Preprints
https://doi.org/10.5194/egusphere-2023-347
https://doi.org/10.5194/egusphere-2023-347
08 Mar 2023
 | 08 Mar 2023
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Atmospheric boundary layer structure over the Arctic Ocean during MOSAiC

Shijie Peng, Qinghua Yang, Matthew D. Shupe, Xingya Xi, Bo Han, Dake Chen, and Changwei Liu

Abstract. The important roles of the atmospheric boundary layer (ABL) over the Arctic Ocean in the Arctic climate system have been recognized, but the atmospheric boundary layer height (ABLH), as a fundamental variable to characterize the vertical structure of ABL, has rarely been investigated. Analyzing a year-round radiosonde dataset during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC), we suggest the optimal critical value of 0.15 of bulk Richardson number to derive ABLH. Based on this algorithm, the hourly ABLH values are derived to analyze the characteristics and variability of ABLH over the Arctic Ocean. The results reveal that the annual cycle is clearly characterized by a distinct peak in May and an abrupt decrease in the following July and August, with a second minimum in December and January. The annual ABLH variation is primarily controlled by the evolution of ABL thermal structure. The temperature inversions in the winter and summer are intensified by seasonal radiative cooling and surface melting, respectively, leading to the low ABLH. The near-surface conditions can also play a significant role in ABLH variation, with turbulent parameters (e.g., friction velocity and turbulent dissipation rate) well correlated with the ABL development. In addition, the MOSAiC ABLH is more suppressed than the ABLH during the Surface Heat Budget of the Arctic Ocean (SHEBA) experiment in the summer, which indicates that there is large variability in the Arctic ABL structure during summer melting season.

Shijie Peng et al.

Status: open (until 19 Apr 2023)

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  • RC1: 'Comment on egusphere-2023-347', Anonymous Referee #1, 26 Mar 2023 reply

Shijie Peng et al.

Shijie Peng et al.

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Short summary
Due to the lack of observations, the structure of Arctic atmospheric boundary layer (ABL) remains to be further explored. By analyzing a year-round radiosonde dataset collected over the Arctic sea-ice surface, we found the annual cycle of the ABL height (ABLH) is primarily controlled by the evolution of ABL thermal structure, and the surface conditions also show high correlation with the ABLH variation. In addition, the Arctic ABLH is found to be decreased in summer compared with 20 years ago.