D. R. Cayan's research while affiliated with University of California, San Diego and other places

Publications (217)

Article
Recent patterns of water use and supply in California are presented based on a new data set compiled from the California Department of Water Resources water balance data for 2002 through 2016. The water use and supply include surface water and groundwater, although groundwater reporting has been incomplete. These data are used to support the Water...
Article
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Santa Ana winds (SAWs) are associated with anomalous temperatures in coastal Southern California (SoCal). As dry air flows over SoCal's coastal ranges on its way from the elevated Great Basin down to sea level, all SAWs warm adiabatically. Many but not all SAWs produce coastal heat events. The strongest regionally averaged SAWs tend to be cold. In...
Article
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Autumn and winter Santa Ana wind (SAW)-driven wildfires play a substantial role in area burned and societal losses in southern California. Temperature during the event and antecedent precipitation in the week or month prior play a minor role in determining area burned. Burning is dependent on wind intensity and number of human-ignited fires. Over 7...
Article
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The response of annual runoff volume to sub‐annual climate warming is highly uncertain, and the governing mechanisms remain poorly understood, challenging adaptive water management. A typical exemplar is the Western United States, where climate models project substantially stronger warming in the warm season (April to September) than in the cool se...
Article
Objective: To test the hypothesis that cases of Kawasaki disease within a temporal cluster have a similar pattern of host response that is distinct from cases of Kawasaki disease in different observed clusters and randomly constructed clusters. Study design: We designed a case-control study to analyze 47 clusters derived from 1332 patients with...
Article
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The responses of individuals and populations to climate change vary as functions of physiology, ecology, and plasticity. We investigated whether annual variation in seasonal temperature and precipitation was associated with relative abundances of breeding bird species at local and regional levels in southern California, USA, from 1968–2013. We test...
Article
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A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.
Article
This paper quantifies insured flood losses across the western United States from 1978 to 2017, presenting a spatiotemporal analysis of National Flood Insurance Program (NFIP) daily claims and losses over this period. While considerably lower (only 3.3%) than broader measures of direct damages measured by a National Weather Service (NWS) dataset, NF...
Article
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As a biodiverse region under a Mediterranean climate with a mix of highly developed and natural watersheds, coastal Santa Barbara County (SB), located in southern California, is susceptible to the hydrologic impacts of climate change. This study investigates the potential changes in hydro-meteorological variables in this region as well as their soc...
Article
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Kawasaki Disease (KD) is the most common cause of pediatric acquired heart disease, but its etiology remains unknown. We examined 1164 cases of KD treated at a regional children’s hospital in San Diego over a period of 15 years and uncovered novel structure to disease incidence. KD cases showed a well-defined seasonal variability, but also clustere...
Article
This study investigates snowmelt and streamflow responses to cloudiness variability across the mountainous parts of the western United States. Twenty years (1996–2015) of Geostationary Operational Environmental Satellite-derived cloud cover indices (CC) with 4-km spatial and daily temporal resolutions are used as a proxy for cloudiness. The primary...
Article
Projections of meteorology downscaled from global climate model runs were used to drive a model of unimpaired hydrology of the Sacramento/San Joaquin watershed, which in turn drove models of operational responses and managed flows. Twenty daily climate change scenarios for water years 1980–2099 were evaluated with the goal of producing inflow bound...
Conference Paper
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Mountain glaciers throughout the world are retreating; a trend that is expected to accelerate over the next several decades due to anthropogenic climate change. In some places glaciers are projected to completely disappear, while the area of frozen ground will diminish and the ratio of snow to rainfall will decrease. These changes will also affect...
Article
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The cryosphere in mountain regions is rapidly declining, a trend that is expected to accelerate over the next several decades due to anthropogenic climate change. A cascade of effects will result, extending from mountains to lowlands with associated impacts on human livelihood, economy, and ecosystems. With rising air temperatures and increased rad...
