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| Titel |
Atmospheric measurements of carbon dioxide and methane at Railroad Valley playa, Nevada, USA |
| VerfasserIn |
Emma Yates, Max Lowenstein, Laura Iraci, Akihiko Kuze, Jovan Tadic, Stephanie Vay, Stephan Kawa |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250053833
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| Zusammenfassung |
| Ground based in-situ measurements of carbon dioxide (CO2) and methane (CH4) at the dry lakebed at Railroad valley (RRV) playa, Nevada, USA (38°30.234’N, 115°41.604’W, elevation 1437 m) were conducted over a five day period from 20-25 June 2010. The playa is a flat, desert site with virtually no vegetation, an overall size of 15 km x 15 km and approximately 110 Km south-west of the nearest city, Ely (elevation 1962 m, inhabitants 4000). The measurements were taken as support and for the vicarious calibration experiment to validate column-averaged dry air mole fractions of CO2 and CH4 (XCO2 and XCH4) retrieved from the Greenhouse Gases Observing Satellite (GOSAT) which was launched in January 2009. This work reports on ground-based in-situ measurements of CO2 and CH4 from RRV playa and comparisons made with XCO2 and XCH4 from GOSAT. Also presented are a comparison of XCO2 and XCH4 with in-situ airborne measurements of CO2 and CH4.
The ground based CO2 and CH4 measurements were conducted using Wavelength-Scanned Cavity Ring-Down Spectroscopy (WS-CRDS) technique. The analyzer (Picarro Inc., CA, USA, model G1302) relies on the use of a high-finesse optical cavity, two lasers, a high-precision wavelength monitor, three high-reflectivity mirrors (>99.995%) and photodetectors to enable extremely precise and simultaneous measurements of CO2 and CH4. Instrument precision was calculated from the average 1-sigma during standard sampling, operating at 2 s temporal resolution, the precision was below 0.17 ppm for CO2 and 0.56 ppb for CH4. Drift was estimated to be -1.9 ppb/day for CO2 and -0.002 ppb/day for CH4.
The minimum and maximum concentrations over the measurement campaign were 358.39 – 404.22 ppm and 1.78 – 1.81 ppm for CO2 and CH4 respectively. As expected for this remote, desert site the mean CO2 and CH4 concentrations on each overpass day were close to the global average of 390 ppm and 1.77 ppm respectively (http://www.esrl.noaa.gov/gmd/dv/iadv/). Daily observed fluctuations (up to 20 ppm for CO2) around the mean concentrations are reported and the reasons for these fluctuations are analysed and discussed.
Comparisons are made between ground based in-situ CO2 and CH4 measurements and meteorological parameters (temperature, humidity, wind speed and direction) and with GOSAT XCO2 and XCH4 retrievals. Comparisons are also made of GOSAT XCO2 and XCH4 with aircraft in-situ measurements up to 12 km altitude over the RRV playa site on 12 July 2010. |
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