The performance of spectral nudging in an investigation of the 2010 East Asia summer monsoon was assessed using the Weather Research and Forecasting (WRF) model, forced by 1-degree NCEP Global Final Analysis (FNL). Tw...The performance of spectral nudging in an investigation of the 2010 East Asia summer monsoon was assessed using the Weather Research and Forecasting (WRF) model, forced by 1-degree NCEP Global Final Analysis (FNL). Two pairs of experiments were made, spectral nudging (SP) and non-spectral nudging (NOSP), with five members in each group. The members were distinguished by different initial times, and the analysis was based on the ensemble mean of the two simulation pairs. The SP was able to constrain error growth in large-scale circulation in upper-level, during simulation, and generate realistic regional scale patterns. The main focus was the model ability to simulate precipitation. The Tropical Rainfall Measuring Mission (TRMM) 3B42 product was used for precipitation verification. Mean precipitation magnitude was generally overestimated by WRF. Nevertheless, SP simulations suppressed overestimation relative to the NOSP experiments. Compared to TRMM, SP also improved model simulation of precipitation in spatial and temporal distributions, with the ability to reproduce movement of rainbands. However, extreme precipitation events were suppressed in the SP simulations.展开更多
The correlation analysis has been used to study the relationship between spring soil moisture over China and East Asian summer monsoon (EASM). It is shown that EASM has a strong positive correlation with spring soil m...The correlation analysis has been used to study the relationship between spring soil moisture over China and East Asian summer monsoon (EASM). It is shown that EASM has a strong positive correlation with spring soil moisture over southwest China and the Great Bend region of the Yellow River. A standard soil moisture index (SMI) has been defined using the observed soil moisture of the two regions. The results show that SMI has a strong correlation with EASM. The years of strong (weak) SMI are associated with stronger (weaker) summer monsoon circulation. In the years of strong SMI, the west Pacific subtropical high is much northward in position and weaker in intensity;the westerlies zone is also more to the north. All of these make EASM circulation move northward and cause the rainfall belt to relocate to North China and Northeast China. SMI can reflect the variation of the summer rainfall anomaly over eastern China. In the years of strong SMI, the rainfall belt is mainly located over the northern part of China. However, during the weak years, the summer rainfall belt is largely located over the mid-and lower-reaches of the Yangtze River. Additionally, the SMI has obvious oscillations of quasi 4-6 years and quasi 2 years. Moreover, negative SMI predicts EASM better than positive SMI.展开更多
The interdecadal variability of the East Asia summer monsoon during 1951～1999 is analyzed by using two different East Asia monsoon indices. The results agree on the point that the East Asia monsoon has undergone an i...The interdecadal variability of the East Asia summer monsoon during 1951～1999 is analyzed by using two different East Asia monsoon indices. The results agree on the point that the East Asia monsoon has undergone an interdecadal variability in the mid-1970s. The intensity of the East Asia monsoon is weaker after this transition. Moreover the intensity and location of subtropical high that is an important component in East Asia monsoon system also shows interdecadal variation obviously. It is the interdecadal variation in atmospheric circulation that causes the drought over North China and flooding along the middle and lower reaches of the Yangtze River after the mid-1970s.展开更多
Wavelet analysis and Mann-Kendall tests are employed to evaluate the variation in the East Asian summer monsoon（EASM） and hydrological variables in the Haihe River basin calculated by the Variable Infiltration Capac...Wavelet analysis and Mann-Kendall tests are employed to evaluate the variation in the East Asian summer monsoon（EASM） and hydrological variables in the Haihe River basin calculated by the Variable Infiltration Capacity model. The relationships between those variables and the EASM are also examined. The results indicate consistent 40 a periodic variation in both the hydrological variables and the EASM. The hydrologic variables show downward trends in the Haihe River basin over the past 60 years, especially in piedmont regions of the Taihang-Yan Mountains. The variables are closely related to the EASM, whose continuous weakening since the 1970 s has resulted in prolonged drought and severe water shortages in the basin. The periodicity of the EASM index was analyzed using continuous wavelet transform methods. We found the most significant periodic signal of the EASM is ~80 years; therefore, the EASM may reinforce and reach a maximum in the 2040 s, resulting in more precipitation and other impacts on basin water resources. Hydrologic variables in the basin in the 2040 s are predicted, and their spatial distributions in the Haihe River basin are also discussed. These results allow for the estimation of water resources under forecasted EASM, which will be useful for water resources management in the Haihe River basin.展开更多
