Using land-use types derived from satellite remote sensing data collected by the EOS Moderate Resolution Imaging Spectroradiometer （EOS/MODIS）, the mesoscale and turbulent fluxes generated by inhomogeneities of the ...Using land-use types derived from satellite remote sensing data collected by the EOS Moderate Resolution Imaging Spectroradiometer （EOS/MODIS）, the mesoscale and turbulent fluxes generated by inhomogeneities of the underlying surface over the Jinta Oasis, northwestern China, were simulated using the Regional Atmospheric Modeling System （RAMS4.4）. The results indicate that mesoscale circulation generated by land-surface inhomogeneities over the Jinta Oasis is more important than turbulence. Vertical heat fluxes and water vapor are transported to higher levels by mesoscale circulation. Mesoscale circulation also produces mesoscale synoptic systems and prevents water vapor over the oasis from running off. Mesoscale circulation transports moisture to higher atmospheric levels as the land-surface moisture over the oasis increases, favoring the formation of clouds, which sometimes leads to rainfall. Large-scale wind speed has a significant impact on mesoscale heat fluxes. During the active phase of mesoscale circulation, the stronger large-scale winds are associated with small mesoscale fluxes; however, background wind seems to intensify the turbulent sensible heat flux and turbulent latent heat flux. If the area of oasis is enlarged properly, mesoscale circulation will be able to transport moisture to higher levels, favoring the formation of rainfall in the oasis and protecting its ＂cold island＂ effect. The impact of irrigation on rainfall is important, and increasing irrigation across the oasis is necessary to protect the oasis.展开更多
This study explores the spatial structure and transport characteristics of eddies in the Arabian Sea(AS)using Argo profiles and satellite measurements.The majority of eddies occur in the northern AS,especially along i...This study explores the spatial structure and transport characteristics of eddies in the Arabian Sea(AS)using Argo profiles and satellite measurements.The majority of eddies occur in the northern AS,especially along its northeastern boundary.In contrast,the western AS had a relatively higher eddy kinetic energy compared to the eastern part.Particularly,the strongest energetic eddies were present in the Somali Current system.The composite results revealed the evident thermohaline anomalies caused by cyclonic eddies(CEs)and anticyclonic eddies(AEs)in the upper 300m layers.The anomalous temperature structure within CEs and AEs showed a dominant dipole structure in the near-surface layer and a monopole structure below,with maximum temperature anomalies of approximately−0.8℃and+1.0℃located at depths of 100–150m,respectively.The composited salinity structures for CEs and AEs exhibited monopole vertical structures and sandwich-like patterns.For AEs,large positive salinity anomalies occurred at subsurface layers of 60–180 m with a peak value of about 0.07,and weak negative values were observed above 60m and below 180 m.A similar vertical structure but with an opposite sign operates for CEs.The composited CE and AE caused an equatorward salt flux with values of−8.1×10^(4)and−2.2×10^(4)kg s^(−1),respectively.CEs caused an equatorward heat flux of−7.7×10^(11)W,and AEs induced a poleward flux of 1.5×1011 W.展开更多
