Spring Planetary Boundary Layer Structure and Corresponding Cloud Characteristics Under Different Prevailing Wind Directions Over the Kuroshio Sea Surface Temperature Front in the East China Sea

Abstract

AbstractThe planetary boundary layer (PBL) structure and corresponding stratocumulus (Sc) clouds under different prevailing wind directions over the East China Sea were studied using CloudSat and sounding observations from March–April 2007–2017. The dominant factors affecting the PBL structure and atmospheric response mechanism associated with the Kuroshio sea surface temperature front (SSTF) differed under the three prevailing wind directions. When northeasterly (NE) wind prevails, the opposite spatially high‐pass‐filtered meteorological parameters between the warm tongue and cold pool indicate that the PBL structure is predominantly determined by the SSTF via the sea level pressure adjustment mechanism. However, when northwesterly (NW) and southeasterly (SE) winds prevail, a downward kinetic energy tongue extends from the free atmosphere to the sea surface, indicating that the dynamic PBL structure is predominantly controlled by atmospheric circulation. The (minor) difference in relative humidity between the cold and warm sides indicates that the thermodynamic PBL structure is dominated by the SSTF through the vertical mixing mechanism (by atmospheric circulation) under NW (SE) prevailing wind. Completely different PBL structures lead to different temperature inversion (TI) and Sc cloud characteristics under the three prevailing wind directions. TI mainly occurs as low tropospheric inversion over the warm tongue, while the frequency of near‐surface inversion is large over the cold pool under NE and SE prevailing wind directions. The Sc cloud fraction over the warm tongue is two times larger than that over the cold pool under NE prevailing wind and is the largest (smallest) when NW (SE) wind prevails.