Monitoring and detection of methane gas in Tehran in Google Earth Engine

Studying the emission of methane gas as the second most important greenhouse gas is vital due to climate change. This study was conducted to check the correctness of the news published by NASA regarding the existence of a methane cloud in the south of Tehran. Due to the importance of the subject, so far many remote sensing satellites such as sentinel-5, MethanSAT, SCIAMACHY, and GOSAT have been provided to monitor pollutants, especially methane gas. Also, much research has been done in evaluating this sensor and monitoring polluted areas. For example, Cherepanova, et al analyzed the spatial-temporal analysis of methane concentration and its relationship with burned areas. Using daily data from the TROPOMI sensor, they concluded that methane concentrations were higher in newly burned areas than in the previous year's burns. Maurya, N.K., et al investigated the concentration of SO2, CO, SOX, and CH4 pollutants using Sentinel-5P TROPOMI data in the periods after wheat and rice harvesting and land burning. The results showed that the concentration of CH4, SO2, SOX, CO, and aerosol increased significantly during the burning period of agricultural land after harvesting rice and wheat every year.

In this research, the daily data series of the TROPOMI sensor on the Santi-5 satellite were used on the Google Earth Engine platform. First, the spatio-temporal analysis of methane dynamics in Tehran has been discussed. In this way, time changes are made from July to October 2022 and also for the spatial analysis of pollutants, a monthly map has been made. Then according to the obtained date, the correctness or incorrectness of the presented map has been checked. Finally, in order to evaluate the results, the length of the methane cloud observed by NASA was compared with the methane cloud extracted by TROPOMI.

The obtained results showed that on September 1st, 2022 methane concentration was high and around 1970 ppm, and other gases did not have a high value on this date, which indicates the lack of effect of other gases on the increase of methane concentration and lack of misdiagnosis and according to the average map in the south of Tehran This gas has been more. Also, the methane cloud observed by NASA on the old Tehran-Qom road near the Qasemabad-Shorabad neighborhood was confirmed by the use of Sentinel-5 satellite data on the Google Earth Engine platform in red, meaning high concentration, which caused the release and concentration of methane gas. It is located in the south of Tehran and its main source was the landfill in this area. In addition, the length reported by NASA was compared with the length of the methane cloud extracted from the TROPOMI instrument, which was 4.8 km and 4.41 km, respectively.

Nowadays, air pollution has become a major problem due to environmental problems and adverse effects on human health, especially in densely populated cities. Based on the obtained results and the image of methane gas on September 1st in the south of Tehran, it was found that the news published by NASA was true and the main factor was that this area is a garbage dump. In this way, the Google Earth Engine platform can be used as a suitable tool for monitoring daily, monthly and annual changes.