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Mt. Kenya
-O3-
| Observation |
| Category |
: |
Air sampling observation |
| Situation |
: |
ongoing |
| Time zone |
: |
UTC |
| Sampling |
| Sampling height |
: |
4.5 |
| Description |
: |
continuous |
| Sampling and analysis frequency |
: |
Continuous sampling with 1-minute or 5-minute averages stored on external data logger. |
| Sampling environment |
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The MKN station is situated on the north-western slope of Mt.Kenya at an altitude of 3680 m a.s.l. and is surrounded by alpine grassland and brushes. As part of the Mt.Kenya National Park the whole mountain area is protected and there are no local anthropogenic emissions, making the site suitable for continuous observations of the background free tropospheric composition. The closest human settlement with rather low emission sources is situated 17 km in north-westerly direction. |
| Description for sampling analysis |
: |
A rain and snow protected air inlet system is mounted 4.5 m
above ground and is connected to a glass manifold (length 3
m, diameter 5 cm) to which individual instruments are connected. The manifold is permanently flushed by a high volume pump. Residence times were estimated to be below 10 s.
Sample air is taken from the glass manifold through a 1.5 m, 4 mm diameter teflon tubing at a flow rate of 2 lpm. A 47 mm teflon filter (5 micron) is installed before the sample gas inlet and is regularly exchanged. |
| Instrument and Analysis |
| Measurement method |
: |
Light absorption analysis (UV) |
| Current status and history of instrument |
: |
01 May 2002 until 01 November 2008: TEI 49-003 S/N #51959-290, with interruptions
since 15 August 2006: TEI 49C #58106-318
TEI 49C #58106-318 was the master instrument since its implementation; as long as two ozone analyzers were in operation (January 2007 till November 2008), data from analyzer TEI 49-003 S/N #51959-290 were used to fill gaps when the master instrument was not operational, see flags in the hourly data files for information on the instrument used |
| Description of instrument |
: |
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| Calibration |
| Current scale employed in the measurement |
: |
NIST SRP #15 |
| Measurement calibration |
: |
The station does not own an ozone calibrator, and the inter-comparison of the analyser by WCC-Empa which is then traced back to SRP 15 (Klausen, 2003) constitutes the only independent assessment at present. |
| Scale and calibration(treasability) |
: |
Inter-comparison with WCC Empa transfer standard (TEI 49C PS, traced back to NIST SRP 15) in 2000, 2002, 2005, 2006, 2008, 2010, 2015. See audit reports, available at www.empa.ch/gaw. |
| Data Processing |
| Measurement unit |
: |
ppb |
| Data processing |
: |
Quality assurance procedures involve time series plots, consistency checks.
1-min averages were stored for TEI 49-003 S/N #51959-290
5-min averages were stored for TEI 49C #58106-318 between 15 August 2006 and 30 October 2008
1-min averages were stored for TEI 49C #58106-318 since 1 November 2008.
Calculation of of hourly aggregates is based on the available highest resolution data. |
| Processing for averaging |
: |
Processing for Hourly Data:
Calculation of hourly aggregates is based on available highest resolution data (see above): minimum requirements for data availability are at least 10 1-min averages or 2 5-min averages. SD denotes the corresponding standard deviation of the mean. ND gives the number of available 1-min or 5-min averages per hour; thus, maximum NDs of 12 (in case of 5-min averages recorded) or 60 (in case of 1-min averages) are possible; the flags (see below) provide information on the instrument/data logger combination used for the reported observations
Processing for Daily Data:
Calculation of daily aggregates is based on available hourly data: minimum requirements for data availability are at least 7 hourly averages per day. SD denotes the corresponding standard deviation of the mean
Processing for Monthly Data:
Calculation of monthly aggregates is based on available daily data: minimum requirements for data availability are at least 5 daily averages per month. SD denotes the corresponding standard deviation of the mean |
| Data flag |
: |
Flags are assigned: 1: TE49 data, 2:TE49C data when 5min data were recorded, 3: TE49C data when 1min data were recorded, 11: TE49 data between 01 January 2007 and 01 December 2008 that filled gaps when no TEI49C were available |
| Data remarks |
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| Other Information |
| Scientific aim |
: |
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| Reference |
: |
Klausen, J., C. Zellweger, B. Buchmann, and P. Hofer, 2003: Uncertainty and bias of surface ozone measurements at selected Global Atmosphere Watch sites. Journal of Geophysical Research-Atmospheres, 108.
Henne, S., et al. (2008), Representativeness and climatology of carbon monoxide and ozone at the global GAW station Mt. Kenya in equatorial Africa, Atmos. Chem. Phys., 8, 3119-3139
Henne, S., et al. (2008), Mount Kenya Global Atmosphere Watch Station (MKN): Installation and Meteorological Characterization, Journal of Applied Meteorology and Climatology, 47, 2946-2962, DOI: 10.1175/2008JAMC1834.1 |
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| submitted by Kenya Meteorological Department / Swiss Federal Laboratories for Materials Testing and Research |
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