White Wolf And Tenaya Lake Snow Sensors Installation

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The California Department of Water Resources (DWR) installed thirteen remote snow sensors in Yosemite National Park, located 6,000 - 10,000 feet in elevation, to provide hourly real time data. Beginning in 2016, these stations are being modernized and maintained collaboratively by DWR and Yosemite National Park personnel. These stations measure water content of the snow pack, snow depth, air temperature, relative humidity, solar radiation, soil moisture, and wind speed.

Of these stations, only two (Gin Flat and Tuolumne Meadows) currently measure total precipitation (rain and snow); thus, gaps in precipitation data exist for large areas of the park where most precipitation occurs. Additionally, warmer winter storms that deliver rain to higher elevations are becoming more frequent and make data from snow sensors less representative of hydrological conditions. Installing total precipitation gages at the existing snow sensors located at Tenaya Lake and White Wolf will fill in total precipitation data gaps in Yosemite's high country and accurately represent hydrologic conditions under warmer climate conditions.

Installed in 1998, the Tenaya Lake snow sensor is located on the Tenaya Lake snow course, approximately 0.25 miles from the Tenaya Lake east beach, outside of designated Wilderness. Installed in 2007, the White Wolf snow sensor is a Remote Automated Weather Station site that is collaboratively operated by the Yosemite Fire program and DWR, it is located 150 feet west of White Wolf Road, outside of designated Wilderness.

Primary actions needed to complete project:
1. All tools and materials will be carried to the site by hand. Hole and trench will be dug using hand tools.
2. Dig hole that is 3 feet in diameter and 3 feet deep that is 20 feet from existing snow pillows.
3. Install concrete footing in hole.
4. Install storage precipitation gage on footing.
5. Connect precipitation gage sensor to existing snow sensor datalogger via a 1 feet wide and 1 feet deep trench from storage precipitation gage to existing snow sensor tower.
6. Storage precipitation gage is 20 - 23 ft tall, 1 - 3 ft wide, has a three foot diameter base, and has a 4 foot diameter wind screen at the top of the precipitation gage.

The accumulation precipitation gages use a non-toxic, biodegradable recharge-solution (propylene glycol and denatured ethanol) to prevent accumulated precipitation from freezing. Operation of these gages requires removal of the precipitation-water/recharge-fluid mixture annually. This volume ranges from 25 - 75 gallons. All recharge fluid will be collected, removed from the sites, and disposed of at RV dump stations.