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Oreopoulos, Lazaros; Mlawer, Eli
doi: 10.1175/2009BAMS2732.1pmid: N/A
No Abstract available.
Navarra, A.; Kinter, J. L.; Tribbia, J.
doi: 10.1175/2009BAMS2712.1pmid: N/A
This article discusses the interplay between computational experiments and scientific advancement in dynamical meteorology and climate dynamics. In doing so, the emphasis is on the dual role of computations in prediction and experimentation, permitting the development of physical insight and confidence in the mechanistic insight through verification. Modern climate dynamics has steadily evolved because of the ready access to computational power that has developed over the past quarter century.The landscape for state-of-the-art computational climate science is changing rapidly, however, with the drive toward greater complexity in climate models in order to more fully represent the interactions among components, the need for higher-resolution atmospheric and oceanic models to fully capture critical aspects of the variability in these components, and the advent of petascale and (eventually) exascale computing facilities. Finally, the manner in which the combination of these changes will likely alter the planning and execution of grand-challenge computational experiments and what this might mean in terms of collaborative climate science is discussed.
doi: 10.1175/2009BAMS2858.1pmid: N/A
Reanalyses are, by a substantial margin, the most utilized climate data products, and they are applied in a myriad of different contexts. Despite their popularity, there are substantial concerns about their suitability for the monitoring of long-term climate trends. This has led to calls for a truly climate quality reanalysis that retains long-term trend fidelity. The authors contend that for such a reanalysis to be achieved, a substantial rethinking of the current strategy for producing reanalysis products is required. First, the problem must be defined clearly. Second, the methodology that is employed must be reconsidered so as to minimize potential nonclimatic artifacts and robustly ascertain the inevitable residual uncertainty. Finally, a set of validation data and metrics must be constructed that the community can use to compare and unambiguously assess the claims of climate quality. The purpose of this essay is very much to initiate discussions to this end rather than to prescribe solutions.
Knapp, Kenneth R.; Kruk, Michael C.; Levinson, David H.; Diamond, Howard J.; Neumann, Charles J.
doi: 10.1175/2009BAMS2755.1pmid: N/A
The goal of the International Best Track Archive for Climate Stewardship (IBTrACS) project is to collect the historical tropical cyclone best-track data from all available Regional Specialized Meteorological Centers (RSMCs) and other agencies, combine the disparate datasets into one product, and disseminate in formats used by the tropical cyclone community. Each RSMC forecasts and monitors storms for a specific region and annually archives best-track data, which consist of information on a storm's position, intensity, and other related parameters. IBTrACS is a new dataset based on the best-track data from numerous sources. Moreover, rather than preferentially selecting one track and intensity for each storm, the mean position, the original intensities from the agencies, and summary statistics are provided. This article discusses the dataset construction, explores the tropical cyclone climatology from IBTrACS, and concludes with an analysis of uncertainty in the tropical cyclone intensity record.
Kucharski, Fred; Kang, In-Sik; Straus, David; King, Martin P.
doi: 10.1175/2009BAMS2834.1pmid: N/A
No Abstract available.
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The National Air Quality Forecast Capability (NAQFC) currently provides next-day forecasts of ozone concentrations over the contiguous United States. It was developed collaboratively by NOAA and Environmental Protection Agency (EPA) in order to provide state and local agencies, as well as the general public, air quality forecast guidance. As part of the development process, the NAQFC has been evaluated utilizing strict monitor-to-gridcell matching criteria, and discrete-type statistics of forecast concentrations. While such an evaluation is important to the developers, it is equally, if not more important, to evaluate the performance using the same protocol as the model's intended application. Accordingly, the purpose of this article is to demonstrate the efficacy of the NAQFC from the perspective of a local forecaster, thereby promoting its use. Such an approach has required the development of a new evaluation protocol: one that examines the ability of the NAQFC to forecast values of the EPA's Air Quality Index (AQI) rather than ambient air concentrations; focuses on the use of categorical-type statistics related to exceedances and nonexceedances; and, most challenging, examines performance, not based on matched grid cells and monitors, but rather over a local forecast region, such as an air shed or metropolitan statistical area (MSA). Results from this approach, which is demonstrated for the Charlotte, North Carolina, MSA and subsequently applied to four additional MSAs during the summer of 2007, reveal that the quality of the NAQFC forecasts is generally comparable to forecasts from local agencies. Such findings will hopefully persuade forecasters, whether they are experienced with numerous tools at their disposal or inexperienced with limited resources, to utilize the NAQFC as forecast guidance.
The StratosphereTroposphere Analyses of Regional Transport 2008 (START08) experiment investigated a number of important processes in the extratropical upper troposphere and lower stratosphere (UTLS) using the National Science Foundation (NSF)NCAR Gulfstream V (GV) research aircraft. The main objective was to examine the chemical structure of the extratropical UTLS in relation to dynamical processes spanning a range of scales. The campaign was conducted during AprilJune 2008 from Broomfield, Colorado. A total of 18 research flights sampled an extensive geographical region of North America (2565N, 80120W) and a wide range of meteorological conditions. The airborne in situ instruments measured a comprehensive suite of chemical constituents and microphysical variables from the boundary layer to the lower stratosphere, with flights specifically designed to target key transport processes in the extratropical UTLS. The flights successfully investigated stratospheretroposphere exchange (STE) processes, including the intrusion of tropospheric air into the stratosphere in association with the secondary tropopause and the intrusion of stratospheric air deep into the troposphere. The flights also sampled the influence of convective transport and lightning on the upper troposphere as well as the distribution of gravity waves associated with multiple sources, including fronts and topography. The aircraft observations are complemented by satellite observations and modeling. The measurements will be used to improve the representation of UTLS chemical gradients and transport in ChemistryClimate models (CCMs). This article provides an overview of the experiment design and selected observational highlights.