Objective:To construct a nomogram based on the albumin-bilirubin(ALBI)grade to provide prognostic value for hepatitis C virus(HCV)-related hepatocellular carcinoma(HCC)patients who underwent ultrasound-guided percutan...Objective:To construct a nomogram based on the albumin-bilirubin(ALBI)grade to provide prognostic value for hepatitis C virus(HCV)-related hepatocellular carcinoma(HCC)patients who underwent ultrasound-guided percutaneous microwave ablation(US-PMWA).Methods:From April 2005 to January 2018,183 treatment-naIve patients with 251 HCV-related HCCs according to the Milan criteria received US-PMWA subsequently.The overall survival(OS)and recurrence-free survival(RFS)were compared between groups classified by ALBI grade.Cox proportional hazard regression model based on risk factors for survival and recurrence was used to construct the nomogram.Results:The cumulative OS rates at 1-,3-,5-and 10-year were 97.7%,73.6%,54.5%and 34.5%,respectively.Stratified according to ALBI grade,the 1-,3-,and 5-year OS in the ALBI grade 1 group and grade 2 group were 99.2%,92.4%,77.9% and 97.7%,52.3%,38.6%,respectively,with significant statistical difference(P<0.001).No significant statistical difference was detected in the1-,3-,and 5-year RFS rates in the ALBI grade 1 group and grade 2 group(P=0.220).The major complication rate was 1.6%.Multivariate analysis results showed age,α-fetoprotein level,tumor number,platelet count,location,Child-Turcotte-Pugh(CTP)and ALBI grade were associated with OS,which generated the nomograms.Internal validation with 1000 bootstrapped sample sets had good concordance index of 0.769(95%CI 0.699-0.839)in OS.Conclusions:This nomogram based on ALBI grade was a visualization risk model,which could provide personalized prediction of long-term outcomes for HCV-related HCC patients after US-PMWA.展开更多
Objective:To explore the association between cholecystectomy and the prognostic outcomes of patients with hepatocellular carcinoma(H CC)who underwent microwave ablation(MWA).Methods:Patients with HCC(«=921)who un...Objective:To explore the association between cholecystectomy and the prognostic outcomes of patients with hepatocellular carcinoma(H CC)who underwent microwave ablation(MWA).Methods:Patients with HCC(«=921)who underwent MWA were included and divided into cholecystectomy(n=114)and non-cholecystectomy groups(n=807).After propensity score matching(PSM)at a 1:2 ratio,overall survival(OS)and disease-free survival(DFS)rates were analyzed to compare prognostic outcomes between the cholecystectomy(«=114)and non-cholecystectomy groups(n=228).Univariate and multivariate Cox analyses were performed to assess potential risk factors for OS and DFS.Major complications were also compared between the groups.Results:After matching,no significant differences between groups were observed in baseline characteristics.The 1-,3-,and 5-year OS rates were 96.5%,82.1%,and 67.1%in the cholecystectomy group,and 97.4%,85.2%,and 74.4%in the non-cholecystectomy group(P=0.396);the 1-,3-,and 5-year DFS rates were 58.4%,34.5%,and 26.6%in the cholecystectomy group,and 73.6%,44.7%,and 32.2%in the non-cholecystectomy group(P=0.026),respectively.The intrahepatic distant recurrence rate in the cholecystectomy group was significantly higher than that in the non-cholecystectomy group(P=0.026),and the local tumor recurrence and extrahepatic recurrence rates did not significantly differ between the groups(P=0.609 and P=0.879).Multivariate analysis revealed that cholecystectomy(HR=1.364,95%Cl 1.023-1.819,P=0.035),number of tumors(2 vs.1:HR=2.744,95%Cl 1.925-3.912,P<0.001;3 vs.1:HR=3.411,95%Cl 2.021-5.759,P<0.001),and y-GT levels(HR=1.003,95%Cl 1.000-1.006,P<0.024)were independent risk factors for DFS.The best y-GT level cut-off value for predicting median DFS was 39.6 U/L(area under the curve=0.600,P<0.05).A positive correlation was observed between cholecystectomy and y-GT level(r=0.108,95%Cl-0.001-0.214,P=0.047).Subgroup analysis showed that the DFS rates were significantly higher in the non-cholecystectomy group than the cholecystectomy group when Y-GT>39.6 U/L(i3=0.044).The 5-,10-,15-,20-,and 25-year recurrence rates from the time of cholecystectomy were 2.63%,21.93%,42.11%,58.77%,and 65.79%,respectively.A significant positive correlation was observed between cholecystectomy and the time from cholecystectomy to recurrence(r=0.205,95%Cl 0.016-0.379,P=0.029).There were no significant differences in complications between groups(P=0.685).Conclusions:Patients with HCC who underwent cholecystectomy were more likely to develop intrahepatic distant recurrence after MWA,an outcome probably associated with increased y-GT levels.Moreover,the recurrence rates increased with time.展开更多
