17:15 〜 18:45
[AAS08-P02] Topographic Convergence Zone due to the Chubu Mountains in the Winter Northwesterly Winds
キーワード：地形性収束線、冬季季節風、駿河湾南東沖
Kawamura(1966) reported that the topographic convergence zone associated with the Chubu Moutains is formed over Suruga Bay in the northwesterly wind field in winter. For this topographic convergence zone, we have performed statistical analyses of pressure and wind fields from 2006 to 2023 using the Japan Meteorological Agency Meso-Scale Model (MSM) dateset. First of all, we calculated the sea level pressure difference between Fukuoka and Nemuro as an indicator of the typical winter pressure distribution which is so-called high pressure in the west and low pressure in the east. The results of the composite analysis (when a distribution of atmospheric pressure in which high pressure lies to the west and low pressure to the east) show that convergence zone are formed in the southern part of Hokkaido and the Kanto coast to Suruga Bay. This is same level with Japan sea Polar airmass Convergence Zone(JPCZ), which bringing heavy snow to Japan Sea coastal areas. Thus topographic convergence zone was prominently identified for the case study of late December 2017, we discussed focuses on the vertical structure. The typical winter pressure distribution was shown from 25th to 27th December 2017, and a topographic convergence zone was identified on 25th December. Convergence values between the strong west winds of south of the topographic convergence zone and the weak north winds that bypassed Chubu Mountains were of the order of 2–6 × 10−4 s−1 . Although some zonal low-level clouds were seen on the Pacific side at the same time, rain-bringing clouds are present on this topographic convergence zone. Convergence on the ground was to about 900 hPa above the surface and diverged above that to about 700 hPa. At the time of our presentation, we plan to discuss a comparison with the JPCZ.