全球和东亚地区CH4浓度时空分布特征分析

利用最新的AIRS卫星观测资料分析了2002年12月~2016年11月全球和东亚地区（70°~140°E，10°~55°N）CH₄浓度的时空变化分布特征.研究发现，2003~2016年，全球CH₄年平均浓度从1774.2×10^-9增加到1789.1×10^-9，年增长率约为1.1×10^-9/a；东亚地区CH₄年平均浓度从1811.5×10^-9增加到1841.0×10^-9，年增长率约为2.0×10^-9/a.在美国西南部、南美洲南部、澳大利亚东南部、中国青藏高原和东北地区等地上空，CH₄浓度增幅比较明显，而在北美洲的东北部上空，CH₄浓度出现负增长.北美洲东北部和俄罗斯东部等地上空CH₄浓度的变化与温度变化呈正相关；如在冬季，该地区温度与周围地区相比更低，同时CH₄浓度更低.本文利用近10a的卫星数据获得了CH₄浓度的垂直廓线，显示不同纬度带CH₄浓度均随着高度的升高逐渐减小，且高纬度地区CH₄浓度减小的最快.近年来，在低纬度地区对流层中低层CH₄浓度变化较为明显.在对流层低层（850hPa），北半球CH₄浓度随着纬度增加逐渐变大；在南半球则随着纬度增加先减小后变大.而在平流层内，CH₄浓度在赤道处最大，且随着纬度的升高逐渐减小.此外，CH₄的浓度分布存在明显的季节变化：在北半球，大部分地区夏季CH₄浓度高于冬季（约20×10^-9~40×10^-9），但在撒哈拉沙漠和中国新疆塔里木盆地等地区上空，冬季CH₄浓度高于夏季（约40×10^-9~60×10^?9）.在冬季，中国四川西部上空的CH₄浓度要比青藏高原上空高（约100×10^-9~120×10^-9）.

The spatial-temporal distribution of CH4 over globe and East Asia

The spatial and temporal characteristics of CH₄ concentration over globe and East Asia (70°~140°E, 10°~55°N) from December 2002 to November 2016 were analyzed based on AIRS (Atmospheric Infrared Sounder) satellite data. The results showed that the global annual mean CH₄ concentration increased from 1774.2×10^-9 in 2003 to 1789.1×10^-9 in 2016, the growth rate was about 1.1×10^-9/a. While it increased from 1811.5×10^-9 to 1841.0×10^-9 (the growth rate around 2.0×10^-9/a) in East Asia. In middle and lower troposphere (1000~400hPa), The growth rate of CH₄ concentration increased obviously over the southwestern America, southeastern Australia, southern South America, and the Tibetan Plateau and the northeastern China. However, the growth rate was negative over northeastern North America. Over northeastern North America and eastern Russia, the changes of the annual mean CH₄ concentration and temperature had a positive correlation. For example, in winter, the temperature in these regions was lower than that of surrounding areas, and the CH₄ concentration was lower than that of surrounding areas, too. The vertical profile of CH₄ concentration was obtained by recent 10-year satellite data in this paper. The results showed that at different latitudes, the CH₄ concentration gradually decreased with the increase of altitude, and the fastest decrease happened in the high latitudes. In the middle and lower troposphere of the low latitudes, the average CH₄ concentration changed obviously. In the lower troposphere (850hPa), the CH₄ concentration gradually increased with the increase of latitudes in the Northern Hemisphere, and decreased first and then increased in the Southern Hemisphere. In the stratosphere, the CH₄ concentration was largest over the equator, and gradually decreased as the latitude increased. Additionally, there was obvious seasonal change in the distribution of CH₄ concentration. In the lower troposphere, over most of the regions in the Northern Hemisphere, the average CH₄ concentration was higher in summer than it in winter. However, over the Sahara Desert and Tarim Basin in China, the average CH₄ concentration was higher in winter than it in summer. In winter, the CH₄ concentration in the western Sichuan Province was much higher than it in the Tibetan Plateau (100×10^-9~120×10^-9).