No.8

Introduction
Data Policy
Data
Documentation
Contact Information



Giordan Lighthouse

-O3-

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Station Contact Person(s) Observation Data and Quick Plot

Observation
Category : Air sampling observation
Situation : ongoing
Time zone : Local time +1


Sampling
Sampling height : 7
Description : continuous
Sampling and analysis frequency : Continuous at ambient pressure
Sampling environment : When wind is blowing from 120-150 (over Malta), it is affected by local pollution and therefore ozone is depleted.
Description for sampling analysis : PTFE intake 4.5 m long with an internal diameter 0.04 m. Intake height: 7 metres above ground. The intake is connected to a glass manifold approximately 0.64 meters long. The manifold consists four nipples to feed trace gases instruments. The flow rate through the complete inlet is supported by a blower. Ambient air is supplied to the analysers via 6mm PTFE tube connected between the manifold and the inlet of the analyser. The analyser is assigned with a 5 micron filter which is changed every two weeks. Air is sampled every 10 seconds and a 1 minute average is stored in the Web Data logger from Envirologger Limited.


Instrument and Analysis
Measurement method : Light absorption analysis (UV)
Current status and history of instrument : 1997 January - 2005 December 1008RS Dasibi 2005 January - 2008 December 1008AH Dasibi
2011 January - present Model 49i Thermo electron corporation
Description of instrument : LDL: 1ppb
measurement range: 0-1000ppb
linearity: ± 1% of full-scale
Zero drift: < 1 ppb/24 hour
< 2 ppb/7 day
Span drift: less than 1% per month (including drift of
transducers)
Response time: 20 seconds (10 seconds lag time)


Calibration
Current scale employed in the measurement : Traceable to Tohoku University Standard Gases
Measurement calibration : Zero and three points span check at 50, 100 and 150 ppbv once per year with a primary standard.
Scale and calibration(treasability) : 1997 - 2008
Zero and three points span check at 50, 100 and 150 ppbv once per year with a transfer standard. The transfer standard is manufactured by UMEG in Baden- Wurttemberg, Germany. The Primary standard is a long path optical cuvette Type R-UV-PH also manufactured and maintained by UMEG in Baden -Wurttemberg, Germany.

2011 - present
Zero and three points span check at 50, 100 and 150 ppbv once per year with a primary standard. The Primary standard is UV-Photometer
Reference Method for Ozone according to VDI-Guideline 2468 Page. 6,manufactured by UMEG in Baden -Wurttemberg, Germany.


Data Processing
Measurement unit : ppb
Data processing : The raw data from the instrument is collected by the data acquisition
system, and stored in the system as one minute average raw data. The
minutely averaged raw data is converted to physical data using
zero/calibration factors measured in the observation sequences.
Invalid data caused by instrumental malfunction are checked by
comparison/correlation with other trace substances and meteorological
data or with information from the station logbook.
Processing for averaging : Processing for Hourly Data:
Hourly data are generated by arithmetic means from the per-minute
data without including invalid data. If the number of valid data
within an hour is less than 30, the hourly mean value is flagged as “2”.
If all data within an hour are invalid, the hourly mean value is “no data”.
Processing for Daily Data:
Daily data are generated by arithmetic means from the per-minute
data without including invalid data. If more than 80% of hourly data with a “0” flag are available daily data is flagged as “0”.Otherwise, daily data is flagged as “2”. If all data within a day are invalid, the daily mean data is “no data”.

Processing for Monthly Data:
Monthly data are generated by arithmetic means from the per-minute
data without including invalid data.“0” flag if more than 1/3 of daily data with a “0” flag are available.Otherwise, monthly data is flagged as “2”. If all data within a month are invalid monthly data is “no data”.
Data flag : 0: Background Data
2: insufficient number of averaging data
Data remarks :


Other Information
Scientific aim : to provide data for research and study to reveal long term trends
Reference :


submitted by University of Malta



The WDCGG is operated by the Japan Meteorological Agency
in collaboration with the World Meteorological Organization