Precipitable water
Precipitable water is the depth of water in a column of the atmosphere, if all the water in that column were precipitated as rain. As a depth, the precipitable water is measured in millimeters or inches. Often abbreviated as "TPW", for Total Precipitable Water.
Measurement
There are different measurement techniques:
- One type of measurement is based on the measurement of the solar irradiance on two wavelengths, one in a water absorption band, and the other not. The precipitable water column is determined using the irradiances in these bands and the Beer–Lambert law.
- The precipitable water can also be calculated by integration of radiosonde data (relative humidity, pressure and temperature) over the whole atmosphere.
- Data can be viewed on a Lifted-K index. The numbers represent inches of water as mentioned above for a geographical location.
- Recently, methods using the Global Positioning System have been developed.{{cite journal
| author=Bevis, M.| title=GPS Meteorology: Remote Sensing of Atmospheric Water Vapor Using the Global Positioning System
| journal=Journal of Geophysical Research
| year=1992
| volume=97
| issue=D14
| pages=15787–15801
| bibcode=1992JGR....9715787B |doi = 10.1029/92JD01517 |display-authors=etal}}
- Some work has been performed to create empirical relationships between surface specific humidity and precipitable water based on localized measurements (generally a 2nd to 5th order polynomial).{{cite journal |last=Liu |first=Timothy |date=27 February 1986 |title=Statistical Relation between Mean Precipitable Water and Surface-Level Humidity over Global Oceans |journal=Monthly Weather Review |volume=114 |issue=8 |pages=1591–1602 |doi= 10.1175/1520-0493(1986)114<1591:srbmmp>2.0.co;2|bibcode = 1986MWRv..114.1591L |doi-access=free }}{{cite journal |last1=Hsu |first1=S.A. |last2=Blanchard |first2=B.W. |date=15 October 1989 |title=The Relationship Between Total Precipitable Water and Surface-Level Humidity Over the Sea Surface: A Further Evaluation |journal=Journal of Geophysical Research |volume=94 |issue=C10 |pages=14539–14545 |doi=10.1029/JC094iC10p14539 |bibcode=1989JGR....9414539H}} {{cite journal |last1=Guangxiong |first1=Peng |last2=Jing |first2=Li |last3=Yunhao |first3=Chen |last4=Norizan |first4=Abdul |last5=Tay |first5=Liphong |date=17 July 2006 |title=High-resolution Surface Relative Humidity Computation Using MODIS Image in Peninsular Malaysia |url=http://egeoscien.neigae.ac.cn/fileup/PDF/20060312.pdf |journal=Chinese Geographical Science |volume=16 |issue=3 |pages=260–264 |doi=10.1007/s11769-006-0260-6 |bibcode=2006ChGpS..16..260P |s2cid=73558154 |accessdate=22 January 2014 |archive-date=4 March 2016 |archive-url=https://web.archive.org/web/20160304044130/http://egeoscien.neigae.ac.cn/fileup/PDF/20060312.pdf |url-status=dead }} However, this method has not received widespread use in part because humidity is a local measurement and precipitable water is a total column measurement.
References
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External links
- [https://earth.nullschool.net/#current/wind/surface/level/overlay=total_precipitable_water/winkel3/ Current global map of precipitable water]
- {{cite journal |last1=Maurellis |first1=A. N. |first2=R. |last2=Lang |first3=W. J. |last3=van der Zande |first4=I. |last4=Aben |first5=W. |last5=Ubachs |year=2000 |title=Precipitable water column retrieval from GOME data |journal=Geophys. Res. Lett. |volume=27 |issue=6 |pages=903–906 |doi=10.1029/1999GL010897 |bibcode = 2000GeoRL..27..903M |hdl=1871/23072 |s2cid=55326173 |url=https://research.vu.nl/ws/files/1684965/128747.pdf }}
- [http://www.csr.utexas.edu/texas_pwv/midterm/gabor/gabor.html Remote Sensing of Water Vapor From GPS Receivers]
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Category:Atmospheric thermodynamics
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