報告書番号

285011

タイトル（和文）

オキシダント濃度に及ぼすバックグラウンドオゾンの影響（２）－関東内陸地域における高濃度オキシダントの生成機構－

タイトル（英文）

IMPACT OF BACKGROUND OZONE ON THE GROUND-LEVEL OXIDANT CONCENTRATION IN THE METROPOLITAN AREA-2-

概要 （図表や脚注は「報告書全文」に掲載しております）

１９８３年４月～１９８４年４月の約１年間，赤城山で実施したオゾンの連続観測データなどをもとに，関東の内陸地域におけるオキシダント濃度に及ぼすバックグラウンドオゾンの影響について検討した。観測データは移動平均法を適用して周期と振幅とが異なる三つの成分に分離し，各成分と気象条件との関係を調べた。山頂における濃度変動は（１）成層圏と対流圏との間のオゾンの交換（１年周期），（２）低気圧の後面におけるバックグラウンドオゾンの取り込み（数日周期）および（３）大気下層におけるオキシダントの生成と局地風系による輸送（１日周期）の三つを重畳したものである。山頂における高濃度エピソードの発生は（２）と（３）による。（２）は主に春の高濃度に，また（３）は主に春と夏の高濃度に寄与している。

概要 （英文）

OZONE CONCENTRATIONS WERE MEASURED AT TWO STATIONS IN MT. AKAGI(1380 AND 470 IN ALTITUDES), LOCATED IN THE NORTHERNKANTO DURING A PERIOD FROM APRIL 1983 TO APRIL 1984. THE CONTRIBUTION OF BACKGROUND OZONE TO THE GROUND-LEVEL AIR QUALITY IN THE INLAND AREA OF KANTO DISTRICT WAS DISCUSSED BASED ON THE DATA OBTAINED. PREFECTURALOXIDANT MONITORING NETWORK DATA AND AEROLOGICAL OBSERVATORY S TOTAL OZONE AMOUNTS DATA WERE ALSO USED FOR THE ANALYSIS. A MOVING AVERAGING METHOD WAS APPLIED TO DIVIDE SOME COMPONENTS WITH DIFFERENT PERIODS AND AMPLITUDES IN THE OBSERVED CONCENTRATION CURVE. TEMPORAL VARIATION IN THE CONCENTRATION OF OZONE WERE DIVIDED INTO THREE PARTS, I.E., VARIATIONWITH A YEAR PERIOD, VARIATION WITH A FEW DAYS PERIOD, AND VARIATION WITH A 24-HOURS PERIOD. THE FORMER WAS SUGGESTED TO RELATE THE EXCHANGE OF OZONE BETWEEN STRATOSPHERE AND TROPOSPHERE, THE MIDDLE, THE TAKE-IN PROCESS OF BACKGROUND OZONE BEHIND CYCLONIC DISTURBANCES AND THE LATTER,THE FORMATION AND DISPERSION OF OXIDANTS IN THE LOWER ATMOSPHERE. TYPICAL ANNUAL MEAN OZONE LEVELS WERE ESTIMATED AS 37 PPB AT THE SUMMIT OF MT. AKAGI, 22 PPB AT ISEZAKI-GUNMA, AND 16 PPB AT KOMAE-TOKYO. THE HYPOTHESIS THAT THE TAKE-IN PROCESS OF BACKGROUND OZONE CONTRIBUTE TOTHE GENERATION OF HIGH OXIDANT EPISODES OBSERVED IN THE INLAND AREA IN SPRINGAND SUMMER SEASON COULD NOT BE SUPPORTED FROM THE ANALYSIS. THE FORMATION AND DISPERSION OF OXIDANTS WAS CONSIDERED TO CONTRIBUTE AN IMPORTANT ROLE ON THE DIURNAL VARIATION OF OZONE EVEN AT THE SUMMIT OF MT. AKAGI. METEOROLOGICAL ANALYSIS SUGGESTED THAT THE OZONE ASSOCIATED WITH HIGH OXIDANT EPISODES HAD THE ANTHROPOGENIC ORIGIN, WHICH HAD BEEN TRANSPORTED FROM THE METROPOLITAN TOKYO BY LOCAL WIND SYSTEM PREVAILING IN THEINLAND AREA.

報告者

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