SHIPBOARD AND HELICOPTER-BORNE OBSERVATIONS OF LOW-ALTITUDE TEMPERATURE INVERSION LAYER OFF THE SOUTH COAST OF KANTO AREA

Abstract

The low-altitude inversion layer above the ocean prevents the diffusion of the aircontaminants released in the coastal area. Additionally, it is known that the vertical gradient of water vapor pressure increases due to the suppressed diffusion in the inversion layer and the duct propagation phenomenon of the microwave arises under the layer. Therefore, the inversion layer affects the radar operation. Observations of vertical profiles of temperature and humidity in the lower atmosphere off the south coast of Kanto were carried out on 12 May 1999 (helicopter-borne) and 3 July 2000 (shipboard) in order to clarify the structure of an inversion layer above the ocean. The inversion layer was found out at the height near several hundred meters in both observations. Aerological data enclosing the area of shipboard observation indicate that environmental downward air motion seems to have some crucial role on the forming of the stable layer. On the other hand, aerological data indicate upward air motion in helicopter-bome observation. Sea surface temperature and surface wind distribution show the existence of the Stable Thermal Internal Boundary Layer. The observed layer seems to be the top layer of the boundary layer.