A regional atmosphere-ocean coupled model, RegCM3-POM, was developed by coupling the regional climate model （RegCM3） with the Princeton Ocean Model （POM）. The performance of RegCM3-POM in simulating a persistent s...A regional atmosphere-ocean coupled model, RegCM3-POM, was developed by coupling the regional climate model （RegCM3） with the Princeton Ocean Model （POM）. The performance of RegCM3-POM in simulating a persistent snow storm over southern China and the impact of the Madden Julian oscillation （MJO） on this persistent snow storm were investigated. Compared with the stand-alone RegCM3, the coupled model performed better at reproducing the spatial-temporal evolution and intensity of the precipitation episodes. The power spectral analysis indicated that the coupled model successfully captured the dominant period between 30 and 60 days in the precipitation field, leading to a notable improvement in simulating the magnitude of intraseasonal precipitation variation, and further in enhancing the intensity of the simulated precipitation. These improvements were mainly due to the well-simulated low-frequency oscillation center and its eastward propagation characteristics in each MJO phase by RegCM3-POM, which improved the simulations of MJO-related low-frequency vertical motions, water vapor transport, and the deep inversion layer that can directly influence the precipitation event and that further improved the simulated MJOprecipitation relationship. Analysis of the phase relationship between convection and SST indicated that RegCM3-POM exhibits a near-quadrature relation between the simulated convection and SST anomalies, which was consistent with the observations. However, such a near-quadrature relation was not as significant when the stand-alone RegCM3 was used. This difference indicated that the inherent coupled feedback process between the ocean and atmosphere in RegCM3-POM played an important part in reproducing the features of the MJO that accompanied the snow storm.展开更多
The Regional Integrated Environmental Model System （RIEMS 2.0） with NCEP Reanalysis II is utilized to simulate the severe freezing rain and snow storm event over southern China in January 2008, which caused severe d...The Regional Integrated Environmental Model System （RIEMS 2.0） with NCEP Reanalysis II is utilized to simulate the severe freezing rain and snow storm event over southern China in January 2008, which caused severe damage in the region. The relationships between the freezing rain process and the large-scale cir- culation, in terms of the westerly and low-level jets, water vapor transportation, and northerly wind area/intensity indices, were analyzed to tmderstand the mechanisms of the freezing rain occurrence. The results indicate the fol- lowing： （1） RIEMS 2.0 reproduced the pattern of precipi- tation in January 2008 well, especially for the temporal evolution of daily precipitation averaged over the Yangtze River valley and southern China; （2） RIEMS 2.0 repro- duced the persistent trough in the South Branch of the westerlies, of which the southwesterly currents trans- ported abundant moisture into southern China; （3） RIEMS 2.0 reasonably reproduced the pattern of frequencies of light and moderate rain, although it overestimated the frequency of rain in southern China. This study shows that RIEMS 2.0 can be feasibly applied to study extreme weather and climate events in East Asia.展开更多
本文采用ECMWF(European Centre for Medium-Range Weather Forecasts)细网格和NCEP(National Centers for Environmental Prediction)模式数据、NCEP 1°×1°再分析资料、降雪加密观测和常规资料,对2022年初的5次降雪过...本文采用ECMWF(European Centre for Medium-Range Weather Forecasts)细网格和NCEP(National Centers for Environmental Prediction)模式数据、NCEP 1°×1°再分析资料、降雪加密观测和常规资料,对2022年初的5次降雪过程进行对比分析,发现5次降雪过程均为雨转雪过程,且持续时间相对较短,平原为雨夹雪或小雪到中雪,山区中到大雪,局部暴雪,数值模式预报的积雪深度与实况相差甚远;大尺度环流形势为500 hPa中低纬南支槽或弱波动配合700 hPa上的暖湿气流和中低层冷空气,造成边界层浅薄的冷垫上温度骤降而在短时间内形成降雪;相较于平原地区,高山区上空温度层结与最大上升运动中心的配置,有利于降雪粒子较长时间维持在有利于枝状雪花的形成区域,且高山区云底云水含量显著偏低、整层温度足够低,故高山区更利于暴雪的形成。展开更多
