, and dehydrogenase showed significant positive correlations with soil chemical properties (P<0.01). It was a comprehensive process that biologic and abiotic factors were effect on soil enzyme activities under different fertilization treatments. To sum up, the variation of hydrothermal conditions in different climate zones and soil chemical properties affect integrally metabolic activity and metabolic finger print of microbial communities in black soil.
基金the Public Research Institute Fun-damental Research Foundation of the Institute of Atmospheric Environment of ChinaChina Meteororlgical Administration(No.2011IAE-CMA01)+1 种基金National Natural Science Foundation of China(No.41171199)the Special Climate Change Research Program Foundation of China Meteororlgical Administration(No.062700s010c01)for providing supports
文摘This paper reviews the studies and research on climate change impacts on the forest ecosystems in Northeast China.The results show that in the context of global and regional warming,the growing season of coniferous forests has been increasing at an average rate of 3.9 d per decade.Regional warming favors the growth of temperate broad-leaved forests and has a detrimental efect on the growth of boreal coniferous forests.Over the past hundred years,the forest edge of the cool temperate zone in the southern Daxing’anling region has retreated 140 km northward.From 1896 to 1986,the northern boundary of broad-leaved forests in Heilongjiang province has extended northwestward about 290 km.Future climatic changes(until 2060)may lead to the northern deciduous needle forests moving out of China’s territory altogether.The occurrence cycles of pests and diseases have shortened;their distribution ranges have expanded.The life cycle of tent caterpillars(Malacosoma neustria testacea Motschulsky)has shortened from 14–15 years in the past to8–10 years now.The pine caterpillar(Dendrolimus tabulaeformis Tsai et Liu),which has spread within western Liaoning province and the nearby areas,can now be found in the north and west.Lightning fires in the Daxing’anling region have significantly increased since 1987,and August has become the month when lightning fires occur most frequently.Overall,the net primary productivity(NPP)of forest in Northeast China has increased.The NPP in 1981 was around 0.27 Pg C,and increased to approximately 0.40 Pg C in 2002.With the current climate,the broad-leaved Korean pine forest ecosystem acts as a carbon sink,with a carbon sink capacity of 2.7 Mg C hm 2.Although the carbon sink capacity of the forest ecosystems in Northeast China has been weakened since 2003,the total carbon absorption will still increase.The forest ecosystems in Northeast China are likely to remain a significant carbon sink,and will play a positive role in the mitigation of climate change.
基金Under the auspices of National Key Research and Development Program of China(No.2017YFC0212301,2016YFC0203304)Basic Research Funds of Central Public Welfare Research Institutes(No.2018SYIAEZD4)+3 种基金Program of Liaoning Meteorological Office(No.201904,D201603)Key Program of National Natural Science Foundation of China(No.41730647)Program of Laboratory of Atmospheric Chemistry,China Meteorological Administration(No.2017B02)Key Program of Natural Science Foundation of Liaoning Province(No.20170520359)
文摘Characteristics of air pollution in Northeast China(NEC) received less research attention in the past comparing to other heavily polluted regions in China.Spatiotemporal variations of six criteria air pollutants(PM10, PM2.5, SO2, NO2, O3 and CO) in Central Liaoning Urban Agglomeration(CLUA) and Harbin-Changchun Urban Agglomeration(HCUA) in NEC Plain were analyzed in this study based on three-year hourly observations of air pollutants and meteorological variables from 2015 to 2017.The results indicated that the annual mean concentrations of air pollutants are generally higher in the middle and southern regions in NEC Plain and lower in the northern region.Megacities such as Shenyang, Harbin and Changchun experience severe air pollution, with a three-year averaged air quality index(AQI) larger than 80, far exceeding the daily AQI standard at the first-level of 50 in China.The annual mean PM and SO2 concentrations decrease most significantly in NEC urban agglomerations from 2015 to 2017, followed by CO and NO2, while O3 shows a slight increasing trend.All the six pollutants exhibit obvious seasonal and diurnal variations, and these variations are dictated by local emission and meteorological conditions.PM2.5 and O3 concentrations in NEC urban agglomerations strongly depend on wind conditions.High O3 concentrations at different cities usually occur in presence of strong winds but are independent on wind direction(WD), while high PM2.5 is usually accompanied by weak winds and poor dispersion condition, and sometimes also occur when the northerly or southerly winds are strong.Regional transport of air pollutants between NEC urban agglomerations is common.A severe haze event on November 1–4, 2017 is examined to demonstrate the role of regional transport on pollution.
