[Objective] The aim was to analyze the changes characteristics of sunshine hours of Dalian City. [Method] Based on the data of sunshine hours of Dalian City during 1951 to 2009 and by dint of linear estimation and acc...[Objective] The aim was to analyze the changes characteristics of sunshine hours of Dalian City. [Method] Based on the data of sunshine hours of Dalian City during 1951 to 2009 and by dint of linear estimation and accumulation anomaly, the change characteristics of decade, annual, seasonal, monthly sunshine hours in Dalian City were analyzed. [Result] The change characteristics of decade, annual, seasonal, monthly sunshine hours in Dalian City were in a decrease trend since recent 59 years. The average sunshine hour in 1950s was the maximum one. Since 21st century, the annual sunshine hour was the lowest one. Annual average sunshine hours were the highest in 1978, and lowest in 2003. There were more sunshine hours before 1989 and later less. Among the four seasons, the sunshine hours in autumn decreased fastest and slowest in spring. The monthly average sunshine hours were the most in May and least in December; the sunshine hours in each month decreased fastest in July. It showed increasing tendency only in March. [Conclusion] The study supplied scientific reference for the reasonable utilization of light energy, agricultural production structure and sustainable development of agricultural economy.展开更多
[Objective] The aim was to study the precipitation changes and agricultural flood and drought degree of crops in Dalian City in recent 60 years. [Method] The monthly precipitation and average temperature data from Apr...[Objective] The aim was to study the precipitation changes and agricultural flood and drought degree of crops in Dalian City in recent 60 years. [Method] The monthly precipitation and average temperature data from April to October during 1951-2010 in Dalian observation station were selected. By dint of linear regression, climate tendency rate and humidity index, the growth changes and agricultural flood and drought degree of crops in recent 60 years in Dalian City were expounded from the aspects of natural precipitation tendency changes and agricultural water satisfaction degree of crops in growth period. [Result] In recent 60 years, the precipitation of crops during growth period in Dalian City had decreasing tendency. The inclination rate was -15.888 m/10 a. Precipitation decreased 95.3 mm in recent 60 years; precipitation increased a little in spring and decreased a lot in summer, then decreased in autumn. The monthly precipitation in each month distributed unevenly. Precipitation in July and August increased, taking account of 53.8% of the total precipitation during the growth period of crops. The K value of humidity index during the growth period of crops in Dalian in recent 60 years was 0.90 in general. It was light drought climate. The humidity index was decreasing. Climate developed toward drought direction; the drought occurrence frequency was 59%. It was mild drought climate in spring and autumn. The climate was generally wet in summer. Seen from the yearly means, besides of July and August, it reached mild drought degree in other months. [Conclusion] The study provided reference for the regional agricultural production, agricultural structure adjustment and drought and flood disaster prevention.展开更多
Air mass is inter-hemispherically redistributed, leading to an interesting phenomenon known as the Inter-Hemispheric Oscillation (IHO). In the present article, the seasonality of the interannual IHO has been examined ...Air mass is inter-hemispherically redistributed, leading to an interesting phenomenon known as the Inter-Hemispheric Oscillation (IHO). In the present article, the seasonality of the interannual IHO has been examined by employing monthly mean reanalyses from NCEP/NCAR, EAR40, and JRA25 for the period of 1958-2006. It is found that the IHO indices as calculated from different reanalyses are generally consistent with each other. A distinct seesaw structure in all four seasons between the northern and southern hemispheres is observed as the IHO signature in both the surface air pressure anomalies (SAPAs) and the leading EOF component of the anomalous zonal mean quantities. When the SAPAs are positive (negative) in the northern hemisphere, they are negative (positive) in the southern hemisphere. Large values of SAPAs are usually observed in mid- and high-latitude areas in all but the solstice seasons. In boreal summer and winter, relatively stronger perturbations of IHO-related SAPA are found in the Asian monsoon region, which shows a large difference from the status in boreal spring and fall. This suggests that seasonal mean monsoon activity is globally linked via air mass redistribution globally on interannual timescales, showing a very interesting linkage between monsoons and the IHO in the global domain. In all seasons, large values of SAPA always exist over the Antarctic and the surrounding regions, implying a close relation with Antarctic oscillations.展开更多
