A global view of stratospheric gravity wave hotspots located with Atmospheric Infrared Sounder observations
A global view of stratospheric gravity wave hotspots located with Atmospheric Infrared Sounder observations
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DOI：
10.1029/2012jd018658
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发表时间：
2012-12
期刊：
影响因子：
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通讯作者：
L. Hoffmann;X. Xue;M. Alexander
中科院分区：
文献类型：
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作者：
L. Hoffmann;X. Xue;M. Alexander
本研究的主要目的是在全球范围内寻找和分类平流层重力波热点。该分析基于NASA Aqua卫星上的大气红外探测器（AIRS）9年（2003年至2011年）的辐射测量记录。我们根据4.3 µm的亮度温度变化检测重力波。我们的方法关注峰值事件，即，局部方差大大超过背景水平的强重力波事件。我们估计这些峰值事件在不同季节和一天中不同时间的发生频率，并使用结果来找到局部最大值或“热点”。此外，我们使用AIRS辐射在8.1微米，同时检测对流事件，包括深对流在热带和中纬度的中尺度对流系统。我们分类的重力波源对流的季节性发生频率的基础上，但也通过时间序列分析和地形数据。我们的研究再现了重力波的著名热点，例如，安第斯山脉和南极半岛。然而，AIRS观测的高水平分辨率也使我们能够定位许多中尺度热点，这些热点到目前为止部分未知或研究不足。大多数中尺度热点都位于山脉、海岸、湖泊、沙漠或孤岛等地形特征附近。这项研究将有助于选择有前途的地区和季节，为未来的案例研究的重力波。
The main aim of this study is to find and classify hotspots of stratospheric gravity waves on a global scale. The analysis is based on a 9 year record (2003 to 2011) of radiance measurements by the Atmospheric Infrared Sounder (AIRS) aboard NASA's Aqua satellite. We detect gravity waves based on 4.3 µm brightness temperature variances. Our method focuses on peak events, i.e., strong gravity wave events for which the local variance considerably exceeds background levels. We estimate the occurrence frequencies of these peak events for different seasons and time of day and use the results to find local maxima or “hotspots.” In addition, we use AIRS radiances at 8.1 µm to simultaneously detect convective events, including deep convection in the tropics and mesoscale convective systems at middle latitudes. We classify the gravity wave sources based on seasonal occurrence frequencies for convection, but also by means of time series analyses and topographic data. Our study reproduces well‐known hotspots of gravity waves, e.g., the Andes and the Antarctic Peninsula. However, the high horizontal resolution of the AIRS observations also allows us to locate numerous mesoscale hotspots, which are partly unknown or poorly studied so far. Most of these mesoscale hotspots are found near orographic features like mountain ranges, coasts, lakes, deserts, or isolated islands. This study will help to select promising regions and seasons for future case studies of gravity waves.