California Applications Program

Yosemite Hydro-Meteorological Monitoring
Link to Yosemite National Park Current Observations and Climate
(courtesy of the Western Regional Climate Center - Kelly Redmond)

Jessica Lundquist (CRD graduate fellow) featured in Cal-(IT) 2 article:
"Ebb and Flow of the Diurnal Cycle: What's Its Relationship to Hydrology?"

Link to recent Yosemite Association Nature Notes article by Jessica Lundquist:
Monitoring Snow from the Beach in San Diego: Automatic Snow Sensors in the Sierra

High elevation snow accumulation and snowmelt are a crucial element of the hydrology and water supply in the western United States and yet we don't understand it very well. Some very important fundamental questions include:

  • How is precipitation distributed over the various elevation zones?
  • Where does it rain and where does it snow?
  • Do higher elevations contribute to snowmelt later than low elevations or do they all melt simultaneously?
  • How long does it take for the high elevation snowmelt to register in lower elevation stream gages?
  • How do these snowmelt contributions integrate into diurnal and multi-day "signals", and how do they propagate down the river?
  • What factors cause/impede snow melt?
  • How do the various nutrients and other chemical species enter the river system and vary over seasons and years?
  • Photos below from instrument installation expeditions spring-fall 2001.


    In view of the large interannual and lower frequency climate variability in the Sierra and to learn more about potentially large impacts due to climate change, a multi-disciplinary, multi-agency team is designing a program to install an upgraded set of meteorological, snow and stream instruments in the Sierra Nevada. In the first phase during summer and fall of 2001, a team from UCSD/Scripps Institution of Oceanography (SIO), USGS, State of California, National Park Service, and the Desert Research Institute (DRI) have laid plans to install an initial set of instruments in Yosemite National Park. Funding comes from NOAA OGP, through the California Applications Program, as well as support from the University of California CalITT^2 program and a new NSF ITR grant.

    Yosemite National Park is a scientific treasure as well as a natural wonder. The park sites astride the high Sierra Nevada and encompasses the pristine watersheds of two important rivers, the Merced and the Tuolumne. Its relatively undisturbed conditions, together with the access that park roads and trails provide to the high country, make it a unique setting for scientific studies of the range. During the 2001 Yosemite Research Workshop, the Park was identified as having a special role in the earth sciences as a locus for trans-Sierran studies and for studies of the responses of natural systems to global to regional climate change. The Park environs also have the potential to be a barometer for hydrologic variations at spatial scales spanning the range to the whole of western North America, and time scales ranging from hours to decades.

    To fulfill this promise, meteorological, snowpack, and hydrologic conditions within the Park must be monitored in more detail and greater consistency than in the past, or elsewhere (at this scale) in the range. Indeed, the presence of the almost century-long meteorological stations and streamflow gaging stations in the Merced River basin have provided much of the incentive for studies that--to date--have demonstrated the remarkable potential of the Park for earth science investigations. However, these relatively few observation sites need now to be augmented with more monitoring sites, and sites monitoring additional parameters, in both the Merced and Tuolumne River basins.

    This field season (summer and early fall 2001), snow and meteorological instruments have been planned for along the Tioga Road corridor traversing the west slope between Crane Flat and Tioga Pass. Stream stage, temperature and chemistry instruments are planned for at a series of sites along the Merced River in Yosemite Valley, along key sites and tributaries of the upper Merced above Happy Isles Bridge, and in several sites and tributaries to the Tuolumne River above Hetch Hetchy reservoir. Our initial concentration is to install a set of key instruments, some at existing snow, weather and stream gage locations to begin to fill in the needed spatial and physical elements to describe the hydrometeorology snow accumulation, snowmelt, and stream/watershed chemistry. At the present stage, our tactic is to collect more and better data, without too much effort to collect it efficiently; much of this data is being gathered on self-recording/not transmitting instruments or is only sampled and transmitted at relatively low data rates. In the next phase, we aim to not only add needed instrumentation, but also produce a modern communications system that will allow real time access and processing of a growing multi-sensor data stream. Thus, the system that is being designed in Yosemite aims to accomodate the needs of more and better information to monitor and understand changes that will affect not only the Park, but also the region and the Nation over the coming decades.

    Instrumenting the Mountain Snow Zone in the California Sierra Nevadas

    From Cal-(IT)2:

    Cal-(IT)2 is working with partner Scripps Institution of Oceanography (SIO) to take the next step in building on the HPWREN wide-area wireless network established by Frank Vernon, UCSD/SIO geophysicist, and Hans-Werner Braun, SDSC networking expert. SIO graduate student Jessica Lundquist is working with SIO climate/hydrology expert Dan Cayan to instrument the water-bearing west slope of the Sierra Nevadas. This region is a crucial source of water for California because snow pack from winter storms forms a natural reservoir central to California's water management -- it runs off in late spring and summer when flows can be stored or released. Importantly, the mountain snow zone is a region that is particularly sensitive to climate variability and change. However, historical measurements of the key physical elements are sparse and not complete, so the nature of these changes and the processes that drive them are not well understood. A real-time monitoring system will help greatly to improve this understanding and better observe climate variability and change as they occur.

    Lundquist is working with the California Snow Surveys, the U.S. Geological Survey, and Yosemite National Park to install meteorological, snow, and streamflow sensors in the southern Sierra Nevada mountains. This first field season will be a crucial start of a project to measure, communicate, and process observed data required for understanding how water is accumulated and released in the Sierra alpine zone. This initial set of sensors, focused in Yosemite National Park, should provide an important underpinning to Cal-(IT)2 with seed funding from NOAAs Office of Global Programs (OGP) through the California Applications Program and (if it is funded) an NSF Information Technology Research proposal in wireless communication led by John Orcutt, SIO geophysicist. For Lundquist, this work is designed to be integral to her Ph.D. research to better understand how climate variations modulate snow melt processes and how they influence spring and summer runoff, which is critical to California's agricultural, industrial, and domestic water supply.