基金U nder the auspices of A pplication Fund of A griculture Science and Technology Fruits of M inistry of Science andTechnology ofChina (N o.04EFN 217400411)
文摘By using,summer temperature data in 26 stations from 1951 to 2003, the variation characteristics of summer temperature in Northeast China (NET) were analyzed based on the background of climate warming. The results showed that the warming in summer was 0.15℃/10a in Northeast China, which was higher than that on the global, Northern Hemisphere or Northeast Asia scale in the recent 50 years. The responses of NET to global warming were shown in 3 aspects mainly. Firstly, it became warm and the average temperature increased in summer; secondly, the temperature variability increased, which displayed the increase of climatic instability; thirdly, the disaster of low temperature decreased and high temperature damage increased obviously, but the disaster of low temperature still existed in some areas under global warming background, which would be worthy of notice further.
基金This research was jointly supported by the National Natural Science Foundation of China(Grant No.42005037)the Liaoning Provincial Natural Science Foundation Project(PhD Start-up Research Fund 2019-BS-214),the Special Scientific Research Project for the Forecaster(Grant No.CMAYBY2018-018)+2 种基金a Key Technical Project of Liaoning Meteorological Bureau(Grant No.LNGJ201903)the National Key Research and Development Project(Grant No.2018YFC1505601)the Open Foundation Project of the Institute of Atmospheric Environment,China Meteorological Administration(Grant Nos.2020SYIAE08 and 2020SYIAEZD5).
文摘The classification of the Northeast China Cold Vortex(NCCV)activity paths is an important way to analyze its characteristics in detail.Based on the daily precipitation data of the northeastern China(NEC)region,and the atmospheric circulation field and temperature field data of ERA-Interim for every six hours,the NCCV processes during the early summer(June)seasons from 1979 to 2018 were objectively identified.Then,the NCCV processes were classified using a machine learning method(k-means)according to the characteristic parameters of the activity path information.The rationality of the classification results was verified from two aspects,as follows:(1)the atmospheric circulation configuration of the NCCV on various paths;and(2)its influences on the climate conditions in the NEC.The obtained results showed that the activity paths of the NCCV could be divided into four types according to such characteristics as the generation origin,movement direction,and movement velocity of the NCCV.These included the generation-eastward movement type in the east of the Mongolia Plateau(eastward movement type or type A);generation-southeast longdistance movement type in the upstream of the Lena River(southeast long-distance movement type or type B);generationeastward less-movement type near Lake Baikal(eastward less-movement type or type C);and the generation-southward less-movement type in eastern Siberia(southward less-movement type or type D).There were obvious differences observed in the atmospheric circulation configuration and the climate impact of the NCCV on the four above-mentioned types of paths,which indicated that the classification results were reasonable.
基金the National Key Research and Development Program of China(Grant Nos.2019YFC1510300 and 2018YFC1507900)the National Natural Science Foundation of China(Grant Nos.41575131).
文摘The presence of embedded convection in stratiform clouds strongly affects ice microphysical properties and precipitation formation.In situ aircraft measurements,including upward and downward spirals and horizontal penetrations,were performed within both embedded convective cells and stratiform regions of a mixedphase stratiform cloud system on 22 May 2017.Supercooled liquid water measurements,particle size distributions,and particle habits in different cloud regions were discussed with the intent of characterizing the riming process and determining how particle size distributions vary from convective to stratiform regions.Significant amounts of supercooled liquid water,with maxima up to 0.6 g m−3,were observed between−3℃ and−6℃ in the embedded convective cells while the peak liquid water content was generally less than 0.1 g m−3 in the stratiform regions.There are two distinct differences in particle size distributions between convective and stratiform regions.One difference is the significant shift toward larger particles from upper−15℃ to lower−10℃ in the convective region,with the maximum particle dimensions increasing from less than 6000μm to over 1 cm.The particles larger than 1 cm at−10℃ are composed of dendrites and their aggregates.The other difference is the large concentrations of small particles(25–205μm)at temperatures between−3℃ and−5℃ in the convective region,where rimed ice particles and needles coexist.Needle regions are observed from three of the five spirals,but only the cloud conditions within the convective region fit into the Hallett-Mossop criteria.