A discrepancy remains in the first two leading empirical orthogonal function(EOF) modes of the tropical Pacific sea surface temperature anomaly(SSTA) based on observations since the 1980s. The EOF1 mode, representing ...A discrepancy remains in the first two leading empirical orthogonal function(EOF) modes of the tropical Pacific sea surface temperature anomaly(SSTA) based on observations since the 1980s. The EOF1 mode, representing the El Ni?o-Southern Oscillation(ENSO), is a robust result. However, the EOF2 features either El Ni?o Modoki(EM) or ENSO evolution during different periods, which is probably associated with the impacts of global warming. The underlying question is what the EOF2 mode of the tropical Pacific would be without global warming. Using the CMIP5 preindustrial scenario to exclude the influence of global warming, we find that the EOF1 mode of the tropical Pacific SSTA represents ENSO and that the EOF2 mode is not EM. According to the lead–lag correlation between the ENSO and EOF2 modes, the linkage between these two modes is as follows: …El Ni?o → EOF2 → La Ni?a →–EOF2 → El Ni?o…. By analyzing the evolution of sea surface temperature, surface wind, and subsurface ocean temperature anomalies, we find the mechanism linking the ENSO and EOF2 modes is the air–sea interaction associated with the ENSO cycle. This result suggests that the EOF2 mode represents an aspect of ENSO evolution under preindustrial conditions. Therefore, this study further indicates that the EM is probably due to the influence of global warming.展开更多
Using model results from the first phase of the Pliocene Model Intercomparison Project （PlioMIP） and four experiments with CAM4, the intensified African summer monsoon （ASM） in the mid-Piacenzian and corresponding...Using model results from the first phase of the Pliocene Model Intercomparison Project （PlioMIP） and four experiments with CAM4, the intensified African summer monsoon （ASM） in the mid-Piacenzian and corresponding mechanisms are analyzed. The results from PlioMIP show that the ASM intensified and summer precipitation increased in North Africa during the mid-Piacenzian, which can be explained by the increased net energy in the atmospheric column above North Africa. Further experiments with CAM4 indicated that the combined changes in the mid-Piacenzian of atmospheric CO2 concentration and SST, as well as the vegetation change, could have substantially increased the net energy in the atmospheric column over North Africa and further intensified the ASM. The experiments also demonstrated that topography change had a weak effect. Overall, the combined changes of atmospheric CO2 concentration and SST were the most important factor that brought about the intensified ASM in the mid-Piacenzian.展开更多
Objective:Thermal ablation poses challenges in the surgical resection(SR)of small hepatocellular carcinoma(HCC),and its therapeutic outcomes for larger lesions remain debated.Methods:This retrospective study evaluated...Objective:Thermal ablation poses challenges in the surgical resection(SR)of small hepatocellular carcinoma(HCC),and its therapeutic outcomes for larger lesions remain debated.Methods:This retrospective study evaluated 729 patients with HCC meeting the Milan criteria,who were treated with curative SR or microwave ablation(MWA)between 2008 and 2014.Overall survival(OS),cancer-specific survival(CSS),disease-free survival(DFS),and local tumor progression(LTP)were compared after propensity score matching(PSM).Co-variates