Publication Date:
2017-08-23
Description:
Atmospheric Infrared Sounder (AIRS) mid-tropospheric methane (CH 4 ) data is utilized to study the variation of methane concentrations over the Pacific Ocean with an emphasis on the correlation to El Niño Southern Oscillation (ENSO). When El Niño events happen, the rising air over the central Pacific can bring low surface concentrations of CH 4 over the ocean into mid-troposphere, resulting in a reduction of mid-tropospheric CH 4 over the region. On the contrary, the rising air over the western Pacific brings low surface CH 4 to the mid-troposphere during the La Nina events, which leads to negative mid-tropospheric CH 4 anomalies over the western Pacific. In the horizontal direction, there are stronger southward winds during El Niño than La Niña months in the region of the western Pacific Ocean. The stronger southward winds during El Niño can enhance the transport of high concentration CH 4 from the northern hemisphere to the tropical western Pacific region and contribute to the positive CH 4 anomalies over the region. The difference of mid-tropospheric CH 4 can reach +15 ppb (-15 ppb) over the western (central) Pacific between El Niño and La Niña events. The noteworthy difference of CH 4 has a significant correlation to the Southern Oscillation Index with a correlation coefficient of 0.74. The change in the transports associated with the ENSO event is an important factor for CH 4 anomalies in the middle troposphere. Results found in this study can help us better understand the spatio-temporal variability of methane.
Electronic ISSN:
2333-5084
Topics:
Geosciences
,
Physics
Permalink