Investigation of near-global daytime boundary layer height using high-resolution radiosondes: first results and comparison with ERA5, MERRA-2, JRA-55, and NCEP-2 reanalyses

Abstract. The planetary boundary layer (PBL) governs the vertical transport of mass, momentum, and moisture between surface free atmosphere, thus determination PBL height (BLH) is recognized as crucial for air quality, weather, climate analysis. Although reanalysis products can provide important insight into global view BLH in a seamless way, observed situ on scale remains poorly understood due to lack high-resolution (1 or 2 s) radiosonde measurements. present study attempts establish near-global climatology at synoptic times (00:00 12:00 UTC) daytime using measurements over 300 sites worldwide period 2012 2019, which then compared against BLHs obtained from four datasets, including ERA5, MERRA-2, JRA-55, NCEP-2. variations exhibit large spatial temporal dependence, result maxima are generally discerned regions such western United States China, balloon launch mostly correspond afternoon. diurnal revealed with peak 17:00 local solar time (LST). most promising product underestimates by around 130 m radiosondes released during daytime. In addition, MERRA-2 well-established has an underestimation 160 m. JRA-55 NCEP-2 might produce considerable additional uncertainties, much larger up 400 largest bias data appears it be attributed maximal afternoon when risen. Statistical analyses further indicate that biases positively associated orographic complexity, well occurrence static instability. To our best knowledge, this presents first radiosonde-derived provides quantitative assessment frequently used products.