基金National Key R&D Plan of China(2017YFC0209606,2016YFC0203305)Major Program of National Natural Science Foundation of China(41630422,41801326,41275017)Science and Technology Program of Foshan Meteorological Bureau(201804)
文摘Meteorological conditions,particularly the vertical wind field structure,have a direct influence on the PM2.5 concentrations over the Pearl River Delta(PRD).In October 2012,an exceptional air pollution event occurred in the PRD,and a high concentration of PM2.5 was registered at some stations.During days with PM2.5 air pollution,the wind speed was less than 3 m s-1 at the surface,and the vertical wind field featured a weak wind layer(WWL)with a thickness of approximately 1000 m.The mean atmospheric boundary layer height was less than 500 m during pollution days,but it was greater than 1400 m during non-pollution days.A strong negative correlation was detected between the PM2.5 concentration and the ventilation index(VI).The VI was less than 2000 m2 s-1 during PM2.5 air pollution days.Because of the weak wind,sea-land breezes occurred frequently,the recirculation factor(RF)values were small at a height of 800 m during pollution days,and the zones with the lowest RF values always occurred between the heights of 300 and 600 m.The RF values during PM2.5 pollution days were approximately 0.4 to 0.6 below a height of 800 m,reducing the transportation capacity of the wind field to only 40%to 60%.The RF and wind profile characteristics indicated that sealand breezes were highly important in the accumulation of PM2.5 air pollution in the PRD.The sea breezes may transport pollutants back inland and may result in the peak PM2.5 concentrations at night.
基金supported by the National Natural Science Foundation of China(GrantNos.40905038,40921003,40775020,and40905071)
文摘In this study,the clear sky hourly global and net solar irradiances at the surface determined using SUNFLUX,a simple parameterization scheme,for three stations(Gaize,Naqu,and Lhasa) on the Tibetan Plateau were evaluated against observation data.Our modeled results agree well with observations.The correlation coefficients between modeled and observed values were > 0.99 for all three stations.The relative error of modeled results,in average was < 7%,and the root-mean-square variance was < 27 W m 2.The solar irradiances in the radiation model were slightly overestimated compared with observation data;there were at least two likely causes.First,the radiative effects of aerosols were not included in the radiation model.Second,solar irradiances determined by thermopile pyranometers include a thermal offset error that causes solar radiation to be slightly underestimated.The solar radiation absorbed by the ozone and water vapor was estimated.The results show that monthly mean solar radiation absorbed by the ozone is < 2% of the global solar radiation(< 14 W m 2).Solar radiation absorbed by water vapor is stronger in summer than in winter.The maximum amount of monthly mean solar radiation absorbed by water vapor can be up to 13% of the global solar radiation(95 W m 2).This indicates that water vapor measurements with high precision are very important for precise determination of solar radiation.
基金supported by the grants from National Natural Science Foundation of China(No.42077454)National Research Program for Key Issues in Air Pollution Control(DQGG202126)National Natural Science Foundation of China(No.41605077).
文摘Background:Biogenic volatile organic compounds(BVOCs)play an essential role in tropospheric atmospheric chemical reactions.There are few studies conducted on BVOCs emission of dominant forest species in the Jing-Jin-Ji area of China.Based on the field survey,forest resources data and the measured standard emission factors,the Guenther model developed in 1993(G93)was applied in this paper to estimate the emission of BVOCs from several dominant forest species(Platycladus orientalis,Quercus variabilis,Betula platyphylla,Populus tomentosa,Pinus tabuliformis,Robinia pseudoacacia,Ulmus pumila,Salix babylonica and Larix gmelinii)in the Jing-Jin-Ji area in 2017.Then the spatiotemporal emission characteristics and atmospheric chemical reactivity of these species were extensively evaluated.Results:The results showed that the total annual BVOCs emission was estimated to be 70.8 Gg C·year^(−1),consisting 40.5%(28.7 Gg C·year^(−1))of isoprene,36.0%(25.5 Gg C·year^(−1))of monoterpenes and 23.4%(16.6 Gg C·year^(−1))of other VOCs.The emissions from Platycladus orientalis,Quercus variabilis,Populus tomentosa and Pinus tabulaeformis contributed 56.1%,41.2%,36.0% and 31.1%,respectively.The total BVOCs emission from the Jing-Jin-Ji area accounted for 61.9% and 1.8%in summer and winter,respectively.Up to 28.8% of emission was detected from Chengde followed by Beijing with 24.9%,that mainly distributed in the Taihang Mountains and the Yanshan Mountains.Additionally,the Robinia pseudoacacia,Populus tomentosa,Quercus variabilis,and Pinus tabulaeformis contributed mainly to BVOCs reaction activity.Conclusions:The BVOCs emission peaked in summer(June,July,and August)and bottomed out in winter(December,January,and February).Chengde contributed the most,followed by Beijing.Platycladus orientalis,Quercus variabilis,Populus tomentosa,Pinus tabulaeformis and Robinia pseudoacacia represent the primary contributors to BVOCs emission and atmospheric reactivity,hence the planting of these species should be reduced.
