Analysis of a Relatively Dry Front during the Taiwan Area Mesoscale Experiment

Abstract

Abstract The evolution of a relatively dry front during the early-summer rainy Season of Taiwan is analyzed. Because of the synoptic subsidence associated with a subtropical high pressure cell over the northern South China Sea, prefrontal soundings over the Taiwan area exhibited a shallow, warm, moist layer in the lowest levels, capped by an inversion with extremely dry air aloft. Over the Taiwan area, the southwest flow ahead of the surface front was more than 10 m s−1 at the 850-mb level. It interacted with the central mountain range, resulting in the windward ridge, leeside trough. Downstream of the blocked region, strong southwesterly winds (∼1 5 m s−1) developed in the lowest levels along the northwest coast, where the flow deflected by the mountain barrier merged with the undetected southwest monsoon flow. The hilly terrain along the southeastern China coast retarded the cold air behind the surface front. The cold air was then ducted around the southeastern China coast. At the 850-mb level, a weak s...