associated with OS,CSS,LTP,and DFS were identified.The risk of death and tumor progression were compared.Results:During the median follow-up of 78.6 months,253 patients were included in each group after PSM.For tumors≤3.0 cm and 3.1–4.0 cm,MWA achieved comparable results in terms of OS,CSS,DFS,and LTP.For tumors 4.1–5.0 cm,MWA had lower OS,CSS,and DFS rates(all P<0.05)than SR.Higher LTP rates were observed in the MWA group for tumors 4.1–5.0 cm,although the difference was not significant(P=0.18).Complication rates(P=0.41)were similar,but MWA led to less estimated blood loss(P<0.01)and shorter postoperative hospitalization times(P<0.01).Conclusions:MWA achieved comparable long-term oncologic outcomes with SR for≤4 cm HCC,with lower complication rates and faster recovery.展开更多
We used simultaneous measurements of surface PM_（2.5） concentration and vertical profiles of aerosol concentration,temperature, and humidity, together with regional air quality model simulations, to study an episode...We used simultaneous measurements of surface PM_（2.5） concentration and vertical profiles of aerosol concentration,temperature, and humidity, together with regional air quality model simulations, to study an episode of aerosol pollution in Beijing from 15 to 19 November 2016. The potential effects of easterly and southerly winds on the surface concentrations and vertical profiles of the PM_（2.5） pollution were investigated. Favorable easterly winds produced strong upward motion and were able to transport the PM_（2.5） pollution at the surface to the upper levels of the atmosphere. The amount of surface PM_（2.5） pollution transported by the easterly winds was determined by the strength and height of the upward motion produced by the easterly winds and the initial height of the upward wind. A greater amount of PM_（2.5） pollution was transported to upper levels of the atmosphere by upward winds with a lower initial height. The pollutants were diluted by easterly winds from clean ocean air masses. The inversion layer was destroyed by the easterly winds and the surface pollutants and warm air masses were then lifted to the upper levels of the atmosphere, where they re-established a multi-layer inversion. This region of inversion was strengthened by the southerly winds, increasing the severity of pollution. A vortex was produced by southerly winds that led to the convergence of air along the Taihang Mountains. Pollutants were transported from southern–central Hebei Province to Beijing in the boundary layer. Warm advection associated with the southerly winds intensified the inversion produced by the easterly winds and a more stable boundary layer was formed. The layer with high PM_（2.5） concentration became dee-per with persistent southerly winds of a certain depth. The polluted air masses then rose over the northern Taihang Mountains to the northern mountainous regions of Hebei Province.展开更多
Reliable national estimates of CH_4 emissions from natural wetlands depend on model validation based on site observations.We therefore evaluated the performance of the CH_4 MODwetlandmodel in simulating CH_4 emissions...Reliable national estimates of CH_4 emissions from natural wetlands depend on model validation based on site observations.We therefore evaluated the performance of the CH_4 MODwetlandmodel in simulating CH_4 emissions from 11 representative wetland sites in five regions of China.Model performance analysis showed that this method effectively simulates differences in the CH_4 fluxes between different sites and regions.The model efficiency for estimating the daily CH_4 fluxes in the northeastern China（NE）,Inner Mongolia and northwestern China（NW）,the North China plain and the Middle-Lower Yangtze Plain（E） and the Qinghai Tibetan Plateau（SW） was 0.51,0.20,0.52 and 0.65,respectively.The efficiency for estimating the annual mean CH_4 fluxes in southern China（S） was 0.99.Systematic negative deviation between the simulated and observed CH_4 emissions existed in all regions,especially in the NW region,which had a mean deviation（RMD） value of-36.7%.On the national scale,the root mean square error（RMSE）,the RMD,the model efficiency（EF）between the simulated and observed seasonal values were 28.7%,-7.8% and 0.93,respectively.The CH_4 emissions showed the highest sensitivity to air temperature in the NE and SW regions,and to water table depth in the E region.Based on the sensitivity analysis,future climate warming and wetting are likely to increase the wetland CH_4 emissions at different levels in all regions of China.展开更多