[Objective] The aim was to study the causes of abnormal weather in winter in 2009 and 2010 in Jinzhou. [Method] By dint of regular meteorological data and weather theory, the abnormal weather in winter from 2009 to 20...[Objective] The aim was to study the causes of abnormal weather in winter in 2009 and 2010 in Jinzhou. [Method] By dint of regular meteorological data and weather theory, the abnormal weather in winter from 2009 to 2010 in Jinzhou was expounded so as to find the reasons for abnormal climate in winter in the region. [Result] The main reason for the consecutive low temperature in winter in Jinzhou from 2009 to 2010 was the abnormal development of the Ural Mountains high-pressure ridge and strong horizontal circulation. The frequent cold air activity was the leading reason for the increase of precipitation in Jinzhou in winter; the high trough and low air torrent were the main weather system for precipitation. Convergence in the low layer was the dynamic condition for the generation of precipitation. [Conclusion] The study provided theoretical basis for the disaster prevention and mitigation work in winter.展开更多
The relationship between time-space variation characteristics and the variation of the general atmospheric circulation of rainfall occurred in Asia, Africa through North Africa-Middle East-Western Middle Asia-Eastern ...The relationship between time-space variation characteristics and the variation of the general atmospheric circulation of rainfall occurred in Asia, Africa through North Africa-Middle East-Western Middle Asia-Eastern Middle Asia, Northwest China-Eastern Northwest China-North China and Northeast China is studied based on the analysis of GPCC rainfall data from 1901 to 2010 and annual precipitation in relevant cities of China from 1901 to 2010, and the data of NCEP of surface pressure as well as 500 Hpa potential high from 1950 to 2010. The result shows that the total precipitation presents a decreasing trend in north Africa to the northeast of China in recent 100 years. It has a mutation in 1950s. The precipitation presented a decreasing trend in North Africa and Middle East, in recent 100 years;it presented a further decreasing trend after 1950s. It presented a decreasing trend before 1950s and an increasing trend after 1950s in Middle Asia and Northwest china. It also presented a decreasing trend before 1950s and an increasing trend between 1950s to 1990s, and decreased later in Eastern Northwest China, North China and Northeast China which also presented in a more or less period in different areas from North Africa to Northeast China. The beginning of less precipitation years and less period occurred after it presented less period in north Africa in time and space. After it moved to the east areas as the year past, at last, the SLPA fields which presented more or less precipitations of years from North Africa to Northeast China were analyzed. It also shows that the SLPA fields which presented more were beneficial to the precipitations and presented negative effects of precipitations in the polar, high and mid- and lower latitudes.展开更多
Based on the use of Global Navigation Satellite System (GNSS) for meteorological detection in the world, we used the GNSS/MET detection equipment in the meteorological departments of Liaoning Province of China and its...Based on the use of Global Navigation Satellite System (GNSS) for meteorological detection in the world, we used the GNSS/MET detection equipment in the meteorological departments of Liaoning Province of China and its data to study and summarize the maintenance methods of GNSS/MET (Global Navigation Satellite System Meteorology) detection equipment and the application of water vapor products in operational systems. The results show that: 1) For GNSS/MET failures, specific inspections and classifications can be performed according to different phenomena;2) The GNSS water vapor measurement station samples every 30 seconds, forming one set of GNSS data every hour, and can detonate the atmospheric precipitation by solving the original data;3) Using the “Navigation Satellite Remote Sensing Water Vapor Application Management System”, the GNSS/MET water vapor products can be directly displayed. We can get the conclusion that GNSS/MET has far-reaching significance for studying the law of atmospheric water vapor changes and enhancing the ability to monitor severe weather such as heavy rain and strong convection.展开更多
