近20年青藏高原云分布特征及云参数时空变化分析

Spatial and Temporal Variations of Cloud Parameters over the Qinghai-Xizang Plateau during the Past Two Decades

准确估算云量是了解青藏高原云参数时空特征的基础。通过相关分析、回归分析、趋势分析方法,分析了近21年来青藏高原云分布的动态变化。利用MODIS云量日产品(MOD08_D3)数据和ERA5再分析资料,分析了青藏高原不同阶段云量分布和云参数的时空特征。结果表明,高云区云量中心位于墨脱县(77.3%),林芝(72.5%)地区云量最大,青藏高原日平均云量在过去21年间减少了0.04%。季节分布上,夏季出现水云的概率最高(31.7%),春季出现冰云的概率最高(26.5%)。每年出现的冰云比水云高2%左右。在全球变暖背景下,青藏高原上空水汽含量呈减少趋势,云水含量呈逐渐增加趋势。年平均云水含量比大气总水汽含量高约0.01 cm,云水总含量增加约0.04 cm。本研究为理解云水资源对全球气候变化和青藏高原地区水循环的影响提供了依据。

Accurate estimation of cloud cover is the basis for understanding the spatial and temporal characteristic of cloud parameters on the Qinghai-Xiznag Plateau(QXP).The dynamic changes in cloud distribution on the Qinghai-Xiznag Plateau are analyzed by the correlation analysis,regression analysis and trend analysis method.Using the MODIS cloud daily product(MOD08_D3) data and ERA5 reanalysis data from 2000 to 2020,the temporal and spatial characteristics of cloud distribution and cloud parameters in different phases over the Tibetan Plateau are analyzed.The results show that the high cloud cover center is located in Medog County(77.3%),and Nyingchi(72.5%) is the maximum cloud cloud-covered area.The total cloud cover over the QXP has decreased by 0.04% in the past 21 years.Regarding seasonal distribution,the probability of liquid water clouds present in Summer is the highest(31.7%),and the probability of ice clouds present in Spring is the highest(26.5%).The ice cloud occurrence per year is about 2% more than liquid cloud.Under the background of global warming,the atmospheric water vapor over the QXP shows a decreasing trend,whereas the cloud water content shows a gradually increasing trend.The annual average cloud water vapor is about 0.01 cm higher than the total atmospheric water vapor,and the total cloud water vapor increased by about 0.04 cm.This study provides a basis for understanding the influence of cloud water resources on global climate change and the water cycle over the QXP.