Retrievals of Atmospheric Temperature and Water Vapor in the Arctic
We show that by incorporating brightness temperature measurements at off-zenith angles, the accuracy of linear statistical retrievals of temperature and water vapor density profiles can be improved. This improvement is limited to clear sky cases where measurements at all angles represent the same at...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.176.3461 http://www.arm.gov/publications/proceedings/conf16/extended_abs/liljegren_jc.pdf |
| Summary: | We show that by incorporating brightness temperature measurements at off-zenith angles, the accuracy of linear statistical retrievals of temperature and water vapor density profiles can be improved. This improvement is limited to clear sky cases where measurements at all angles represent the same atmospheric conditions. We present contribution functions to show how the off-zenith measurements affect the retrieval performance. We show that the brightness temperatures calculated using the MonoRTM and modified Rosenkranz models are affected by the choice of spectroscopic parameters for microwave absorption by oxygen, and how these choices affect the retrievals. We also show that by combining brightness temperature measurements near the 22.235-GHz water vapor line with measurements near the 183.31-GHz line into a physical retrieval, the accuracy of the retrieved water vapor density profile for very low water vapor conditions can be significantly improved. Background The Atmospheric Radiation Measurement (ARM) Program has operated a twelve-channel microwave radiometer profiler (MWRP) (Liljegren 2002) since February 2004 at ARM Climate Research Facility (ACRF) North Slope of Alaska (NSA) field site near Barrow, Alaska. The MWRP has five channels in |
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