This study investigates influencing weather systems for and the effect of Tibetan Plateau(TP)'s surface heating on the heavy rainfall over southern China in June 2010, focusing on the four persistent heavy rainfal...This study investigates influencing weather systems for and the effect of Tibetan Plateau(TP)'s surface heating on the heavy rainfall over southern China in June 2010, focusing on the four persistent heavy rainfall events during 14–24 June 2010. The major weather systems include the South Asian high, midlatitude trough and ridge, western Pacific subtropical high in the middle troposphere, and shear lines and eastwardmoving vortices in the lower troposphere. An ensemble of convection-permitting simulations(CTL) is carried out with the WRF model for these rainfall events, which successfully reproduce the observed evolution of precipitation and weather systems. Another ensemble of simulations(SEN) with the surface albedo over the TP and its southern slope changed artificially to one, i.e., the surface does not absorb any solar heating,otherwise it is identical to CTL, is also performed. Comparison between CTL and SEN suggests that the surface sensible heating of TP in CTL significantly affects the temperature distributions over the plateau and its surroundings, and the thermal wind adjustment consequently changes atmospheric circulations and properties of the synoptic systems, leading to intensified precipitation over southern China. Specifically,at 200 hPa, anticyclonic and cyclonic anomalies form over the western and eastern plateau, respectively,which enhances the southward cold air intrusion along the eastern TP and the divergence over southern China; at 500 hPa, the ridge over the northern plateau and the trough over eastern China are strengthened,the southwesterly flows along the northwestern side of the subtropical high are intensified, and the positive vorticity propagation from the plateau to its downstream is also enhanced significantly; at 850 hPa, the lowpressure vortices strongly develop and move eastward while the southwesterly low-level jet over southern China strengthens in CTL, leading to increased water vapor convergence and upward motion over the precipitation region.展开更多
Quantitative Precipitation Forecast(QPF)is a challenging issue in seamless prediction.QPF faces the following difficulties:(i)single rather than multiple model products are still used;(ii)most QPF methods require long...Quantitative Precipitation Forecast(QPF)is a challenging issue in seamless prediction.QPF faces the following difficulties:(i)single rather than multiple model products are still used;(ii)most QPF methods require long-term training samples not easily available,and(iii)local features are insufficiently reflected.In this work,a multi-model blending(MMB)algorithm with supplemental grid points(SGPs)is experimented to overcome these shortcomings.The MMB algorithm includes three steps:(1)single-model bias-correction,(2)dynamic weight MMB,and(3)light-precipitation elimination.In step 1,quantile mapping(QM)is used and SGPs are configured to expand the sample size.The SGPs are chosen based on similarity of topography,spatial distance,and climatic characteristics of local precipitation.In step 2,the dynamic weight MMB uses the idea of ensemble forecasting:a precipitation process can be forecast if more than 40% of the models predict such a case;moreover,threat score(TS)is used to update the weights of ensemble members.Finally,in step 3,the number of false alarms of light precipitation is reduced,thus alleviating unreasonable expansion of the precipitation area caused by the blending of multiple models.Verification results show that using the MMB algorithm has effectively improved the TS and bias score(BS)for blended 6-h QPF.The rate of increase in TS for heavy rainfall(25-mm threshold)reaches 20%-40%;in particular,the improvement has reached 47.6% for forecast lead time of 24 h,compared with the ECMWF model.Meanwhile,the BS is closer to 1,which is better than any single-model forecast.In sum,the QPF using MMB with SGPs shows great potential to further improve the present operational QPF in China.展开更多
By the numerical simulation,the sea surface temperature anomaly(SSTA)of the Pacific andIndian Oceans.being introduced into IAP AGCM,the observed anomalous circulationcharacteristics on the monthly mean 850 hPa have be...By the numerical simulation,the sea surface temperature anomaly(SSTA)of the Pacific andIndian Oceans.being introduced into IAP AGCM,the observed anomalous circulationcharacteristics on the monthly mean 850 hPa have been confirmed:during an El Nino episode thereappears anomalous westerly flow in the low-level atmosphere over the low-latitude Pacific and theanomalous equatorward air flow over the Southeast Asia coast:during a La Nina episode thereappears anomalous easterly flow in the low-level atmosphere over the low-latitude Pacific and theanomalous off-equator air flow over the Southeast Asia coast.If we introduce only Pacific SSTAinto or take off orographic forcing from the model,the simulated anomalous air flow in the low-level atmosphere over the low latitudes will be different.The precipitation departure in conformitywith the observation over the low latitudes has been simulated with this model as well.展开更多
