California Applications Program Success Stories
May 2003

Highlights for advancing integrated multidisciplinary research and expanding decision maker's options in the face of climate change and variability

Contributions to Decision Support: Tools and Resource Forecasts

• US Streamflow Forecasts: Based on interannual and interdecadal predictors, CAP researchers create streamflow forecasts considering the variability of streamflow and the anticipated water year atmospheric conditions. Historical daily flow records from over 1200 streamgaging stations across the US were used to compute flood statistics and winter and spring seasonal averages for each stations period of record. Historical conditioning of flow terciles by ENSO and PDO status were analyzed and then used together with summertime predictions of the following years ENSO and PDO conditions to develop a streamflow forecast. (http://meteora.ucsd.edu/cap/flow2003_fcast.html)
• Forecasts of temperature and precipitation extremes: Using observed and model predictors, CAP researchers developed a statistical downscaling scheme to produce useful seasonal forecasts of climate extremes, such as temperature and precipitation. Energy, water and fire resource managers use the extreme forecasts in planning for critical or emergency situations, such as increased power demand or increased threat of flood or fire.
• Western US seasonal snowpack forecasts: Using summer and fall climate conditions, CAP researchers developed a principal component analysis method for predicting April 1 snowpack over the western US. Snowpack, as measured on April 1, is the primary source of warm-season streamflow for most of the western US and thus represents an important source of water supply. (http://tenaya.ucsd.edu/~dettinge/pdosnow.pdf)
• Wildfire forecasts for the western US: For lead times of a season to two years, CAP researchers have developed statistical forecasts of seasonal area burned based on drought severity indices. For the past two years, these forecasts have successfully predicted many features of the western US wildfire season. Fire managers use these early forecasts for requesting supplemental resources and making decisions about temporary fire suppression personnel. (http://meteora.ucsd.edu/cap/fire_forecast2003.html)

Engaging stakeholders

• Northern California water resource prediction/management (Folsom): Working with Staff of Central Valley Operations of the Bureau of Reclamation and NOAAs regional River Forecast Center in Sacramento, CAP researchers provide streamflow simulations for the operational management of the Folsom Lake Reservoir. Demonstration of the feasibility and utility of climate-hydrology forecasting and water resources management is accomplished by inter comparing retrospective reservoir operations under: (1) current operational practice, (2) integrated forecast-control operation using climate forecasts based on historical/climatological information and (3) integrated forecast-control operation using climate forecasts based on global climate model simulations. (http://www.hrc-web.org/FOLSOM/)
• Medium Range Forecasts for city of San Francisco: For the City of San Francisco / Hetch Hetchy water/power system, CAP researchers have averaged and scaled 12 individual 15-day forecasts of precipitation and temperature from the current NCEP medium-range forecast ensemble. The forecasts are rescaled from the globalgrid of the MRF weather model (roughly 2 degrees of latitude by 2 degrees of longitude), and from the 850 millibar pressure level in the atmosphere, to be equivalent to the temperatures routinely observed by the Tuolumne Meadows SNOWTEL site. Precipitation is scaled to have the same monthly means as the Hetch Hetchy precipitation station. These rescaled forecasts were designed to be suitable for input to statistical predictors of Hetch Hetchy inflows. (http://tenaya.ucsd.edu/~dettinge/hetchy/)
• Web pages: Public web pages communicate with stakeholders on issues of immediate interest such as drought, wildfire, snowfall, Santa Ana and May Gray/June gloom conditions. Web pages also provide data and forecast resources for stakeholders. CAP actively maintains and updates two main web informational sources: (1) the California Applications Program web site (http://meteora.ucsd.edu/cap) and (2) the California Assessment for the United States Global Change Research Program: Preparing for a Changing Climate (http://tenaya.ucsd.edu/~meyer/calif_usgcrp.html)
• Stakeholder briefings: CAP researchers respond to numerous requests for specific briefings on issues of climate conditions, forecasts and long-range planning. For example, a recent presentation was made for the USBR Yuma desalinization plant (Department of Water Resources) concerning flood and drought possibilities for the next 30 years. Also, a plenary talk briefed the 2003 Southwest Drought Summit on current and changing southwest climate conditions. In addition, the Mojave Water Agency requested information on the most suitable historic periods for testing its long-term water-resource management alternatives. Recently, many stakeholders, including Ventura and San Diego counties, have expressed interest in climatic periods suitable for analyzing total maximum daily loads, as this is important to water quality.

