Paleoenvironmental records from the Quelccaya ice cap, Peru and preliminary results from the Dunde ice cap, China [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): The 1000 year records of particulate deposition (soluble and insoluble), oxygen isotopic ratios, and net accumulation from the Quelccaya ice cap are presented. The net accumulation record from Quelccaya is shown to serve as a reasonable proxy for the water levels in Lake Titicaca. ... The ice core record from the Dunde ice cap offers the potential to reconstruct a very detailed history of environmental conditions on the Tibetan Plateau for the last 3000 years.

Meteorological influences on North America quail populations [abstract, table, and figure]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Comparative study of environmental influences on the population dynamics of three North American species of quail, California quail (Callipepla california), Gambel's quail (C. gambellii), and scaled quail (C. squamata) has lead to identification of differential sensitivity of these species to global weather patterns.

A review of water year 1987 in northern California [abstract and figures]

EXTRACT (SEE PDF FOR FULL ABSTRACT): It seems that an average water year is a rare beast; 1987 was no exception. It turned out to be the ninth driest this century in Northern California's Sacramento River basin. I'd like to summarize for you some interesting facts about water year 1987 and how it affected rainfall, snowpack, runoff, and water storage in California.

Trans-Sierran climatic contacts during the last 12,000 years [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): The early-Holocene warm period, ca. 9000 years ago, is a realistic analog for the possible effects of greenhouse warming. At that time the vegetation of the western Sierra Nevada resembled that currently found east of the crest. ... Tourism, water supply, and the logging industry will be negatively effected if climate changes during the next century are in the direction and magnitude of those of the early Holocene. Increased precipitation in the eastern Sierra could offset some of the effects.

Associations among chlorophyll concentration and climatic variables for Suisun Bay and the Sacramento-San Joaquin Delta [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): The recent changes in phytoplankton production and community composition within the Suisun Bay and Sacramento-San Joaquin Delta may be related to climate. Chlorophyll a concentration, decreased by 42% (spring-summer) and 29% (fall) between 1972 through 1976 and 1977 through 1981. The decrease in biomass was characterized by a shift in phytoplankton community dominance from Skeletonema spp., Cyclotella spp. and Coscinodiscus spp. to Melosira granulata. The possible influence of climate on phytoplankton abundance was suggested by multivariate statistical analyses that demonstrated an association between changes in phytoplankton community composition and abundance between 1975 and 1982 and the climate related variables wind velocity, precipitation, river flow and water temperature.

Record of the 1983 El Nino in Santa Barbara basin [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): The 1983 El Nino resulted in a decrease in the flux of diatoms and planktonic foraminiferans into the Santa Barbara basin. These may both be related to the decrease in productivity and therefore standing crops of these two groups.

A sensitivity analysis of Southwestern climate [abstract and conclusions]

EXTRACT (SEE PDF FOR FULL ABSTRACT): We provide here an estimate of the extent that modern climate in the southwest US is sensitive to changes in several parameters that reflect global climatic changes. For the purposes of this study, we define modern climate as mean monthly values for the months of February and August (called winter and summer, respectively) of temperature and precipitation, at points representing the average of cells of dimension 7.5' on a side. The area studied surrounds the drainage basin of Death Valley, California.

A mechanism for the link between solar-irradiance variations and regional precipitation

Although the mechanisms of climatic fluctuations are not completely understood, changes in global solar irradiance show a link with regional precipitation. A proposed mechanism for this linkage begins with absorption of varying amounts of solar energy by tropical oceans, which may aid in development of ocean temperature anomalies. These anomalies are then transported by major ocean currents to locations where the stored energy is released into the atmosphere, altering pressure and moisture patterns that can ultimately affect regional precipitation. Correlation coefficients between annual averages of monthly differences in empirically modeled solar-irradiance variations and annual state-divisional precipitation values in the United States for 1950 to 1988 were computed with lag times of 0 to 7 years. The highest correlations (R=0.65) occur in the Pacific Northwest with a lag time of 4 years, which is about equal to the travel time of water within the Pacific Gyre from the western tropical Pacific Ocean to the Gulf of Alaska. With positive correlations, droughts coincide with periods of negative irradiance differences (dry, high-pressure development), and wet periods coincide with periods of positive differences (moist, low-pressure development).

A multi-basin seasonal streamflow model for the Sierra Nevada

Linear regression models are constructed to predict seasonal runoff by fitting streamflow to temperature, precipitation, and snow water content across a range of elevations. The models are quite successful in capturing the differences in discharge between different elevation watersheds and their interannual variations. This exercise thus provides insight into seasonal changes in streamflow at different elevation watersheds that might occur under a changed climate.

Climate studies in the Long-Term Ecological Program

Since the inception of the LTER Program in 1980, climate has been studied at individual LTER sites and an LTER Climate Committee has been responsible for inter-site activities. At individual sites, climate studies support ecological research, emphasize inter-site heterogeneity, and often relate to other national monitoring and research programs. In inter-site work, the Climate Committee has produced protocols for meteorological observations, described and compared climates of the first 11 sites, and raised important issues regarding climate variability and ecosystem response.

Sea surface temperature and the subsequent freshwater survival rate of some salmon stocks: a surprising link between the climate of land and sea

Previous consideration of the relationship between climate and the survival rate of Pacific salmon eggs and fry has been confined to effects of large variation in the ambient freshwater environment; e.g., stream discharge, temperature, turbidity. This analysis shows sea surface temperatures during the last year of life of maturing adult salmon are also strongly associated with the subsequent survival rate of salmon eggs and fry is fresh water, presumably through development of the future eggs or sperm. In several stocks of three species of North American salmon, the association between the "marine" climate and egg survival is stronger than, or additive to, any estimated climatic association in fresh water. This apparent and surprising link between fresh water and the distant ocean has some interesting and complex implications for management of future salmon production.

Meteorological and hydrologic studies in the Alaskan Arctic in support of long-term ecological research

Long-term hydrologic studies in the Arctic simply do not exist. Although the Arctic has been identified as an area that is extremely sensitive to climate change, continuous scientific research has been limited to the past seven years. Earlier research was spotty, of short duration, and directed at only one or two hydrologic elements. Immediate future research needs to encompass all the major hydrologic elements, including winter processes, and needs to address the problem of scaling from small to larger areas in hydrologic models. Also, an international program of cooperation between northern countries is needed to build a greater scientific base for monitoring and identifying potential changes wrought by the climate.

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.

Regulation of primary production in the Gulf of California through interaction of large-scale and local ocean processes [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): The suppression of primary productivity observed in eastern boundary ecosystems of the Pacific during El Nino episodes does not occur throughout the Gulf of California. On the contrary, analysis of the modern siliceous phytoplankton record from annually layered sediments and compilation of available primary productivity measurements indicate that production is significantly increased in the central Gulf during El Nino years compared to anti-El Nino years. Integrated observations of biological and physical variability during the spring of 1983, under the influence of the strong El Nino, show that very high primary productivity occurred along the eastern margin of the central Gulf. This resulted from the upwelling of a nutrient rich source provided by the locally formed Gulf water mass originating in the northern Gulf. Lower productivity and phytoplankton biomass were associated with the anomalous penetration of Tropical Surface Water along the western side of the Gulf.

Climatic controls on diatom succession at Elk Lake, Minnesota [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Sediment traps placed in the profundal region of Elk Lake, north central Minnesota during the 1979 spring and 1983-84 fall and spring seasons monitored seasonal diatom production for two climatically distinctive periods.