文摘[Objective] The aim was to analyze the changes characteristics of sunshine hours of Dalian City. [Method] Based on the data of sunshine hours of Dalian City during 1951 to 2009 and by dint of linear estimation and accumulation anomaly, the change characteristics of decade, annual, seasonal, monthly sunshine hours in Dalian City were analyzed. [Result] The change characteristics of decade, annual, seasonal, monthly sunshine hours in Dalian City were in a decrease trend since recent 59 years. The average sunshine hour in 1950s was the maximum one. Since 21st century, the annual sunshine hour was the lowest one. Annual average sunshine hours were the highest in 1978, and lowest in 2003. There were more sunshine hours before 1989 and later less. Among the four seasons, the sunshine hours in autumn decreased fastest and slowest in spring. The monthly average sunshine hours were the most in May and least in December; the sunshine hours in each month decreased fastest in July. It showed increasing tendency only in March. [Conclusion] The study supplied scientific reference for the reasonable utilization of light energy, agricultural production structure and sustainable development of agricultural economy.
文摘[Objective] The aim was to study the precipitation changes and agricultural flood and drought degree of crops in Dalian City in recent 60 years. [Method] The monthly precipitation and average temperature data from April to October during 1951-2010 in Dalian observation station were selected. By dint of linear regression, climate tendency rate and humidity index, the growth changes and agricultural flood and drought degree of crops in recent 60 years in Dalian City were expounded from the aspects of natural precipitation tendency changes and agricultural water satisfaction degree of crops in growth period. [Result] In recent 60 years, the precipitation of crops during growth period in Dalian City had decreasing tendency. The inclination rate was -15.888 m/10 a. Precipitation decreased 95.3 mm in recent 60 years; precipitation increased a little in spring and decreased a lot in summer, then decreased in autumn. The monthly precipitation in each month distributed unevenly. Precipitation in July and August increased, taking account of 53.8% of the total precipitation during the growth period of crops. The K value of humidity index during the growth period of crops in Dalian in recent 60 years was 0.90 in general. It was light drought climate. The humidity index was decreasing. Climate developed toward drought direction; the drought occurrence frequency was 59%. It was mild drought climate in spring and autumn. The climate was generally wet in summer. Seen from the yearly means, besides of July and August, it reached mild drought degree in other months. [Conclusion] The study provided reference for the regional agricultural production, agricultural structure adjustment and drought and flood disaster prevention.
基金supported jointlyby the National Key Technology R&D Program (GrantNo. 2007BAC29B02)the National Natural Science Foundation of China (NSFC, Grant No. 40675025)the Key Laboratory of Meteorological Disasters, Nanjing University of Information Science & Technology (NUIST,KLME060101)
文摘Air mass is inter-hemispherically redistributed, leading to an interesting phenomenon known as the Inter-Hemispheric Oscillation (IHO). In the present article, the seasonality of the interannual IHO has been examined by employing monthly mean reanalyses from NCEP/NCAR, EAR40, and JRA25 for the period of 1958-2006. It is found that the IHO indices as calculated from different reanalyses are generally consistent with each other. A distinct seesaw structure in all four seasons between the northern and southern hemispheres is observed as the IHO signature in both the surface air pressure anomalies (SAPAs) and the leading EOF component of the anomalous zonal mean quantities. When the SAPAs are positive (negative) in the northern hemisphere, they are negative (positive) in the southern hemisphere. Large values of SAPAs are usually observed in mid- and high-latitude areas in all but the solstice seasons. In boreal summer and winter, relatively stronger perturbations of IHO-related SAPA are found in the Asian monsoon region, which shows a large difference from the status in boreal spring and fall. This suggests that seasonal mean monsoon activity is globally linked via air mass redistribution globally on interannual timescales, showing a very interesting linkage between monsoons and the IHO in the global domain. In all seasons, large values of SAPA always exist over the Antarctic and the surrounding regions, implying a close relation with Antarctic oscillations.
