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 Organization

NO 3
Acronym AEMET
Name State Meteorological Agency of Spain
Address 1 Izana Atmospheric Research Center
Address 2 C/ La Marina, 20, Planta 6, 38001 Santa Cruz de tenerife, Spain
Address 3
Country/Territory Spain
Website http://izana.aemet.es/

 Contact(s)

Name Emilio Cuevas
Prefix Dr.
Email ecuevasa@aemet.es
Organization No 3
Organization acronym AEMET
Organization name State Meteorological Agency of Spain
Organization country/territory Spain
Address 1 C/ La Marina, 20, Planta 6, 38001 Santa Cruz de Tenerife, Spain
Address 2
Address 3
Country/territory Spain
Tel +34-922-151718
Fax +34-922-574475
Last updated date 2020-07-23


 Background observation
 UTC
 ppb
 9999-12-31 00:00:00 - 9999-12-31 23:59:59: WMO CH4 X2004A
 9999-12-31 00:00:00 - 2013-12-31 23:59:59: GC-3800, DANI(Gas chromatography (FID))
 2014-01-01 00:00:00 - 2018-12-31 23:59:59: GC-3800, VARIAN(Gas chromatography (FID))
 2019-01-01 00:00:00 - 9999-12-31 23:59:59: Picarro G2401
#2352-CFKADS2196(CRDS)
 9999-12-31 00:00:00 - 1999-12-31 23:59:59: 13 (m)
 2000-01-01 00:00:00 - 2005-05-31 23:59:59: 8 (m)
 2005-06-01 00:00:00 - 9999-12-31 23:59:59: 30 (m)
 30 seconds
 A linear response function forced through cero is used. The instrument had been calibrated every 30 minutes using a working gas tank (at minutes 15 and 45 every hour) before January 2014. After such date, a different instrument has been in operation, and the working gas injections have been carried out every 15 minutes (at minutes 00, 15, 30 and 45 every hour).
The working gas tank is calibrated every two weeks against the methane Izana primary standards (prepared by WMO GAW CH4 CCL).
 Before January 2014, four samples had been automatically measured every hour: at 00 and 30 minutes the sample is ambient air, at 15 and 45 minutes the sample is working gas. After such date, a different instrument and measurement scheme have been used: eight samples are automatically measured every hour: at 00, 15, 30 and 45 minutes the samples are working standard gas; and at 7.5, 22.5, 37.5, and 52.5 minutes the samples are ambient air.

Raw data concerning CH4 peaks are stored. Physical data for each ambient air injection are obtained using the two bracketing instrument calibrations (injections of working gas). Several procedures are used to identify periods of malfunction of the instrumental system and the associated measurements are discarded (no flags are used).

For the period April 26, 2006 (lotus time in days: lt0=38833.64) till May 28, 2008 (lotus time in days: ltf=39596.42), a significant systematic deviation has been appreciated when comparing continuous in-situ CH4 data with collocated NOAA flasks (weekly sampling). The reasons of such deviation are still not known. For such period, we have added a cubic (in time) correction to the continuous in-situ data, being the correction in ppb: -2.556E-07 * t^3 + 4.042E-04 * t^2 -1.477E-01 * t -1.408E+01, where t=lt-lt0, and lt is lotus time in days.
 [Hourly] Dani 3800 & Varian 3800: Hourly data are computed averaging the corresponding physical data for valid ambient injections. SD: standard deviation of the sample. ND (provided only for years after 2002): number of ambient injections used to compute the hourly mean.
Picarro G2401: Hourly data are generated by arithmetic means from the 10 minutes means without including invalid data. SD: standard deviation of the sample (including the internal standard deviation of the 10 min means). ND: number of 10 minutes means used to compute the hourly mean.
 [Daily] The daily mean for the day "n" is computed averaging the corresponding available hourly means between 20:00 UTC of day "n-1" and 08:00 UTC of day "n" (so, they could be called "daily night means"). As explained in the paragraph "Sampling environment", the atmospheric conditions at the station during night time correspond to background pure free troposphere. SD: standard deviation of the sample of hourly means (without taking into account the internal SD of each hourly mean). ND: number of hourly means available for computing the daily night mean (max=12).
 [Monthly] Monthly data are computed averaging the corresponding daily night means (see paragraph "processing on daily data"). SD: standard deviation of the sample of daily night means (without taking into account the internal SD of each daily night mean). ND: number of valid daily night means used.
 No flags are used. Several procedures have been used to identify periods of malfunction of the instrumental system and the associated measurements have been discarded. All the reported data are data that have passed internal quality control procedures.
 Operational/Reporting
 Scientific Aim : To determine temporal variability of atmospheric CH4 at Izaña (North Atlantic free troposphere background conditions): short-term variability, seasonal variability and long-term trend. To provide data to WDCGG as a Global GAW station.

