UCM sites. Snow depth, soil moisture and soil temperature are measured near the Merced Grove, Gin Flat, Smoky Jack Creek, and Olmsted Quarry with a distributed array of 6-7 sensor nodes at each location. Snow depth is measured in the open, at the drip edge and under canopies, as well as 3-4 other sites representative of an area of 1-2 hectares. Soil moisture and temperature are measured at 10, 30, 60 and 90 cm depths coincident with the three canopy snow depth nodes at each site. Raw data have been processed to hourly level 1 (QA/QC) and level 2 (gap-filled, derived) data. Time period: water year 2009 through water year 2014.

SIO sites. Air temperature, relative humidity, solar radiation, precipitation (unheated tipping bucket), fuel moisture, soil moisture and soil temperature are measured at nine locations including four sites collocated with the UCM sites. Air temperature, solar radiation, relative humidity, and precipitation are located at the top of a 20-foot tower. Fuel moisture is measured at the base of the tower a few centimeters from the soil surface and soil moisture and temperature are measured at 10, 30, 60, and 90 cm depths. Raw air temperature and relative humidity data have been processed to hourly level 1 (QA/QC) and level 2 (gap-filled, derived) data. The remaining data is available in raw format only. Time period: water year 2008 through water year 2014.

Other climate sites. We assembled air temperature, relative humidity, solar radiation, wind speed and direction, precipitation, and snow water equivalent data from available stations operated by the California Department of Water Resources, NOAA Climate Reference Network, Merced Irrigation District, NRCS Snotel Program, Hetch Hetchy Water and Power, Pacific Gas & Electric, and the Bureau of Land Management Fire Remote Access Weather Station network. Raw data have been processed to hourly level 1 (QA/QC) and level 2 (gap-filled, derived) data. Time period: water year 2010 through water year 2014.

Spatial data. We assembled static data layers in support of snow energy and mass balance modeling over the Tuolumne and Merced watersheds, all in Universal Transverse Mercator Zone 11 projection and a 1983 North American Datum. Vector layers include Environmental Systems Research Institute (ESRI) format polygon shapefiles of the Merced and Tuolumne watersheds and a point shapefile of all climate stations in this data set. 100-m raster layers include a digital elevation model, a mask of the watersheds, and US Forest Service Calveg-derived canopy cover, vegetation type, vegetation height, canopy transmissivity to radiation, and the decay coefficient of light transmissivity through the canopy.

UCM sites: Soil volumetric water content (VWC) and soil temperature measured using Decagon Devices ECHO-TM at depths of 10, 30, 60, an 90 cm below the mineral soil surface. Sensor now equivalent to 5TM (http://www.decagon.com/soil-moisture-sensors/). Distance to snow/soil surface and air temperature measured with Judd Communications ultrasonic depth sensor, using analog control ( http://www.juddcom.com/).

SIO sites: Same soil volumetric water content, soil temperature instrumentation as UCM sites. Temperature sensors are custom calibrated thermistors. Relative humidity sensors are Sensirion SHT15DV (https://www.emesystems.com/sht15dv/main.html).

Other sites: California Department of Water Resources Sites: Air temperature and relative humidity measured primarily with Vaisala HMP45A/H DUS sensors (https://www.vaisala.com/sites/default/files/documents/HMP45AD-User-Guide-U274EN.pdf) (FTS THS-3 at the Mariposa Grove site (https://ftsinc.com/meteorology/products/sensors/temperature-and-humidity-sensor/)), precipitation measured using storage gauges equipped with a pressure transducer, solar radiation measured with LICor 441A (https://www.licor.com/env/products/light/), wind speed and direction measured primarily with a Vaisala 425A (https://www.vaisala.com/sites/default/files/documents/WS425_User_Guide_in_English.pdf) utrasonic meter, snow depth measured with Judd Communications ultrasonic depth sensor, using analog control ( http://www.juddcom.com/). 

Bureau of Land Management Fire Remote Access Weather Stations (RAWS): (various; see https://famit.nwcg.gov/applications/RAWS) for a description of instrument types.)

Merced Irrigation District and Pacific Gas and Electric: Precipitation measured using weighing-type, ETI Instrument Systems (http://www.etisensors.com/precip.htm).

National Resource Conservation Service Snotel: Precipitation measured using storage gauge with pressure transducer.

National Oceanic and Atmospheric Administration and Hetch Hetchy Water and Power: Precipitation measured using GeonorTM gauges (http://geonor.com/live/products/weather-instruments/t-200b-weather-precipitation-rain-gauge/)