Diurnal fluctuations in remote precipitation gage readings

TitleDiurnal fluctuations in remote precipitation gage readings
Publication TypeConference Proceedings
Year of Conference1987
AuthorsCooley, K. R., Robertson D. C., Lute D., and Beard G. A.
Conference Name55th Annual Western Snow Conference
Series TitleProceedings of the 55th Annual Western Snow Conference
Date PublishedApril 1987
PublisherWestern Snow Conference
Conference LocationVancouver, British Columbia
KeywordsFlood Forecasts, Rainfall Measurements, Water Supply

Precipitation gage readings from hundreds of remote sites could dramatically improve the accuracy of western streamflow forecasts. Unfortunately, diurnal fluctuations of more that 3 cm have been observed when precipitation did not occur. Reliable data must be available for forecasts to be accurate, since errors of 3 cm could indicate catastrophic flooding. This study attempted to determine the cause of the diurnal fluctuations. A simulated remote precipitation gage site was installed so that temperature and pressure readings could be monitored at 15-minute intervals, and visual observations and changes to the system could be made frequently. Results indicated that: (1) thermal expansion and contraction produced daily pressure changes of less than 0.3 cm of H20; (2) concentration of methyl alcohol-ethylene glycol affects the magnitude of the fluctuations; and (3) diurnal fluctuations (etc.).