The spatial and temporal distribution characteristics of rainstorm disaster in Sichuan Province were investigated by statistical analysis method based on 2002-2015 rainstorm disaster data of Sichuan Province. As shown...The spatial and temporal distribution characteristics of rainstorm disaster in Sichuan Province were investigated by statistical analysis method based on 2002-2015 rainstorm disaster data of Sichuan Province. As shown by the results, the rainstorm disaster in Sichuan Province was distributed mainly in four regions including Liangshan Prefecture and Sichuan Basin during 2002-2015, and the rainstorm disaster distribution had a good corresponding relationship with the rainstorm center regions;in terms of annual variation trend, the variation of rainstorm disaster frequency showed a significant quasi-2-3-year oscillation period;in terms of monthly distribution, June, July and August saw the heaviest rainstorms;the high death toll from rainstorms was attributed to not only routine rainfall, occurrence time and terrain feature, but also the populace’s awareness of disaster prevention and the disaster prevention measures they adopted. The research result has important significance to improve the pertinence and practicability of decision-making meteorological services.展开更多
NCEP/NCAR data are utilized to analyze an extreme flood year(1998) and an extreme dry year(2006) in the Sichuan-Chongqing region(SCR) and the results are as follows. The positive divergence of South Asia High(SAH) is ...NCEP/NCAR data are utilized to analyze an extreme flood year(1998) and an extreme dry year(2006) in the Sichuan-Chongqing region(SCR) and the results are as follows. The positive divergence of South Asia High(SAH) is stronger in the flood year; the position of the ridge line of SAH is southward compared with the annual average; Western Pacific Subtropical High(WPSH) extends westward and its ridge line is southward. In the drought year, the positive divergence of SAH is weaker, its ridge line is northward, and the position of WPSH is also northward. As shown in the dynamics, in drought(flood) years, negative(positive) vorticity advection in the upper atmosphere can cause the atmosphere to ascend(descend), and anomalous circulation of SAH displays divergence(convergence), and anomalous circulation of the lower atmosphere shows convergence(divergence). Thermal structure of the atmosphere shows that there is warm(cold) temperature advection in the lower atmosphere, and the vertical distribution of diabetic heating causes SAH's local circulation to display convergence(divergence) and affects vertical motion of the lower atmosphere circulation eventually. To some extent, the two extreme years in the SCR is closely related to the vertical motion of atmosphere circulation and the variation of such vertical motion is caused by differences of interactions between SAH and lower atmosphere circulations.展开更多
Based on an Ensemble Prediction System with the BGM method on the regional numerical prediction model AREM,Static State Perturbation(SSP,including Initial Random Perturbation and Perturbation Restriction) and Dynamic ...Based on an Ensemble Prediction System with the BGM method on the regional numerical prediction model AREM,Static State Perturbation(SSP,including Initial Random Perturbation and Perturbation Restriction) and Dynamic State Perturbation(DSP) are designed.The impacts of both perturbations on precipitation prediction are studied by analyzing a strong precipitation process occurring during July 20-21,2008.The results show that both SSP and DSP play a positive role in prediction of mesoscale precipitation,such as lowering the(missing) rate of precipitation prediction.SSP is mainly helpful for the 24-hour prediction,while DSP can improve both 24-hour and 48-hour prediction.DSP is better than the two SSPs in the hit rate of regional precipitation prediction.However,the former also has a little higher false alarm rate than the latter.DSP enlarges in some extent the dispersion of EPS,which is good for EPS.展开更多
By using the twice-daily atmospheric observation data from 1998 to 2012,station rainfall data,Tropical Rainfall Measure Mission(TRMM) data,as well as the plateau vortex and shear line year book,characteristics of the ...By using the twice-daily atmospheric observation data from 1998 to 2012,station rainfall data,Tropical Rainfall Measure Mission(TRMM) data,as well as the plateau vortex and shear line year book,characteristics of the sustained departure plateau vortexes(SDPVs) are analyzed.Some new useful observational facts and understanding are obtained about the SDPV activities.The following results are obtained.(1)The active period of SDPVs is from June to August,most in July,unlike that of the unsustained departure plateau vortexes(UDPVs),which have same occurrence frequencies in the three summer months.(2)The SDPVs,generated mainly in the Qumalai neighborhood and situated in a sheared surrounding,move eastward or northeastward,while the UDPVs are mainly led by the upper-level trough,and move eastward or southeastward.(3) The SDPVs influence wide areas of China,even far to the Korean Peninsula,Japan,and Vietnam.(4) The SDPVs change their intensities and properties on the way to the east.Most of them become stronger and produce downpour or sustained regional rainstorms to the south of Yellow River.(5)The longer the SDPV sustains,the more baroclinity it has.(6) When an SDPV moves into the sea,its central pressure descends and rainfall increases in all probability.(7) An SDPV might spin over the bend of the Yellow River when there exists a tropical cyclone in the East China Sea.It could also move oppositely to a landed tropical low pressure originated from the sea to the east of Taiwan or from the South China Sea.展开更多
文摘The spatial and temporal distribution characteristics of rainstorm disaster in Sichuan Province were investigated by statistical analysis method based on 2002-2015 rainstorm disaster data of Sichuan Province. As shown by the results, the rainstorm disaster in Sichuan Province was distributed mainly in four regions including Liangshan Prefecture and Sichuan Basin during 2002-2015, and the rainstorm disaster distribution had a good corresponding relationship with the rainstorm center regions;in terms of annual variation trend, the variation of rainstorm disaster frequency showed a significant quasi-2-3-year oscillation period;in terms of monthly distribution, June, July and August saw the heaviest rainstorms;the high death toll from rainstorms was attributed to not only routine rainfall, occurrence time and terrain feature, but also the populace’s awareness of disaster prevention and the disaster prevention measures they adopted. The research result has important significance to improve the pertinence and practicability of decision-making meteorological services.
