# Measuring Gas Flaring in Russia with Multispectral VIIRS Nightfire
## 1 Introduction  
For the past decade, Russia has stayed as the top country with regard to the gas flaring associated with oil and gas exploration, with reported annual flaring estimates ranging from 10 to 20.5 BCM depending on the year of estimate and the source [1; 2; 3; 4]. Because of the lack of publicly available detailed reporting from flare operators in the country and the remote nature of many flare locations in Sakhalin and sub-arctic Siberia, satellite sensors are an attractive option for the monitoring of gas flares. Applications for the estimation of flared gas volumes include carbon cycle analyses that rely on site-specific knowledge of the locations and magnitudes of greenhouse gas emissions into the atmosphere, tracking of activities to reduce gas flaring, and the identification of potentially attractive locations for gas utilization. In this paper, we provide a detailed catalog of the gas flares situated at upstream (production sites), midstream (transportation infrastructure) and downstream (refineries) oil and gas sector facilities and an in-depth analysis at the country, regional, company and site level of the satellite monitoring results of flaring in Russia in the period of 2012-2020. Our analysis is based on the VIIRS Nightfire data product originally developed and maintained by NOAA, and later by the Payne Institute for Public Policy at Colorado School of Mines [5; 6] and validated against open sources of high spatial resolution daytime satellite images, together with the open access geographical and geological metadata published by the oil and gas companies and the Russian government. The possibility of detecting and parameterizing gas flares using the satellite Defense Meteorological Satellite Program Operational Linescan System (DMSP-OLS) and Landsat platforms was first noted in the 1970s [7]. The authors of [8] performed the first estimate of the temperature and area of the gas flare using images from the AVHRR sensor of the TIROS-N satellites for the Persian Gulf (as further practice showed, the temperature was underestimated). Declassifying digital images from DMSP satellite series with OLS sensors since 1992 has made possible the first global assessment of flaring based on the luminosity of flares in the visible spectrum band and its correlation with the World Bank expert estimates [9]. Gas flares were identified visually in DMSP data, because the sensor detects electric lights from cities and towns, as well as gas flares. Estimation of gas flaring volumes using DMSP data ended in 2012 due to orbit degradation, resulting in solar contamination. In Russia, in the mid-2000s, an experimental method of gas flare volume estimation based on MODIS imagery was developed with a reported R\({}^{2}\) = 0.81 for the experimental gas flare flowmeter data and compared against the available 2004-2010 reported data in Khanty-Mansi Autonomous Oktug, with a result of R\({}^{2}\) = 0.92 for 17 separate gas flares [10]. The authors of [11] demonstrated a technique for using IR channels of ATSR sensors for the night-time detection of gas flares. Approaching the flaring problem, the authors applied the idea from volcanology to detect high-temperature sources (\(T\) > 1000 K) using night-time data from near-infrared channels, which are not subject to \"noise\" from solar reflection and are independent of the background temperature. After the launch of the Suomi NPP satellite in 2012 with VIIRS multi-spectrometer onboard, [PERSON] et al. developed the VIIRS Nightfire (VNF) method for multispectral detection and the measurement of temperature and radiative heat of the IR emitters on the ground at night, including gas flares, industrial sites, biomass burning, volcanoes, etc. [5]. In 2016, the same authors published the first global survey of gas flaring [6].