Article
Full-text available
The cryosphere in mountain regions is rapidly declining, a trend that is expected to accelerate over the next several decades due to anthropogenic climate change. A cascade of effects will result, extending from mountains to lowlands with associated impacts on human livelihood, economy, and ecosystems. With rising air temperatures and increased rad...
Article
This study investigates the spatial and temporal variability of cloudiness across mountain zones in the western United States. Daily average cloud albedo is derived from a 19-yr series (1996-2014) of half-hourly Geostationary Operational Environmental Satellite (GOES) images. During springtime when incident radiation is active in driving snowmelt-r...
Chapter
The agent of Kawasaki disease (KD) remains unknown after more than 40 years of intensive research, but new information from analyses of KD time series from locations worldwide suggests that KD activity is modulated by weather and climate processes. Most Northern Hemisphere locations with a sufficient number of KD cases to allow for analysis exhibit...
Article
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Humidity is important to climate impacts in hydrology, agriculture, ecology, energy demand, and human health and comfort. Nonetheless humidity is not available in some widely-used archives of statistically downscaled climate projections for the western U.S. In this work the Localized Constructed Analogs (LOCA) statistical downscaling method is used...
Article
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Satellite remote sensing has enabled remarkable progress in the ocean, earth, atmospheric, and environmental sciences through its ability to provide global coverage with ever-increasing spatial resolution. While exceptions exist for geostationary ocean color satellites, the temporal coverage of low-Earth-orbiting satellites is not optimal for ocean...
Article
Full-text available
Satellite remote sensing has enabled remarkable progress in the ocean, earth, atmospheric, and environmental sciences through its ability to provide global coverage with ever-increasing spatial resolution. While exceptions exist for geostationary ocean color satellites, the temporal coverage of low-Earth-orbiting satellites is not optimal for ocean...
Article
Full-text available
The variability of precipitation and water supply along the U.S. West Coast creates major challenges to the region’s economy and environment, as evidenced by the recent California drought. This variability is strongly influenced by atmospheric rivers (ARs), which deliver much of the precipitation along the U.S. West Coast and can cause flooding, an...
Article
The western United States has been experiencing severe drought since 2013. The solid earth response to the accompanying loss of surface and near-surface water mass should be a broad region of uplift. We use seasonally adjusted time series from continuously operating global positioning system stations to measure this uplift, which we invert to estim...
Article
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Evidence indicates that the densely cultivated region of northeastern China acts as a source for the wind-borne agent of Kawasaki disease (KD). KD is an acute, coronary artery vasculitis of young children, and still a medical mystery after more than 40 y. We used residence times from simulations with the flexible particle dispersion model to pinpoi...
Article
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Understanding global seasonal patterns of Kawasaki disease (KD) may provide insight into the etiology of this vasculitis that is now the most common cause of acquired heart disease in children in developed countries worldwide. Data from 1970-2012 from 25 countries distributed over the globe were analyzed for seasonality. The number of KD cases from...
Article
study investigates the variability of clouds, primarily marine stratus clouds, and how they are associated with surface temperature anomalies over California, especially along the coastal margin. We focus on the summer months of June to September when marine stratus are the dominant cloud type. Data used include satellite cloud reflectivity (cloud...
Article
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Ancient blue oak trees are still widespread across the foothills of the Coast Ranges, Cascades and Sierra Nevada in California. The most extensive tracts of intact old-growth blue oak woodland appear to survive on rugged and remote terrain in the southern Coast Ranges and on the foothills west and southwest of Mt. Lassen. In the authors' sampling o...
Article
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When correcting for biases in general circulation model (GCM) output, for example when statistically downscaling for regional and local impacts studies, a common assumption is that the GCM biases can be characterized by comparing model simulations and observations for a historical period. We demonstrate some complications in this assumption, with G...
Chapter
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Extreme events can be defined in many ways. Typical definitions of weather and climate extremes consider either the maximum value during a specified time interval (such as season or year) or exceedance of a threshold (the “peaks-over-threshold” [POT] approach), in which universal rather than local thresholds are frequently applied. For example, tem...
