Analysis of Methane (CH4) Distribution in Northeast Asia Based on Satellite Measurement Data; 위성관측자료 기반 동북아시아 대기 메테인(CH4) 분포 특성 분석

초록

We investigate methane distribution in Northeast Asia based on both nadir viewing Greenhouse-gases Observing SATellite (GOSAT) and limb-viewing Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) satellite measurements. Using climatological mean of GOSAT data, we found the latitudinal difference of methane mixing ratio: ~10 ppbv difference between South and North Korea and ~25 ppbv difference between East and Northeast China. Comparing to the methane provided from the climate modeling results of Coupled Model Intercomparison Project - phase 6 (CMIP6) during the historical period, methane from climate modeling data were lower than that from the GOSAT measurement, implying the necessity to correct methane emission in climate model. We also tried to see methane distribution in the Upper Troposphere and Lower Stratosphere (UTLS). As a result, we found that the lower latitudinal region (15 to 25°N) in Northeast Asia shows increasing methane up to ~20 km height, but higher latitudinal region (45 to 55°N) does only ~10 km height. When we estimated the correlation of methane between the surface and UTLS, we did not see any significant correlation, which is very different from the high correlation of carbon dioxide (CO2) between the surface and UTLS. This pattern depicts that the characteristic of methane distribution is not very homogeneous in whole atmosphere, and increasing trend of methane is obvious near the surface, but not in the upper atmosphere. Our study reveals that the typical assumption for the spatial homogeneity of greenhouse gases should be carefully considered.

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