Accession Number:

AD0671941

Title:

MEASUREMENT OF SNOWFALL BY RADAR,

Descriptive Note:

Corporate Author:

MCGILL UNIV MONTREAL (QUEBEC) STORMY WEATHER GROUP

Personal Author(s):

Report Date:

1968-03-01

Pagination or Media Count:

41.0

Abstract:

Using wavelength 3.2 cm in dry snow, radar returns from a layer at an average height of 5000 ft were converted to snowfall rates and integrated to obtain isohyets for a 48-hour period, during which snow accumulated to an average depth of 5 inches. First, radar-derived isohyets based on the Z 2000 R2.0 relation for aggregate snow were mapped to 100-miles range. These were then compared with isohyets based on ground measurements of new-fallen snow at 140 climatological stations. Within 58-miles range, there was good agreement on maximum snowfall amounts 10 inches, most of which fell at high rates but the radar underestimated the minimum amounts 2 inches, all of which fell at low rates. Agreement between radar and ground measurements was generally improved by applying a modified relation, Z 1000 R2.67. For this relation, the values of RADARCLIMAT ratio radar-measured to ground-measured amounts at grid points within 58-miles range had a near-Gaussian distribution, with a mean value of 0.98 and standard deviation of 0.29. Beyond 58-miles range, underestimation by the radar increased with range, particularly for the larger snowfall amounts. Comparison of radar-measured snowfall rates at a fixed point aloft with rates measured by a recording gauge at the ground showed good agreement after allowance was made for horizontal displacement of the snow during its fall. Author

Subject Categories:

  • Meteorology
  • Snow, Ice and Permafrost

Distribution Statement:

APPROVED FOR PUBLIC RELEASE