報告書番号

T95053

タイトル（和文）

地球温暖化に伴う東アジア地域の気候変化予測（その４）－高解像度地域気候モデルの性能評価－

タイトル（英文）

PREDICTION OF 2CO2 CLIMATE FOR THE EAST ASIAN REGION (4) EVALUATION OF HIGH-RESOLUTION REGIONAL CLIMATE MODEL PERFORMANCE

概要 （図表や脚注は「報告書全文」に掲載しております）

空間解像度５０ｋｍ（Ｂａｓｅケース），２５ｋｍ（Ｈｉｇｈケース）の地域気候モデルを用いた梅雨期，冬季各１ヵ月の気候再現実験を行い，モデルの高解像度化に伴う影響について検討した。（１）高解像度化に伴って気圧は梅雨期，冬季とも全域的に有意に低下し，再現結果を向上させた。これらは主に中・小低気圧（低圧部）の発達に伴うものであるが，Ｂａｓｅケースで見られた大規模循環場に伴う高気圧の発達を抑制する効果が大きかった。（２）高解像度化の気温への影響は夏季に有意であるが，特に降水パターン（降水強度）の変化に伴う日射量の増加との関連性が示された。（３）高解像度化は領域の中心で降水量を有意に増加させた。低気圧の発達と関連した増加傾向は冬季，梅雨期共通の特徴であるが特に梅雨期に顕著であった。高解像度化に伴う地形の変化について，特に，冬季・日本海側での海岸線の再現精度向上が海岸付近の降水ピーク位置を正しく修正する効果が大きかった。

概要 （英文）

AS THE THIRD STEP IN SERIES OF STUDIES TO EVALUATE THE GCM/REGCM(REGIONAL CLIMATE MODEL) NESTING APPROACH TO PREDICFUTURE CLIMATE CHANGE CAUSED BY GLOBAL WARMING IN THE EAST ASIA REGION,SENSITIVITY ANALYSES WERE CONDUCTED ON THE SPATIALRESOLUTION OF THE MODEL. FOUR MODEL EXPERIMENTS WERE CARRIED OUT WITH A GRID SPACING OF 50KM (BASE CASE) AND 25KM (HIGH CASE),USING ECMWF LARGE-SCALE ANALYSIS OF THE BAI-U SEASON (JUNE1990) AND WINTER SEASON (JANUARY1991) AS LATERAL BOUNDARY CONDITIONS. (1)SEA LEVEL PRESSURE WAS LOWER AND BETTER REPRODUCED IN THE HIGH CASE THAN IN THE BASE CASE BOTH IN JUNE AND JANUALY. INTHE HIGH CASE,THE INTENSITY OF CYCLONES TENDED TO BE STRONGER AND ANTICYCOLONES WERE MODIFIED TO BE WEAK AND REALISTIC,WHICH WERE NOT WELL REPRODUCED IN THE BASE CASE IN BOTH SEASONS. (2)THE HIGH-RESOLUTION EFFECTS OF THE MODEL ON SURFACE AIR TEMPERATURE WERE SIGNIFICANT IN THE SUMMER SEASON,WHICH SEEMS TO RESULT FROM INCREASES IN SUNSHINE DURATION CAUSED BY INTENSIFICATION OF CYCLONES OR RELATED WEATHER PATTERN CHANGES. (3)THE HIGH-RESOLUTION MODEL INCREASES PRECIPITATION IN THE CENTRAL REGION OF THE DOMAIN IN BOTH SEASONS,ESPECILLY THE RAINY SEASON (JUNE),WHICH IS CAUSED MAINLY BY INTENSIFICATION OF CYCLONES. FOR THE DIRECT TOPOGRAPHIC EFFECTS ON PRECIPTATION,THE MORE REALISTIC GEOGRAPHICAL POSITION OF SHORELINE IN THE HIGH CASE REPRODUCED THE PEAK OF PRECIPITATION WELL IN WINTER ALONG THE REGION FACING THE JAPAN SEA.

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