Comparative Analysis of Marine Atmospheric Boundary Layer Height Changes in the East China Sea Based on FNL and ERA5 Data

Abstract

This study compiled the NCEP FNL and ERA5 data from 2010 to 2019 to study the characteristics of the height changes of the marine atmospheric boundary layer (MABL) in the East China Sea and selected coastal (region A), offshore (region B), and Kuroshio areas (region C) for comparative analysis. The results show that, in general, the MABL heights of both datasets show a decreasing trend year by year, and the FNL decreasing trend is more significant. The two datasets show the largest difference in the eastern regions, while they are more consistent in the Taiwan Strait, suggesting substantial regional variations. The FNL decreasing trend is more significant than the ERA5 decreasing trend in regions A, B and C from 2014 to 2017. The root mean square (RMS) of the difference between FNL and ERA5 MABL is the largest in winter, followed by summer, showing significant seasonal variations. Regional MABL variations in the ERA5 dataset were more pronounced in summer and the areas with greater regional variations coincided with the areas with mean absolute differences and the RMS large value area of the MABL variation. Both datasets show region A had the largest differences in fall while regions B and C had the largest differences in winter. In terms of daily variation, both MABL reached their highest at 14:00, with the largest differences at 14:00 in regions A and C and at 20:00 and 02:00 in region B. Region A had the largest daily variations as reflected by its largest mean absolute difference and RMS of the 14:00 MABL differences. The effect of seasonal and daily variations in different regions must be considered to study the variation of MABL height in the East China Sea.