Isotope ratios of precipitation and water vapor observed in Typhoon Shanshan
Isotope ratios of precipitation and water vapor observed in Typhoon Shanshan
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DOI：
10.1029/2007jd009313
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发表时间：
2008-06-26
影响因子：
4.4
通讯作者：
Ozawa, K.
中科院分区：
文献类型：
--
作者：
Fudeyasu, H.;Ichiyanagi, K.;Ozawa, K.
2006 年 9 月 15 日至 16 日，在台风珊珊经过日本西南部石垣岛期间，观测到了降水和水汽的同位素比。这种高分辨率同位素观测可以对大气水分循环进行定性了解；他们发现，在气旋外部区域，降水和水蒸气的同位素比率呈径向向内下降；气旋内部区域出现异常高的同位素比率；气旋内部区域的 d-excess 趋于减少。在气旋的外部区域，由于降雨效应，水蒸气的同位素耗尽，这涉及到向内增加的云厚度所反映的冷凝效率以及落下的水滴与周围水蒸气之间的同位素交换。相比之下，由于降雨效应较弱，加上同位素比较高的海浪和海面的强烈同位素补给，气旋内部区域的水蒸气同位素富集。由于水汽主要是降水的来源，降水的同位素比值也存在系统变化。一个独特的情况是与几乎饱和的表面空气和强风的同位素交换强度，导致气旋内部区域异常高的同位素比率和低的 d 过剩值。
Isotope ratios of precipitation and water vapor were observed during the passage of Typhoon Shanshan at Ishigaki Island, southwestern Japan, on 15-16 September 2006. Such high-resolution isotopic observations allow for qualitative understanding of atmospheric moisture cycling; they revealed that isotope ratios of both the precipitation and water vapor decreased radially inward in the cyclone's outer region; anomalously high isotope ratios appeared in the cyclone's inner region; and d-excess tended to decrease in the cyclone's inner region. In the cyclone's outer region, the water vapor was isotopically depleted due to the rainout effect which involves both condensation efficiency as reflected in inwardly increasing cloud thickness and isotopic exchange between falling droplets and the ambient water vapor. In contrast, water vapor in the cyclone's inner region was isotopically enriched due to weak rainout effect in conjunction with intensive isotopic recharge from the sea spray and sea surface with heavy isotope ratios. Since water vapor mainly acts as a source of precipitation, the isotope ratios of precipitation also had systematic variation. A unique circumstance is the intensity of isotopic exchange with almost saturated surface air and high winds, causing anomalously high isotope ratios and low d-excess values in the cyclone's inner region.