A comprehensive measurement of planetary boundary layer(PBL)meteorology was conducted at 140 and 280 m on a meteorological tower in Beijing,China,to quantify the effect of aerosols on radiation and its role in PBL dev...A comprehensive measurement of planetary boundary layer(PBL)meteorology was conducted at 140 and 280 m on a meteorological tower in Beijing,China,to quantify the effect of aerosols on radiation and its role in PBL development.The measured variables included four-component radiation,temperature,sensible heat flux(SH),and turbulent kinetic energy(TKE)at 140 and 280 m,as well as PBL height(PBLH).In this work,a method was developed to quantitatively estimate the effect of aerosols on radiation based on the PBLH and radiation at the two heights(140 and 280 m).The results confirmed that the weakened downward shortwave radiation(DSR)on hazy days could be attributed predominantly to increased aerosols,while for longwave radiation,aerosols only accounted for around onethird of the enhanced downward longwave radiation.The DSR decreased by 55.2 W m^(-2) on hazy days during noontime(1100–1400 local time).The weakened solar radiation decreased SH and TKE by enhancing atmospheric stability,and hence suppressed PBL development.Compared with clean days,the decreasing rates of DSR,SH,TKE,and PBLH were 11.4%,33.6%,73.8%,and 53.4%,respectively.These observations collectively suggest that aerosol radiative forcing on the PBL is exaggerated by a complex chain of interactions among thermodynamic,dynamic,and radiative processes.These findings shed new light on our understanding of the complex relationship between aerosol and the PBL.展开更多
基金supported by the National Key R&D Program of China (Grant No. 2017YFC0112000)the National Natural Science Foundation of China (Grants No. 81627803, 91859201, and 81871374)the State Key Project on Infectious Disease of China (Grant No. 2018ZX10723204)
文摘Objective:To construct a nomogram based on the albumin-bilirubin(ALBI)grade to provide prognostic value for hepatitis C virus(HCV)-related hepatocellular carcinoma(HCC)patients who underwent ultrasound-guided percutaneous microwave ablation(US-PMWA).Methods:From April 2005 to January 2018,183 treatment-naIve patients with 251 HCV-related HCCs according to the Milan criteria received US-PMWA subsequently.The overall survival(OS)and recurrence-free survival(RFS)were compared between groups classified by ALBI grade.Cox proportional hazard regression model based on risk factors for survival and recurrence was used to construct the nomogram.Results:The cumulative OS rates at 1-,3-,5-and 10-year were 97.7%,73.6%,54.5%and 34.5%,respectively.Stratified according to ALBI grade,the 1-,3-,and 5-year OS in the ALBI grade 1 group and grade 2 group were 99.2%,92.4%,77.9% and 97.7%,52.3%,38.6%,respectively,with significant statistical difference(P<0.001).No significant statistical difference was detected in the1-,3-,and 5-year RFS rates in the ALBI grade 1 group and grade 2 group(P=0.220).The major complication rate was 1.6%.Multivariate analysis results showed age,α-fetoprotein level,tumor number,platelet count,location,Child-Turcotte-Pugh(CTP)and ALBI grade were associated with OS,which generated the nomograms.Internal validation with 1000 bootstrapped sample sets had good concordance index of 0.769(95%CI 0.699-0.839)in OS.Conclusions:This nomogram based on ALBI grade was a visualization risk model,which could provide personalized prediction of long-term outcomes for HCV-related HCC patients after US-PMWA.
基金the National Key R&D Program of China(Grant No.2017 YFC0112000)the National Natural Science Foundation of China(Grant Nos.81627803 and 91859201).
