Tropopause and hygropause variability over the equatorial Indian Ocean during February and March 1999
Tropopause and hygropause variability over the equatorial Indian Ocean during February and March 1999
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1999年2月至3月赤道印度洋对流层顶和湿层顶的变化
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
V. Yushkov
中科院分区：
文献类型：
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作者：
A. MacKenzie;C. Schiller;T. Peter;A. Adriani;J. Beuermann;O. Bujok;F. Cairo;T. Corti;G. Didonfrancesco;I. Gensch;C. Kiemle;M. Krämer;C. Kröger;S. Merkulov;A. Oulanovsky;F. Ravegnani;S. Rohs;V. Rudakov;P. Salter;V. Santacesaria;L. Stefanutti;V. Yushkov
1999年2月和3月，在西赤道印度洋上空进行了温度、水汽、总水量、臭氧和云特性的测量。冷点对流层顶的平均气压高度为17 km，相当于380 K的位温，平均温度为190 K。在湿层顶的总水混合比在1.4和4.1 ppmv之间变化。在冷点的平均饱和水蒸气混合比为3.0 ppmv。这并不能准确地表示测量的总水混合比的平均值，因为在约40%的测量中，空气在冷点处是不饱和的。以及在冷点处的不饱和度，在几乎30%的曲线上在冷点以上观察到饱和度。在这样的剖面中，空气相对于水冰是饱和的，但没有云（即，在对流层顶和湿层顶上方5 K以上的位温下，后向散射比<2）。个别廓线显示冷点和湿层顶的潜在温度有很大的变化。我们把这归因于叠加在季节周期上的短时间尺度和空间尺度扰动。既没有一个明确的和一致的“设置”对流层顶和湿层顶的相同高度的脱水过程，也没有一个明确的和一致的分离对流层顶和湿层顶的布鲁尔-多布森环流。同样，对流层顶和湿层顶都不能提供一个条件始终接近简单的“对流层顶冷冻干燥”或“平流层喷泉”假设所暗示的条件的位置。
Measurements of temperature, water vapor, total water, ozone, and cloud properties were made above the western equatorial Indian Ocean in February and March 1999. The cold-point tropopause was at a mean pressure-altitude of 17 km, equivalent to a potential temperature of 380 K, and had a mean temperature of 190 K. Total water mixing ratios at the hygropause varied between 1.4 and 4.1 ppmv. The mean saturation water vapor mixing ratio at the cold point was 3.0 ppmv. This does not accurately represent the mean of the measured total water mixing ratios because the air was unsaturated at the cold point for about 40% of the measurements. As well as unsaturation at the cold point, saturation was observed above the cold point on almost 30% of the profiles. In such profiles the air was saturated with respect to water ice but was free of clouds (i.e., backscatter ratio <2) at potential temperatures more than 5 K above the tropopause and hygropause. Individual profiles show a great deal of variability in the potential temperatures of the cold point and hygropause. We attribute this to short timescale and space-scale perturbations superimposed on the seasonal cycle. There is neither a clear and consistent “setting” of the tropopause and hygropause to the same altitude by dehydration processes nor a clear and consistent separation of tropopause and hygropause by the Brewer-Dobson circulation. Similarly, neither the tropopause nor the hygropause provides a location where conditions consistently approach those implied by a simple “tropopause freeze drying” or “stratospheric fountain” hypothesis.