基金supported by the National Key Research and Development Program Pilot Projects of China(2016YFA0601901)the National Science Fund for Distinguished Young Scholars(41825011)the National Natural Science Foundation of China(42030608,41590874,and 41941011)。
文摘The optical and microphysical properties of aerosols remain one of the greatest uncertainties associated with evaluating the climate forcing attributed to aerosols.Although the trends in aerosol optical depth(AOD)at global and regional scales have been widely examined,little attention has been paid to the trends in type-dependent AODs related to aerosol particle properties.Here,using the aerosol optical component dataset from the Multi-angle Imaging SpectroRadiometer(MISR)instrument,we investigate decadal-scale trends in total aerosol loading as well as AODs for five aerosol components by particle size and morphology during 2003–2018 over land.Relationships between the total AOD(TAOD)trends and type-dependent AOD changes were examined,and the relative contribution of each type-dependent AOD to the overall TAOD trends was quantified.By dividing the TAOD values into four different aerosol pollution levels(APLs)with splits at 0.15,0.40,and 0.80,we further explored the relationships between TAOD changes and interannual variations in the frequency-of-occurrences(FoOs)of these APLs.Long-term trends in FoOs in the different APLs show that there was a significant improvement in air quality between 2003 and 2018 in most land areas,except South Asia,corresponding to a shift from lightly polluted to clean conditions.However,the effects of different APLs on TAOD changes are regionally dependent and their extent of correlation varied spatially.Moreover,we observed that the annual mean TAOD has decreased by 0.47%.a^(-1)over land since 2003(P<0.05).This significant reduction was mainly attributed to the continued reduction in small-sized(<0.7 mm diameter)AOD(SAOD)(-0.74%.a^(-1))and spherical AOD(SPAOD)(-0.46%.a^(-1)).Statistical analysis shows that SAOD and SPAOD respectively accounted for 57.5%and 89.6%of the TAOD,but contributed 82.6%and 90.4%of the trend in TAOD.Our study suggests that small-sized and spherical aerosols composed of sulfate,organic matter,and black carbon play a dominant role in determining interannual variability in land TAOD.
基金supported by the joint research projects entitled “Observing and Modelling Study on Spatial and Temporal Variation of Radiation Budget and PAR in Regional Scale” and “Evaluation on Detailed Agro-climatic Potential Productivity and Effects of Climate Change in Northeast China” (Grant No.CCSF201313)
文摘SUNFLUX is a fast parameterization scheme for determination of the solar radiation at the Earth's surface.In this paper,SUNFLUX is further modified in the treatment of aerosols.A new aerosol parameterization scheme is developed for five aerosol species.Observational data from Baseline Surface Radiation Network(BSRN),Surface Radiation Budget Network(SURFRAD) and Aerosol Robotic Network(AERONET) stations are used to evaluate the accuracy of the original and modified SUNFLUX schemes.General meteorological data are available at SURFRAD stations,but not at BSRN stations.Therefore,the total precipitable water content and aerosol data are obtained from AERONET stations.Fourteen stations are selected from both BSRN and AERONET.Cloud fraction data from MODIS are further used to screen the cloud.Ten-year average aerosol mixing ratios simulated by the CAM-chem system are used to calculate the fractions of aerosol optical depth for each aerosol species,and these fractions are further used to convert the observed total aerosol optical depth into the components of individual species for use in the evaluations.The proper treatment of multiple aerosol types in the model is discussed.The evaluation results using SUNFLUX with the new aerosol scheme,in terms of the BSRN dataset,are better than those using the original aerosol scheme under clear-sky conditions.However,the results using the SURFRAD dataset are slightly worse,attributable to the differences in the input water vapor and aerosol optical depth.Sensitivity tests are conducted to investigate the error response of the SUNFLUX scheme to the errors in the input variables.