基金funded by the Major Program of the National Natural Science Foundation of China[grant number 41991283]the National Key Research and Development Program of China[grant number 2016YFA0600703]+1 种基金the Funding of the Jiangsu Innovation&Entrepreneurship Teamthe Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions。
文摘[Objective] The aim was to study the causes of abnormal weather in winter in 2009 and 2010 in Jinzhou. [Method] By dint of regular meteorological data and weather theory, the abnormal weather in winter from 2009 to 2010 in Jinzhou was expounded so as to find the reasons for abnormal climate in winter in the region. [Result] The main reason for the consecutive low temperature in winter in Jinzhou from 2009 to 2010 was the abnormal development of the Ural Mountains high-pressure ridge and strong horizontal circulation. The frequent cold air activity was the leading reason for the increase of precipitation in Jinzhou in winter; the high trough and low air torrent were the main weather system for precipitation. Convergence in the low layer was the dynamic condition for the generation of precipitation. [Conclusion] The study provided theoretical basis for the disaster prevention and mitigation work in winter.
文摘The relationship between time-space variation characteristics and the variation of the general atmospheric circulation of rainfall occurred in Asia, Africa through North Africa-Middle East-Western Middle Asia-Eastern Middle Asia, Northwest China-Eastern Northwest China-North China and Northeast China is studied based on the analysis of GPCC rainfall data from 1901 to 2010 and annual precipitation in relevant cities of China from 1901 to 2010, and the data of NCEP of surface pressure as well as 500 Hpa potential high from 1950 to 2010. The result shows that the total precipitation presents a decreasing trend in north Africa to the northeast of China in recent 100 years. It has a mutation in 1950s. The precipitation presented a decreasing trend in North Africa and Middle East, in recent 100 years;it presented a further decreasing trend after 1950s. It presented a decreasing trend before 1950s and an increasing trend after 1950s in Middle Asia and Northwest china. It also presented a decreasing trend before 1950s and an increasing trend between 1950s to 1990s, and decreased later in Eastern Northwest China, North China and Northeast China which also presented in a more or less period in different areas from North Africa to Northeast China. The beginning of less precipitation years and less period occurred after it presented less period in north Africa in time and space. After it moved to the east areas as the year past, at last, the SLPA fields which presented more or less precipitations of years from North Africa to Northeast China were analyzed. It also shows that the SLPA fields which presented more were beneficial to the precipitations and presented negative effects of precipitations in the polar, high and mid- and lower latitudes.
文摘Based on the use of Global Navigation Satellite System (GNSS) for meteorological detection in the world, we used the GNSS/MET detection equipment in the meteorological departments of Liaoning Province of China and its data to study and summarize the maintenance methods of GNSS/MET (Global Navigation Satellite System Meteorology) detection equipment and the application of water vapor products in operational systems. The results show that: 1) For GNSS/MET failures, specific inspections and classifications can be performed according to different phenomena;2) The GNSS water vapor measurement station samples every 30 seconds, forming one set of GNSS data every hour, and can detonate the atmospheric precipitation by solving the original data;3) Using the “Navigation Satellite Remote Sensing Water Vapor Application Management System”, the GNSS/MET water vapor products can be directly displayed. We can get the conclusion that GNSS/MET has far-reaching significance for studying the law of atmospheric water vapor changes and enhancing the ability to monitor severe weather such as heavy rain and strong convection.