Article
Precipitable water or integrated water vapor can be obtained from zenith travel-time delays from global positioning system (GPS) signals if the atmospheric pressure and temperature at the GPS site is known. There have been more than 10 000 GPS receivers deployed as part of geophysics research programs around the world; but, unfortunately, most of t...
Article
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A fully coupled regional ocean-atmosphere model system that consists of the regional spectral model and the regional ocean modeling system for atmosphere and ocean components, respectively, is applied to downscale the present climate (1985–1994) over California from a global simulation of the Community Climate System Model 3.0 (CCSM3). The horizont...
Article
Full-text available
When correcting for biases in general circulation model (GCM) output, for example when statistically downscaling for regional and local impacts studies, a common assumption is that the GCM biases can be characterized by comparing model simulations and observations for a historical period. We demonstrate some complications in this assumption, with G...
Presentation
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Final technical review of the NOAA GPS Met project held at the David Skaggs Research Center, Boluder Colorado on August 7, 2012.
Article
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The levee system in California's Sacramento-San Joaquin Delta helps protect freshwater quality in a critical estuarine ecosystem that hosts substan- tial agricultural infrastructure and a large human population. We use space-based synthetic aperture radar interferometry (InSAR) to provide synoptic vertical land motion measurements of the Delta and...
Article
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Sixteen global general circulation models were used to develop probabilistic projections of temperature (T) and precipitation (P) changes over California by the 2060s. The global models were downscaled with two statistical techniques and three nested dynamical regional climate models, although not all global models were downscaled with all techniqu...
Article
A better understanding of how climate change will affect water resources in the Western U.S. is crucial, since much of the region is arid and yet is experiencing the most rapid population growth in the nation. Climate fluctuations associated with natural modes of variability such as the Pacific Decadal Oscillation (PDO) and El Nino-Southern Oscilla...
Article
Precipitable water derived from GPS zenith delays is used to study the onshore penetration of enhanced moisture associated with landfalling atmospheric rivers. Precipitable water is the integral of the water vapor density from the surface to the top of the atmosphere, so its value is dependent on the elevation of the observation site, consequently...
Article
California's Central Valley is one of the most important agricultural areas in the world and is highly dependent on the availability and management of surface water and groundwater. As such, it is a valuable large-scale system for investigating the interaction of climate variability and water-resource management on surface-water and groundwater int...
Conference Paper
Climate projections for the remainder of this century for the U.S. Southwest, including parts of California, suggest a drying trend (reductions ~ 10 -15 %). Thus, understanding factors which could potentially influence the amount and type of precipitation is critical to future water resources in California. Previous studies suggest aerosols transpo...
Article
Many GCMs have exhibited unrealistic teleconnections between ENSO fluctuations and extratropical circulation patterns, driven in part from having poorly represented physical processes in the core ENSO region. CESM is a coupled climate model with land, atmosphere, ocean, and sea ice components that can be used to simulate the Earth's climate system,...
Article
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California’s mountainous topography, exposure to occasional heavily moisture-laden storm systems, and varied communities and infrastructures in low lying areas make it highly vulnerable to floods. An important question facing the state—in terms of protecting the public and formulating water management responses to climate change—is “how might futur...
Data
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1] Warm season climate warming will be a key driver of annual streamflow changes in four major river basins of the western U.S., as shown by hydrological model simula-tions using fixed precipitation and idealized seasonal temper-ature changes based on climate projections with SRES A2 forcing. Warm season (April-September) warming reduces streamflow...
Article
Increased temperatures will lead to fundamental changes in the seasonal distribution of streamflow and the management of water resources, especially in the western United States. Understanding the potential of these changes is, however, complicated by the wide range of projections from climate models, which can obscure the basin-specific hydrologic...
