Applications of a Passive Satellite-borne Microwave Retrieval of Water Vapour Column during the Arctic Winter.

Abstract:

A water vapor column retrieval for use during the Arctic Winter is presented. The retrieval, known as PLDC15, uses data from several passive microwave satellite instruments which measure brightness temperatures near the 183 GHz water vapor absorption line in conjunction with a priori information. Comparisons to a ground truth in Barrow, Alaska, the G-Band Vapor Radiometer (GVR), gives a standard deviation of 0.39 kg m^-2 and a bias of 0.07 kg m^-2 for water vapor column less than 6 kg m^-2. This error is smaller when compared to other microwave techniques and comparable to re-analyses datasets while having a higher spatial resolution (< 40 km) with significantly more structure (See attached figure for water vapour column comparison of a) PLDC15 retrieval and b) Arctic System Reanalysis dataset). Pan-Arctic maps of water vapor column are produced many times daily using the large number of datasets from passive microwave instruments that are available.

The PLDC15 retrieval is used for several purposes. A comparison to Arctic Radiosonde measurements of water vapor column is shown to assess the Radiosondes capability of measuring water vapor at various locations in the Arctic in terms of standard deviation and bias. Using the high resolution maps of water vapor column, estimates of water vapor contribution from ice leads can be obtained, particularly in 2013 and 2015 at which time there was a considerable number of leads.

The PLDC15 retrieval can further be used to improve re-analysis data sets, for numerical weather prediction models, and water vapor budgets of the Arctic.