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Baring Head
-CO-
| Observation |
| Category |
: |
Air sampling observation |
| Situation |
: |
ongoing |
| Time zone |
: |
Local time +12 |
| Sampling |
| Sampling height |
: |
10 |
| Description |
: |
flask |
| Sampling and analysis frequency |
: |
60-100 per year. |
| Sampling environment |
: |
|
| Description for sampling analysis |
: |
Sample collection is typically with southerly (on-shore) winds.
CO concentration measurements are made on the same high and low pressure air samples as those used for CH4 concentration measurements.
The high pressure samples are dry whole air samples collected iin light gauge 70 L stainless steel tanks and 50L Aluminium cylinders, with the air sampled through a 10 m long 12.5 mm o.d. stainless steel
tube attached to the Baring Head sampling mast. The air is pumped from the mast to the tanks
using a KNF Neuberger diaphram pump (model N400.3 ANL) and dried using a 1 L stainless steel
trap containing 3 mm 13X molecular sieve pellets.
The low pressure air samples are collected in 2 L light gauge stainless steel cans using a
rubber diaphragm pump through the same air line without drying.
Since 1996 samples have also been collected in 2 L glass flasks with magnesium perchlorate
drying, and pumped with a metal bellows pump (model MB 158).
The tanks and flasks are pumped using an automated sampling system that samples in conditions
when the wind comes from the clean southerly sector at speeds greater than 7.5 m/s and when CO2 has not changed by more than 0.02 ppm in the previous 4 hours.
The samples are analysed in the NIWA laboratory at Greta Point, Wellington, New Zealand |
| Instrument and Analysis |
| Measurement method |
: |
Gas Chromatography (other) |
| Current status and history of instrument |
: |
GC- RGD until December 2009
GC-CVAFS from December 2009
|
| Description of instrument |
: |
Hewlett Packard
HP 5890 |
| Calibration |
| Current scale employed in the measurement |
: |
NOAA04 scale |
| Measurement calibration |
: |
CO concentration is determined by gas chromatography fitted with flame ionisation detection and compared against standards purchased from NOAA/ESRL CCL and were last recalibrated in 2010. |
| Scale and calibration(treasability) |
: |
NOAA04 scale |
| Data Processing |
| Measurement unit |
: |
ppb |
| Data processing |
: |
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| Processing for averaging |
: |
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| Data flag |
: |
Data are flagged for offshore or onshore wind.
Flag = 2 indicates onshore winds,
Flag = 1 indicates off shore winds,
Flag = 0 indicates not specified. |
| Data remarks |
: |
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| Other Information |
| Scientific aim |
: |
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| Reference |
: |
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| submitted by National Institute of Water & Atmospheric Research Ltd. |
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