A comparison of the Stratospheric Aerosol and Gas Experiment II tropospheric water vapor to radiosonde measurements

Journal Article · Sat Mar 20 04:00:00 EST 1993 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/92JD01630· OSTI ID:6619193

Larsen, J C; Chiou, E W ^[1]; Chu, W P; McCormick, M P; McMaster, L R ^[2]; Oltmans, S ^[3]; Rind, D ^[4]

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1. Hughes STX Corp., Hampton, VA (United States)
2. NASA Langley Research Center, Hampton, VA (United States)
3. NOAA Climate Modeling and Diagnostic Lab., Boulder, CO (United States)
4. NASA Goddard Inst. for Space Studies, New York, NY (United States)

Upper tropospheric Stratospheric Aerosol and Gas Experiment II (SAGE II) water vapor observations are compared to correlative radiosonde observations and radiosonde based climatologies. The SAGE II 1987 monthly zonal mean water vapor climatology is compared to both the Global Atmospheric Circulation Statistics (1963-1973) climatology and to the 1987 radiosonde climatology. The clear sky SAGE II climatology is found to be approximately half the level of both the clear/cloudy sky radiosonde climatologies. To determine whether this is realistic for these two different climatologies or includes additional observational and instrumental biases, the authors took the 1987 radiosonde data set and identified approximately 800 correlative profile pairs. The observational biases inherent to SAGE II and the radiosondes produce a set of profile pairs characteristic of clear sky, land conditions. A critical review of the radiosonde measurement capability was carried out to establish the operating range and accuracy in the upper troposphere. The authors show that even with tight coincidence criterion, the quality of the profile pair comparisons varies considerably because of strong water vapor variability occurring on small time and space scales. Annual zonal means calculated from the set of profile pairs again finds SAGE II significantly drier in many latitude bands. Resolving the radiosonde data base by hygrometer type shows this to be true for all hygrometers except for the thin film capacitive type (Vaisala Humicap). For this hygrometer, between 4.5 and 6.5 km SAGE II is drier by approximately 25.%, and from 8.5 to 11.5 km they are nearly equivalent when global annual means are compared. The good agreement with the Vaisala Humicap, currently the most accurate and responsive hygrometer in operational use, suggests existing radiosonde climatologies contain a significant moist bias in the upper troposphere. 31 refs., 16 figs., 6 tabs.

• OSTI ID: 6619193
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 98:D3; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
ACCURACY
ATMOSPHERIC CIRCULATION
COMPARATIVE EVALUATIONS
EARTH ATMOSPHERE
ECOLOGICAL CONCENTRATION
EVALUATION
FILMS
FLUIDS
GASES
HYGROMETRY
MATHEMATICS
REMOTE SENSING
SKY
SPACE
STATISTICS
THIN FILMS
TROPOSPHERE
VAPORS
WATER VAPOR