The Izaña station is located at 2372.90 m above sea level, on the Island of Tenerife, Spain. The ground in the vicinity around Izaña is loosely covered with light volcanic soil. The vegetation in the surrounding area is sparse, consisting mainly of broom. A belt of pine forest grows between 1000 and 2000 meters a.s.l. During nighttime (20UTC-08UTC), in situ measurements are representative of free troposphere background conditions. This is due to the following facts: a) usually a strong subtropical temperature inversion layer is located at a lower altitude than Izana station; b) Izana station is located on the top of a crest, so during the night period downslope (catabatic) wind produces (by mass conservation) the arrival of free troposphere air to Izana. During daytime, small amounts of air coming from the forest can arrive to the station due to surface upslope wind produced by ground diurnal heating. Apart from this effect, there is no arrival of polluted air from the rest of the island, due to the presence of the strong subtropical temperature inversion layer.
Ambient air injection every 30 minutes. Since January 2014, the ambient air injections have been carried out every 15 minutes.

The general ambient air inlet, which provides ambient air for all instruments that analyze it, is an 8cm inner diameter (ID) stainless steel pipe and has a high flow rate. This inlet is situated on top of the building tower; the height above the ground has changed through the years: 13 m (1984-2000), 8 m (2000- May 2005) and 30 m (from June 2005). Upstream of the GC sample loop (10 ml size), a cryocool trap is used to reduce the dew point of ambient air to -60 C.
 Wind direction: 1
 Wind speed: 1
 Relative humidity: 1
 Precipitation amount: 0
 Air pressure: 0
 Air temperature: 1
 Dew point temperature: 0
 Sea water temperature: 0
 Sea surface water temperature: 0
 Sea water salinity: 0
 Sea surface water salinity: 0
Meteorological data may remain as first provded, even when greenhouse gas data are updated.
 
1  Gomez-Pelaez, A.J., R. Ramos, V. Gomez-Trueba, R. Campo-Hernandez, E. Reyes-Sanchez: "GGMT-2015 Izaña station update: instrumental and processing software developments, scale updates, aircraft campaign, and plumbing design for CRDS" in GAW report (No. 229) of the "18th WMO/IAEA Meeting on Carbon Dioxide, Other Greenhouse Gases, and Related Measurement Techniques (GGMT) (La Jolla, CA, USA, 13-17 September, 2015)", edited by P. Tans and C. Zellweger, World Meteorological Organization, 125-131,2016
2  Gomez-Pelaez, A.J., Ramos, R., Perez-delaPuerta, J., "Methane and carbon dioxide continuous measurements at Izana GAW station (Spain)" in GAW Report (No. 168) of the "13th WMO/IAEA Meeting of Experts on Carbon Dioxide Concentration and Related Tracers Measurement Techniques (Boulder, Colorado, USA, 19-22 September 2005)", edited by J.B. Miller, World Meteorological Organization (TD No. 1359), 180-184, 2006
3  Zellweger, C., M. Steinbacher, B. Buchmann, R. Steinbrecher (2015), System and Performance Audit of Surface Ozone, Methane, Carbon Dioxide, Nitrous Oxide and Carbon Monoxide at the Global GAW Station Izaña, September 2013. WCC-Empa Report 13/2
4  Gomez-Pelaez, A.J., R. Ramos, V. Gomez-Trueba, R. Campo-Hernandez, P. Novelli "In-situ carbon monoxide measurements at Izaña global GAW station: 2008-2011 time series, uncertainty analysis, and comparison with collocated weekly samples" in GAW report (No. 206) of the "16th WMO/IAEA Meeting on Carbon Dioxide, Other Greenhouse Gases, and Related Measurement Techniques (GGMT-2011) (Wellington, New Zealand, 25-28 October 2011)", edited by Gordon Brailsford, World Meteorological Organization, 91,2012
5  Gomez-Pelaez, A.J., Ramos, R., "Improvements in the Carbon Dioxide and Methane Continuous Measurement Programs at Izaña Global GAW Station (Spain) during 2007-2009", in GAW report (No. 194) of the "15th WMO/IAEA Meeting of Experts on Carbon Dioxide, Other Greenhouse Gases, and Related Tracer Measurement Techniques (Jena, Germany; September 7-10, 2009)", edited by Willi A. Brand, World Meteorological Organization (TD No. 1553), 133-138, 2011
6  Gomez-Pelaez, A.J., Ramos, R., Cuevas, E., Gomez-Trueba, V., “25 years of continuous CO2 and CH4 measurements at Izaña Global GAW mountain station: annual cycles and interannual trends”, Proceedings of the “Symposium on Atmospheric Chemistry and Physics at Mountain Sites (ACP Symposium 2010, June 8-10, 2010, Interlaken, Switzerland)”, 157-159, 2010