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Sofia
-NO2-
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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Description |
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continuous |
Sampling and analysis frequency |
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Several times a day |
Sampling environment |
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Description for sampling analysis |
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Sampling duration is 1/2 hour. Eight samples per day are made, at 0, 3, 6, 9, 12, 15, 18, 21 UTC. Single beam spectrometer with continuous spectrum and manual adjustment of the beam. Spectral interval is 350-850 nm. Measurement for NO2 is performed at 520 nm. |
Instrument and Analysis |
Measurement method |
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Current status and history of instrument |
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Spectrophotometer |
Description of instrument |
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Karl Zeiss, Jena SPECOL 9 was used since October 1980. It has been changed to SPECOL 11 in October 1990. |
Calibration |
Current scale employed in the measurement |
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Measurement calibration |
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The method is photometric. Standard solutions are prepared at the stations every 3 days. A calibration curve is plotted and used in measurement procedure. The sensitivity of the method is 0.1 microgram per 3 ml measured solution. A solution of Griss' reagent is used during the measurements. The relative error of the method is 15%. the method is registered under Bulgarian State Standard (BSS)-BSS 17.2.4.22-83. |
Scale and calibration(treasability) |
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Bulgarian State Standard (BSS)-BSS 17.2.4.22-83 |
Data Processing |
Measurement unit |
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mg/m3-25C |
Data processing |
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Processing for averaging |
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Processing for Daily Data: Arithmetic mean from the eight measurements. Processing for Monthly Data: Arithmetic mean of the daily data. |
Data flag |
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Data remarks |
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Other Information |
Scientific aim |
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Reference |
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submitted by National Institute of Meteorology and Hydrology |
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