基金supported by grants from the National Basic Research Program of China (973 Program,Grant Nos.2012CB955901 and 2011CB952002)the National Science and Technology Support Program of China (Grant No.2009BAC51B03)the National Natural Science Foundation of China (Grant Nos. 41105044 and 41105045)
文摘A regional atmosphere-ocean coupled model, RegCM3-POM, was developed by coupling the regional climate model （RegCM3） with the Princeton Ocean Model （POM）. The performance of RegCM3-POM in simulating a persistent snow storm over southern China and the impact of the Madden Julian oscillation （MJO） on this persistent snow storm were investigated. Compared with the stand-alone RegCM3, the coupled model performed better at reproducing the spatial-temporal evolution and intensity of the precipitation episodes. The power spectral analysis indicated that the coupled model successfully captured the dominant period between 30 and 60 days in the precipitation field, leading to a notable improvement in simulating the magnitude of intraseasonal precipitation variation, and further in enhancing the intensity of the simulated precipitation. These improvements were mainly due to the well-simulated low-frequency oscillation center and its eastward propagation characteristics in each MJO phase by RegCM3-POM, which improved the simulations of MJO-related low-frequency vertical motions, water vapor transport, and the deep inversion layer that can directly influence the precipitation event and that further improved the simulated MJOprecipitation relationship. Analysis of the phase relationship between convection and SST indicated that RegCM3-POM exhibits a near-quadrature relation between the simulated convection and SST anomalies, which was consistent with the observations. However, such a near-quadrature relation was not as significant when the stand-alone RegCM3 was used. This difference indicated that the inherent coupled feedback process between the ocean and atmosphere in RegCM3-POM played an important part in reproducing the features of the MJO that accompanied the snow storm.
基金supported by the National Basic Research Program of China (Grant Nos. 2010CB950900 and 2009CB421100)the National Natural Science Foundation of China (Grant No. 91025003)
文摘The Regional Integrated Environmental Model System （RIEMS 2.0） with NCEP Reanalysis II is utilized to simulate the severe freezing rain and snow storm event over southern China in January 2008, which caused severe damage in the region. The relationships between the freezing rain process and the large-scale cir- culation, in terms of the westerly and low-level jets, water vapor transportation, and northerly wind area/intensity indices, were analyzed to tmderstand the mechanisms of the freezing rain occurrence. The results indicate the fol- lowing： （1） RIEMS 2.0 reproduced the pattern of precipi- tation in January 2008 well, especially for the temporal evolution of daily precipitation averaged over the Yangtze River valley and southern China; （2） RIEMS 2.0 repro- duced the persistent trough in the South Branch of the westerlies, of which the southwesterly currents trans- ported abundant moisture into southern China; （3） RIEMS 2.0 reasonably reproduced the pattern of frequencies of light and moderate rain, although it overestimated the frequency of rain in southern China. This study shows that RIEMS 2.0 can be feasibly applied to study extreme weather and climate events in East Asia.
文摘本文采用ECMWF(European Centre for Medium-Range Weather Forecasts)细网格和NCEP(National Centers for Environmental Prediction)模式数据、NCEP 1°×1°再分析资料、降雪加密观测和常规资料,对2022年初的5次降雪过程进行对比分析,发现5次降雪过程均为雨转雪过程,且持续时间相对较短,平原为雨夹雪或小雪到中雪,山区中到大雪,局部暴雪,数值模式预报的积雪深度与实况相差甚远;大尺度环流形势为500 hPa中低纬南支槽或弱波动配合700 hPa上的暖湿气流和中低层冷空气,造成边界层浅薄的冷垫上温度骤降而在短时间内形成降雪;相较于平原地区,高山区上空温度层结与最大上升运动中心的配置,有利于降雪粒子较长时间维持在有利于枝状雪花的形成区域,且高山区云底云水含量显著偏低、整层温度足够低,故高山区更利于暴雪的形成。