文摘Objective:To explore the association between cholecystectomy and the prognostic outcomes of patients with hepatocellular carcinoma(H CC)who underwent microwave ablation(MWA).Methods:Patients with HCC(«=921)who underwent MWA were included and divided into cholecystectomy(n=114)and non-cholecystectomy groups(n=807).After propensity score matching(PSM)at a 1:2 ratio,overall survival(OS)and disease-free survival(DFS)rates were analyzed to compare prognostic outcomes between the cholecystectomy(«=114)and non-cholecystectomy groups(n=228).Univariate and multivariate Cox analyses were performed to assess potential risk factors for OS and DFS.Major complications were also compared between the groups.Results:After matching,no significant differences between groups were observed in baseline characteristics.The 1-,3-,and 5-year OS rates were 96.5%,82.1%,and 67.1%in the cholecystectomy group,and 97.4%,85.2%,and 74.4%in the non-cholecystectomy group(P=0.396);the 1-,3-,and 5-year DFS rates were 58.4%,34.5%,and 26.6%in the cholecystectomy group,and 73.6%,44.7%,and 32.2%in the non-cholecystectomy group(P=0.026),respectively.The intrahepatic distant recurrence rate in the cholecystectomy group was significantly higher than that in the non-cholecystectomy group(P=0.026),and the local tumor recurrence and extrahepatic recurrence rates did not significantly differ between the groups(P=0.609 and P=0.879).Multivariate analysis revealed that cholecystectomy(HR=1.364,95%Cl 1.023-1.819,P=0.035),number of tumors(2 vs.1:HR=2.744,95%Cl 1.925-3.912,P<0.001;3 vs.1:HR=3.411,95%Cl 2.021-5.759,P<0.001),and y-GT levels(HR=1.003,95%Cl 1.000-1.006,P<0.024)were independent risk factors for DFS.The best y-GT level cut-off value for predicting median DFS was 39.6 U/L(area under the curve=0.600,P<0.05).A positive correlation was observed between cholecystectomy and y-GT level(r=0.108,95%Cl-0.001-0.214,P=0.047).Subgroup analysis showed that the DFS rates were significantly higher in the non-cholecystectomy group than the cholecystectomy group when Y-GT>39.6 U/L(i3=0.044).The 5-,10-,15-,20-,and 25-year recurrence rates from the time of cholecystectomy were 2.63%,21.93%,42.11%,58.77%,and 65.79%,respectively.A significant positive correlation was observed between cholecystectomy and the time from cholecystectomy to recurrence(r=0.205,95%Cl 0.016-0.379,P=0.029).There were no significant differences in complications between groups(P=0.685).Conclusions:Patients with HCC who underwent cholecystectomy were more likely to develop intrahepatic distant recurrence after MWA,an outcome probably associated with increased y-GT levels.Moreover,the recurrence rates increased with time.
