亚洲季风区大气CH4浓度时空变化特征与影响因素

基于2009—2018年亚洲季风区7个大气本底站印度尼西亚Bukit Kototabang(BKT)站、中国鹿林(LLN)站和瓦里关(WLG)站、日本Ryori(RYO)站和Yonagunijima(YON)站、韩国Tae-ahn Peninsula(TAP)站、蒙古Ulaan Uul(UUM)站]地面观测资料,利用谐波模型拟合和最大信息非参数探索方法,对亚洲季风区大气CH₄浓度时空变化特征及影响因素进行分析。结果表明: 亚洲季风区大气CH₄浓度范围在1853.04～1935.61 nmol·mol^-1,高于同期美国夏威夷Mauna Loa(MLO)站观测值(1838.33 nmol·mol^-1),总体呈现由北向南依次递减的纬向分布特征,两个高值中心为韩国TAP站(1935.61 nmol·mol^-1)和日本RYO站(1907.19 nmol·mol^-1)。大气CH₄浓度平均季振幅最大为日本YON站(108.20 nmol·mol^-1),最小为中国WLG站(29.48 nmol·mol^-1),同时韩国TAP(4.49 nmol·mol^-1·a^-1)站表现出更高的季振幅变化速率;除中国WLG站和韩国TAP站外,其他本底站均呈现夏低冬高的季节循环特征;从长期变化上看,中国LLN站(7.68 nmol·mol^-1·a^-1)和WLG站(7.56 nmol·mol^-1·a^-1)大气CH₄浓度增长趋势最明显。相对于风速而言,气温和降水量对亚洲季风区大气CH₄浓度的影响程度更高,两个气象因子与大气CH₄浓度之间均呈现显著负相关;局地排放对部分站点大气CH₄浓度具有显著正向效应。

Spatio-temporal variation of atmospheric CH4 concentration and its driving factors in monsoon Asia.

Based on the ground-based observations from seven atmospheric background stations during 2009 to 2018 in monsoon Asia (including BKT station in Indonesia, LLN and WLG stations in China, RYO and YON stations in Japan, TAP station in Republic of Korea, and UUM station in Mongolia), we analyzed the temporal and spatial variation of atmospheric CH₄ concentration and its driving factors using harmonic model and maximal information-based nonparametric exploration. The results showed that the CH₄ concentration in monsoon Asia varied from 1853.04 to 1935.61 nmol·mol^-1, higher than that in Mauna Loa (MLO) station (1838.33 nmol·mol^-1) in Hawaii, USA. The CH₄ concentration decreased from north to south, with the highest value in TAP station (1935.61 nmol·mol^-1) in Republic of Korea and RYO station (1907.19 nmol·mol^-1) in Japan. The average seasonal amplitude at YON station in Japan was the largest (108.20 nmol·mol^-1); while that at WLG station in China was the smallest (29.48 nmol·mol^-1). The seasonal amplitude of TAP station in Republic of Korea changed faster at the rate of 4.49 nmol·mol^-1·a^-1. Except for WLG and TAP stations, CH₄ concentrations were low in summer and high in winter. From the long-term perspective, the CH₄ concentration at LLN (7.68 nmol·mol^-1·a^-1) and WLG (7.56 nmol·mol^-1·a^-1) stations in China exhibited the most obvious growth trend. Compared with wind speed, temperature and precipitation had greater impact on CH₄ concentration, which were negatively associated with CH₄ concentration. Local CH₄ emission at some stations had a significant positive effect on CH₄ concentration.