Show simple item record

contributor authorRacette, Paul E.
contributor authorWestwater, Ed R.
contributor authorHan, Yong
contributor authorGasiewski, Albin J.
contributor authorKlein, Marian
contributor authorCimini, Domenico
contributor authorJones, David C.
contributor authorManning, Will
contributor authorKim, Edward J.
contributor authorWang, James R.
contributor authorLeuski, Vladimir
contributor authorKiedron, Peter
date accessioned2017-06-09T17:22:43Z
date available2017-06-09T17:22:43Z
date copyright2005/04/01
date issued2005
identifier issn0739-0572
identifier otherams-84095.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4227393
description abstractExtremely dry conditions characterized by amounts of precipitable water vapor (PWV) as low as 1?2 mm commonly occur in high-latitude regions during the winter months. While such dry atmospheres carry only a few percent of the latent heat energy compared to tropical atmospheres, the effects of low vapor amounts on the polar radiation budget?both directly through modulation of longwave radiation and indirectly through the formation of clouds?are considerable. Accurate measurements of PWV during such dry conditions are needed to improve polar radiation models for use in understanding and predicting change in the climatically sensitive polar regions. To this end, the strong water-vapor absorption line at 183.310 GHz provides a unique means of measuring low amounts of PWV. Weighting function analysis, forward model calculations based upon a 7-yr radiosonde dataset, and retrieval simulations consistently predict that radiometric measurements made using several millimeter-wavelength (MMW) channels near the 183-GHz line, together with established microwave (MW) measurements near the 22.235-GHz water-vapor line and ?31-GHz atmospheric absorption window can be used to determine within 5% uncertainty the full range of PWV expected in the Arctic. This combined capability stands in spite of accuracy limitations stemming from uncertainties due to the sensitivity of the vertical distribution of temperature and water vapor at MMW channels. In this study the potential of MMW radiometry using the 183-GHz line for measuring low amounts of PWV is demonstrated both theoretically and experimentally. The study uses data obtained during March 1999 as part of an experiment conducted at the Department of Energy?s Cloud and Radiation Testbed (CART) site near Barrow, Alaska. Several radiometers from both NOAA and NASA were deployed during the experiment to provide the first combined MMW and MW ground-based dataset during dry Arctic conditions. Single-channel retrievals of PWV were performed using the MW and MMW data. Discrepancies in the retrieved values were found to be consistent with differences observed between measured brightness temperatures (TBs) and forward-modeled TBs based on concurrent radiosonde profiles. These discrepancies are greater than can be explained by radiometer measurement error alone; errors in the absorption models and uncertainty in the radiosonde measurements contribute to the discrepancies observed. The measurements, retrieval technique, and line model discrepancies are discussed, along with difficulties and potential of MMW/MW PWV measurement.
publisherAmerican Meteorological Society
titleMeasurement of Low Amounts of Precipitable Water Vapor Using Ground-Based Millimeterwave Radiometry
typeJournal Paper
journal volume22
journal issue4
journal titleJournal of Atmospheric and Oceanic Technology
identifier doi10.1175/JTECH1711.1
journal fristpage317
journal lastpage337
treeJournal of Atmospheric and Oceanic Technology:;2005:;volume( 022 ):;issue: 004
contenttypeFulltext


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record