Climate data continuity with ASOS in precipitation and temperature

The introduction of the Automated Surface Observing System (ASOS) by the National Weather Service in the early 1990s has produced cooler temperatures and a series of concerns regarding precipitation observations. This presentation will compare ASOS daily rainfall with locations with a Universal Rain Gage (UNIV) and discuss the estimate of average temperature for ASOS locations which may or may not have had an HO-83 previously at the ASOS location.

Rainfall comparisons of the ASOS Heated Tipping Bucket have been made for 44 locations with the Universal Rain Gage for daily observations in the warm season. The six locations with three summers of observations have an average ratio of ASOS to UNIV of 1.00 with a range of 0.91 to 1.05. The ten sites with two summers of observation had an average ratio of 1.01 with a range of 0.93 to 1.06, and the twenty-eight sites with one summer of observations had an average of 0.98 and a range of 0.80 to 1.13. A discussion will be included of the current and future prospects of precipitation observations with ASOS.

A comparison of ASOS temperature observations with nearby cooperative temperature observations will be presented to evaluate how well climatological averages might be estimated for ASOS sites.