NOAA Dual-Beam UV Absorption Ozone Photometer

Principal Investigators: Joshua Ballard, Ru-Shan Gao


National Oceanographic and Atmospheric Administration
Chemical Sciences Division
325 Broadway
Boulder, CO 80305

Phone: (303) 497-5337 (JB), (303) 497-5431 (RG)


Principle of Operation:

Ozone is measured in situ using a photometer consisting of a mercury lamp, two sample that can be periodically scrubbed of ozone, and two detectors that measure the 254-nm radiation transmitted through the chamber (Proffitt et al. [1983]). The ozone number density is calculated using the ozone absorption cross-section at 254 nm and the Beer-Lambert Law. Since the two absorption chambers are identical, virtually continuous measurements of ozone are made by alternating the ambient air sample and ozone-scrubbed sample between the two chambers. A flow of ambient air through the chambers is maintained with dynamic pressure at the inlet opening outside the fuselage. At a one-second data collection rate, the minimum detectable concentration of ozone (one standard deviation) is 1.5 x 1010 molecules/ cm3 (0.6ppbv at STP). This instrument has a long and successful history of operation on the NASA ER-2 and WB-57 high-altitude research aircraft. Over 300 flights have been logged (~1800 flight hours) during stratospheric missions dating back to 1985. The instrument has most recently flown on the Tropical Composition, Cloud and Climate Coupling (TC4) mission.

Instrument Specifications:

Accuracy 3% + precision
Precision 1.5 x1010 molecules/cm3
Weight 24 kg
Data rate 1 second
Power 250 W max. (28 VDC)

Partial Mission History:

Missions and latitude coverage for NOAA-AL Ozone Photometer
Mission Base Location Lat range Time Span Platform Hours
STEP California 40N - 35N 1986 U-2 40
STEP Darwin, Australia 37N - 30S 1987 ER-2 121
AAOE Punta Arenas, Chile 37N - 72S 1987 ER-2 120
AASE Stavanger, Norway 82N - 37N 1988 - 1989 ER-2 123
SAGE Validation California 37N - 34N 1991 ER-2 11
AASEIIBangor/Fairbanks 90N - 22N 1991 - 1992 ER-2 202
SPADE California 60N - 14N 1992 - 1993 ER-2 114
ASHOE/MAESACalifornia/New Zealand 61N - 70S 1994 ER-2 283
STRAT California/Hawaii 62N - 2S 1995 - 1996 ER-2 260
POLARIS Fairbanks/Hawaii 90N - 3S 1997 ER-2 168
WAM Houston 45N - 10N 1998 WB-57 51
RISO Houston 34N - 28N 1999 WB-57 24
ACCENT Houston 45N - 9N 1999 WB-57 45
SOLVE Kiruna, Sweden 89N - 21S 1999 - 2000 ER-2 128
ACCENT2 Houston 30N - 4S 2000 WB-57 27
CAMEX-4 Jacksonville 16N-39N 2001 ER-2 83

Publications Describing the Instrument:

Proffitt, M. H., and R. J. McLaughlin, Fast-response dual-beam UV absorption ozone photometer suitable for use on stratospheric balloons, Rev. Sci. Instrum. 54, 1719-1728, 1983.
Proffitt, M. H. et al., Ozone loss in the Arctic polar vortex inferred from high-altitude aircraft measurements, Nature, 347, 31-36, 1990.
Proffitt, M. H., et al., Ozone loss inside the northern polar vortex during the 1991-1992 Winter, Science, 261, 1150-1154, 1993.
Richard, E. C., et al., Severe chemical ozone loss inside the Arctic polar vortex during Winter 1999-2000 inferred from in situ airborne measurements, Geophys. Res. Lett., 28, 2197-2200, 2001.