4.1.3. Calibration of Dobson Ozone Spectrophotometers
Fifteen Dobson ozone spectrophotometers were calibrated during 1996 and 1997. Table 4.4 lists all of the instruments calibrated and the resulting calibration difference expressed in percentage of ozone difference. This percentage of difference is for ozone calculated from the test instrument and the standard instrument measurements with the double wavelength pair (A and D) on the direct sun (DS) with the ground quartz plate in place (GQP) observation type at a Mu value of 2 and a total ozone value of 300 Dobson Units (DU) before any repair or calibration adjustment is made. The table also lists the place of the calibration and the standard instrument used.
TABLE 4.4. Dobson Ozone Spectrophotometers Calibrated in 1996-1997
|
Instrument |
Calibration |
Calibration |
Standard |
|||
|
Station |
Number |
Date |
Correction (%) |
Number |
Place |
|
|
1996 |
||||||
|
Manila, Philippines |
52 |
June 1990 |
0.8% |
116* |
Tsukuba, Japan |
|
|
Bangkok, Thailand |
09 |
Oct. 1987 |
N/A (Instrument damaged) |
116* |
Tsukuba, Japan |
|
|
New Delhi, India |
112 |
Dec. 1984 |
0.0% |
116* |
Tsukuba, Japan |
|
|
Seoul, Korea |
124 |
July 1991 |
3.6% |
116* |
Tsukuba, Japan |
|
|
SPO |
80 |
NA |
NA |
83 |
Boulder, Colorado |
|
|
1997 |
||||||
|
Singapore |
07 |
Sept. 1990 |
1.0% |
83 |
Perth, Australia |
|
|
SMO |
42 |
Sept. 9, 1991 |
0.0% |
83 |
Perth, Australia |
|
|
Lauder, New Zealand |
72 |
July 22, 1992 |
0.0% |
83 |
Perth, Australia |
|
|
Perth, Australia |
81 |
July 7, 1992 |
-0.2% |
83 |
Perth, Australia |
|
|
Irene, South Africa |
89 |
May 1993 |
-0.3% |
83 |
Perth, Australia |
|
|
Melbourne, Australia (regional standard) |
105 |
June 29, 1992 |
0.0% |
83 |
Perth, Australia |
|
|
SPO |
82 |
Aug. 27, 1992 |
-0.7% |
83 |
Boulder, Colorado |
|
|
Hohenpeissenberg, Germany |
64 |
Aug. 2, 1990 |
-1.4% |
65 |
Stiga Ski Field, Greece |
|
|
Hradec Kralove, Czech Republic |
74 |
Aug. 2, 1990 |
+1.4 |
65 |
Stiga Ski Field, Greece |
|
|
Cairo, Egypt |
96 |
July 10, 1997 |
-2.0% |
65 |
Stiga Ski Field, Greece |
|
|
St. Petersburg, Russia |
108 |
May 25, 1993 |
-0.5% |
65 |
Stiga Ski Field, Greece |
|
|
Athens, Greece |
118 |
Aug. 5, 1990 |
+0.8% |
65 |
Stiga Ski Field, Greece |
|
|
Bucharest, Romania |
121 |
1995 |
N/A |
65 |
Stiga Ski Field, Greece |
|
*Although CMDL instruments were not involved, the CMDL World Dobson Calibration Center supervised the Tsukuba intercomparison.
In 1996 the SPO instrument had a calibration defined before being sent to the station in replacement of instrument no. 82.
Instrument no. 121 was optically realigned and thus had no existing calibration record.
As part of its role as the World Center for Dobson Calibrations, CMDL participated in international Dobson spectrophotometer calibrations at the Aerological Observatory, Tsukuba, Japan (February 26 to March 26, 1996); Perth Airport, Australia (February 3 to 14, 1997); and Stiga Ski Field, near Kalavryta, Greece (July 20 to August 8, 1997). In cooperation with the WMO Global Atmosphere Watch (GAW) program, CMDL personnel made a physical inspection and evaluation of sites operating Dobson spectrophotometers in Argentina, Uruguay, and Brazil during April 1997.
The world standard Dobson ozone spectrophotometer calibration was checked in summer campaigns (1996 and 1997) at MLO. The calibration was verified to be in error by less that 1% in both campaigns. These campaigns are a cooperative effort with NASA, and the data obtained are also used as validation for satellite measurements.