Influencing operations and policy

• CALFED and climate change in California: CAP researchers engaged the interests of CALFED, a CALifornia FEDeration Program of more than 20 state and federal agencies working with local communities to develop and implement plans to restore ecological health and improve water management for the San Francisco Bay-Delta system over the next 30 years. This system provides water for 2/3 of the state of California (22 million people), irrigation supplies for $27 billion in agriculture (45% of the nations produce) and is a primary water source for California's trillion-dollar economy. The ecosystem and its freshwater supply are in jeopardy because of freshwater diversions. CAP is working with CALFED to integrate climate change and variability into its restoration plans so that they will be able to accommodate California's highly variable climate. (http://meteora.ucsd.edu/cap/calfed_climate.html)
• Real-time climate monitoring for wildfire: CAP's CEFA (Program for Climate, Ecosystem and Fire Applications), has developed a web-based near-real-time climate monitoring section that offers 10 and 30 day anomaly maps of remote automatic weather station and lightning strikes over the west. Developed for stakeholders, this site offers previously unavailable information to land managers and fire weather forecasters. (http://cefa.dri.edu/Assessment_Products/ClimMon/RawsReanalanoms.html)
• Ventura Basin ground-water management: Working with the United Water Agency, CAP researchers are developing a ground-water/surface-water model that incorporates long-range (seasonal) forecasts to address management issues. Ensembles of hindcast climate simulations from 1950 to 1998, by three different climate-prediction model runs, have been used to force a calibrated model of ground-water/surface-water conditions in the Santa Clara-Calleguas basin of southern California. (http://meteora.ucsd.edu/cap/ventura.html)

Significant additions to knowledge

• Climate change impacts on California: CAP research alerted the California hydrologic community that even modest climate changes could mean a significant decrease in snowmelt, which was unexpected. Simulated snowpack under warmed conditions depicts a severe loss of snow as indicated by changes in the snow water equivalent (SWE). By 2030, under the "business-as-usual" scenario, temperature is projected to rise about 0.6 degrees C, resulting in a minor decrease in April snowpack at lower elevations. However, by 2060 a temperature rise of 1.6 degrees C results in a loss of one-third of the total snowpack. This loss is focused in mid to lower elevations since the snowpack there is more sensitive to temperature changes than at higher, colder elevations. By 2090, a projected temperature increase of 2.1 degrees C results in a loss of about half of the average April snowpack storage, with greatest losses in the northern headwaters. Spring runoff is reduced by 5.6 cubic km, with associated increases in winter flood peaks. (http://meteora.ucsd.edu/cap/hydro_glwarming.html)
• Mosquito abundance and seasonal moisture: Working with a group led by Bill Reisen, Arbovirus Research Station, Bakersfield, CA, CAP researchers are finding links between seasonal moisture indices and mosquito abundance. With the expected near-future arrival of West Nile virus in California, the ability to anticipate mosquito abundances has taken on increased public interest. There has been considerable interannual variability in mosquito abundance, part of which is correlated across the entire state of California. Summer mosquito numbers correlate positively with moisture accumulation, as indicated by precipitation, streamflow and snow water content. Prediction of summer mosquito abundance from prior winter moisture variables may provide a useful look ahead at several months lead-time. (http://meteora.ucsd.edu/cap/calif_health.html)
• Building a climate observational capacity: CAP has initiated several projects towards building climate observational capacity in California and the western US.
  • CAP is part of a multi-disciplinary, multi-agency team installing an upgraded set of meteorological, snow and stream instruments in the Sierra Nevada. These instruments are critical tools for collecting information leading to further understanding of the large interannual and lower frequency climate variability in the Sierra and to learn more about potential large impacts due to climate change. Historical measurements of key physical elements in the mountain snow zone are sparse and not complete, so the nature of recent, and future, 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. (http://meteora.ucsd.edu/cap/snow_monitor.html)
  • CAP is also part of an effort to use wireless communication to provide real-time detailed weather observations. This hydro-meteorological effort is located in the coastal sagebrush of the Santa Margarita Ecological Reserve (SMER), north of San Diego in southern California. Towers containing instruments have been established at strategic locations in SMER to allow for detailed monitoring of air and water mass transfer. (http://tenaya.ucsd.edu/~meyer/smer_hydromet.pdf)
  • CAP has assumed the role of maintaining the lilac and honeysuckle records from the Western Regional Phenological Network (WRPN). This network (established in 1957 for lilac and 1968 for honeysuckle), shows key phonological phases have fluctuated over the last 4-5 decades indicating warmer-than-normal springs which may be an expression of natural variability or a symptom of global warming. (http://meteora.ucsd.edu/cap/lilac.html)
• Medium-range forecast (MRF) archive: The CAP historical MRF ensemble project uses a single, unchanging, global atmospheric model to make a set of daily medium range (0-14 day) forecasts over a long historical period. This MRF history is needed to allow objective, quantitative assessments of forecast skill and the predictability of various kinds of weather events. For every day from 1979 to present, CAP is making an ensemble of 10 forecasts. The model employed is the National Centers for Environmental Prediction (NCEP)'s MRF model (Reanalysis II version). To produce an ensemble of 10 forecasts we have adopted the NCEP "breeding" procedure to make 5 pairs of positively and negatively perturbed initial conditions for each of the individual forecast runs. (http://meteora.ucsd.edu/cap/hindcast.html)