This paper is based on the precipitation of a period of ten days in 336stations which are divided into seven areas of China from 1951 to 1995. We analysed drought and flood facts in the active period of summer monsoon...This paper is based on the precipitation of a period of ten days in 336stations which are divided into seven areas of China from 1951 to 1995. We analysed drought and flood facts in the active period of summer monsoon in recent 45 yearsusing Person Ⅲ Z index of drought and flood, and assessed the impact of droughtand flood展开更多
In the late 1920’s,a mega-drought in China resulted in widespread crop failure and famine.Sufficient evidence suggests that this drought belonged to a dry period ranging from approximately 1922 to 1932.To understand ...In the late 1920’s,a mega-drought in China resulted in widespread crop failure and famine.Sufficient evidence suggests that this drought belonged to a dry period ranging from approximately 1922 to 1932.To understand the characteristics and the cause of this persistent drought period,we combined various data,including observations,tree ring proxy data,reanalysis data,simulation results of the Fifth Phase of the Coupled Model Intercomparison Project and numerical downscaling simulations.The results show that during 1922-1932,most regions in eastern China suffered from a persistent drought that lasted for six years,and the maximum negative precipitation anomaly reached−1.5 times the standard deviation.Given its spatial coverage,duration,and strength,the 1920s drought was unique for the 20th century.The 1920s drought was primarily caused by internal variability.Strong easterlies in lower latitudes,strong monsoon circulation,and abnormally high geopotential heights at middle and upper levels were responsible for the 1920s drought conditions in eastern China;these drought conditions could be further attributed to the joint impact of the Atlantic Multidecadal Oscillation,Pacific Decadal Oscillation and Indian Ocean Basin Mode.展开更多
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX2-YW-Q11-02)
文摘The performance of spectral nudging in an investigation of the 2010 East Asia summer monsoon was assessed using the Weather Research and Forecasting (WRF) model, forced by 1-degree NCEP Global Final Analysis (FNL). Two pairs of experiments were made, spectral nudging (SP) and non-spectral nudging (NOSP), with five members in each group. The members were distinguished by different initial times, and the analysis was based on the ensemble mean of the two simulation pairs. The SP was able to constrain error growth in large-scale circulation in upper-level, during simulation, and generate realistic regional scale patterns. The main focus was the model ability to simulate precipitation. The Tropical Rainfall Measuring Mission (TRMM) 3B42 product was used for precipitation verification. Mean precipitation magnitude was generally overestimated by WRF. Nevertheless, SP simulations suppressed overestimation relative to the NOSP experiments. Compared to TRMM, SP also improved model simulation of precipitation in spatial and temporal distributions, with the ability to reproduce movement of rainbands. However, extreme precipitation events were suppressed in the SP simulations.
文摘The correlation analysis has been used to study the relationship between spring soil moisture over China and East Asian summer monsoon (EASM). It is shown that EASM has a strong positive correlation with spring soil moisture over southwest China and the Great Bend region of the Yellow River. A standard soil moisture index (SMI) has been defined using the observed soil moisture of the two regions. The results show that SMI has a strong correlation with EASM. The years of strong (weak) SMI are associated with stronger (weaker) summer monsoon circulation. In the years of strong SMI, the west Pacific subtropical high is much northward in position and weaker in intensity;the westerlies zone is also more to the north. All of these make EASM circulation move northward and cause the rainfall belt to relocate to North China and Northeast China. SMI can reflect the variation of the summer rainfall anomaly over eastern China. In the years of strong SMI, the rainfall belt is mainly located over the northern part of China. However, during the weak years, the summer rainfall belt is largely located over the mid-and lower-reaches of the Yangtze River. Additionally, the SMI has obvious oscillations of quasi 4-6 years and quasi 2 years. Moreover, negative SMI predicts EASM better than positive SMI.
