報告書番号

282031

タイトル（和文）

関東南方海上におけるサブミクロンエアロゾルの分布特性

タイトル（英文）

ON THE SPATIAL DISTRIBUTION OF SUBMICRON AEROSOLS AROUND THE IZU ISLANDS, PACIFIC OCEAN

概要 （図表や脚注は「報告書全文」に掲載しております）

１９８１年１０月～１１月，相模湾沿岸から八丈島に致る海域の上空と八丈島の地上において，サブミクロンエアロゾルの挙動に関する観測を実施した。観測には静電力方式と光散乱方式の２台のエアロゾル計を併用し，粒径０．００３～１０μｍの粒子総数と粒径分布を求めた。観測データを解析した結果，エアロゾル濃度と粒径分布は，海域の気象条件に大きく依存することがわかった。高気圧に覆われ弱い北東風が卓越する条件下では，エアロゾルは相模湾の沿岸で最大濃度（１．０Ｅ＋０３）毎立方ｃｍを示し，離岸距離に対して距離定数（１．０Ｅ－０５）～（１．０Ｅ－０６）毎ｍの指数関数型の減衰を呈した。これに対して海上に優勢な偏西風が卓越する条件下では，八丈近岸のエアロゾル濃度は平常時よりも３倍近い増加を認めることがあった。トラジェクトリ解析の結果，この汚染気魂は中京地域から輸送されたものと推定された。一方，前線性の擾乱に伴う降水雲

概要 （英文）

MEASUREMENTS ON THE TOTAL CONCENTRATION AND SIZE DISTRIBUTION OF SUBMICRON AEROSOLS IN THE MIXING LAYER WERE PERFORMED AROUND THE IZU ISLANDS OF JAPAN,DURING OCTOBER TO NOVEMBER 1981.THEPURPOSE OF OBSERVATION WAS TO GET INFORMATION ABOUT TRANSPORT,TRANSFORMATION AND REMOVAL PROCESSES OF ANTHROGENIC MATERIALS FROM LAND TO OCEAN.CONTINUOUS RECORDS OF TOTAL CONCENTRATION WERE OBTAINED BY USING ELECTRICAL AEROSOL PARTICLE COUNTER(E.A.A.)AND LIGHT SCATTERING PARTICLE COUNTER(L.S.)WHICH,OVERLAPPING STEPS COVERED A SIZE RANGE 0.0032 TO 10 MUM DIAMETER. RESULTS OBTAINED IN THE PRESENT WORK SHOWED THAT THERE WASA NOTABLE DIFFERENCE IN THE FATE AND BEHAVIOR OF AEROSOLS DEPENDING ONTHE METEOROLOGICAL CONDITION. IN THE CASE OF QUIET AND SETTLED WEATHERCONDITION SUCH AS ANTICYCLONE OVER THE MAINLAND OF JAPAN,TOTAL CONCENTRATION OF AEROSOLS SHOWED MAXIMUM VALUE(1.0E+3/CUBIC CM)NEAR THE COASTAL AREA OF SAGAMI BAY AND MINIMUM VALUE(1.0E/+2/CUBIC CM)NEAR HACHIJO IS..THEIR DILUTION FACTOR ASSOCIATED WITH SPATIAL DISPERSION WAS ESTIMATED THE ORDER OF 1.0E-6 TO 1.0E-5/M. IN THE CASE OF WESTERLY WIND PREVALING IN THE MARINE AREA,TOTAL CONCENTRATION OF SUBMICRON AEROSOLS WAS INCREASED AND THE WIND TRAJECTRY ANALYSIS SUGGESTED THAT POLLUTED AIR-MASSHAD BEEN TRANSPORTED FROM CHUKYO AREA OF THE MAINLAND OF JAPAN. ON THEOTHER HAND,AT THE CONDITION OF STRATOCUMLUS PRECIPITATION WITH MEDIUM CLOUD BASE,TOTAL CONCENTRATION OF AEROSOLS WAS DECREASED AND DISTRIBUTION CURVE WAS DEFORMED FROM JUNGE POWER LAW DISTRIBUTION OF AVERAGE MARITIME COMPONENT.THE SCAVENGING COLLECTION EFFICIENCY OF SUBMICRON AEROSOLS CALCULATED FROM OBSERVATIONAL RESULTS WAS MUCH HIGHER THAN THE VALUEWHICH RECENT THEORIES PREDICT.SOME POSSIBLE EXPLANATIONS OF THESE DISCREPANCIES WERE ALSO DISCUSSED.

報告者

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