Research On The Temporal And Spatial Distribution Of Atmospheric Boundary Layer Height In The Yangtze River Delta Based On CALIPSO And Sounding Dat

The Atmospheric Boundary Layer Height(ABLH)represents the degree of vertical mixing within the boundary layer and the exchange between the free convective layer,which affects the distribution of aerosols,convection activity,and land-sea surface fluxes.Studying its spatio-temporal distribution patterns is of great significance.In this article,based on CALIPSO and sounding data,the ABLH during three time periods(morning,midday,and evening)in the Yangtze River Delta region was inverted.The relationship between ABLH and DEM,NDVI,and ground meteorological elements under different spatio-temporal conditions was also studied,leading to the following conclusions:(1)Compared with the ABLH inverted from sounding data,the Leventidou method has the best fitting accuracy among the commonly used CALIPSO satellite inversion methods for ABLH compared with the Maximum Variance Method and Wavelet Covariance Transform Method.Additionally,the seasonal variation of ABLH obtained by the Leventidou method is consistent with that obtained from sounding data,making it the optimal method at present.(2)The midday ABLH in the Yangtze River Delta region is stable on an interannual scale,with the following seasonal order: spring(1.74 km)> summer(1.58 km)>autumn(1.54 km)> winter(1.44 km).Regardless of the average distribution of ABLH over multiple years or each season,it gradually increases from coastal to inland regions,with the main differences in spatial distribution being reflected in the northwest and north-central parts.In terms of frequency distribution,ABLH in the range of 1.2-1.5 km is the most common,accounting for 68.5% of ABLH in the range of 0.6-2.1 km,and there are even ultra-high ABLH values exceeding 4.2 km.The spatio-temporal distribution of morning and evening ABLH differs significantly from that of midday ABLH,with coastal sites exhibiting higher values than hilly sites in multiple seasons.For both morning and evening detection times,the highest values at each site appear in summer,while the lowest values at 8 am occur in winter but not necessarily at 8 pm In terms of frequency distribution,ABLH is most common in the range of 0-0.1 km,and there are hardly any ABLH values above 2 km.(3)The spatial distribution of midday ABLH is highly positively correlated with DEM and NDVI,which is extremely significant on both an interannual and seasonal scale(P<0.01).At 8 am and 8 pm,the ground wind speed(WS)at each site has the highest correlation with ABLH.Ground temperature(TS)and pressure(PS)show no significant relationship with ABLH at the Quzhou station,but exhibit significant positive or negative correlations at other stations under different spatio-temporal conditions.Relative humidity(RH)shows significant negative correlations with ABLH under all spatio-temporal conditions except for 8 pm at the Quzhou and Shanghai stations,where it exhibits significant positive correlations.The correlation between LTS and ABLH varies at each site.Ground meteorological elements have the greatest impact on ABLH at the Shanghai station at 8 am,but other factors may also influence it.The effects of ground meteorological elements are more stable at the Xuzhou and Quzhou stations,while they decrease at the Quzhou and Shanghai stations at 8 pm,and other factors affecting ABLH become more apparent.WS is the most important factor affecting ABLH development under all spatio-temporal conditions,and the Quzhou station located in the hills is mainly affected by RH except for WS.Except for WS,TS and PS have a high importance in influencing ABLH at most stations,while LTS has the weakest importance under all spatio-temporal conditions.