Cryogenic Frostpoint Hygrometer (CFH) launch activities at the ARM Southern Great Plains (SGP) site: 2018 Updates, Data Evaluation, and Opportunities
Poster PDF
Authors
Martin Stuefer — University of Alaska, Fairbanks
Telayna Wong — University of Alaska, Fairbanks
Donna Holdridge — Argonne National Laboratory
Jenni Kyrouac — Argonne National Laboratory
Lori Borg — University of Wisconsin
Chris Martin — Southern Great Plains
James Edward Martin — U.S. Department of Energy/ARM Program
Douglas L Sisterson — Argonne National Laboratory
Category
ARM field campaigns – Results from recent ARM field campaigns
Description
Cryogenic Frostpoint Hygrometer (CFH) has been established as a baseline instrument at the ARM Southern Great Plains (SGP). CFH balloon launches are conducted once a month to measure tropospheric and stratospheric water vapor with increased accuracy and sensitivity. The CFH, which uses a temperature-controlled chilled mirror to directly measure the ambient frostpoint, is particularly useful for studying the dry conditions of the lower stratosphere due to the instrument’s sensitivity within a few parts-per-million mixing ratios. The total uncertainty of all frostpoint or dewpoint temperature measurements using the CFH are less than 0.2 K under good conditions, and systematic errors are less than 0.1 K, allowing for reliable long-term climate tracking. CFH humidity profile observations are compared with corresponding radiosonde and High Resolution Rapid Refresh (HRRR) numerical weather model data. We determine the amplitudes of the radiosonde humidity bias, and check how humidity is represented in the HRRR at the levels of the Upper Troposphere/Lower Stratosphere (UTLS). In addition to radiosonde and model comparisons, we aim to use the CFH instrument data for evaluation of spaceborne humidity profilers and new radiosonde measurements. Currently CFH launch packages include the IMet and Vaisala RS-92 radiosondes. The replacement of the IMet radiosonde with the new Vaisala RS-41 instrument is anticipated in support of the Radiosonde Intercomparison & Validation (RIVAL) IOP.