基金Natural Science Foundation of China (40365001) Intramural research program of Yunnan University (2002Q014ZH)
文摘The interdecadal variability of the East Asia summer monsoon during 1951～1999 is analyzed by using two different East Asia monsoon indices. The results agree on the point that the East Asia monsoon has undergone an interdecadal variability in the mid-1970s. The intensity of the East Asia monsoon is weaker after this transition. Moreover the intensity and location of subtropical high that is an important component in East Asia monsoon system also shows interdecadal variation obviously. It is the interdecadal variation in atmospheric circulation that causes the drought over North China and flooding along the middle and lower reaches of the Yangtze River after the mid-1970s.
基金the National Major Basic Research Program of China(2010CB428404)the“Hundred Talents Program”of Chinese Academy of Sciences(for Dong Chen)Open Foundation of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,Hohai University(2015490711)
文摘Wavelet analysis and Mann-Kendall tests are employed to evaluate the variation in the East Asian summer monsoon（EASM） and hydrological variables in the Haihe River basin calculated by the Variable Infiltration Capacity model. The relationships between those variables and the EASM are also examined. The results indicate consistent 40 a periodic variation in both the hydrological variables and the EASM. The hydrologic variables show downward trends in the Haihe River basin over the past 60 years, especially in piedmont regions of the Taihang-Yan Mountains. The variables are closely related to the EASM, whose continuous weakening since the 1970 s has resulted in prolonged drought and severe water shortages in the basin. The periodicity of the EASM index was analyzed using continuous wavelet transform methods. We found the most significant periodic signal of the EASM is ~80 years; therefore, the EASM may reinforce and reach a maximum in the 2040 s, resulting in more precipitation and other impacts on basin water resources. Hydrologic variables in the basin in the 2040 s are predicted, and their spatial distributions in the Haihe River basin are also discussed. These results allow for the estimation of water resources under forecasted EASM, which will be useful for water resources management in the Haihe River basin.
文摘This paper is based on the precipitation of a period of ten days in 336stations which are divided into seven areas of China from 1951 to 1995. We analysed drought and flood facts in the active period of summer monsoon in recent 45 yearsusing Person Ⅲ Z index of drought and flood, and assessed the impact of droughtand flood
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDA20020201)the National Key R&D Program of China (Grant No. 2016YFA0600403)+2 种基金the General Project of the National Natural Science Foundation of China (Grant No. 41875134)the National Key R&D Program of China (Grant No. 2016YFA0602501)the Science and Technology Program of Yunnan “Impact assessments and monitorforecasting technology of meteorological disasters for Yunnan Plateau characteristic agriculture under climate change” (Grant No. 2018BC007)
文摘In the late 1920’s,a mega-drought in China resulted in widespread crop failure and famine.Sufficient evidence suggests that this drought belonged to a dry period ranging from approximately 1922 to 1932.To understand the characteristics and the cause of this persistent drought period,we combined various data,including observations,tree ring proxy data,reanalysis data,simulation results of the Fifth Phase of the Coupled Model Intercomparison Project and numerical downscaling simulations.The results show that during 1922-1932,most regions in eastern China suffered from a persistent drought that lasted for six years,and the maximum negative precipitation anomaly reached−1.5 times the standard deviation.Given its spatial coverage,duration,and strength,the 1920s drought was unique for the 20th century.The 1920s drought was primarily caused by internal variability.Strong easterlies in lower latitudes,strong monsoon circulation,and abnormally high geopotential heights at middle and upper levels were responsible for the 1920s drought conditions in eastern China;these drought conditions could be further attributed to the joint impact of the Atlantic Multidecadal Oscillation,Pacific Decadal Oscillation and Indian Ocean Basin Mode.
