On the Formation of Convective Cloud Cells during Cold Air Outbreaks in AMTEX '75
1978 Volume 29 Issue 2 Pages 65-73
Details
1978 Volume 29 Issue 2 Pages 65-73
An analytical study was done on two cases, that is, on 15th and 22nd Feb., when a typical convective cloud cell structure appeared over the AMTEX area by cold air outbreaks from the continent. DMSP satellite pictures both visual and infrared and the AMTEX aerological data were mainly used for the analysis.
According to the result of analysis of the case on 15th Feb., there was a single mixing layer extending from the northwestern coastal region of the East China Sea to the southeast of the AMTEX area. The height and temperature of the mixing layer was, respectively,900 mb and 0°C at the northwestern region, reaching to 800 mb and 4°C around NAHA and then lowering again but further rising in temperature to the southeast. From the consideration of humidity distribution, the existence of clouds could be recognized at the upper part of the mixing layer. This could be interpreted as a continental cold air mass being warmed from the sea surface below and giving rise to a mixing layer which grew taller and taller until around NAHA, until it merged into the inversion layer directly connected with the polar front.
In the case of 22nd Fe b., a similar mixing layer to the case of 15 Feb. was observed in the southern part of the East China Sea including NAHA and the RYOFUMARU but another mixing layer, of a different kind, could be observed in the northern part including CHEJU ISLAND and KAGOSHIMA. This second one is taller and colder than the first, that is, with a height and temperature of 700 mb and 20°C respectively. This latter layer corresponded to the cloud region of open cell structure that was discussed by Agee. In this latter case, the air mass transformation was active and the mixing layer reached higher levels on 22nd than on 15th. The difference of the mixing layer thickness seems to be the cause of the appearance of closed and open cell type convective cloud. Following the Agee's discussion of this phenomenon on extensive statistics, our case of the AMTEX satellite pictures seems to have shown the convective cell developing from the less flat radar cell through the flat closed cell until to that of the more flat open cell.