On 12 August 2004, Typhoon Rananim （0414） moved inland over China and stagnated over the Poyang Lake area, resulting in torrential rainfall and severe geologic hazards. The Advanced Weather Research and Forecasting ...On 12 August 2004, Typhoon Rananim （0414） moved inland over China and stagnated over the Poyang Lake area, resulting in torrential rainfall and severe geologic hazards. The Advanced Weather Research and Forecasting （ARW-WRF） model and its different land surface models （LSMs） were employed to study the impacts of land surface process on the inland behavior of Typhoon Rananim. Results show that simulations, coupled with LSMs or not, have no significant differences in predicting typhoon track, intensity, and largescale circulation. However, the simulations of mesoscale structure, rainfall rate, and rainfall distribution of typhoon are more reasonable with LSMs than without LSMs. Although differences are slight among LSMs, NOAH is better than the others. Based on outputs using the NOAH scheme, the interaction between land surtace and typhoon was explored in this study. Notably, typhoon rainfall and cloud cover can cool land surface, but rainfall expands the underlying saturated wetland area, which exacerbates the asymmetric distribution of surface heat fluxes. Accordingly, an energy frontal zone may form in the lower troposphere that enhances ascending motion and local convection, resulting in heavier rainfall. Moreover, the expanded underlying saturated wetlands provide plentiful moisture and unstable energy for the maintenance of Typhoon Rananim and increased rainfall in return.展开更多
应用中尺度区域模式RAMS(the regional atmospheric model system),在40余组不同参数的条件下模拟中国干旱半干旱黑河地区的地表能量通量和土壤温度特征,并以此探索模式在干旱半干旱地区的适用性。为了证明模拟结果的准确性和模式的稳定...应用中尺度区域模式RAMS(the regional atmospheric model system),在40余组不同参数的条件下模拟中国干旱半干旱黑河地区的地表能量通量和土壤温度特征,并以此探索模式在干旱半干旱地区的适用性。为了证明模拟结果的准确性和模式的稳定性,模拟连续运行30天,其中包含晴好和阴雨的天气过程。模拟结果表明:即使使用较为可靠的NECP再分析气压层资料和实地探测资料,进行初始场和参数的输入,RAMS的默认设置也很难较为合理地反演出地表能量通量,只有合理地调整好其土壤特征参数,RAMS才能得到与实测资料符合得较好的结果。土壤特征参数对模拟结果影响较大,影响因子的重要性依次为:土壤含水量、土壤层总厚度、土壤温度。展开更多
基金supported by the National Basic Research Program (also called 973 Program) (Grant No. 2009CB421402)Chinese National Science Foundation Program (Grant No. 40975007),Chinese National Science Foundation Program (Grant No. 40633014)+1 种基金China Postdoctoral Science Foundation (Grant No. 119100581F)Important Program of State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences (Grant No. 2010LASW-A02)
文摘Using land-use types derived from satellite remote sensing data collected by the EOS Moderate Resolution Imaging Spectroradiometer （EOS/MODIS）, the mesoscale and turbulent fluxes generated by inhomogeneities of the underlying surface over the Jinta Oasis, northwestern China, were simulated using the Regional Atmospheric Modeling System （RAMS4.4）. The results indicate that mesoscale circulation generated by land-surface inhomogeneities over the Jinta Oasis is more important than turbulence. Vertical heat fluxes and water vapor are transported to higher levels by mesoscale circulation. Mesoscale circulation also produces mesoscale synoptic systems and prevents water vapor over the oasis from running off. Mesoscale circulation transports moisture to higher atmospheric levels as the land-surface moisture over the oasis increases, favoring the formation of clouds, which sometimes leads to rainfall. Large-scale wind speed has a significant impact on mesoscale heat fluxes. During the active phase of mesoscale circulation, the stronger large-scale winds are associated with small mesoscale fluxes; however, background wind seems to intensify the turbulent sensible heat flux and turbulent latent heat flux. If the area of oasis is enlarged properly, mesoscale circulation will be able to transport moisture to higher levels, favoring the formation of rainfall in the oasis and protecting its ＂cold island＂ effect. The impact of irrigation on rainfall is important, and increasing irrigation across the oasis is necessary to protect the oasis.
基金supported by grants from the National Natural Science Foundation of China(No.42130406)the Scientific Research Foundation of Third Institute of Oceanography,MNR(Nos.2022027 and 2023018)+2 种基金the Deep Sea Habitats Discovery Project of China Deep Ocean Affairs Administration(No.DY-XZ-04)the Asian Countries Maritime Cooperation Fund(No.99950410)the Global Change and Air-Sea Interaction II(Nos.GASI-04-WLHY-01 and GASI-01-SIND-STwin).
