28 May 2021

28 May 2021

Review status: this preprint is currently under review for the journal ACP.

Quantification of CH4 emissions from waste disposal sites near the city of Madrid using ground- and space-based observations of COCCON, TROPOMI and IASI

Qiansi Tu1, Frank Hase1, Matthias Schneider1, Omaira García2, Thomas Blumenstock1, Tobias Borsdorff3, Matthias Frey1,a, Farahnaz Khosrawi1, Alba Lorente3, Carlos Alberti1, Juan J. Bustos2, Andre Butz4, Virgilio Carreño2, Emilio Cuevas2, Roger Curcoll5,b, Christopher J. Diekmann1, Darko Dubravica1, Benjamin Ertl1,6, Carme Estruch5, Sergio Fabián León-Luis2, Carlos Marrero2, Josep-Anton Morgui5, Ramón Ramos2, Christian Scharun1, Carsten Schneider4, Eliezer Sepúlveda2, Carlos Toledano7, and Carlos Torres2 Qiansi Tu et al.
  • 1Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research (IMK-ASF), Karlsruhe, Germany
  • 2Izaña Atmospheric Research Centre (IARC), Meteorological State Agency of Spain (AEMet), Tenerife, Spain
  • 3SRON Netherlands Institute for Space Research, Utrecht, the Netherlands
  • 4Institut für Umweltphysik, Heidelberg University (UH), Germany
  • 5Institut de Ciència i Tecnologia Ambientals (ICTA) - Autonomous University of Barcelona, Spain
  • 6Karlsruhe Institute of Technology, Steinbuch Centre for Computing (SCC), Karlsruhe, Germany
  • 7Group of Atmospheric Optics, University of Valladolid, Spain
  • anow at: National Institute for Environmental Studies, Tsukuba, Japan
  • bnow at: Institute of Energy Technologies, Polytechnic University of Catalonia, Barcelona, Spain

Abstract. The objective is to derive methane (CH4) emissions of the metropolitan city Madrid Spain from the CH4 enhancements seen by the space-borne and the ground-based instruments. This study applies satellite-based measurements from the TROPOspheric Monitoring Instrument (TROPOMI) and the Infrared Atmospheric Sounding Interferometer (IASI) together with measurements from the ground-based COllaborative Carbon Column Observing Network (COCCON) instruments.

In 2018, a two-week field campaign for measuring the atmospheric concentrations of greenhouse gases was performed in Madrid in the framework of Monitoring greenhousE Gas EmIssions of Madrid city (MEGEI-MAD) project. Five COCCON instruments were deployed at different locations around the Madrid city center enabling the observation of total column averaged CH4 mixing ratios (XCH4). Using available wind data, the differences between CH4 columns observed at these locations allow to estimate the emissions emerging from the surrounded area. In addition, based on the dominating wind direction in the Madrid region, we calculate the difference of the satellite data maps for two opposite wind regimes (northeast – southwest, NE – SW). In the following, we refer to the resultant signal as the wind-assigned anomaly. We use TROPOMI tropospheric nitrogen dioxide (NO2) observations as a test to verify our method of wind-assigned anomaly and its implementation, taking advantage of the much better detectability of the plume due to the short lifetime and low background concentrations of NO2. Pronounced bipolar plumes are found along NE and SW wind direction, which implies that our method of wind-assigned anomaly is working as expected. The wind-assigned TROPOMI XCH4 anomaly shows much weaker symmetric plumes than NO2 due to the long lifetime of CH4 and in consequence a high accumulated background of CH4 in the atmosphere. The wind-assigned plume method is also applied to the tropospheric and upper tropospheric/stratospheric column averaged CH4 mixing ratio products (in the following referred to as TXCH4 and UTSXCH4) derived from a-posteriori merged Infrared Atmospheric Sounding Interferometer (IASI) profile and TROPOMI total column data.

Based on the NE and SW wind fields, we developed a simple plume model locating the source at three waste disposal sites east of Madrid for CH4. As CH4 emission strength we estimate 7.4 × 1025 ± 6.4 × 1024 molec s−1 from the TROPOMI XCH4 data and 7.1 × 1025 ± 1.0 × 1025 molec s−1 from the TROPOMI&IASI merged TXCH4 data. The COCCON observations indicate a weaker CH4 emission strength of around 3.7 × 1025 molec s−1 from local source (near to the Valdemingómez waste plant) in accordance with observations in a single day and. All emission rates estimated from the different observations are significantly larger than the emission rates provided via the official Spanish Register of Emissions and Pollutant Sources.

Qiansi Tu et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-437', Anonymous Referee #1, 22 Jul 2021
    • AC1: 'Reply on RC1', Qiansi Tu, 02 Aug 2021
  • RC2: 'Comment on acp-2021-437', Anonymous Referee #2, 03 Aug 2021
    • AC2: 'Reply on RC2', Qiansi Tu, 24 Aug 2021

Qiansi Tu et al.

Qiansi Tu et al.


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Short summary
We use different methane ground- and space-based remote sensing data sets for investigating the emission strength of three waste disposal sites close to Madrid. We present a method that uses wind-assigned anomalies for deriving emission strengths from satellite data and estimating their uncertainty to 9–14 %. The emission strengths estimated from the remote sensing data sets are significantly larger than the values published in the official register.