Total Column Water Vapour Retrieval in the Arctic using Satellite-Borne Measurements from the Microwave Humidity Sounder

Abstract:

The Microwave Humidity Sounder (MHS) is a satellite-borne instrument onboard the polar orbiting NOAA-18, NOAA19, MetOp-A, and MetOp-B satellites. MHS measures brightness temperatures near a strong water vapour absorption line at 183 GHz for the purpose of measuring water vapour without significant interference from ice or water clouds.

A water vapour retrieval technique that is independent of surface emissivity and favours low column amounts of water vapour is shown and is ideal for Arctic winter measurements. The retrieval uses a-priori information to produce a pan-Arctic water vapour column dataset that has high spatial (15 km at nadir) and temporal resolution (twice daily) with relatively low amounts of error compared to other retrievals. A comparison of the MHS retrieval with the satellite-borne Atmospheric Infrared Sounder (AIRS) instrument and Reanalysis datasets was completed using the G-Band Water Vapour Radiometer (GVR), located in Barrow, Alaska (71N, 156W).

An assessment of the Arctic radiosonde network is shown to quantify the quality of water vapour measurements at each station. Time evolution of the precipitable water fields can provide insight into the dehydration of the atmosphere in the Arctic. A water budget for the Arctic can be constructed using the high spatial and temporal resolution analysis. The high resolution and low noise of this retrieval technique will potentially allow for the measurement of water vapour from Arctic phenomena such as ice leads.