Dehydration in the tropical tropopause layer: A case study for model evaluation using aircraft observations
Dehydration in the tropical tropopause layer: A case study for model evaluation using aircraft observations
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热带对流层顶层的脱水：利用飞机观测进行模型评估的案例研究
DOI：
10.1002/2013jd021381
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
J. Dean‐Day
中科院分区：
文献类型：
--
作者：
R. Ueyama;E. Jensen;L. Pfister;G. Diskin;T. Bui;J. Dean‐Day
利用2011年秋季热带对流层顶试验（Airborne Tropopopaque Experiment）三次飞行中采样的气包沿沿着后向轨迹的冰云模拟，研究了影响热带对流层顶水汽浓度的动力学和微物理过程。ERA-与飞机测量的热带冷点温度相比，插值到飞行轨迹上的中期再分析温度具有可忽略的（-0.09 K）冷偏差，因此允许进行TTL脱水的案例研究模拟。当考虑次网格尺度波、云微物理过程和对流的影响时，在40天后向轨迹的最后一天模拟的水汽混合比显示出的平均廓线在350和410 K位温水平之间的垂直廓线机动期间收集的飞机测量值的平均值的20-30%以内。在三次飞行中平均，由次网格尺度波驱动的温度变化使360-390 K层脱水约-0.5 ppmv，而包括含水气溶胶的均匀冻结和随后的冰晶升华和再水化使380 K以下的水蒸气增加约+1 ppmv。对流的主要影响是润湿TTL，导致在370 K水平以下平均增强+1至5 ppmv。使用轨迹模型对TTL水汽进行准确（在0.5-1 ppmv范围内）预测需要适当地表示波、原位冰云形成和对流影响，这些因素共同决定了空气包的饱和历史。
The dynamical and microphysical processes that influence water vapor concentrations in the tropical tropopause layer (TTL) are investigated in simulations of ice clouds along backward trajectories of air parcels sampled during three flights of the Airborne Tropical Tropopause Experiment over the central to eastern tropical Pacific in boreal fall 2011. ERA‐Interim reanalysis temperatures interpolated onto the flight tracks have a negligible (−0.09 K) cold bias compared to aircraft measurements of tropical cold point temperature thus permitting case study simulations of TTL dehydration. When the effects of subgrid‐scale waves, cloud microphysical processes, and convection are considered, the simulated water vapor mixing ratios on the final day of 40 day backward trajectories exhibit a mean profile that is within 20–30% of the mean of the aircraft measurements collected during vertical profiling maneuvers between the 350 and 410 K potential temperature levels. Averaged over the three flights, temperature variability driven by subgrid‐scale waves dehydrated the 360–390 K layer by approximately −0.5 ppmv, whereas including homogeneous freezing of aqueous aerosols and subsequent sublimation and rehydration of ice crystals increased water vapor below the 380 K level by about +1 ppmv. The predominant impact of convection was to moisten the TTL, resulting in an average enhancement below the 370 K level by +1 to 5 ppmv. Accurate (to within 0.5–1 ppmv) predictions of TTL water vapor using trajectory models require proper representations of waves, in situ ice cloud formation, and convective influence, which together determine the saturation history of air parcels.
DOI：
10.1002/2013jd020817
发表时间：
2014-02
期刊：
Journal of Geophysical Research: Atmospheres
影响因子：
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作者：
Andrew W. Rollins;Andrew W. Rollins;T. Thornberry;T. Thornberry;R. Gao;Jessica B. Smith;D. Sayres;M. R. Sargent;Cornelius Schiller;Martina Krämer;N. Spelten;D. Hurst;D. Hurst;A. Jordan;A. Jordan;E. Hall;E. Hall;H. Vömel;G. Diskin;J. R. Podolske;L. Christensen;K. Rosenlof;Eric J. Jensen;D. W. Fahey;D. W. Fahey
通讯作者：
Andrew W. Rollins;Andrew W. Rollins;T. Thornberry;T. Thornberry;R. Gao;Jessica B. Smith;D. Sayres;M. R. Sargent;Cornelius Schiller;Martina Krämer;N. Spelten;D. Hurst;D. Hurst;A. Jordan;A. Jordan;E. Hall;E. Hall;H. Vömel;G. Diskin;J. R. Podolske;L. Christensen;K. Rosenlof;Eric J. Jensen;D. W. Fahey;D. W. Fahey