基金supported by the National Key Research and Development Program on Monitoring,Early Warning and Prevention of Major Natural Disasters(2018YFC1506006)the National Natural Science Foundation of China Project(41805054,41875108,41805041,41705065)the Scientific Research Fund of the Chengdu University of Information Technology(KYTZ201724,KYTZ201602,KYTZ201727)
文摘A discrepancy remains in the first two leading empirical orthogonal function(EOF) modes of the tropical Pacific sea surface temperature anomaly(SSTA) based on observations since the 1980s. The EOF1 mode, representing the El Ni?o-Southern Oscillation(ENSO), is a robust result. However, the EOF2 features either El Ni?o Modoki(EM) or ENSO evolution during different periods, which is probably associated with the impacts of global warming. The underlying question is what the EOF2 mode of the tropical Pacific would be without global warming. Using the CMIP5 preindustrial scenario to exclude the influence of global warming, we find that the EOF1 mode of the tropical Pacific SSTA represents ENSO and that the EOF2 mode is not EM. According to the lead–lag correlation between the ENSO and EOF2 modes, the linkage between these two modes is as follows: …El Ni?o → EOF2 → La Ni?a →–EOF2 → El Ni?o…. By analyzing the evolution of sea surface temperature, surface wind, and subsurface ocean temperature anomalies, we find the mechanism linking the ENSO and EOF2 modes is the air–sea interaction associated with the ENSO cycle. This result suggests that the EOF2 mode represents an aspect of ENSO evolution under preindustrial conditions. Therefore, this study further indicates that the EM is probably due to the influence of global warming.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB03020602)the National Natural Science Foundation of China (Grant Nos. 41175072, 41305073, 41402158 and 41472160)
文摘Using model results from the first phase of the Pliocene Model Intercomparison Project （PlioMIP） and four experiments with CAM4, the intensified African summer monsoon （ASM） in the mid-Piacenzian and corresponding mechanisms are analyzed. The results from PlioMIP show that the ASM intensified and summer precipitation increased in North Africa during the mid-Piacenzian, which can be explained by the increased net energy in the atmospheric column above North Africa. Further experiments with CAM4 indicated that the combined changes in the mid-Piacenzian of atmospheric CO2 concentration and SST, as well as the vegetation change, could have substantially increased the net energy in the atmospheric column over North Africa and further intensified the ASM. The experiments also demonstrated that topography change had a weak effect. Overall, the combined changes of atmospheric CO2 concentration and SST were the most important factor that brought about the intensified ASM in the mid-Piacenzian.
基金supported by The National Key R&D Program of Ministry of Science and Technology of China(Grant No.2018ZX10723-204)The National Scientific Foundation Committee of China(Grant Nos.81801722,81971625,82030047,81627803,and 91859201)and The National Scientific Foundation Committee of Beijing(Grant No.JQ18021).
文摘Objective:Thermal ablation poses challenges in the surgical resection(SR)of small hepatocellular carcinoma(HCC),and its therapeutic outcomes for larger lesions remain debated.Methods:This retrospective study evaluated 729 patients with HCC meeting the Milan criteria,who were treated with curative SR or microwave ablation(MWA)between 2008 and 2014.Overall survival(OS),cancer-specific survival(CSS),disease-free survival(DFS),and local tumor progression(LTP)were compared after propensity score matching(PSM).Co-variates associated with OS,CSS,LTP,and DFS were identified.The risk of death and tumor progression were compared.Results:During the median follow-up of 78.6 months,253 patients were included in each group after PSM.For tumors≤3.0 cm and 3.1–4.0 cm,MWA achieved comparable results in terms of OS,CSS,DFS,and LTP.For tumors 4.1–5.0 cm,MWA had lower OS,CSS,and DFS rates(all P<0.05)than SR.Higher LTP rates were observed in the MWA group for tumors 4.1–5.0 cm,although the difference was not significant(P=0.18).Complication rates(P=0.41)were similar,but MWA led to less estimated blood loss(P<0.01)and shorter postoperative hospitalization times(P<0.01).Conclusions:MWA achieved comparable long-term oncologic outcomes with SR for≤4 cm HCC,with lower complication rates and faster recovery.
基金Supported by the National Key Research and Development Program of China(2016YFA0602004)Natural Science Foundation of Beijing(8161004 and 8172051)+1 种基金National Key Technologies R&D Program of China(2014BAC23B01)China Meteorological Administration Special Public Welfare Research Fund(GYHY201206015)
文摘We used simultaneous measurements of surface PM_（2.5） concentration and vertical profiles of aerosol concentration,temperature, and humidity, together with regional air quality model simulations, to study an episode of aerosol pollution in Beijing from 15 to 19 November 2016. The potential effects of easterly and southerly winds on the surface concentrations and vertical profiles of the PM_（2.5） pollution were investigated. Favorable easterly winds produced strong upward motion and were able to transport the PM_（2.5） pollution at the surface to the upper levels of the atmosphere. The amount of surface PM_（2.5） pollution transported by the easterly winds was determined by the strength and height of the upward motion produced by the easterly winds and the initial height of the upward wind. A greater amount of PM_（2.5） pollution was transported to upper levels of the atmosphere by upward winds with a lower initial height. The pollutants were diluted by easterly winds from clean ocean air masses. The inversion layer was destroyed by the easterly winds and the surface pollutants and warm air masses were then lifted to the upper levels of the atmosphere, where they re-established a multi-layer inversion. This region of inversion was strengthened by the southerly winds, increasing the severity of pollution. A vortex was produced by southerly winds that led to the convergence of air along the Taihang Mountains. Pollutants were transported from southern–central Hebei Province to Beijing in the boundary layer. Warm advection associated with the southerly winds intensified the inversion produced by the easterly winds and a more stable boundary layer was formed. The layer with high PM_（2.5） concentration became dee-per with persistent southerly winds of a certain depth. The polluted air masses then rose over the northern Taihang Mountains to the northern mountainous regions of Hebei Province.
