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Abstract
An experiment, aimed at forecasting the formation and intensification of extra-tropical cyclones, was conducted from 4 January 1954 to 20 March 1954. The working hypothesis to be tested was formulated as follows: cyclonic development at sea level occurs when and where an area of positive vorticity advection in the upper troposphere becomes super-imposed upon a frontal zone at sea level. The experiment, which was conducted in connection with the routine operation of the U. S. Weather Bureau's District Forecast Center in Chicago, resulted in 97 verifiable forecasts. The verification indicated that the working hypothesis is useful.
Abstract
An experiment, aimed at forecasting the formation and intensification of extra-tropical cyclones, was conducted from 4 January 1954 to 20 March 1954. The working hypothesis to be tested was formulated as follows: cyclonic development at sea level occurs when and where an area of positive vorticity advection in the upper troposphere becomes super-imposed upon a frontal zone at sea level. The experiment, which was conducted in connection with the routine operation of the U. S. Weather Bureau's District Forecast Center in Chicago, resulted in 97 verifiable forecasts. The verification indicated that the working hypothesis is useful.
Abstract
A new four-dimensional ocean interpolation system based on locally weighted least squares fitting is presented. A loess filter is used to interpolate irregularly spaced data onto a uniform grid. This involves projecting the data onto quadratic functions of latitude and longitude while simultaneously fitting annual and semiannual harmonics by weighted least squares. The smoothness scale of the mapping method adapts to match the data density, thus producing gridded estimates with maximum resolution. The filter has a vertical dimension, such that the data on adjacent levels are included in the computation. This greatly reduces the effects of discontinuities in data distributions between adjacent levels, since the estimates at each level are no longer independent. The loess scheme has been further modified so that the weighting of data points is adjusted to allow for the influence of both bathymetry and land barriers. This allows the bathymetry to influence the mapped fields in a natural way, reduces leakage of structure between deep and shallow regions and produces far more realistic coastal gradients. The flexibility of the loess approach has allowed further adjustments to compensate for irregularities in spatial and temporal sampling. The mapping is shown to be statistically consistent with an objective measure of the a priori noise of the dataset. Departures of the mapped fields from independent surface temperature climatologies and mean vertical sections derived from withheld expendable bathythermograph (XBT) data are within error limits.
The method is applied to the major seas around Australia, New Zealand, Papua New Guinea, and Indonesia (50°S–10°N, 100°E;–180°) to form a high-resolution seasonal climatology of temperature, salinity, oxygen, nitrate, phosphate, and silicate, referred to as the CSIRO (Commonwealth Scientific and Industrial Research Organisation) Atlas of Regional Seas (CARS). Stringent quality control procedures have been applied to a comprehensive dataset assembled from all known sources. The resulting maps successfully resolve both the large-scale structure and narrow coastal features and illustrate how the bathymetry influences the property distributions.
Abstract
A new four-dimensional ocean interpolation system based on locally weighted least squares fitting is presented. A loess filter is used to interpolate irregularly spaced data onto a uniform grid. This involves projecting the data onto quadratic functions of latitude and longitude while simultaneously fitting annual and semiannual harmonics by weighted least squares. The smoothness scale of the mapping method adapts to match the data density, thus producing gridded estimates with maximum resolution. The filter has a vertical dimension, such that the data on adjacent levels are included in the computation. This greatly reduces the effects of discontinuities in data distributions between adjacent levels, since the estimates at each level are no longer independent. The loess scheme has been further modified so that the weighting of data points is adjusted to allow for the influence of both bathymetry and land barriers. This allows the bathymetry to influence the mapped fields in a natural way, reduces leakage of structure between deep and shallow regions and produces far more realistic coastal gradients. The flexibility of the loess approach has allowed further adjustments to compensate for irregularities in spatial and temporal sampling. The mapping is shown to be statistically consistent with an objective measure of the a priori noise of the dataset. Departures of the mapped fields from independent surface temperature climatologies and mean vertical sections derived from withheld expendable bathythermograph (XBT) data are within error limits.
The method is applied to the major seas around Australia, New Zealand, Papua New Guinea, and Indonesia (50°S–10°N, 100°E;–180°) to form a high-resolution seasonal climatology of temperature, salinity, oxygen, nitrate, phosphate, and silicate, referred to as the CSIRO (Commonwealth Scientific and Industrial Research Organisation) Atlas of Regional Seas (CARS). Stringent quality control procedures have been applied to a comprehensive dataset assembled from all known sources. The resulting maps successfully resolve both the large-scale structure and narrow coastal features and illustrate how the bathymetry influences the property distributions.
