摘要
大气冰冻圈是大气层内所有冰体的总称,包括冰晶、雪花等,对全球辐射平衡、水循环和灾害天气的形成均具有重要影响,长期以来受到广泛关注.然而,将大气冰冻圈作为一个整体圈层的定量研究较少,相关认识基本停留在概念和理论阶段.本文基于CloudSat和CALIPSO卫星数据联合反演的DARDAR产品,估算了全球大气冰冻圈的总量、三维空间分布和季节变化特征.结果显示:大气冰冻圈总质量约为63[58.8~65.7]Gt,上界为高层冰云的云顶,下界略低于零温层.大尺度环流系统决定了大气冰冻圈的纬向带状分布特征,冰晶形成与增长的微物理机制导致大气冰体在热带上空–8°C等温层出现高值中心.大气冰体的高值区主要分布于低纬度强对流区,从垂直剖面上看,主要分布于对流层中层和低层.痕量冰区(冰水路径<15.0 g/m^(2))主要分布于副热带等高压系统控制区.在高海拔地区,由于水汽含量较低,大气冰含量整体偏低,如青藏高原冬季冰水路径仅为31.3 g/m^(2),约为全球平均值的四分之一.该项研究为进一步认识大气冰冻圈的天气气候效应奠定了基础.
The aerial cryosphere includes all ice bodies in the atmosphere, which are widely distributed in the troposphere and lower stratosphere. It plays an important role in the global radiation budget, water cycle and the formation of disastrous weather.Understanding the spatiotemporal distribution of these ice bodies is therefore the basis for quantifying the climatic effects of aerial cryosphere. However, there are few quantitative studies on the aerial cryosphere, leading to the related knowledge remaining at the conceptual and theoretical stage. The goal of this study is to estimate the total mass, spatial distribution and seasonal variation of the aerial cryosphere through evaluating ice bodies in the atmosphere based on the DARDAR satellite product during 2007–2010. The DARDAR product is jointly retrieved from CloudSat and CALIPSO satellite measurements, which can describe the thin cirrus clouds and the vertical structure of thick clouds, thus enabling identification of the ice bodies in the whole atmospheric column. Results show that the total mass of the aerial cryosphere was about 63[58.8~65.7] Gt during the period with satellite observation. The concentrations of atmospheric ice range from10–6to 1 g/m^(3)around the globe. More than 99% of the total ice mass in the atmosphere located in places with ice concentrations higher than 10–3g/m^(3). In general, the top of the aerial cryosphere is located at the tropopause or the lower stratosphere, depending on the height of the top of the high-level cirrus clouds. The bottom of aerial cryosphere is slightly lower than the zero-temperature layer. Furthermore, the reasons for the spatial difference of atmospheric ice are explored based on ERA5 reanalysis data. It shows that the large-scale circulation systems determine the zonal distribution of the aerial cryosphere, and the microphysical mechanism responsible for ice crystal formation and growth leads to the high ice concentration at –8°C isothermal layer above the tropics. Vertically, the ice bodies were mainly distributed in the middle and lower troposphere. The high ice concentration areas were mainly distributed in the deep convective areas at low latitudes. In addition, the sharp drop in air temperature due to frontal uplift and radiation cooling can also promote the formation of a large number of ice crystals, which is another important reason leading to the high concentration area. The trace ice areas(ice water path < 15 g/m~2) were mainly distributed in the areas under the control of high-pressure systems,such as subtropical high-pressure zones. At high-altitude areas, lower atmospheric ice concentrations are observed mainly due to the scarce water vapor over these areas. The ice water path in the Qinghai-Tibet Plateau in boreal winter, for example, was only 31.3 g/m~2in average during 2007–2010, which was approximately a quarter of the global mean value.There are obvious seasonal differences in the spatial distribution of the aerial cryosphere. In the tropics, for example, the high ice concentration areas are mainly distributed in the north of the equator in northern summer, while they are mainly distributed in the south of the equator in northern winter. The seasonal variation of the total ice mass is relatively small. It is slightly less in northern winter than in the other seasons. The main reason for that is the retreat of high ice concentration areas near the equator and the strengthening of the high-pressure systems over the North American and the central Eurasian in northern winter.
作者
许高洁
窦挺峰
杨一帆
岳瀚栋
胡斯勒图
马丽娟
效存德
Gaojie Xu;Tingfeng Dou;Yifan Yang;Handong Yue;Husi Letu;Lijuan Ma;Cunde Xiao(College of Resources and Environment,University of Chinese Academy of Sciences,Beijing 100049,China;State Key Laboratory of Remote Sensing Science,Aerospace Information Research Institute,Chinese Academy of Sciences,Beijing 100094,China;National Climate Center,China Meteorological Administration,Beijing 100081,China;State Key Laboratory of Earth Surface Processes and Resource Ecology,Beijing Normal University,Beijing 100875,China)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2022年第34期4130-4139,共10页
Chinese Science Bulletin
基金
国家自然科学基金(41971084,42222608)资助。
关键词
大气冰冻圈
强对流
冰水路径
零温层
痕量冰区
aerial cryosphere
deep convection
ice water path
zero temperature layer
trace ice area
