A Method for Prediction of California Summer Air Surface Temperature. E. Alfaro, A. Gershunov, D. Cayan A., Steinemann, D. Pierce, T. Barnett.
http://dx.doi.org/10.1029/2004EO510001 DOI: 10.1029/2004EO510001
A methodology to asess relations between climatic variability and variations in hydrologic time series in the southwestern United States. Hanson, R T; Newhouse, M W & Dettinger, M D.
Journal of Hydrology:
http://dx.doi.org/10.1016/j.jhydrol.2003.10.006 DOI: 10.1016/j.jhydrol.2003.10.006
A new method for frequency analysis of hydrologic time series was developed to facilitate the estimation and reconstruction of individual or groups of frequencies from hydrologic time-series and facilitate the comparison of these isolated time-series components across data types, between different hydrologic settings within a watershed, between watersheds, and across frequencies. While climate-related variations in inflow to and outflow from aquifers have often been neglected, the development and management of ground-water and surface-water resources has required the inclusion of the assessment of the effects of climatic variability on the supply and demand and sustainability of use. The regional assessmentof climatic variability of surface-water and ground-water flow throughout the southwestern United States required this new systematic method of hydrologic time-series analysis. To demonstrate the application of this new method, six hydrologic time-series from the Mojave River Basin, California were analyzed. The results indicate that climatic variability exists in all the data types and are partially coincident with known climate cycles such as the Pacific Decadal Oscillation and the El Nino-Southern Oscillation. The time-series also indicate lagged correlations between tree-ring indices, streamflow, stream base flow, and ground-water levels. These correlations and reconstructed time-series can be used to better understand the relation of hydrologic response to climatic forcings and to facilitate the simulation of streamflow and ground-water recharge for a more realistic approach to water-resource management.
A Multiple-Case Analysis of Nocturnal Radiation-Fog Development in the Central Valley of California Utilizing the GOES Nighttime Fog Product. S. Jeffrey Underwood, Gary P. Ellrod, and Aaron L. Kuhnert.
American Meteorological Society:
Radiation fog in the Central Valley of California has received very little attention in terms of climatological research. This study uses the Geostationary Operational Environmental Satellite (GOES) nighttime fog product to develop a sequence of images and datasets that reveal patterns of nocturnal radiation-fog development in the Central Valley. Twenty long-lived, spatially extensive radiation-fog episodes, occurring from October through January, were selected for the period of 1997-2000. Mean hourly parameters for fog cover, fog development rate, and vertical development were calculated for the 20 episodes in the Central Valley. The study region is separated into five analysis divisions oriented from south to north for spatial comparisons within the valley. Large-scale radiation fog begins developing before 1800 LST, and rates of development vary widely from south to north. Radiation fog develops earlier and covers a larger area of the southern valley as compared with the central and northern portions of t e valley. The horizontal extent of radiation fog is maximized at 0600 LST in the southern valley and near midnight in the central and northern parts of the valley. Vertical development reaches 300 m with regularity in the southern valley. Radiation-fog development of greater than 300 m occurs primarily in the early morning hours. Vertical development ''bursts'' are also observed in the southern valley during the morning hours. Climatologically important conditions for radiation-fog development in the Central Valley include cool 1600 LST surface temperatures, moisture availability as reflected by 1600 LST dewpoint temperatures, early evening surface cooling trends, the rapidity with which mean relative humidity reaches 90%, and the presence of cool, dry air aloft (700-500 hPa).
An aggregate drought index: Assessing drought severity based on fluctuations in the hydrologic cycle and surface water storage. Keyantash, John & Dracup, John A..
Water Resources Research:
An aggregate drought index (ADI) has been developed, and evaluated within three diverse climate divisions in California. The ADI comprehensively considers all physical forms of drought (meteorological, hydrological, and agricultural) through selection of variables that are related to each drought type. Water stored in large surface water reservoirs was also included. Hydroclimatic monthly data for each climate division underwent correlation-based principal component analysis (PCA), and the first principal component was deseasonalized to arrive at a single ADI value for each month. ADI time series were compared against the Palmer Drought Severity Index (PDSI) to describe two important droughts in California, the 1976-1977 and 1987-1992 events, from a hydroclimatological perspective. The ADI methodology provides a clear, objective approach for describing the intensity of drought and can be readily adapted to characterize drought on an operational basis.
Annual dynamics of soil organic matter in the context of long-term trends. Doane, Timothy A & Horwath, William R.
Global Biogeochemical Cycles:
http://dx.doi.org/10.1029/2004GB002252 DOI: 10.1029/2004GB002252
Long-term research has provided a great deal of information regarding the influence of management on the equilibrium dynamics of soil organic matter (SOM), although short-term dynamics remain largely uninvestigated. An improved approach of characterizing SOM dynamics in managed ecosystems would consider both short-term and long-term changes in content and composition. This approach and its implications are illustrated for an experimental site comparing agricultural management practices. Changes in soil C composition were assessed semiquantitatively using 13C natural abundance measurements, demonstrating their useful although rarely applied role in short-term studies. This information is a valuable complement to long-term data, since net differences since the site's inception fail to reveal a timeline marked by repeated changes in soil C content and composition. Such data are also useful for reinforcing and understanding long-term simulation models, which are typically driven by temporally dynamic events but are often fit against temporally sparse SOM data sets.
One of the direct consequences of climatic changes will be a rise in sea level due to the melting of land ice and the expansion of the upper layers of the ocean as they warm. This study looks at the potential costs to society of protecting against an increase in sea level, and applies this method to the San Francisco Bay area -- a region of great ecological diversity, economic importance, and vulnerability. Effects of rising sea levels around the margin of San Francisco Bay are evaluated, structural options for protecting property are identified and chosen for threatened areas, and estimates of costs of protection are determined.
