Based on combined CloudSat/CALIPSO detections, the seasonal occurrence of deep convective clouds （DCCs） over the midlatitude North Pacific （NP） and cyclonic activity in winter were compared. In winter, DCCs are mo...Based on combined CloudSat/CALIPSO detections, the seasonal occurrence of deep convective clouds （DCCs） over the midlatitude North Pacific （NP） and cyclonic activity in winter were compared. In winter, DCCs are more frequent over the central NP, from approximately 30~N to 45~N, than over other regions. The high frequencies are roughly equal to those occurring in this region in summer. Most of these DCCs have cloud tops above a 12 km altitude, and the highest top is approximately 15 km. These wintertime marine DCCs commonly occur during surface circulation conditions of low pressure, high temperature, strong meridional wind, and high relative humidity. Further, the maximum probability of DCCs, according to the high correlation coefficient, was found in the region 10^-20~ east and 5^-10~ south of the center of the cyclones. The potential relationship between DCCs and cyclones regarding their relative locations and circulation conditions was also identified by a case study. Deep clouds were generated in the warm conveyor belt by strong updrafts from baroclinic flows. The updrafts intensified when latent heat was released during the adjustment of the cyclone circulation current. This indicates that the dynamics of cyclones are the primary energy source for DCCs over the NP in winter.展开更多
Spinel LiMn_(2)O_(4)has been considered to be the most promising alternative cathode material for the new generation of lithium-ion batteries in terms of its low cost,non-toxicity and easy manufacture.The spinel lithi...Spinel LiMn_(2)O_(4)has been considered to be the most promising alternative cathode material for the new generation of lithium-ion batteries in terms of its low cost,non-toxicity and easy manufacture.The spinel lithium manganese mixed oxides were prepared from lithium nitrate,manganese nitrate and citric acid by a sol-gel method and were characterized by thermogravimetric analysis,X-ray diffraction,cyclic voltammetry and constant current charging-discharging technique.The different sintering temperatures for different time have strong influence on the structure,initial discharge capacity and cycling performance of the lithium manganese oxide.It shows that the lithium manganese oxides sintered at 700℃for 10 h have a single spinel structure and better electrochemical properties.The initial discharging capacity can be up to 125.9 mAh·g^(-1),even after six cycles,it still retains 109.1 mAh·g^(-1).展开更多
A 6-year dataset of summer monthly mean precipitation derived from Tropical Precipitation Measure-ment Mission (TRMM)-Microwave Imager (TMI) was used to delineate the spatial distribution patterns of precipitation thr...A 6-year dataset of summer monthly mean precipitation derived from Tropical Precipitation Measure-ment Mission (TRMM)-Microwave Imager (TMI) was used to delineate the spatial distribution patterns of precipitation throughout Asian areas, which indicates that there are three rainfall centers located at the northern coast of the Bay of Bengal, the South China Sea and the western equatorial Pacific Warm Pool, respectively. Based upon the analysis of horizontal distribution, the capability of TMI for characterizing terrestrial and maritime precipitation has been evaluated and compared with Global Precipitation Climatology Project (GPCP) dataset. It was found that TMI and GPCP are well consistent with each other, while a few significant differences occur at several regions over land. By investigating rainfall esti-mates over six specific locations in Asia, a systematic underestimation of TMI was demonstrated, which could be explained by the inherent deficiency within TMI terrestrial algorithm relying on scat-tering signal from ice particles in a precipitation system. A further analysis shows that the highly in-homogeneous distribution of rain gauges employed by GPCP contributes a great deal to the significant discrepancy between GPCP and TMI, especially over regions surrounding the Tibetan Plateau where rain gauges are quite scarce.展开更多
基金funded by the National Natural Science Foundation of China (Grant Nos. 41105031, 41230419, 91337213 and 41205126)the China Special Fund for Meteorological Research in the Public Interest (Grant Nos. GYHY201306017 and GYHY201306077)+2 种基金the Strategic Priority Research Program (Grant No. XDA05100303)the Major State Basic Research Development Program (Grant No. 2010CB428601)Environmental Public Welfare Scientific Research (Grant No. 201209006)
文摘Based on combined CloudSat/CALIPSO detections, the seasonal occurrence of deep convective clouds （DCCs） over the midlatitude North Pacific （NP） and cyclonic activity in winter were compared. In winter, DCCs are more frequent over the central NP, from approximately 30~N to 45~N, than over other regions. The high frequencies are roughly equal to those occurring in this region in summer. Most of these DCCs have cloud tops above a 12 km altitude, and the highest top is approximately 15 km. These wintertime marine DCCs commonly occur during surface circulation conditions of low pressure, high temperature, strong meridional wind, and high relative humidity. Further, the maximum probability of DCCs, according to the high correlation coefficient, was found in the region 10^-20~ east and 5^-10~ south of the center of the cyclones. The potential relationship between DCCs and cyclones regarding their relative locations and circulation conditions was also identified by a case study. Deep clouds were generated in the warm conveyor belt by strong updrafts from baroclinic flows. The updrafts intensified when latent heat was released during the adjustment of the cyclone circulation current. This indicates that the dynamics of cyclones are the primary energy source for DCCs over the NP in winter.
基金This work was financially supported by the Program of YET and NCET and the Specialized Research Fund for the Doctoral Program of Higher Education of MOE of China(No.20050699011).
文摘Spinel LiMn_(2)O_(4)has been considered to be the most promising alternative cathode material for the new generation of lithium-ion batteries in terms of its low cost,non-toxicity and easy manufacture.The spinel lithium manganese mixed oxides were prepared from lithium nitrate,manganese nitrate and citric acid by a sol-gel method and were characterized by thermogravimetric analysis,X-ray diffraction,cyclic voltammetry and constant current charging-discharging technique.The different sintering temperatures for different time have strong influence on the structure,initial discharge capacity and cycling performance of the lithium manganese oxide.It shows that the lithium manganese oxides sintered at 700℃for 10 h have a single spinel structure and better electrochemical properties.The initial discharging capacity can be up to 125.9 mAh·g^(-1),even after six cycles,it still retains 109.1 mAh·g^(-1).
基金the NKBRDPC (Grant No. 2004CB418304)the State Key Task in the 11th Five-Year Plan (06013140B)+1 种基金the NSFC (Grant Nos. 40175015 and 40375018)NFC grant of the Joint Research Fund for Overseas Chinese Young Scholars (Grant No. 40428006)
文摘A 6-year dataset of summer monthly mean precipitation derived from Tropical Precipitation Measure-ment Mission (TRMM)-Microwave Imager (TMI) was used to delineate the spatial distribution patterns of precipitation throughout Asian areas, which indicates that there are three rainfall centers located at the northern coast of the Bay of Bengal, the South China Sea and the western equatorial Pacific Warm Pool, respectively. Based upon the analysis of horizontal distribution, the capability of TMI for characterizing terrestrial and maritime precipitation has been evaluated and compared with Global Precipitation Climatology Project (GPCP) dataset. It was found that TMI and GPCP are well consistent with each other, while a few significant differences occur at several regions over land. By investigating rainfall esti-mates over six specific locations in Asia, a systematic underestimation of TMI was demonstrated, which could be explained by the inherent deficiency within TMI terrestrial algorithm relying on scat-tering signal from ice particles in a precipitation system. A further analysis shows that the highly in-homogeneous distribution of rain gauges employed by GPCP contributes a great deal to the significant discrepancy between GPCP and TMI, especially over regions surrounding the Tibetan Plateau where rain gauges are quite scarce.
