Precipitation Occurrence Sensor System (POSS)

The Precipitation Occurrence Sensor System (POSS) is a small X-band 10.525 GHz continuous-wave bi-static vertically pointing Doppler radar. The system reports precipitation occurrence, type and intensity of precipitation at 1-min temporal resolution. Raw measurements are 960 samples per minute. Doppler velocity and return power of hydrometeors intersect the sensing volume near and up to about 3 m above the sensor head.

Post-processing of the spectral data produces a results file containing derived precipitation rate and radar reflectivity, for both liquid and solid precipitation assumptions, at 1-minute temporal resolution.

The minutely POSS precipitation rates are estimated using two different methods. The “mass flux (MF) method” is for liquid precipitation. The “regression method” or “Z-R method” is used by large-scale precipitation radars where there is a relationship (regression) between radar reflectivity (Z) and precipitation rate (R).

POSS units have been deployed at a number of sites worldwide. Datasets are listed as follows,

1) YEU, 2007-07-28 to 2020-03-01 - Eureka, Nunavut, Canada.

2) GNL, 2010-09-15 to 2020-05-01 - Summit Station, Greenland Ice Sheet.

3) CAR, 2011-01-01 to 2019-08-23 - Egbert, Ontario, Canada.

4) YYZ, 2013-06-11 to 2019-05-23 - Toronto Pearson Int. Airport, Ontario, Canada.

5) JAR, 2010-09-17 to 2011-04-20 - Jarvenpaa (40 km N of Helsinki), Finland.

6) EMA, 2010-09-18 to 2010-10-22 - Emasalo (50 km E of Helsinki), Finland.