A top-down methodology for developing diurnal and seasonal anthropogenic heating profiles for urban areas. Sailor, D. J. & Lu, L..
A generalized approach for estimating season-specific diurnal profiles of anthropogenic heating for cities is presented. Each profile consists of heat released from three components: building sector, transportation sector, and metabolism. In turn, the building sector is divided into heat released from electricity consumption and heat released from heating fuels such as natural gas and fuel oil. Each component is developed separately based on a population density formulation. The profiles are based on commonly available data resources that are mapped onto the diurnal cycle using seasonal profile functions. Representative winter and summer weekday profiles are developed and presented for six large US cities. The diurnal profiles have morning and evening peaks, with summertime maxima up to 60 W m(-2). Anthropogenic heating in winter is generally larger, with maxima up to 75 W m(-2). While these analyses were carried out at the city-scale the paper discusses how the same data sources could be applied at scales down to the individual census tract (or traffic analysis zone), resulting in high spatial resolution profiles and larger maxima corresponding to higher population densities in the urban core. Based on our analysis of San Francisco we find that the urban core region may have a daytime population density that is 5-10 times that of the city-scale value. Hence, the corresponding anthropogenic heating values in the urban core will be 5-10 times the magnitudes of the city-scale values presented in this paper.
Baseline Development and Estimation of Carbon Benefits for Extending Forested Riparian Buffer Zones In Two Regions: Blodgett Forest Research Station and Jackson State Demonstration Forest. Brown, Sandra; Shoch, David; Pearson, Tim; Delaney, Matt & Dushku, Aaron.
California Energy Commission :
A measurement and monitoring activity was carried out to assess the relative biomass carbon storage potential of extending forested buffer zones by 200 feet (100 feet either side of existing regulations) at two study sites representing key timber production regions in California: Sierran mixed conifers at Blodgett Forest Research Station(BFRS) in the Sierra Nevada and coastal redwoods at Jackson Demonstration State Forest (JDSF). Each of these site assessments is presented as a specific and independent case study, and each reflects a unique set of conditions (e.g., species composition), which determines the response to different management practices. The assessments were based on a combination of existing field data from forest inventory plots gathered by the respective forest sites, new field measurements for missing components, empirical modeling, and data integration. Researchers estimated the changes in carbon stocks for baseline conditions (continued harvesting) and compared these to the carbon stocks from conserving the forests with no harvesting. Extension of riparian buffer zones can lead to estimated benefits of 1,100-1,200 tons of carbon (C) per kilometer (km) of stream (or 2.3-2.5 t C/hectare per year (ha.yr)) over 80 years in mixed Sierran conifer forests and 920-1,270 tons C per km of stream (or 1.5-2.1 t C/ha.yr) over 100 years in coastal redwood forests. The carbon benefit arises from the increased biomass in living and dead trees in the forest exceeding the carbon stored in wood products and logging slash. Additional environmental benefits would include habitat for wildlife, protection for fish breeding and migrating sites, and a reduction in runoff from the land.
The project described in Baseline Greenhouse Gas Emissions and Removals for Forest, Range, and Agricultural Lands in California sought to quantify the baseline of changes in carbon stocks on forest, range, and agricultural lands in California for the 1990s filling the gaps for those sectors that existed in the 2002 California Energy Commission report, Inventory of California Greenhouse Gas Emissions and Sinks: 1990-1999. These baselines provide an estimate of the emissions and removals of GHGs attributable to changes in the use and management of land, and are useful for identifying where major opportunities could exist in California for enhancing carbon stocks and/or reducing carbon sources to potentially mitigate GHG emissions. The analysis revealed that forests and rangelands were responsible for a net removal of carbon dioxide from the atmosphere of 7.55 million metric tons of carbon dioxide per year (MMTCO2eq/yr), and that agricultural lands were responsible for a net emission of 0.35 MMTCO2eq/yr. Non-CO2 GHG emissions from forest and range lands were estimated to be 0.16 MMTCO2eq/yr, or equivalent to about 2% of the removals by these systems. Nitrous oxide (N2O) emissions (in CO2 eq) from agricultural lands are more than 40 times higher than carbon emission due to land use change. The overall net result was a removal of 7.20 MMTCO2eq/yr by forests and 0.18 MMTCO2eq/yr by rangelands, and an emission of 14.19 MMTCO2eq/yr by agricultural land.
The project described in Carbon Supply for Forest, Range, and Agricultural Lands of California was a portion of the Baseline, Classification, Quantification, and Measurement for Carbon Market Opportunities in California project. This project estimated the quantity and cost of carbon storage opportunities in California and developed carbon supply curves for the most important classes of carbon sequestration activities in land-use change and forestry projects. The research found that the cost of carbon sequestration from changing forest management practices is relatively high. No forest management project, regardless of length of project, can provide carbon sequestration at less than $2.70/MTCO2. The largest potential source of carbon from forest management is for lengthening rotation by five years, which can potentially provide 2.16 to 3.91 MMTCO2 at a cost of less than $13.60 per ton. For afforestation of rangelands, longer durations produce lower cost carbon. Afforestation of rangelands provides the most carbon at the least cost ($2.7/MT CO2) - about 33 MMTCO2 at 20 years to 4.57 billion MTCO2 at 80 years. Conservation tillage (CT) seems to offer the greatest potential for producing carbon on agricultural land in California. It is estimated that California agricultural land could produce up to 3.9 MMTCO2 /year through CT. This report can help stakeholders more accurately estimate the quantity of carbon credits that might be available at different price points for different classes of projects. The estimates can help in preparation of a portfolio of potential stakeholder responses for a range of future climate scenarios.