Water vapor heterogeneity related to tropopause folds over the North Atlantic revealed by airborne water vapor differential absorption lidar
Water vapor heterogeneity related to tropopause folds over the North Atlantic revealed by airborne water vapor differential absorption lidar
复制标题
机载水汽差分吸收激光雷达揭示与北大西洋对流层顶褶皱相关的水汽异质性
DOI：
10.1029/2004jd004957
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发表时间：
2005
影响因子：
--
通讯作者：
M. Wirth
中科院分区：
文献类型：
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作者：
H. Flentje;A. Dörnbrack;G. Ehret;A. Fix;C. Kiemle;G. Poberaj;M. Wirth
[1]2002年5月13日至15日和6月16日至18日通过北大西洋传输的对流层水汽和气溶胶/云的机载差分吸收激光雷达测量结果。大西洋上空强烈的动力活动反映在复杂的结构中，如深对流层顶褶皱、延长的干层和倾斜的气溶胶细丝。H2O混合比小于0.03g kg−-1的侵入在强气旋上方的风暴路径上有规律地发展，并与分析的(欧洲中期天气预报中心)或模拟的位涡异常相对应。倾斜褶皱在垂直剖面上通常有1公里厚，但在水平剖面上就像几百公里宽的长丝。在对流层顶褶皱的内部和轴线上，存在着由大约微米大小的固体颗粒组成的丝状结构。这些粒子很可能源自森林大火，在那里它们通过深对流被注入平流层下部，然后在形成斜压扰动的过程中重新进入对流层。它们的层状外观表明，这些侵入岩还没有混合，而是在比几天大得多的时间尺度上被拉伸-稀释、搅拌，最后才是湍流扩散所侵蚀。MM5中尺度模式模拟和ECMWF分析(精度较低)能够再现与观测到的干侵入有关的动力结构。然而，在尺度较小的侵入体深处，即使是MM5模拟的水蒸气混合比也是观测到的两倍以上。水汽混合比的大动态范围(3个数量级)和大梯度(>；2g kg−1 KM−1在侵入体边界)对未来的星载水汽测报系统构成了挑战。
[1] Airborne differential absorption lidar (DIAL) measurements of tropospheric water vapor and aerosol/clouds are presented from transfers across the North Atlantic on 13–15 May and 16–18 June 2002. The intense dynamical activity over the Atlantic is reflected in complex structures like deep tropopause folds, extended dry layers, and tilted aerosol filaments. Intrusions with H2O mixing ratios below 0.03 g kg−1 regularly develop along the storm track over intense cyclones and correspond to analyzed (European Centre for Medium-Range Weather Forecasts (ECMWF)) or simulated (MM5) potential vorticity anomalies. Sloping folds are typically 1 km thick in vertical profiles but on horizontal sections resemble long filaments with widths of a few hundred kilometers. Filaments of solid, roughly micron-sized particles occur inside and along the axes of the tropopause folds. The particles most likely originate in forest fires, from where they are injected to the lower stratosphere by deep convection and later on reenter the troposphere in developing baroclinic disturbances. Their laminar appearance indicates that these intrusions have not yet been mixed but are eroded on timescales significantly larger than a few days by stretching-thinning, stirring, and only finally, turbulent diffusion. MM5 mesoscale model simulations and, with less accuracy, also ECMWF analyses are capable of reproducing the dynamical structures associated with the observed dry intrusions. However, deep inside the intrusions where scales are small, even the MM5-simulated water vapor mixing ratios are more than twice those observed. The large dynamical range of water vapor mixing ratios (3 orders of magnitude) and large gradients (>2 g kg−1 km−1 at the intrusions' boundaries) constitute a challenge for future space-borne water vapor DIAL systems.