Data
Effects of high river flows on errors in modeled annual average Delta water temperatures. Difference between modeled and observed yearly average water temperature is compared to the annually averaged Sacramento River flow; model-observation deviations occur in years with high river flow. (TIF)
Data
Expanded description of methods with supporting references. (RTF)
Data
Mean annual turbidity, declining throughout the Sacramento-San Joaquin Delta from 1975–2008. From monthly data provided by California Department of Water Resources, Environmental Monitoring Program. (TIF)
Data
GFDL and PCM scenarios for suspended sediment concentration (SSC) in the Sacramento River at Rio Vista for constant and decreasing sediment supply. Each band represents the interquartile range of SSC. (TIF)
Data
Sediment rating curve for the Sacramento River at Rio Vista, 1998–2002. (TIF)
Article
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Accumulating evidence shows that the planet is warming as a response to human emissions of greenhouse gases. Strategies of adaptation to climate change will require quantitative projections of how altered regional patterns of temperature, precipitation and sea level could cascade to provoke local impacts such as modified water supplies, increasing...
Article
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The USGS Multihazards Project is working with numerous agencies to evaluate and plan for hazards and damages that could be caused by extreme winter storms impacting California. Atmospheric and hydrological aspects of a hypothetical storm scenario have been quantified as a basis for estimation of human, infrastructure, economic, and environmental im...
Article
Streamflows in the snowmelt dominated catchments of the western United States contain a strong seasonal structure in which peak discharge occurs in spring through early summer, depending on elevation and other influences. However, a key component of streamflow, even in snowmelt-driven catchments, is that a substantial portion occurs in pulses that...
Article
Implications of climate change on Sierra Nevada snowpack are assessed using a set of global climate model simulations as input to the Variable Infiltration Capacity (VIC) hydrological model. By the end of the 21st Century, the likelihood of years having very low spring snowpack, aggregated over the Sierra Nevada, increases markedly over historical...
Article
Downscaling climate model output for regional impact analysis must accommodate the biases in the climate model, since the biases tend to be large enough to confound meaningful local and regional scale impacts analysis. The bias correction is generally based on the assumption that the bias, as estimated for some base period, is stationary, so the sa...
Article
The early 21st century drought is an example of the kinds of droughts the Southwest United States is prone to. Such droughts tend to take on large southwest footprints, although both observations and climate model simulations display different degrees of dryness in California, the Great Basin, and the Colorado basin. The early 21st century drought...
Article
In water controlled agrosystems such as California's Central Valley, assessing the interdependence between climate and surface hydrology is needed to better understand the sustainability of water resources. The Central Valley also represents an important ``field-laboratory'' to assess large-scale aspects of the hydrological cycle and water resource...
Article
In 2008, NOAA, the California Department of Water Resources, and Scripps Institution of Oceanography began implementation of a 5-year project to bring 21st century observations, high resolution numerical model ensembles, display systems, and decision support tools to bear on the state's water resource and flood protection issues. This paper focuses...
Article
Full-text available
Competition for water resources is growing throughout California, particularly in the Central Valley where about 20% of all groundwater used in the United States of America is consumed for agriculture and urban water supply. Continued agricultural use coupled with urban growth and potential climate change would result in continued depletion of grou...
Article
Full-text available
Three statistical downscaling methods were applied to NCEP/NCAR reanalysis (used as a surrogate for the best possible general circulation model), and the downscaled meteorology was used to drive a hydrologic model over California. The historic record was divided into an "observed" period of 1950–1976 to provide the basis for downscaling, and a "pro...
Article
Full-text available
Three statistical downscaling methods were applied to NCEP/NCAR reanalysis (used as a surrogate for the best possible general circulation model), and the downscaled meteorology was used to drive a hydrology model over California. The historic record was divided into an "observed" period of 1950–1976 to provide the basis for downscaling, and a "proj...
Article
Competition for water resources is growing throughout California, particularly in the Central Valley where about 20% of all groundwater used in the United States of America is consumed for agriculture and urban water supply. Continued agri