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Atmospheric Station Kresin u Pacova
-O3-
| Observation |
| Category |
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Air sampling observation |
| Situation |
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ongoing |
| Time zone |
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UTC |
| Sampling |
| Sampling height |
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50 |
| Description |
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continuous |
| Sampling and analysis frequency |
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Continuous flow of 1.3 l/min.
6/9/2013 - 17/12/2013 - 1 hour mean value was provided by the instrument (cycle time 10 s).
17/12/2013 - 24/01/2014 - 5 minute mean was provided by the instrument (cycle time 4 s).
Since 24/01/2014 - 1 minute mean is provided by the instrument (cycle time 4 s).
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| Sampling environment |
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The station is located in a rural background area with no significant traffic, industrial emissions and use of chemical solvents in its nearby surroundings. A highway is located 6 km to the north and east of the station, the wind frequency from these directions is 9 and 5%, respectively. Small (several hundreds of inhabitants) villages are at least 3 km far from the station, the closest towns (10-15 000 inhabitants) are 20 km far. Small wood-processing industry is located 20 km to the west (prevailing wind direction, frequency 27%).
The landscape around the station is agricultural with occasional mixed forests.
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| Description for sampling analysis |
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The instrument is located in an air-conditioned rack placed on a platform in 50 m height on the tower.
Inlet tubing is made of teflon, 1/4´´ OD, 1 m length, flow rate 1.3 l/min, a teflon filter (5um porosity, 47 mm diameter) is placed in front of instrument in the tubing. The inlet tubing end outside the rack is protected by a polypropylene sampling head of 15 cm length.
The sampled air is not dried.
From September 2014: Once per 3-4 months cleaning of sampling tubes is performed (tubes are flushed by methanol and distilled water). Zero check is performed two times per year (with zero gas). Once per 4 weeks filters are replaced and a leak test is performed.
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| Instrument and Analysis |
| Measurement method |
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Light absorption analysis (UV) |
| Current status and history of instrument |
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Period in use: start in September 2013
Instrument name: Thermo 49i
Manufacturer: Thermo Scientific, USA
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| Description of instrument |
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Linearity: ±1% full scale
Lower Detectable Limit: 1.0ppb
Precision: 1ppb
Measurement Range: 100 ppb
Response Time: 20 seconds (10 second lag time)
Zero Noise: 0.25ppb RMS
Cycle time: fast
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| Calibration |
| Current scale employed in the measurement |
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| Measurement calibration |
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| Scale and calibration(treasability) |
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The instrument was calibrated by the manufacturer before shipping.
The instrument is calibrated every year at the Czech Hydrometeorological Institute´s calibraton laboratory in Prague. The working standard is the O3 TE 49C analyzer linked to the NIST SRP no. 17. The calibrations were performed in May 2014 and May 2015.
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| Data Processing |
| Measurement unit |
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ppb |
| Data processing |
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Raw data from the instrument is collected manually once per week and stored in the server as 1 min average data.
Data validation until December 2013: Invalid data caused by instrumental malfunction were checked by comparison with information from the station logbook.
Data validation from January 2014: (1) Automated validation - Missing values are assigned the 999 flag. Ozone analyzer diagnostic parameters are automatically checked and values exceeding selected limits are automatically labeled as invalid by a corresponding flag and excluded from further analysis. Statistical analysis - O3 concentration values are smoothed by using kernel regression; time series of O3 concentrations is divided into several intervals on the base of variability changes of O3 concentration deviations from the smoothed line identified by using the PELT algorithm; for the individual intervals a corresponding critical boundary of 6 standard deviations is calculated; O3 concentration data exceeding this critical boundary are identified and assigned by a corresponding flag. (2) Manual validation - Visual check of automatically validated data, assigning flags corresponding to events at the station. Invalid data caused by instrumental malfunction are checked by comparison with information from the station logbook.
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| Processing for averaging |
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Processing for Hourly Data:
Processing of 2013 data:
Hourly measurements: 6/9/2013 16:00 - 17/12/2013 17:00
Hourly means calculated from 5 minutes measurements: 17/12/2013 18:00 - 31/12/2013 22:00
Processing of 2014 data (calculation of hourly averages):
Calculated from 1 min (or 5 min) data. Only valid or valid with warning data was used. 66% of valid or valid with warning data were the limit for calculating hourly averages.
Processing for Daily Data:
Processing of 2013 data:
Averaging of hourly data. Only valid data was used for the calculation of averages (data flagged as 220 was excluded).
Processing of 2014 data (calculation of daily averages):
Calculated from hourly averages. Only valid or valid with warning data was used. 66% of valid or valid with warning data were the limit for calculating hourly averages.
Processing for Monthly Data:
Processing of 2013 data:
Averaging of daily data. Only valid data was used for the calculation of averages (data flagged as 220 was excluded).
Processing of 2014 data (calculation of monthly averages):
Calculated from the daily averages. Only valid or valid with warning data was used. 66% of valid or valid with warning data were the limit for calculating hourly averages. |
| Data flag |
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Flags used for 2013 data:
000: no flag
220: Too rapid change in mole fraction values (change between two consecutive values exceeds 10 ppb)
310: operation of diesel lift on the tower
311: recorded operation of the diesel lift during the averaging period
320: non-background conditions (biomass burning in station surroundings, field work, work of diesel generating set)
410: value below the limit of detection (< 1 ppb)
430: positive or negative outlier value (< 0.0 ppb or > 300 ppb)
Flags used for 2014 data:
M - Missing data
N - valid, non-background conditions (i.e. various kinds of local influences)
W - warning (instrument not working 100% optimally, but still acceptable)
U - valid, one or more values in the aggregation limit under limit of detection
V - valid, background conditions |
| Data remarks |
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The data are obtained thanks to the Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Program I (NPU I), grant number LO1415. |
| Other Information |
| Scientific aim |
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To provide data for research, i.e. process studies and determination of long-term trends. |
| Reference |
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| submitted by Global Change Research Centre AS CR, v.v.i. |
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