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Can liquid water profiles be retrieved from passive microwave zenith observations?
Author(s) -
Crewell Susanne,
Ebell Kerstin,
Löhnert Ulrich,
Turner D. D.
Publication year - 2009
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2008gl036934
Subject(s) - liquid water content , zenith , microwave , cloud computing , microwave radiometer , environmental science , radiometer , brightness , brightness temperature , remote sensing , liquid water , liquid water path , meteorology , optics , physics , geology , precipitation , computer science , thermodynamics , quantum mechanics , operating system
The ability to determine the cloud boundaries and vertical distribution of cloud liquid water for single‐layer liquid clouds using zenith‐pointing microwave radiometers is investigated. Simulations are used to demonstrate that there is little skill in determining either cloud base or cloud thickness, especially when the cloud thickness is less than 500 m. It is also shown that the different distributions of liquid water content within a cloud with known cloud boundaries results in a maximum change in the brightness temperature of less than 1 K at the surface from 20 to 150 GHz, which is on the order of the instrument noise level. Furthermore, it is demonstrated using the averaging kernel that the number of degrees of freedom for signal (i.e., independent pieces of information) is approximately 1, which implies there is no information on vertical distribution of liquid water in the microwave observations.