基金Supported by the National(Key) Basic Research and Development(973) Program of China(2012CB417202)National Natural Science Foundation of China(41175049 and 41221064)+1 种基金Basic Research Funds of the Chinese Academy of Meteorological Sciences(2012Y001)National Science and Technology Support Program of China(2012BAC22B03)
文摘This study investigates influencing weather systems for and the effect of Tibetan Plateau(TP)'s surface heating on the heavy rainfall over southern China in June 2010, focusing on the four persistent heavy rainfall events during 14–24 June 2010. The major weather systems include the South Asian high, midlatitude trough and ridge, western Pacific subtropical high in the middle troposphere, and shear lines and eastwardmoving vortices in the lower troposphere. An ensemble of convection-permitting simulations(CTL) is carried out with the WRF model for these rainfall events, which successfully reproduce the observed evolution of precipitation and weather systems. Another ensemble of simulations(SEN) with the surface albedo over the TP and its southern slope changed artificially to one, i.e., the surface does not absorb any solar heating,otherwise it is identical to CTL, is also performed. Comparison between CTL and SEN suggests that the surface sensible heating of TP in CTL significantly affects the temperature distributions over the plateau and its surroundings, and the thermal wind adjustment consequently changes atmospheric circulations and properties of the synoptic systems, leading to intensified precipitation over southern China. Specifically,at 200 hPa, anticyclonic and cyclonic anomalies form over the western and eastern plateau, respectively,which enhances the southward cold air intrusion along the eastern TP and the divergence over southern China; at 500 hPa, the ridge over the northern plateau and the trough over eastern China are strengthened,the southwesterly flows along the northwestern side of the subtropical high are intensified, and the positive vorticity propagation from the plateau to its downstream is also enhanced significantly; at 850 hPa, the lowpressure vortices strongly develop and move eastward while the southwesterly low-level jet over southern China strengthens in CTL, leading to increased water vapor convergence and upward motion over the precipitation region.
基金Supported by the National Key Research and Development Program of China(2017YFC1502004)Special Project for Forecasters of China Meteorological Administration(CMAYBY2020-162)Special Project for Forecasters of National Meteorological Center(Y202135)。
文摘Quantitative Precipitation Forecast(QPF)is a challenging issue in seamless prediction.QPF faces the following difficulties:(i)single rather than multiple model products are still used;(ii)most QPF methods require long-term training samples not easily available,and(iii)local features are insufficiently reflected.In this work,a multi-model blending(MMB)algorithm with supplemental grid points(SGPs)is experimented to overcome these shortcomings.The MMB algorithm includes three steps:(1)single-model bias-correction,(2)dynamic weight MMB,and(3)light-precipitation elimination.In step 1,quantile mapping(QM)is used and SGPs are configured to expand the sample size.The SGPs are chosen based on similarity of topography,spatial distance,and climatic characteristics of local precipitation.In step 2,the dynamic weight MMB uses the idea of ensemble forecasting:a precipitation process can be forecast if more than 40% of the models predict such a case;moreover,threat score(TS)is used to update the weights of ensemble members.Finally,in step 3,the number of false alarms of light precipitation is reduced,thus alleviating unreasonable expansion of the precipitation area caused by the blending of multiple models.Verification results show that using the MMB algorithm has effectively improved the TS and bias score(BS)for blended 6-h QPF.The rate of increase in TS for heavy rainfall(25-mm threshold)reaches 20%-40%;in particular,the improvement has reached 47.6% for forecast lead time of 24 h,compared with the ECMWF model.Meanwhile,the BS is closer to 1,which is better than any single-model forecast.In sum,the QPF using MMB with SGPs shows great potential to further improve the present operational QPF in China.
文摘By the numerical simulation,the sea surface temperature anomaly(SSTA)of the Pacific andIndian Oceans.being introduced into IAP AGCM,the observed anomalous circulationcharacteristics on the monthly mean 850 hPa have been confirmed:during an El Nino episode thereappears anomalous westerly flow in the low-level atmosphere over the low-latitude Pacific and theanomalous equatorward air flow over the Southeast Asia coast:during a La Nina episode thereappears anomalous easterly flow in the low-level atmosphere over the low-latitude Pacific and theanomalous off-equator air flow over the Southeast Asia coast.If we introduce only Pacific SSTAinto or take off orographic forcing from the model,the simulated anomalous air flow in the low-level atmosphere over the low latitudes will be different.The precipitation departure in conformitywith the observation over the low latitudes has been simulated with this model as well.
