Uncertainties in climatological tropical humidity profiles: Some implications for estimating the greenhouse effect

Journal Article · Sat May 01 00:00:00 EDT 1993 · Journal of Climate; (United States)

DOI:https://doi.org/10.1175/1520-0442(1993)006<0978:UICTHP>2.0.CO;2· OSTI ID:6317212

Gutzler, D S ^[1]

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1. Atmospheric and Environmental Research, Inc., Cambridge, MA (United States)

The vertical profile of water vapor, the principal infrared-absorbing gas in the atmosphere, is an important factor in determining the energy balance of the climate system. This study examines uncertainties in calculating a climatological humidity profile: specifically one derived from radiosonde data representative of the moist and highly convective region over the western tropical Pacific Ocean. Uncertainties in the humidity data are large in conditions of low temperature or low humidity in the mid- and upper troposphere. Results derived from a single United States station (Koror) and from an average of four United States-operated stations (all near the equator west of the date line) yield nearly identical results. No humidity measurements are reported in fully the upper third of the troposphere. The implications of these uncertainties for determining the climatological humidity profile are quantitatively assessed by bracketing the range of plausible assumptions for unreported humidity to produce extreme estimates of the climatological profile. These profiles, together with the observed climatological temperature profile, are used as input to a radiative transfer model to ascertain the uncertainty in clear-sky outgoing infrared radiance due to water vapor uncertainties. The radiance uncertainty is shown to be comparable in magnitude to the purely radiative response of the tropical atmosphere to doubling carbon dioxide. The uncertainty associated with unmeasured upper-tropospheric humidity is approximately equal to that arising from incompletely measured midtropospheric humidity. Clear-sky radiative uncertainties, however, are modest relative to the uncertainty associated with variations of infrared absorption due to clouds, as demonstrated by introducing citrus ice particles into the radiative transfer calculations.

• OSTI ID: 6317212
• Journal Information: Journal of Climate; (United States), Vol. 6:5; ISSN 0894-8755
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CLIMATE MODELS
HUMIDITY
GREENHOUSE EFFECT
FORECASTING
VARIATIONS
TROPICAL REGIONS
CARBON DIOXIDE
CITRUS
CLOUDS
ENERGY BALANCE
EQUATOR
ICE
PACIFIC OCEAN
PARTICLES
TROPOSPHERE
WATER VAPOR
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CLIMATIC CHANGE
EARTH ATMOSPHERE
FLUIDS
GASES
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MATHEMATICAL MODELS
OXIDES
OXYGEN COMPOUNDS
PLANTS
SEAS
SURFACE WATERS
VAPORS
540110*
540120 - Environment
Atmospheric- Chemicals Monitoring &amp; Transport- (1990-)