|
| 
Halley Bay
-O3-
| Observation |
| Category |
: |
Air sampling observation |
| Situation |
: |
ongoing |
| Time zone |
: |
UTC |
| Sampling |
| Sampling height |
: |
8 |
| Description |
: |
continuous |
| Sampling and analysis frequency |
: |
Continuous 1-minute averaged data |
| Sampling environment |
: |
These measurements are carried out at the Clean Air Sector laboratory at Halley research station on the Brunt ice shelf located 1100m SSE with respect to the main base.
http://www.antarctica.ac.uk/bas_research/support/labs/caslab/index.php
|
| Description for sampling analysis |
: |
Sampling is taken from about 8m above the snow surface. Air intake consists of a high volume fan drawing air through an electronically polished stainless steel tube from which a sub-sample is drawn to the instrument.
Ozone is sampled through 1 m of 1/4" teflon tube and passes through a dust filter before it enters the instrument.
|
| Instrument and Analysis |
| Measurement method |
: |
Light absorption analysis (UV) |
| Current status and history of instrument |
: |
2007-2011 Thermo Scientific Ozone Analyser model Tei49C (Instrument 1)
2012-2013 Thermo Scientific Ozone Analyser model Tei49i (Instrument 2)
2013-2014 2B technologies Model 2B205 (Instrument 3) due to failure of Tei49i (Instrument 2).
2014-2015 Thermo Scientific Ozone Analyser model Tei49i (Instrument 2) fixed and re-certified.
2015-present Thermo Scientific Ozone Analyser model Tei49i (Instrument 4) run with Tei49i (instrument 2)as a spare. |
| Description of instrument |
: |
Thermo Scientific Ozone Analyser model Tei49C (factory specification):
Zero noise: 0.5 ppb RMS
Lower detectable limit: 1.0 ppb
Zero drift: < 1 ppb/24 hour
Response time: 20 seconds (10 seconds lag time)
Linearity: ± 1% of full-scale
Thermo Scientific Ozone Analyser model Tei49i
http://www.thermoscientific.com/en/product/model-49-i-i-i-ozone-analyzer.html
2B205 Dual beam analyser
http://www.twobtech.com/model_205.htm
|
| Calibration |
| Current scale employed in the measurement |
: |
Traveling standard, traceable to NIST |
| Measurement calibration |
: |
Before transport to Antarctica all instruments are calibrated against the NIST traceable Thermo Scientific Ozone Analyser model Tei49PS and whilst in Antarctica are calibrated yearly against a traveling secondary calibration source (2B205, Tei49 ozonator). All calibrations are performed to verify that the 49 analyzer remains within ±2% of the calibration unit. If not, corrective action is taken. As of 2015 a model 2B306 which is factory calibrated against a NIST-traceable ozone standard is used as the main calibration source.
Two point span checks (zero and a 80% of full scale) are routinely performed every month using an internal ozonator to verify that the 49 analyzer remains within ±4% of the ozonator. If not, corrective action is taken, the 49 re-calibrated, a new equation determined, and evaluated against the NIST certified photometer standard (2B306). A full seven points calibration (zero and six points between zero and 80% of full scale), is performed 6-monthly.
NB: adjustments are made to the data and not to the instrument which ensures traceability.
|
| Scale and calibration(treasability) |
: |
Traveling standard, traceable to NIST. |
| Data Processing |
| Measurement unit |
: |
ppb |
| Data processing |
: |
SPAN, calibrations, zero values or any data which is invalid are omitted from data sets before averaging. Reduced quality data will be flagged appropriately.
Hourly files will be submitted in addition to daily and monthly. This data is obtained by averaging 1-minute data within a 1 hour period for example between 00:00 - 01:00. |
| Processing for averaging |
: |
Processing for Hourly Data:
1-min data are averaged to form the basis of hourly mean values.
Processing for Daily Data:
1-min data are averaged to form the basis of daily mean values.
Processing for Monthly Data:
1-min data are averaged to form the basis of monthly mean values
|
| Data flag |
: |
Error Flag = 0 Good data
Error Flag = 1 Reduced quality data
Error Flag = 2 Below detection limit
Error Flag = 3 Invalid or missing data |
| Data remarks |
: |
|
| Other Information |
| Scientific aim |
: |
To study the role of ozone within a variety of events such as long-range transport, stratospheric intrusion and photochemistry within a pristine environment.
|
| Reference |
: |
|
|
| submitted by British Antarctic Survey |
|
|
