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準実スケール人工雲実験施設を用いた硫酸アンモニウムエアロゾルが雲粒生成に与える影響の検討
山形, 定;三浦, 二郎;太田, 幸雄;藤吉, 康志
Permalink : http://hdl.handle.net/2115/55014
Abstract
高度430mにおよぶ準実スケールの人工雲実験施設において硫酸アンモニウムエアロゾル粒子を発生させ, 雲核活性化が起きる高度40m程度までのエアロゾル, 雲粒について測定をおこなった. バックグラウンド粒子数濃度を低下させたことにより, 実験室用粒子発生装置を用いた安定的なエアロゾル粒子供給が可能となった. エアロゾル粒子および雲粒を同時に捕集可能な２段式インパクターを用い複数高度で両粒子の数濃度, 粒径分布を求めた.粒子発生用の硫酸アンモニウム溶液濃度を高くすると, 発生粒子個数が増加したが粒径に大きな変化は見られなかった. エアロゾル粒子数増加により生成する雲粒粒子数は増加, 雲粒径は減少し, Twomey効果が検証された.
The volume fraction (ε) of water soluble material in atmospheric aerosol particles is an important parameter related to their hygroscopicity and activation processes to form cloud and ice particles. To estimateεof coarse dust particles, confocal scanning laser microscope was applied to measure the volume difference of individual particles before and after water dialysis directly. Individual particles (sphere equivalent diameter approx. 1-8 μm) of Asian reference dusts (CJ1 and CJ2) and atmospheric coarse particles during four Asian dust events were analyzed to ascertainε. Median values ofεfor CJ1 and CJ2 were, respectively, 29% and 13% with no size trend. Median values ofεfor coarse aerosol particles during two dust events were 18-42%. Dust particles with high εare potentially important for acting as giant CCN. Therefore aging of dust particles during transport might enhance the number of giant CCN over the North Pacific.
The volume fraction (ε) of water soluble material in atmospheric aerosol particles is an important parameter related to their hygroscopicity and activation processes to form cloud and ice particles. To estimateεof coarse dust particles, confocal scanning laser microscope was applied to measure the volume difference of individual particles before and after water dialysis directly. Individual particles (sphere equivalent diameter approx. 1-8 μm) of Asian reference dusts (CJ1 and CJ2) and atmospheric coarse particles during four Asian dust events were analyzed to ascertainε. Median values ofεfor CJ1 and CJ2 were, respectively, 29% and 13% with no size trend. Median values ofεfor coarse aerosol particles during two dust events were 18-42%. Dust particles with high εare potentially important for acting as giant CCN. Therefore aging of dust particles during transport might enhance the number of giant CCN over the North Pacific.
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