基金supported by the Chinese Academy of Sciences(CAS) strategic pilot technology special funds(No.XDA05020204)the National Natural Science Foundation of China(Nos.31000234,41321064 and 41573069)the Climate Change Special Foundation of China Meteorological Administration(No.CCSF201604)
文摘Reliable national estimates of CH_4 emissions from natural wetlands depend on model validation based on site observations.We therefore evaluated the performance of the CH_4 MODwetlandmodel in simulating CH_4 emissions from 11 representative wetland sites in five regions of China.Model performance analysis showed that this method effectively simulates differences in the CH_4 fluxes between different sites and regions.The model efficiency for estimating the daily CH_4 fluxes in the northeastern China（NE）,Inner Mongolia and northwestern China（NW）,the North China plain and the Middle-Lower Yangtze Plain（E） and the Qinghai Tibetan Plateau（SW） was 0.51,0.20,0.52 and 0.65,respectively.The efficiency for estimating the annual mean CH_4 fluxes in southern China（S） was 0.99.Systematic negative deviation between the simulated and observed CH_4 emissions existed in all regions,especially in the NW region,which had a mean deviation（RMD） value of-36.7%.On the national scale,the root mean square error（RMSE）,the RMD,the model efficiency（EF）between the simulated and observed seasonal values were 28.7%,-7.8% and 0.93,respectively.The CH_4 emissions showed the highest sensitivity to air temperature in the NE and SW regions,and to water table depth in the E region.Based on the sensitivity analysis,future climate warming and wetting are likely to increase the wetland CH_4 emissions at different levels in all regions of China.
基金the National Key Research and Development Program of China(2017YFC0209604 and 2018YFF0300101)Beijing Natural Science Foundation(8204062)。
文摘A comprehensive measurement of planetary boundary layer(PBL)meteorology was conducted at 140 and 280 m on a meteorological tower in Beijing,China,to quantify the effect of aerosols on radiation and its role in PBL development.The measured variables included four-component radiation,temperature,sensible heat flux(SH),and turbulent kinetic energy(TKE)at 140 and 280 m,as well as PBL height(PBLH).In this work,a method was developed to quantitatively estimate the effect of aerosols on radiation based on the PBLH and radiation at the two heights(140 and 280 m).The results confirmed that the weakened downward shortwave radiation(DSR)on hazy days could be attributed predominantly to increased aerosols,while for longwave radiation,aerosols only accounted for around onethird of the enhanced downward longwave radiation.The DSR decreased by 55.2 W m^(-2) on hazy days during noontime(1100–1400 local time).The weakened solar radiation decreased SH and TKE by enhancing atmospheric stability,and hence suppressed PBL development.Compared with clean days,the decreasing rates of DSR,SH,TKE,and PBLH were 11.4%,33.6%,73.8%,and 53.4%,respectively.These observations collectively suggest that aerosol radiative forcing on the PBL is exaggerated by a complex chain of interactions among thermodynamic,dynamic,and radiative processes.These findings shed new light on our understanding of the complex relationship between aerosol and the PBL.
