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Atmospheric Station Kresin u Pacova
-O3-
Observation |
Category |
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Air sampling observation |
Situation |
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Time zone |
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UTC |
Sampling |
Sampling height |
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8 |
Description |
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continuous |
Sampling and analysis frequency |
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Continuous flow of 1.3 l/min, a 1 minute mean is provided by the instrument. |
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 the height of 8 m on the tower since 17/12/2014. It is the same instrument that was located in 125 m height until 17/12/2014.
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.
QA/QC from 09/2014:
Once per 3-4 months a cleaning of sampling tubes is performed (tubes are flushed by methanol and distilled water).
Zero check is performed two times per a year (with zero gas).
Once per 4 weeks (month) the filters are replaced a leak test is made.
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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 autumn 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 from: (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 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 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 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 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
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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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