文摘This study explores the spatial structure and transport characteristics of eddies in the Arabian Sea(AS)using Argo profiles and satellite measurements.The majority of eddies occur in the northern AS,especially along its northeastern boundary.In contrast,the western AS had a relatively higher eddy kinetic energy compared to the eastern part.Particularly,the strongest energetic eddies were present in the Somali Current system.The composite results revealed the evident thermohaline anomalies caused by cyclonic eddies(CEs)and anticyclonic eddies(AEs)in the upper 300m layers.The anomalous temperature structure within CEs and AEs showed a dominant dipole structure in the near-surface layer and a monopole structure below,with maximum temperature anomalies of approximately−0.8℃and+1.0℃located at depths of 100–150m,respectively.The composited salinity structures for CEs and AEs exhibited monopole vertical structures and sandwich-like patterns.For AEs,large positive salinity anomalies occurred at subsurface layers of 60–180 m with a peak value of about 0.07,and weak negative values were observed above 60m and below 180 m.A similar vertical structure but with an opposite sign operates for CEs.The composited CE and AE caused an equatorward salt flux with values of−8.1×10^(4)and−2.2×10^(4)kg s^(−1),respectively.CEs caused an equatorward heat flux of−7.7×10^(11)W,and AEs induced a poleward flux of 1.5×1011 W.
基金financed by the National Grand Fundamental Research 973 Program of China (Grant No. 2009CB421504)the Natural Science Foundation of China (Grant Nos. 41175063,40975032,and 41275066)
文摘On 12 August 2004, Typhoon Rananim （0414） moved inland over China and stagnated over the Poyang Lake area, resulting in torrential rainfall and severe geologic hazards. The Advanced Weather Research and Forecasting （ARW-WRF） model and its different land surface models （LSMs） were employed to study the impacts of land surface process on the inland behavior of Typhoon Rananim. Results show that simulations, coupled with LSMs or not, have no significant differences in predicting typhoon track, intensity, and largescale circulation. However, the simulations of mesoscale structure, rainfall rate, and rainfall distribution of typhoon are more reasonable with LSMs than without LSMs. Although differences are slight among LSMs, NOAH is better than the others. Based on outputs using the NOAH scheme, the interaction between land surtace and typhoon was explored in this study. Notably, typhoon rainfall and cloud cover can cool land surface, but rainfall expands the underlying saturated wetland area, which exacerbates the asymmetric distribution of surface heat fluxes. Accordingly, an energy frontal zone may form in the lower troposphere that enhances ascending motion and local convection, resulting in heavier rainfall. Moreover, the expanded underlying saturated wetlands provide plentiful moisture and unstable energy for the maintenance of Typhoon Rananim and increased rainfall in return.
文摘应用中尺度区域模式RAMS(the regional atmospheric model system),在40余组不同参数的条件下模拟中国干旱半干旱黑河地区的地表能量通量和土壤温度特征,并以此探索模式在干旱半干旱地区的适用性。为了证明模拟结果的准确性和模式的稳定性,模拟连续运行30天,其中包含晴好和阴雨的天气过程。模拟结果表明:即使使用较为可靠的NECP再分析气压层资料和实地探测资料,进行初始场和参数的输入,RAMS的默认设置也很难较为合理地反演出地表能量通量,只有合理地调整好其土壤特征参数,RAMS才能得到与实测资料符合得较好的结果。土壤特征参数对模拟结果影响较大,影响因子的重要性依次为:土壤含水量、土壤层总厚度、土壤温度。
文摘利用NCEP 1°×1°资料、加密自动站降水资料及FY2C红外云图资料对2012年7月6-9日及2011年7月4—6日期间发生在四川盆地并造成强降水的4次相似MCC过程的卫星云图特征进行了对比分析,探讨了MCC生成及发展旺盛期的环流场特征,进一步诊断了MCC发展过程的水汽、热力以及动力机制(垂直散度通量、干位涡).研究表明:2例过程中4次MCC的第1、3个是在进入盆地的卷云羽上的对流云团中生成和发展,2、4个MCC是在残留云系上的对流云团中生成、发展和合并,形成过程中均表现为亮温降低、面积增大,川西高原及MCS周围云系逐渐减弱的特点.在强且持续的孟湾水汽输送和不稳定层结条件下,对流层低层西南涡区辐合抬升造成强烈的散度通量辐合向上输送与高层辐散耦合是MCC发展持续的动力机制,且850 h Pa垂直散度通量辐合区与MCC持续区域及观测的地面强降水落区具有良好的时空对应关系.中高纬的高值位涡具有向南向下延伸,低纬低层的低值位涡具有向上向北传播的特点.当干冷空气与较强暖湿气流相交汇时,850h Pa急流左前侧的西南涡区强烈的风场切变与辐合导致强上升运动,触发对流不稳定能量释放,激发MCC云团,造成强降水.
