Climatic Variations in the Boundary Layer Height of Arid and Semiarid Areas in East Asia and North Africa

Abstract

Based on the ERA-20C, climatic variations of the boundary layer height (BLH) over arid and semiarid areas in East Asia and North Africa that span 1900-2010 were analyzed. In East Asia, the BLH exhibited a descending trend from arid region centers to the periphery. Over the past 111 years, the BLH has had a rising trend of 14.0 m decade . in the representative region (NA2) of other regions with the 111-year average of 882 m. In the 1940s and the 1970s, NA1's BLH had two obvious increases that caused the average to increase by 51 m and 22 m, respectively, while NA2's BLH had two obvious declines that caused the average to decrease by 48 m and 7 m, respectively. On the spatial distribution, the BLH, sensible heat flux, latent heat flux, and volumetric soil water had a good corresponding relationship. On the temporal change, the BLH in East Asia had a stronger correlation with thermodynamic factors, whereas the BLH in North Africa had a stronger correlation with dynamic factors. Besides, the upper-level stratification also has some influence on the BLH's change.

Characteristics and relationships between daily maximum boundary layer height and precipitation in the arid and semi‐arid regions of East Asia

“…This is similar to the findings of Zhao et al . (2017a,b) who verified the applicability of the BLH dataset in arid and semi‐arid regions of East Asia by comparing the sounding data with the ERA‐Interim dataset. These indicate that the ERA‐20C data should have good applicability within the study area.…”

Diurnal climatology of correlations between the planetary boundary layer height and surface meteorological factors over the contiguous United States

“…It is shallow at night (<500 m) as a result of surface radiation cooling but deepens during the day (by several kilometres) mainly due to solar heating (Molod et al ., 2015). In addition to surface radiation, the PBLH is also closely related to meteorological factors such as the cloud cover, soil moisture content, wind speed, surface temperature, and specific humidity (Wang and Wang, 2004; Molod et al ., 2015; Zhao et al ., 2017). A further exploration of the relationship between the PBLH and meteorological factors will help us to better understand the evolution of the boundary layer structure and its association with land–atmosphere feedback mechanisms.…”

“…There are also spatial variations in the correlations between the PBLH and meteorological factors (Seidel et al, 2012;Guo et al, 2016). Based on monthly reanalysis data, Zhao et al (2017) reported that the PBLH trend in East Asia has a stronger correlation with thermodynamic (the surface sensible and latent heat fluxes) than dynamic (wind components and wind shear) factors, whereas in North Africa, the PBLH trend has a stronger correlation with dynamic factors. This partly results from the internal spatial variability of the PBLH (Zhang et al, 2020b), which may be attributed to hydrological factors (Seidel et al, 2012).…”

Relationship between the development of a convective mixed layer and dust weather in arid and semi‐arid regions of East Asia

“…Gamo (1996) and Zhao et al . (2017) investigated the characteristics of the PBL height in arid/semi‐arid regions, but they did not examine the relationship of the PBL characteristics with the occurrence of dust events.…”

“…However, the relationship between the development of convective mixed layers and the occurrence of dust events is not well documented from a statistical point of view. Gamo (1996) and Zhao et al (2017) investigated the characteristics of the PBL height in arid/semi-arid regions, but they did not examine the relationship of the PBL characteristics with the occurrence of dust events.…”