Introduction

The University of the Highlands & Islands Metek Micro Rain Radar (MRR) at Lews Castle, Stornoway provides start-of-the-art information on the precipitation affecting Stornoway. Installed by NASA in 2015 to ground-truth light low-level precipitation for the Global Precipitation Mission, it is able to perform the following functions (see below for an example image and an explanation of the colours):

Detects a vertical profile of the dBZ (reflectivity) of precipitation, every minute, up to a height of 3.1km at a vertical resolution of 100m
Detects fall speed (m/s) of precipitation at same resolutions
Detects direction and speed of movement of precipitation (through use of the Doppler facility)
Detects very light low-level precipitation / drizzle in 'warm' clouds (common at this site, and which are otherwise missed by conventional radar)
Detects the height of the atmospheric boundary layer

The radar can therefore detect the rate (intensity) of precipitation, whether it is about to start raining (or cease) imminently. It can also determine the type of precipitation (i.e hail, snow, sleet or rain) and also determine height of the melting layer (the level at which snow turns to rain, known to meteorologists as the 'bright band'). It can also warn of imminent snowfall or freezing rain.

Radar updates can be seen on Twitter (updated every hour) at: https://twitter.com/lewscastleradar - please follow!

NASA Global Precipitation Mission (GPM) Micro Rain Radar (MRR) at the University of the Highlands and Islands, Stornoway

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