基金funded by the National Natural Science Foundation of China (grant no. 41705011, 91837310)the National Key R&D Program of China (2018YFC1506803, 2018YFC1507302, 2018YFC1507200)the Second Tibetan Plateau Scientific Expedition and Research (STEP) program (Grant No. 2019QZKK0104)。
文摘This study investigates diurnal variations of precipitation during May–August, 1998–2012, over the steep slopes of the Himalayas and adjacent regions(flat Gangetic Plains–FGP, foothills of the Himalayas–FHH, the steep slope of the southern Himalayas–SSSH, and the Himalayas-Tibetan Plateau tableland–HTPT). Diurnal variations are analyzed at the pixel level utilizing collocated TRMM precipitation radar and visible infrared data. The results indicate that rain parameters(including rain frequency, rain rate, and storm top altitude) are predominantly characterized by afternoon maxima and morning minima at HTPT and FGP, whereas, maximum rain parameters at FHH typically occur in the early morning. Rain parameters at SSSH are characterized by double peaks;one in the afternoon and one at midnight. Over HTPT and FGP,convective activity is strongest in the afternoon with the thickest crystallization layer. Over FHH, the vertical structure of precipitation develops most vigorously in the early morning when the most intense collision and growth of precipitation particles occurs. Over SSSH, moist convection is stronger in the afternoon and at midnight with strong mixing of ice and water particles. The results of harmonic analysis show that rain bands move southward from lower elevation of SSSH to FHH with apparent southward propagation of the harmonic phase from midnight to early morning. Moreover, the strongest diurnal harmonic is located at HTPT, having a diurnal harmonic percentage variance of up to 90%. Large-scale atmospheric circulation patterns exhibit obvious diurnal variability and correspond well to the distribution of precipitation.
基金Supported by Open Foundation Project of Shenyang Institute of Atmospheric Environment,China Meteorological Administration(2016SYIAE14)Natural Science Foundation of Anhui Province,China(1708085QD89)National Natural Science Foundation of China(41805080)
文摘The paper discusses the core parameters of the 3 D and 4 D variational merging based on L1 norm regularization,namely optimization characteristic correlation length of background error covariance matrix and regularization parameter. Classical 3 D/4 D variational merging is based on the theory that error follows Gaussian distribution. It involves the solution of the objective functional gradient in minimization iteration,which requires the data to have continuity and differentiability. Classic 3 D/4 D-dimensional variational merging method was extended,and L1 norm was used as the constraint coupling to the classical variational merged model. Experiment was carried out by using linear advection-diffusion equation as four-dimensional prediction model,and parameter optimization of this method is discussed. Considering the strong temporal and spatial variation of water vapor,this method is further applied to the precipitable water vapor( PWV) merging by calculating reanalysis data and GNSS retrieval.Parameters were adjusted gradually to analyze the influence of background field on the merging result,and the experiment results show that the mathematical algorithm adopted in this paper is feasible.
基金Supported by the Science Technology Foundation of State Grid Corporation of ChinaNatural Science Foundation of Anhui Province(1708085QD89)+1 种基金Huaihe River Basin Meteorological Open Research Fund(HRM201407)Shenyang Institute of Atmospheric Environment of China Meteorological Administration Open Fund Project(2016SYIAE14)
文摘Different from other domestic and foreign research in which the optimum interpolation(OI) merging algorithm is commonly used,this paper constructs the non-Gaussian model for generalized variational precipitation data merging research based on the non-Gaussianity of precipitation data. For CMORPH data correction,the probability density function( PDF) matching method is adopted,during which the GAMMA function fitting is utilized,and the generalized variational merging based on non-Gaussian model is used to merge corrected CMORPH precipitation data and station ground observation precipitation data. Meanwhile,we carry out an experiment on CMORPH precipitation data correction and the merging of multisource precipitation data based on non-Gaussian model. By measuring the structural similarity between the merged field and the reference field,we get a merging method that can better retain useful " outliers" which represent weather phenomena. The experimental results accord with our expectations.
基金supported by National Key Research and Development Project of China(No.2019YFC1805503)National Engineering Laboratory for Mobile Source Emission Control Technology(No.NELMS2019A13)+1 种基金the Open Project Program of the State Key Laboratory of Petroleum Pollution Control(No.PPC2019013)Major Science and Technology Projects of Shanxi Province(No.20181102017)。
文摘The presented work reports the selective catalytic reduction(SCR)of NO_(x) assisted by dielectric barrier discharge plasma via simulating marine diesel engine exhaust,and the experimental results demonstrate that the low-temperature activity of NH_(3)-SCR assisted by non-thermal plasma is enhanced significantly,particularly in the presence of a C_(3)H_(6) additive.Simultaneously,CeMnZrO_(x)@TiO_(2) exhibits strong tolerance to SO_(2) poisoning and superior catalytic stability.It is worthwhile to explore a new approach to remove NO_(x) from marine diesel engine exhaust,which is of vital significance for both academic research and practical applications.
