ASR FY02 Banner

Table of Contents | Director's Message
Scientific Highlights | Fundamental Research | Enhancing Productivity | Protection of Life and Property
Education & Outreach | Additional Educational Activities | Publications | Community Service
Staff, Visitors and Collaborators | ASR 2002 Home

Fundamental Research

Climate Forecasting in the La Plata Basin

The La Plata Basin covers portions of the five countries that make up the economic common market known as "Mercosur." A significant source of natural capital for the growing populations of Argentina, Brazil, Bolivia, Paraguay, and Uruguay, the La Plata Basin generates 70% of the total GNP of these countries and is critical to local economies as an agricultural center, natural waterway for ground transportation, and primary producer of hydroelectric energy. In FY02, Heidi Cullen initiated an integrated assessment to establish how best to move forward with the development of climate applications in the basin. The potential for integrated earth system models in water resource management and agricultural planning is tested by evaluating three types of variability that collectively create the backdrop for sustainable resource management. These are climate variability, climate change, and human-induced change. This assessment will continue in FY03. A website for the assessment is maintained by Cullen.

Climate Variability and Political Disruption in Southwest and Central Asia

Central Southwest Asia (CSWA) is in the midst of the fourth year of a severe drought. The hydrology of this semi-arid region shows significant variability over the length of a rather short historical record. Because both natural fluctuations and anthropogenic factors impact and alter the water cycle of CSWA, there is a need to probe more deeply into the interactive processes within the water cycle, quantify inherent variability and alterations caused by global change, and determine the impacts of these processes on water resources. In FY02, Heidi Cullen, along with Matthew Barlow and Bradford Lyon (both of IRI, U. Columbia), and Jennifer Mangan (ASP) formed a Central Asia Research Group to study CSWA teleconnections and water resources in the region. Research will continue during FY03, and a website will be updated with current research on the project.

Effects of Climate on Simulated Crops

While most studies of the impacts of climate change on ecosystems have examined the effect of mean change in climate, it is widely believed that climate variability, in addition to the mean, has substantial effects on ecosystems. This issue is becoming more important as we learn more about how climate may vary in coming decades. During FY02, Linda Mearns and colleagues continued examination of the possible additional effects of changes in variability on simulated crops. Mearns, with Cynthia Rosenzweig and Richard Goldberg (NASA Goddard, New York), continued research on the effect of changes in variability of climate on simulated crop yields at other locations in the Great Plains and Midwest. They applied time series of temperature and precipitation with changed variances to CERES-corn and CROPGRO-soybean models. Results so far indicate that increased variance of temperature and precipitation cause substantial decreases in yield, while decreases in variability cause only slight increases in yield. They have begun applying changes in variance from two major AOGCMs, the NCAR PCM, and that of GISS, for the region of the Midwest and Great Plains to these crop models for the end of the twenty-first century. With Marta Vinocur (National University of Redo, Cordoba, Argentina), Mearns has investigated simulated peanut crop responses to climate variability in Cordoba, Argentina. Using PeanutGRO, they explored the effects of different combinations of mean and variance changes of temperature. They found that the crop model was sensitive to both mean and variance changes, but that increases in temperature variance substantially exacerbated decreases in yield and greatly increased the likelihood of crop failures. They are currently exploring the causes for these crop model responses.

Methods and Models for Integrated Assessment

Linda Mearns and colleagues have developed a project focusing on agricultural assessment that formally quantifies uncertainties in spatial assessments based on data set sources and various methods of spatial scaling of the data sets and various means of calibrating and validating crop models over space. Climate, soils, and crop management data sets are included. They are creating methods of aggregation of different types of data over space in the Southeastern US, where they have already developed a number of data sets, and by so doing determine appropriate scale matches for the different variable types. Part of this involves determining what the concept of matching scales really means operationally. Moreover, the scaling of inputs will be extended for support of an additional goal of calibrating and validating crop models over space. This project is in collaboration with the University of Florida. In FY02, the ESIG portion of the project involved comparisons of daily weather datasets for the Southeast; and with Sarah Streett (GSP), an exploration of the uncertainty of estimates of daily generated climate using a weather generator approach.

