The results of estimation of natural gas flaring volume at the Western Siberia flares for some periods of 2013-2019 are presented. These estimates were obtained in the framework of technology which includes the flares characteristic retrieval from satellite night-time data in the visible and near IR ranges, as well as the regression relationship between the source's power and the volume of the gas flaring. It was found that during this period the volume of gas flaring at the Western Siberia flares varied from 15.7 bcm in 2013 to 14.8 bcm in 2019.
The physical basis of the method for temperature retrieval of high-temperature thermal anomalies, including FUs, is the statement that on a moonless night, the entire flux of electromagnetic energy going into outer space in the visible and near infrared range, is basically the radiation of such source itself.
Registration of radiation in VIIRS channels in the visible and near IR ranges allows to retrieve the Planck distribution for the analyzed high-temperature source.
It is clear that the pixel that includes the anomaly is a gray body. In this case, the intensity recorded in this pixel by the VIIRS is equal to the product of the Planck function at the source temperature and the scaling factor , which is defined as the ratio of the intensity observed by the satellite to the pixel intensity at this temperature , provided that the entire pixel has this temperature [2]. The source area is found by multiplying the pixel area by .
In the case of the flaring of pure methane, the combustion temperature of which is 2223 K, taking into account Wien’s displacement law, it follows that the wavelength, which accounts for the maximum of intensity of radiation is equals to ~1.3 µm, i.e. it is between the channels M8 (1.2 µm) and M10 (1.6 µm) (see figure 1). This fact makes it possible to use the readings of the M10 channel as thresholds for the identification of thermal anomalies.
In the algorithm [5] used to determine the thermal anomalies, it is considered that such an anomaly is identified in a particular VIIRS pixel if the M10 channel reading for this pixel exceeds the threshold value + 6 , where is the average noise value in the M10 channel, and is its standard deviation. For a scene pixel identified as a thermal anomaly, the source temperature and scaling factor were retrieved. To solve this problem using the LevenbergMarquardt algorithm, the optimization of the objective function of variables and was carried out: min ( , ) = ,
∑ ={ radiometer. As initial values of the source temperature and the scaling factor 0 = 600 K and 0 = 0.01 were used, The source area was found using the expression = ∆ ∆ [5], where ∆ is the pixel size along the scanning direction, and ∆ – one along the satellite path (see expressions (4) and (5) of [5]). 4
The approach outlined above was implemented at the Space Monitoring Center of Altai State University to search for high-temperature sources of radiation from
> 1500 K in Western Siberia for 2013, 2015, 2017 and 2019.
Thermal anomalies identified only once in a series of observations were excluded from further analysis.
As a result of the work for each of the study periods ~300 anomalies were found. As an example, figure 2 shows the spatial distribution of the sources found for 2013.
The estimation of the flared gas volume is based on the regression relationship between the source power assessment [2]
Using the expressions (2) and (4) and the results of identification of high-temperature radiation sources, the volume of flared gas for each FU in Western Siberia was estimated. Total estimates of the volume of gas flared in the
found 336 315 291 311
V, bcm 15.7 14.1 14.9 14.8
The obtained results show that the maximum volume of flared associated gas in the FUs of Western Siberia according to VIIRS data is observed in 2013 and equals to 15.7 bcm. 6
The results of estimation of natural gas flaring volume at the Western Siberia flares for 2013, 2015, 2017 and 2019 are presented. These estimates were obtained in the framework of technology which includes the flares characteristic retrieval from VIIRS/Suomi-NPP night-time data in the visible and near IR ranges, as well as the regression relationship between the source's power and the volume of the gas flaring. It was found that during this period the volume of gas flaring at the Western Siberia flares varied from 15.7 bcm in 2013 to 14.8 bcm in 2019.
Elvidge C.D., Bazilian M.D., Zhizhin M. et al. The potential role of natural gas flaring in meeting greenhouse gas mitigation targets // Energy Strategy Reviews. 2018. Vol. 20. Pp. 156-162.
Elvidge C.D., Zhizhin M., Baugh K. et al. Methods for global survey of natural gas flaring Visible Infrared Imaging Radiometer Suite data // Energies. 2016. Vol. 9.
Hillger D., Kopp T, Lee T. et al. First-light imagery from SUOMI NPP VIIRS // BAMS. 2013. Vol. 94. Pp. 1019-1029.
Powell A.M., Jr., Weng F. Introduction to special section on Suomi National Polar-Orbiting Partnership satellite Elvidge C.D., Zhizhin M., Hsu F-C. et al. VIIRS Nightfire: Satellite pyrometry at night // Remote Sens. 2013.