First estimation of CH₄fluxes using the²²²Rn Tracer Method over the central Iberian Peninsula

Abstract

Emissions of CH 4 over the central Iberian Peninsula have been estimated experimentally for the first time using the Radon Tracer Method (RTM), which uses the atmospheric noble radioactive gas ²²²Rn as an auxiliary tracer. The nocturnal enhancement ratios of atmospheric concentrations of CH 4 and 222 Rn, continuously measured at the station of Gredos and Iruelas within the IC3 network since 2012, were used to early estimate the methane emissions in this region by multiplying for a constant radon flux. The possible influence of different methane source areas was observed by footprint analysis of FLEXPART with ECMWF meteorological input at 0.2 degrees horizontal resolution. A linear relationship between atmospheric radon and methane concentrations has been found to occur in 20% of the nocturnal episodes and an average methane emission of 0.12 mg m-2 h-1 ± 0.03 (1 σ). The data coverage and method is coherent with CH 4 fluxes inferred with the same RTM in Germany, Canada and East Asia and our flux estimates are similar to methane emissions reported by the bottom-up inventory EDGARv4.2 .

Analysis of ground‐based 222Rn measurements over Spain: Filling the gap in southwestern Europe

“…The mountains of Gredos feature the highest mountain range in the E‐W orientated central mountain system that divides the Iberian Peninsula in two parts. Atmospheric 222 Rn concentrations have been measured at GIC3 since December 2012 together with atmospheric concentrations of CH 4 and CO 2 [ Grossi et al ., ].…”

“…Due to its physical characteristics, presented in classical literature such as Fleischer et al . [], Tanner [], Nazaroff and Nero [], Nazaroff [], and Porstendorfer [], the radioactive noble gas 222 Rn is widely used by the scientific community to study a number of different research topics, such as (i) to improve inverse transport models, which are used to calculate emissions of greenhouse gases (GHGs) [ Biraud et al ., ; Hirao et al ., ; Locatelli et al ., ]; (ii) to study atmospheric transport and mixing processes within the planetary boundary layer [ Zahorowski et al ., ; Galmarini , ; Vinuesa et al ., ; Baskaran , ; Chambers et al ., , ; Williams et al ., , ; Grossi et al ., ; Vogel et al ., ; Hernández‐Ceballos et al ., ; Vargas et al ., ]; (iii) to improve radon flux inventories [ Szegvary et al ., ; Griffiths et al ., ; López‐Coto et al ., ; Karstens et al ., ]; (iv) to experimentally estimate GHGs fluxes by using the Radon Tracer Method [ Levin et al ., ; Vogel et al ., ; Wada et al ., ; Grossi et al ., ]; (v) to understand the influence of climate change on the atmospheric radon increase and its associated health risks [ Nazaroff , ; Bochicchio et al ., ; Bossew et al ., ]; and (vi) to refine baseline selection and characterization techniques and analyze air mass history and fetch at remote sites [ Zahorowski et al ., ; Chambers et al ., , , ].…”

Study of the daily and seasonal atmospheric CH<sub>4</sub> mixing ratio variability in a rural Spanish region using <sup>222</sup>Rn tracer

“…The average 222 Rn flux in this area is about 70-100 Bq m −2 h −1 (e.g. López-Coto et al, 2013;Karstens et al, 2015), which is almost twice the average radon flux in central Europe (Szegvary et al, 2009, López-Coto et al, 2013Grossi et al, 2016). The vegetation in the GIC3 area is stratified according to altitude and the main land use practice is a mixture of agro-forestry exploitation (EEA, 2013) Livestock farming is one of the main economic activities in the area around the GIC3 station (Ruiz Perez and Valero Sáez, 1990;López Saéz et al, 2009;MMA, 2016;Hernández, 2016).…”

“…CH 4 and CO 2 are measured with a frequency of 0.2 Hz using a G2301 analyser (Picarro Inc., USA). Hourly atmospheric 222 Rn concentrations are measured using an atmospheric radon monitor (ARMON) (Grossi et al, 2012(Grossi et al, , 2016. A schematic diagram of the measurement set-up used at the GIC3 station is shown in Fig.…”

“…Galmarini, 2006;Vinuesa and Galmarini, 2007), and soil-atmosphere exchanges (e.g. Schery et al, 1998;Zahorowski et al, 2004;Szegvary et al, 2009;Grossi et al, 2012Grossi et al, , 2016Vargas et al, 2015). European GHG-monitoring infrastructures already include atmospheric 222 Rn monitors in their stations (e.g.…”