The North Atlantic Oscillation (NAO)

NAO and Energy Markets in Scandinavia

More than two centuries ago, missionaries first noticed that year-to-year fluctuations in wintertime climate on both sides of the North Atlantic were often out of phase with one another. When temperatures are below normal over Greenland, they are above normal in Scandinavia, and vice versa. This mode of climate variability is now known as the North Atlantic Oscillation (NAO), a name first cited by Sir Gilbert Walker in 1924. It is now firmly established that its fluctuations influence climate from North America to Siberia and from the Arctic Ocean to the equator, and perhaps beyond. A number of recent studies have investigated the impact of the NAO on climate shifts and variability on land and within the ocean, thereby affecting the marine and terrestrial ecosystem. Heidi Cullen and colleagues began a study in FY02 that focuses on the impacts of the North Atlantic Oscillation on the energy sector in Scandinavia. In particular, Norway's hydropower generation's deficit during a large negative NAO index event during the winter of 1995-1996 shows how swings in the climate system can significantly affect the energy sector. The impacts of this particular low rainfall season were felt strongly, since it occurred during a decade of a mostly positive NAO index years.

NAO Extreme Temperatures and Forest Dieback

Linda Mearns, Justin Wettstein (U Washington), and Larry McDaniel, in collaboration with Allan Auclair (Rand Corporation) continued their NOAA study of the effects of climate variability on forest dieback in the northeastern United States. In FY02, they focused on analyzing the relationships between the NAO/Arctic Oscillation (AO) and local temperature conditions. They found an intensification of spatial patterns of contrasts in winter maximum and minimum temperature in extreme phases of the AO. For example, an extreme positive AO index winter had minimum temperatures 2.5 degrees C warmer in the southwest portion of the Northeast, and .5 degrees C cooler in the Northeast, compared to the extreme negative AO index. Important variations in the daily variance of temperature were also found. A paper describing these results was published in the Journal of Climate.

Research of ASP Postdoctoral Fellow in ESIG

Eugene Wahl (ASP) began a comparison of climate model output with paleoclimate data in FY02, for the purposes of diagnosing model performance and characterizing model uncertainty (click on image to enlarge). This research is part of the Weather and Climate Impact Assessment Strategic Initiative (see below) with Mearns and Cullen. Wahl is also examining paleoclimate and paleoecological reconstruction methods, including a systematic analysis focused on optimizing pollen-based reconstructions. He also began an examination of ethical and philosophical dimensions of environmental issues, including examination of the generation and use of climate and weather forecasts. A portion of this work he is doing independently, and in other portions he works in collaboration with John Firor and Rebecca Morss. By the end of 2002, he will have completed and sent for review six science articles, two related to dissertation results and four in the area of optimizing pollen-based paleoenvironmental reconstructions. An additional article in environmental ethics and theology was published in FY02.

Statistics of Extremes

Richard Katz's research on statistics of extremes develops and applies improved statistical methodology for climate variability, climate change, and impacts (both hydrologic and economic) involving extreme events. In collaboration with Marc Parlange (Johns Hopkins U) and Philippe Naveau (École Polytechnique, France and U Colorado), a review of the use of the statistics of extremes was completed during FY02. Evidence is increasing that climate variables (e.g., precipitation), related variables (e.g., streamflow), and impact variables (e.g., economic damages) all have distributions with heavy upper tails (adjacent figure illustrates this for hurricane damage [click on figure to enlarge]). Yet, this characteristic is not routinely taken into account in the statistical analysis of extremes (e.g., trend detection). Work also began during FY02 with Greg Young (formerly in RAP) on the development of an extremes "toolkit" as part of the new NCAR Weather and Climate Impact Assessment Strategic Initiative. This toolkit would contribute to the goals of the next IPCC assessment, improving the treatment of climate extremes by making the appropriate statistical methodology more readily accessible to researchers in climate and climate impacts.

Weather and Climate Impact Assessment Strategic Initiative

Beginning in FY01, Linda Mearns and Warren Washington (CGD) began a multi-year, multidisciplinary initiative with other ESIG and NCAR scientists in order to establish a Weather and Climate Impact Assessment Science Initiative at NCAR. This initiative has three components: (1) characterizing uncertainty in impact assessment science; (2) extreme weather and climate events, and (3) climate and health interactions. The initiative will help to produce the next generation of scholars dedicated to these issues. A workshop was held in July to begin first steps for Component (1), which aimed to develop a unified program of climate scenario production and distribution, as well as to propose and implement a five-year Action Plan. Additional aspects of the initiative are under way in other NCAR divisions, and other components are scheduled for implementation in FY03. Another major accomplishment in FY02 was the development of a website for the project, which is available at

Table of Contents | Director's Message
Scientific Highlights | Fundamental Research | Enhancing Productivity | Protection of Life and Property
Education & Outreach | Additional Educational Activities | Publications | Community Service
Staff, Visitors and Collaborators