Upload
blake-adams
View
221
Download
0
Embed Size (px)
Citation preview
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
Brewer calibrations: Brewer calibrations: what do they accomplish?what do they accomplish?
Volodya SavastioukVolodya SavastioukInternational Ozone Services Inc.International Ozone Services Inc.
Full Spectrum Science Inc.Full Spectrum Science Inc.
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
•Why do Brewers need calibrations?
•What is done during calibrations?
•Recommended calibration frequency.
Presentation outline:
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
1. The most important aspect of Brewer calibrations: maintaining the same ozone reference for all Brewersa) The world’s reference for Brewers is the triad of Brewers
in Torontob) Traveling reference Brewers with the triad either directly
in Toronto or using traveling references #017 and #1452. Keeping the Brewers in working condition and fixing what’s
broken3. Measuring Brewer characterization parameters
a) Dead time, dispersion, UV response, ND filtersb) Optimal high voltage, SL power
4. Training and educating local personnel
Why do Brewers need calibrations?
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
Extra Terrestrial Coefficients (ETC):Only a few Brewers are in locations that allow reliable absolute calibrations using the Langley extrapolation technique (Mauna Loa, Izana); the majority of instruments require comparisons with calibrated Brewers for establishing the ETC.
Why do Brewers need calibrations?
Remember how ozone is calculated in the Brewer software?
X=(R6-ETC)/(a*mu)
Measured CalEstablished CalEstablished Calculated
Ozone absorption coefficient (a):established using the results of the dispersion test and the
laboratory-measured ozone cross-sections.
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
What is done during calibrations?
1. Initial comparison with the traveling standard (if the Brewer is working) Analysing available historical data Collecting solar/sky data side-by-side with the standard Applying the necessary corrections to the ozone calculations
2. Brewer inspection/maintenance Tracker plate, micrometers, push rod, etc. The extent of this is based on the history of the Brewer
3. Characterization tests Dispersion, UV response, ND filters, dead time
4. Final comparison with the standard Adjusting the ETC if needed
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
Data evolution
Calibration
ETC SL ratio R6cal
Run/Stop
Dead Time
Steps per revolution
High voltage
Data collection: 1. Observations2. Tests3. Notes (log-file)
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
Red marks indicate that the Run/Stop test was not ideal
Any individual test result does not necessarily describe the state of the instrument.Looking at the historical record is a much more reliable way to diagnose a Brewer.
Overall, this instrument is working fine.
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
A calibration visit and maintenance improved the RS results
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
o3 DEADTIME TEST AT 03:46:45, sep 08, 07Deadtime (ns) for filter position 0 (high intensity) 3.787239E-08 (at 03:47:05) 3.875278E-08 (at 03:47:26) 3.93215E-08 (at 03:47:46) 3.742871E-08 (at 03:48:06) 3.821398E-08 (at 03:48:26) Mean = 38.317 Std Dev = .7 Deadtime (ns) for filter position 1 (low intensity) 3.635986E-08 (at 03:49:07) 3.64374E-08 (at 03:49:27) 3.58004E-08 (at 03:49:47) 3.638064E-08 (at 03:50:07) 3.434979E-08 (at 03:50:27) 3.624829E-08 (at 03:50:47) 3.821146E-08 (at 03:51:07) 4.033888E-08 (at 03:51:27) 3.89437E-08 (at 03:51:47) 3.515724E-08 (at 03:52:07) Mean = 36.822 Std Dev = 1.8
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
Dead time slowly changed from 34 ns to 32 ns
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
Look for sudden changes in the SL test results
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
A/D Values for sep 09/07 at 00:24:56 for instrument number ###
Channel# Name Value Value (Lamps off) (Lamps on) 0 Brewer temp 1 (deg C) 23.75 22.81 1 Brewer temp 2 (deg C) -10.94 -10.94 2 Brewer temp 3 (deg C) 21.88 21.88 3 H.T. voltage (V) 1446.46 1446.46 4 +15V power supply (V) 14.87 14.87 5 + 5V power supply (V) 5.03 5.00 6 -15V power supply (V) -15.05 -15.05 7 +24V power supply (V) 23.40 23.75 8 Rate meter (kc/s) 0.00 15.60 9 Not used (bits) 0.00 0.00 10 Not used (bits) 0.00 0.00 11 Not used (bits) 0.00 0.00 12 + 5V ss (V) 4.95 4.95 13 - 8V ss (V) -8.11 -8.15 14 Std lmp current (A) 0.07 1.68 15 Std lmp voltage (V) 0.00 10.23
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
Sun scan test – final wavelength setting for the Brewer
Cal.step
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
Data evolution
Calibration DS ozone observations
SL tests
ETCReal-time ozone values
SL-corrected ozone values
SL ratio R6cal
ETC*=ETC+(R6-R6cal)Calibration
ETC SL ratio R6cal
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
Data evolution
Calibration
Observation
Calibration
Observation
When to do maintenance to preserve calibration history?
Calibration
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
Recommended calibration frequency
This is a difficult one. From our experience, a calibration every two years is enough for most Brewers. However, we definitely see the most stability with Brewers that are visited every year.
Historical data are often a good indicator on whether the Brewer may benefit from annual calibrations.
Of course, all of this is based on the assumption that regular normal maintenance is done to the Brewer between the calibration visits, but that’ll be the topic of another talk.
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
In order to maintain (and improve) the quality of the Brewer ozone data regular calibration and maintenance visits are required.
It is extremely important to keep the Brewer network traceable the the main Brewer reference, the triad.
Conclusions:
13th Brewer User Workshop. Beijing, ChinaSeptember 12-16, 2011
Volodya [email protected]
Thank you!
Eureka, Canada, February 2011