基金National Key Basic Research Development Program Project of China(2012CB417202)Key Project of National Natural Science Foundation(91337215)National Natural Science Foundation of China(41275051)
文摘NCEP/NCAR data are utilized to analyze an extreme flood year(1998) and an extreme dry year(2006) in the Sichuan-Chongqing region(SCR) and the results are as follows. The positive divergence of South Asia High(SAH) is stronger in the flood year; the position of the ridge line of SAH is southward compared with the annual average; Western Pacific Subtropical High(WPSH) extends westward and its ridge line is southward. In the drought year, the positive divergence of SAH is weaker, its ridge line is northward, and the position of WPSH is also northward. As shown in the dynamics, in drought(flood) years, negative(positive) vorticity advection in the upper atmosphere can cause the atmosphere to ascend(descend), and anomalous circulation of SAH displays divergence(convergence), and anomalous circulation of the lower atmosphere shows convergence(divergence). Thermal structure of the atmosphere shows that there is warm(cold) temperature advection in the lower atmosphere, and the vertical distribution of diabetic heating causes SAH's local circulation to display convergence(divergence) and affects vertical motion of the lower atmosphere circulation eventually. To some extent, the two extreme years in the SCR is closely related to the vertical motion of atmosphere circulation and the variation of such vertical motion is caused by differences of interactions between SAH and lower atmosphere circulations.
基金supported by the Special Fund for Meteorology Scientific Research in the Public Interest in 2007(GYHY(QX)2007-6-12)
文摘Based on an Ensemble Prediction System with the BGM method on the regional numerical prediction model AREM,Static State Perturbation(SSP,including Initial Random Perturbation and Perturbation Restriction) and Dynamic State Perturbation(DSP) are designed.The impacts of both perturbations on precipitation prediction are studied by analyzing a strong precipitation process occurring during July 20-21,2008.The results show that both SSP and DSP play a positive role in prediction of mesoscale precipitation,such as lowering the(missing) rate of precipitation prediction.SSP is mainly helpful for the 24-hour prediction,while DSP can improve both 24-hour and 48-hour prediction.DSP is better than the two SSPs in the hit rate of regional precipitation prediction.However,the former also has a little higher false alarm rate than the latter.DSP enlarges in some extent the dispersion of EPS,which is good for EPS.
基金Supported by the National Natural Science Foundation of China(41275052)National(Key)Basic Research and Development(973)Program of China(2012CB417202)
文摘By using the twice-daily atmospheric observation data from 1998 to 2012,station rainfall data,Tropical Rainfall Measure Mission(TRMM) data,as well as the plateau vortex and shear line year book,characteristics of the sustained departure plateau vortexes(SDPVs) are analyzed.Some new useful observational facts and understanding are obtained about the SDPV activities.The following results are obtained.(1)The active period of SDPVs is from June to August,most in July,unlike that of the unsustained departure plateau vortexes(UDPVs),which have same occurrence frequencies in the three summer months.(2)The SDPVs,generated mainly in the Qumalai neighborhood and situated in a sheared surrounding,move eastward or northeastward,while the UDPVs are mainly led by the upper-level trough,and move eastward or southeastward.(3) The SDPVs influence wide areas of China,even far to the Korean Peninsula,Japan,and Vietnam.(4) The SDPVs change their intensities and properties on the way to the east.Most of them become stronger and produce downpour or sustained regional rainstorms to the south of Yellow River.(5)The longer the SDPV sustains,the more baroclinity it has.(6) When an SDPV moves into the sea,its central pressure descends and rainfall increases in all probability.(7) An SDPV might spin over the bend of the Yellow River when there exists a tropical cyclone in the East China Sea.It could also move oppositely to a landed tropical low pressure originated from the sea to the east of Taiwan or from the South China Sea.
