SLIDES: California Water and Climate Change

Presenter: Dan Cayan, Scripps Institution of Oceanography 32 slides Dan Cayan (1,2) 1 Mike Dettinger (2,1) SIO 2 USGS

SLIDES: California Water and Climate Change

Presenter: Dan Cayan, Scripps Institution of Oceanography 32 slides Dan Cayan (1,2) 1 Mike Dettinger (2,1) SIO 2 USGS

The California flooding rains during February, 1986 [abstract]

After an unusually strong and persistent pattern of atmospheric circulation over the United State[s] in Fall 1985, it became quite changeable (although high amplitude anomalies still prevailed). Following a fall that was cold in the West and warm in the East with heavy precipitation, a high pressure ridge set in over the West during December, with generally light precipitation over most of the country. Throughout the winter, the central North Pacific was very active, with large negative atmospheric pressure anomalies centered at about 45°N, l60°W. This activity may have been encouraged by an enhanced meridional eastern North Pacific sea surface temperature (SST) gradient, with positive SST anomalies in the subtropics and negative anomalies in midlatitudes. However, in January, the western high pressure ridge remained strong and temperatures were remarkably warm, increasing the threat of drought in California after the two previous dry winters. However, in February, storms from a greatly expanded and southerly displaced Aleutian Low broke into the West Coast. An unusual siege from February 11 to February 20 flooded central and northern California, with very heavy precipitation and record to near-record runoff. Upwards of 50 percent of annual average precipitation fell on locations from the upper San Joaquin to the Feather River drainage basins, and the largest flow since observations began in the early 1900's was recorded on the Sacramento River at Sacramento. The atmospheric pattern that was responsible for this remarkable stormy spell developed when the western high pressure retrograded to the northwest into the Aleutians, accompanied by the strengthened and southerly extended storm tract that moved into California. Although exact details vary from case to case, this episode displayed meteorological conditions similar to those in several other historical California winter flood events. These included a long duration of very strong westerly to southwesterly winds over a long subtropical fetch into California. Much of the precipitation during this series of storms was orographically induced by the moisture laden flow rising over the Sierra ranges. Due to the warm air mass, snow levels were relatively high (about 7500 feet) during the heaviest precipitation, resulting in copious runoff

Patterns of orographic uplift in the Sierra Nevada and their relationship to upper-level atmospheric circulation

We examine monthly and seasonal patterns of precipitation across various elevations of the eastern Central Valley of California and the Sierra Nevada. A measure of the strength of the orographic effect called the “precipitation ratio” is calculated, and we separate months into four groups based on being wet or dry and having low or high precipitation ratios. Using monthly maps of mean 700-mb height anomalies, we describe the northern hemisphere mid-tropospheric circulation patterns associated with each of the four groups. Wet months are associated with negative height anomalies over the eastern Pacific, as expected. However, the orientation of the trough is different for years with high and low precipitation ratios. Wet months with high ratios typically have circulation patterns factoring a west-southwest to east-northeast storm track from around the Hawaiian Islands to the Pacific Northwest of the United States. Wet months with low precipitation ratios are associated with a trough centered near the Aleutians and a northwest to southeast storm track. Dry months are marked by anticyclones in the Pacific, but this feature is more localized to the eastern Pacific for months with low precipitation ratios than for those with high ratios. Using precipitation gauge and snow course data from the American River and Truckee-Tahoe basins, we determined that the strength of the orographic effect on a seasonal basis is spatially coherent at low and high elevations and on opposite sides of the Sierra Nevada crestline

Kawasaki disease and ENSO-driven wind circulation

Kawasaki disease (KD) is the most common cause of acquired heart disease in children worldwide. Recently, a climatological study suggested that KD may be triggered by a windborne agent traveling across the north Pacific through the westerly wind flow prevailing at midlatitudes. Here we use KD records to describe the association between enhanced disease activity on opposite sides of the basin and different phases of the El Niño-Southern Oscillation (ENSO) phenomenon, via the linkage to these tropospheric winds. Results show that years with higher-than-normal KD cases in Japan preferentially occur during either El Niño Modoki or La Niña conditions, while in San Diego during the mature phase of El Niño or La Niña events. Given that ENSO offers a degree of predictability at lead times of 6 months, these modulations suggest that seasonal predictions of KD could be used to alert clinicians to periods of increased disease activity

Decadal hydroclimatic variability over western North America [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Variability of precipitation over North America on ENSO and decadal time scales is examined from several decades of precipitation and snow course records

Public Health-Related Impacts of Climate Change in California

In June 2005 Governor Arnold Schwarzenegger issued Executive Order S-3-05 that set greenhouse gas emission reduction targets for California, and directed the Secretary of the California Environmental Protection Agency to report to the governor and the State legislature by January 2006 and biannually thereafter on the impacts to California of global warming, including impacts to water supply, public health, agriculture, the coastline, and forestry, and to prepare and report on mitigation and adaptation plans to combat these impacts. This report is a part of the report to the governor and legislature, and focuses on public health impacts that have been associated with climate change. Considerable evidence suggests that average ambient temperature is increasing worldwide, that temperatures will continue to increase into the future, and that global warming will result in changes to many aspects of climate, including temperature, humidity, and precipitation (McMichael and Githeko, 2001). It is expected that California will experience changes in both temperature and precipitation under current trends. Many of the changes in climate projected for California could have ramifications for public health (McMichael and Githeko, 2001), and this document summarizes the impacts judged most likely to occur in California, based on a review of available peer-reviewed scientific literature and new modeling and statistical analyses. The impacts identified as most significant to public health in California include mortality and morbidity related to temperature, air pollution, vector and water-borne diseases, and wildfires. There is considerable complexity underlying the health of a population with many contributing factors including biological, ecological, social, political, and geographical. In addition, the relationship between climate change and changes in public health is difficult to predict for the most part, although more detailed information is available on temperature-related mortality and air pollution effects than the other endpoints discussed in this document. Consequently, these two topics are discussed in greater detail. Where possible, estimates of the magnitude and significance of these impacts are also discussed, along with possible adaptations that could reduce climate-related health impacts. In the context of this review, weather refers to meteorological conditions at a specific place and time over a relatively short time frame, such as up to a year or two. Climate, on the other hand, refers to the same meteorological conditions, but over a longer time frame, such as decades or centuries

Climatic Data Collection, Analyses, And Modeling — Phase Ii

The California Climate Change Center, with core activities at Scripps Institution of Oceanography, has continued to conduct research to better monitor and understand climate change and its impacts over California. The work includes 1) upgrading and maintaining an archive of historical climate data for the state; 2) installation, maintenance and data management of instrumentation for climate observations in climate-sensitive mountain, watershed and coastal settings; 3) statistical and dynamical regional climate modeling; and 4) diagnosing past and potential future climate variations and changes