Based on idealized numerical simulations, the impacts of the diurnal cycle of solar radiation on the diurnal variation of outer rainbands in a tropical cyclone are examined. It is found that cold pools associated with...Based on idealized numerical simulations, the impacts of the diurnal cycle of solar radiation on the diurnal variation of outer rainbands in a tropical cyclone are examined. It is found that cold pools associated with precipitation-driven downdrafts are essential for the growth and propagation of spiral rainbands. The downdrafts result in surface outflows, which act as a lifting mechanism to trigger the convection cell along the leading edge of the cold pools. The diurnal cycle of solar radiation may modulate the diurnal behavior of the spiral rainbands. In the daytime, shortwave radiation will suppress the outer convection and thus weaken the cold pools. Meanwhile, the limited cold pool activity leads to a strong modification of the moisture field, which in turn inhibits further convection development.展开更多
To investigate the impacts of the diurnal cycle on tropical cyclones （TCs）,a set of idealized simulations were conducted by specifying different radiation （i.e.,nighttime-only,daytime-only,full diurnal cycle）.It w...To investigate the impacts of the diurnal cycle on tropical cyclones （TCs）,a set of idealized simulations were conducted by specifying different radiation （i.e.,nighttime-only,daytime-only,full diurnal cycle）.It was found that,for an initially weak storm,it developed faster during nighttime than daytime.The impacts of radiation were not only on TC intensification,but also on TC structure and size.The nighttime storm tended to have a larger size than its daytime counterparts.During nighttime,the radiative cooling steepened the lapse rate and thus reduced the static stability in cloudy regions,enhancing convection.Diabatic heating associated with outer convection induced boundary layer inflows,which led to outward expansion of tangential winds and thus increased the storm size.展开更多
The one-dimensional Kraus- Turner mixed layer model improved by Liu is developed to consider the effect of salinity and the equa- tions of temperature and salinity under the mixed layer. On this basis, the processes o...The one-dimensional Kraus- Turner mixed layer model improved by Liu is developed to consider the effect of salinity and the equa- tions of temperature and salinity under the mixed layer. On this basis, the processes of growth and death of surface layer temperature inversion is numerically simulated under different environmental parameters. At the same time, the physical mechanism is preliminari- ly discussed combining the observations at the station of TOGA- COARE 0°N, 156°E. The results indicate that temperature inversion sensitively depends on the mixed layer depth, sea surface wind speed and solar shortwave radiation, etc., and appropriately meteoro- logical and hydrological conditions often lead to the similarly periodical occurrence of this inversion phenomenon.展开更多
基金sponsored by the National Science Foundation of China (Grant No. 41575056)the Key Basic Research Program of China (Grant No. 2015CB452803)+2 种基金the State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences (Grant No. 2014LASW-B08)a “Six Peaks of High-Level Talents” funded projectthe Key University Science Research Project of Jiangsu Province (Grant No. 14KJA170005)
文摘Based on idealized numerical simulations, the impacts of the diurnal cycle of solar radiation on the diurnal variation of outer rainbands in a tropical cyclone are examined. It is found that cold pools associated with precipitation-driven downdrafts are essential for the growth and propagation of spiral rainbands. The downdrafts result in surface outflows, which act as a lifting mechanism to trigger the convection cell along the leading edge of the cold pools. The diurnal cycle of solar radiation may modulate the diurnal behavior of the spiral rainbands. In the daytime, shortwave radiation will suppress the outer convection and thus weaken the cold pools. Meanwhile, the limited cold pool activity leads to a strong modification of the moisture field, which in turn inhibits further convection development.
基金sponsored by the National Natural Science Foundation of China (Grant Nos. 41275095, 41075037)the National Key Basic Research Program of China (Grant No.2012CB955204)the Key University Science Research Project of Jiangsu Province (Grant No.14KJA170005)
文摘To investigate the impacts of the diurnal cycle on tropical cyclones （TCs）,a set of idealized simulations were conducted by specifying different radiation （i.e.,nighttime-only,daytime-only,full diurnal cycle）.It was found that,for an initially weak storm,it developed faster during nighttime than daytime.The impacts of radiation were not only on TC intensification,but also on TC structure and size.The nighttime storm tended to have a larger size than its daytime counterparts.During nighttime,the radiative cooling steepened the lapse rate and thus reduced the static stability in cloudy regions,enhancing convection.Diabatic heating associated with outer convection induced boundary layer inflows,which led to outward expansion of tangential winds and thus increased the storm size.
文摘The one-dimensional Kraus- Turner mixed layer model improved by Liu is developed to consider the effect of salinity and the equa- tions of temperature and salinity under the mixed layer. On this basis, the processes of growth and death of surface layer temperature inversion is numerically simulated under different environmental parameters. At the same time, the physical mechanism is preliminari- ly discussed combining the observations at the station of TOGA- COARE 0°N, 156°E. The results indicate that temperature inversion sensitively depends on the mixed layer depth, sea surface wind speed and solar shortwave radiation, etc., and appropriately meteoro- logical and hydrological conditions often lead to the similarly periodical occurrence of this inversion phenomenon.
