Diurnal asymmetry of desert amplification and its possible connections to planetary boundary layer height: a case study for the Arabian Peninsula
Diurnal asymmetry of desert amplification and its possible connections to planetary boundary layer height: a case study for the Arabian Peninsula
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DOI：
10.1007/s00382-021-05634-x
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发表时间：
2021-01
期刊：
影响因子：
4.6
通讯作者：
Liming Zhou
中科院分区：
文献类型：
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作者：
Liming Zhou
利用观测、再分析数据和气候模式模拟的最新研究表明，在世界上最热和最干燥的撒哈拉沙漠和阿拉伯半岛，2 m地表气温（T2 m）被放大，称为沙漠放大（DA）。这项研究对1979-2018年期间的每小时地面观测，无线电探空仪测量和两个最新的最先进的再分析产品进行了全面分析，以检查DA的日变化和垂直变化及其与行星边界层高度（PBLH）的联系。它的重点是阿拉伯半岛（AP），那里的观测相对丰富，而撒哈拉地区的数据稀缺。观测资料和再分析资料都表明，地面增温率的日变化在一定程度上与气候PBLH的大小成反比，因此DA具有明显的日不对称性，PBLH越浅，增温越强。高层大气廓线的分析结果表明，DA是一个底部重的增暖廓线，在近地面最大，随高度迅速减小，仅限于对流层低层（> 700 hPa）和地面。主要的PBLH偏差可以解释，至少部分地，在再分析的一些昼夜和垂直的升温/降温的偏见。这些结果表明，除了地面辐射强迫，PBLH可能发挥重要作用，通过湍流混合热量再分配调制的昼夜和垂直结构的DA在AP。
Recent studies using observations, reanalysis data and climate model simulations documented that 2 m surface air temperature (T2m) has been amplified over the world’s hottest and driest Sahara Desert and the Arabian Peninsula, referred to as desert amplification (DA). This study presents a comprehensive analysis of hourly surface observations, radiosonde measurements, and two latest state-of-the-art reanalysis products for the period 1979–2018 to examine the diurnal and vertical variations of DA and their connections with planetary boundary layer height (PBLH). It focuses on the Arabian Peninsula (AP), where observations are relatively abundant compared to the data scarce Sahara regions. Both observational and reanalysis data show that the diurnal cycle of surface warming rate depends, to some extent, inversely on the magnitude of climatological PBLH, and so DA has a distinct diurnal asymmetry with a stronger warming for a shallower PBLH. Results of upper air profiles reveal that DA is a bottom-heavy warming profile, which maximizes near the surface, decreases quickly with height, and is limited to the lower troposphere (> 700 hPa) and surface. The major PBLH biases could explain, at least partially, some of the diurnal and vertical warming/cooling biases in the reanalyses. These results suggest that besides the surface radiative forcing, the PBLH may play an important role in modulating the diurnal and vertical structure of DA over the AP through heat redistributing via turbulent mixing.