OVERCOLLECTION OF SOLID PRECIPITATION
BY A STANDARD PRECIPITATION GAGE,
NIWOT RIDGE, COLORADO

Tim Bardsley and Mark W. Williams

Institute of Arctic and Alpine Research and
Department of Geography, CB 450,
University of Colorado, Boulder, CO

Figure 8.
The overcollection of snow by the Belfort recording gage appears to occur during blowing snow events when there is no precipitation. For January and February, 1997, we investigated these blowing snow events by determining that blowing snow was occurring when there was no precipitation if two of these three criteria were meant:

• Solar radiation was greater than the five year monthly average
• The precipitation sensor on the NADP wet chemistry collector was closed.
• Personal observations.

The adjusted January and February data were similar to the 10-year average, with the recorded precipitation amount at the Saddle being 69% greater than the adjusted values for January and February, similar to the long-term overcatch at the Saddle of 61%. The slightly higher overcatch that we report for 1997 compared to the long-term average is most likely because January and February have higher winds and more snow available for transport than earlier or later in the winter.