A decadal satellite record of gravity wave activity in the lower stratosphere to study polar stratospheric cloud formation
A decadal satellite record of gravity wave activity in the lower stratosphere to study polar stratospheric cloud formation
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DOI：
10.5194/acp-17-2901-2017
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发表时间：
2017-02-24
影响因子：
6.3
通讯作者：
Stein, Olaf
中科院分区：
文献类型：
--
作者：
Hoffmann, Lars;Spang, Reinhold;Stein, Olaf
大气重力波产生了相当大的小范围温度波动，可以触发极地平流层云(PSCs)的形成。本文介绍了极地低平流层重力波活动的新卫星记录，以研究这一过程。该记录包括2003年1月至2012年12月NASA AQUA卫星上的大气红外探测仪(AIRS)的观测。重力波活动是用去趋势和噪声校正的15微米亮度温度变化来衡量的，这些变化是从对大约17-32公里高度的温度波动最敏感的AIRS通道计算得出的。对数据集的时间模式的分析表明，波浪活动具有很强的季节性周期，在中高纬度有冬季最大值。对空间格局的分析表明，地形以及急流和风暴源是观测到的波浪的主要原因。海浪活动与30百帕纬向风密切相关，这归因于AIRS观测过滤器的作用。我们使用新的数据集来评估欧洲中期天气预报中心(ECMWF)业务分析中明确解决的重力波引起的温度波动。结果发现，该分析在正确的位置再现了地形和非地形的波型，但波幅通常被低估了2-3倍。此外，在对AIRS和迈克尔逊干涉仪联合进行的被动大气探测(MIPAS)卫星观测的第一次调查中，查明了近50次重力波引起的PSC形成事件。调查表明，新的AIRS数据集可以帮助更好地识别此类事件，并更普遍地突出了这一过程对极地臭氧化学的重要性。
Atmospheric gravity waves yield substantial small-scale temperature fluctuations that can trigger the formation of polar stratospheric clouds (PSCs). This paper introduces a new satellite record of gravity wave activity in the polar lower stratosphere to investigate this process. The record is comprised of observations of the Atmospheric Infrared Sounder (AIRS) aboard NASA's Aqua satellite from January 2003 to December 2012. Gravity wave activity is measured in terms of detrended and noise-corrected 15 mu m brightness temperature variances, which are calculated from AIRS channels that are the most sensitive to temperature fluctuations at about 17-32 km of altitude. The analysis of temporal patterns in the data set revealed a strong seasonal cycle in wave activity with wintertime maxima at mid-and high latitudes. The analysis of spatial patterns indicated that orography as well as jet and storm sources are the main causes of the observed waves. Wave activity is closely correlated with 30 hPa zonal winds, which is attributed to the AIRS observational filter. We used the new data set to evaluate explicitly resolved temperature fluctuations due to gravity waves in the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis. It was found that the analysis reproduces orographic and non-orographic wave patterns in the right places, but that wave amplitudes are typically underestimated by a factor of 2-3. Furthermore, in a first survey of joint AIRS and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) satellite observations, nearly 50 gravity-wave-induced PSC formation events were identified. The survey shows that the new AIRS data set can help to better identify such events and more generally highlights the importance of the process for polar ozone chemistry.