Meteorological parameters (air temperature, relative humidity, wind speed and direction, barometric pressure, solar radiation, precipitation quantity and snowpack water equivalent) are measured at the main monitoring station outside the Turkey Lakes Watershed (TLW) boundary. Precipitation quantity and snowpack water equivalent are measured at several locations within the TLW to determine spatial variability (Figure 1).
Figure 1: Location of the main meteorology, precipitation and snowpack sites.
From 1980 to 2007, annual precipitation ranged from 892 mm (1997) to 1535 mm (1988) with an average of 1198 ±143 mm, 2/3 as rain, 1/3 as snow (Figure 2). Higher elevations receive 5% more precipitation. One third of the annual precipitation occurs in autumn. The maximum mean snow depth was 1.4 m (February, 1989). Stream flow accounts for 2/3 of incoming precipitation. The rest is lost as evaporation or evapotranspiration.
Figure 2: Annual precipitation (rain and snow components) and temperature.The dashed line shows the average rate of temperature increase.
The mean annual air temperature is 4.63 ±1.15 °C, and it has been increasing at the rate of 0.09 °C per year (Figure 2) mostly due to warmer values in June and September. Northerly and westerly winds predominate. There is much day-to-day and seasonal variability, both in direction (Figure 3) and speed (Figure 4).
The 10m tower in the background of the picture above supports all the sensors for measuring wind, temperature, relative humidity, solar radiation, etc. (detail below).
Meterological Instruments Deck
A: ”CAPMoN” wet-only samplers,
B: Organic Contaminants sampler,
C: “Great Lakes” 28-days wet-only sampler,
D: Belfort recording rain/snow gauge (Nipher shield removed),
E: Bulk precipitation samplers,
F: Nipher snow gauge,
G: Standard rain gauge.
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