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Atmospheric Water Vapor

Other Names

H2O, H2O Concentration, Moisture, Humidity, Specific Humidity, Relative Humidity, Dew Point Temperature, Precipitable Water Vapor, Total Precipitable Water Vapor, Water Vapor Column Density

Definition

Atmospheric Water Vapor, Precipitable Water Vapor, or Humidity is a measure of the water vapor content of the air. It is one of the most important greenhouse gas of the atmosphere.
More than fifty percent of all of the atmospheric water vapor is found below 2-km altitude, and only a minute fraction of the total occurs above the tropopause. Water vapor is a major vehicle for the transport of energy (latent heat) and acts as a regulator of planetary temperatures through absorption and emission of radiation, most significantly in the thermal infrared (the greenhouse effect).

There are number of atmospheric variables that are used to express the amount of water vapor present in the atmosphere. Some of them are briefly described below:
Absolute Humidity: The mass of water vapor per unit volume of air containing the the water vapor (units g/m3)
Specific Humidity: It is ratio of weight of water vapor in a specified volume to the weight of dry air in the same volume(dimensionless).
Relative Humidity: It is ratio of actual measured water vapor amount to the saturation vapor pressure (the maximum possible water vapor amount after which it condenses as dew) at a specific temperature.
Precipitable Water Vapor: Amount of water ( depth of vertical column of unit-crossectional area) which would be obtained if all the water vapor in a specified column of the atmosphere were condensed to liquid.
Dewpoint Temperature: It is the temperature to which a given parcel of air must be cooled (at constant pressure) for saturation to occur. It is also used as a measure of humidity.

Applications

(1) Surface energy budget (5) Agriculture
(2) Global energy budget (6) Atmospheric Models
(3) Climate change (7) Tracer of Air Motions
(4) Global warming (8) stratosphere-troposphere exchange

GES DISC Datasets

Quick Search for 'Atmospheric Water Vapor' with Mirador
Click on the corresponding 'Data access' links in the table below to access products containing specific parameter.

Parameter Units Platform /Instrument Data Products
Begin Date End Date Data Access Doc
Water Vapor Mixing Ratio Profile (layer H2O Concentration)
(ground pixel resolution)
mixing ratio Aura/MLS 2004-08-08 Current ML2H2O Y
Aura/HIRDLS 2004-07-15 Current HIRDLS2 Y
Water Vapor Mixing Ratio Profile (layer H2O Concentration)
(daily, global, gridded )
mixing ratio Aura/MLS 2004-08-08 Current   Y
Aura/HIRDLS 2004-07-15 Current   Y
Water Vapor Mixing Ratio Profile (pixel resolution) mixing ratio UARS/HALOE 1991-10-11 2005-11-21 UARHA2FN Y
Nimbus-7/LIMS 1978-10-25 1985-05-01 LIMSN7L2 Y
NOAA/TOVS 1978-11-30 1995-07-05 NOAA/TOVS Y
Water Vapor Mixing Ratio Profile (Global Gridded Daily, at equal interval of Latitude or Time mixing ratio UARS/HALOE 1991-10-11 2005-11-21 UARHA3AT Y
UARS/CLAES 1991-10-25 1993-05-05 UARCL3AL Y
UARCL3AT Y
UARS/ISAMS 1991-09-26 1992-07-29 UARIS3AL Y
UARIS3AT Y
UARS/MLS 1991-09-18 1999-07-28 UARML3AL Y
UARML3AT Y
Water Vapor Mixing Ratio and
Saturation Mass Mixing Ratio Profiles
(ground pixel resolution, 45 x 45 km at Nadir)
gm/kgm Aqua/AIRS 2002-08-30 Current AIRX2RET Y
Water Vapor Mixing Ratio and Std.Dev(Daily, Weekly and Monthly Averages, Global 1deg x 1deg grids) gm/kgm Aqua/AIRS 2002-08-30 Current AIRS Level3 Y
Water Vapor Mixing Ratio for 18 pressure layers
(Daily and Monthly Averages, at 4 deg intervals of latitude )
ppmv Nimbus-7/LIMS 1978-10-25 1985-05-01 LIMSN7L2 Y
Water Vapor Profile
(ground pixel resolution, 45 x 45 km at nadir)
molecules/cm2 Aqua/AIRS 2002-08-30 Current AIRX2SUP Y
Water Vapor Profile(daily daytime/nighttime, 5-day,and Monthly Averages, Global 1 deg x 1 deg grids) cm NOAA/TOVS 1978-11-30 1995-07-05 NOAA/TOVS Y
Total Water Vapor(Daily, Weekly, and Monthly Averages, Global 1deg x 1deg grids) kg/m2 Aqua/AIRS 2002-08-30 Current AIRS Level3 Y
Precipitable Water Vapor (daily, global gridded) cm TRMM/TMI 1997-12-07 Current TRMM_2A12 Y
TRMM_3A12 Y
TRMM/PR 1997-12-07 Current TRMM_3B31 Y
Relative Humidity and Std.Dev.for 12 atmospheric layers(Daily Weekly and Monthly Averages, Global 1deg x 1deg grids) unitless Aqua/AIRS 2002-08-30 Current AIRS Level3 Y
Relative Humidity with respect to Ice
(ground pixel resolution, 45 km at nadir)
unitless Aura/MLS 2004-08-08 Current ML2RHI Y
Relative Humidity with respect to Ice
(daily, global, gridded)
unitless Aura/MLS 2004-08-08 Current   Y

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Last updated: May 13, 2013 09:09 AM ET