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The 2002 Winter Olympic and Paralympic Games will be hosted by Salt Lake City, Utah, during February–March 2002. Adverse weather during this period may delay sporting events, while snow and ice-covered streets and highways may impede access by the athletes and spectators to the venues. While winter snowstorms and other large-scale weather systems typically have widespread impacts throughout northern Utah, hazardous winter weather is often related to local terrain features (the Wasatch Mountains and Great Salt Lake are the most prominent ones). Examples of such hazardous weather include lake-effect snowstorms, ice fog, gap winds, down-slope windstorms, and low visibility over mountain passes.
A weather support system has been developed to provide weather information to the athletes, games officials, spectators, and the interested public around the world. This system is managed by the Salt Lake Olympic Committee and relies upon meteorologists from the public, private, and academic sectors of the atmospheric science community. Weather forecasting duties will be led by National Weather Service forecasters and a team of private weather forecasters organized by KSL, the Salt Lake City NBC television affiliate. Other government agencies, commercial firms, and the University of Utah are providing specialized forecasts and support services for the Olympics. The weather support system developed for the 2002 Winter Olympics is expected to provide long-term benefits to the public through improved understanding, monitoring, and prediction of winter weather in the Intermountain West.
The 2002 Winter Olympic and Paralympic Games will be hosted by Salt Lake City, Utah, during February–March 2002. Adverse weather during this period may delay sporting events, while snow and ice-covered streets and highways may impede access by the athletes and spectators to the venues. While winter snowstorms and other large-scale weather systems typically have widespread impacts throughout northern Utah, hazardous winter weather is often related to local terrain features (the Wasatch Mountains and Great Salt Lake are the most prominent ones). Examples of such hazardous weather include lake-effect snowstorms, ice fog, gap winds, down-slope windstorms, and low visibility over mountain passes.
A weather support system has been developed to provide weather information to the athletes, games officials, spectators, and the interested public around the world. This system is managed by the Salt Lake Olympic Committee and relies upon meteorologists from the public, private, and academic sectors of the atmospheric science community. Weather forecasting duties will be led by National Weather Service forecasters and a team of private weather forecasters organized by KSL, the Salt Lake City NBC television affiliate. Other government agencies, commercial firms, and the University of Utah are providing specialized forecasts and support services for the Olympics. The weather support system developed for the 2002 Winter Olympics is expected to provide long-term benefits to the public through improved understanding, monitoring, and prediction of winter weather in the Intermountain West.
Abstract
A vertical array of acoustic current meters measures the vector flow field in the lowest 5 m of the oceanic boundary layer. By resolving the velocity to 0.03 cm s−1 over 15 cm paths, it samples the dominant turbulent eddies responsible for Reynolds stress to within 50 cm of the bottom. Profiles through the inner boundary layer, from six sensor pods, of velocity, turbulent kinetic energy, and Reynolds stress can be recorded for up 10 four months with a 2 Hz sample rate and 20 min averaging interval. We can study flow structure and spectra from as many as four event-triggered recordings of unaveraged samples, each lasting one hour, during periods of intense sediment transport. Acoustic transducer multiplexing permits 24 axes to be interfaced to a single receiving circuit. Electrical reversal of transducers in each axis eliminates zero drift. A deep-sea tripod supports the sensor array rigidly with minimum flow disturbance, yet releases on command for free vehicle recovery.
Abstract
A vertical array of acoustic current meters measures the vector flow field in the lowest 5 m of the oceanic boundary layer. By resolving the velocity to 0.03 cm s−1 over 15 cm paths, it samples the dominant turbulent eddies responsible for Reynolds stress to within 50 cm of the bottom. Profiles through the inner boundary layer, from six sensor pods, of velocity, turbulent kinetic energy, and Reynolds stress can be recorded for up 10 four months with a 2 Hz sample rate and 20 min averaging interval. We can study flow structure and spectra from as many as four event-triggered recordings of unaveraged samples, each lasting one hour, during periods of intense sediment transport. Acoustic transducer multiplexing permits 24 axes to be interfaced to a single receiving circuit. Electrical reversal of transducers in each axis eliminates zero drift. A deep-sea tripod supports the sensor array rigidly with minimum flow disturbance, yet releases on command for free vehicle recovery.
Meteorological data from over 2800 automated environmental monitoring stations in the western United States are collected, processed, archived, integrated, and disseminated as part of the MesoWest program. MesoWest depends upon voluntary access to provisional observations from environmental monitoring stations installed and maintained by federal, state, and local agencies and commercial firms. In many cases, collection and transmission of these observations are facilitated by NWS forecast offices, government laboratories, and universities. MesoWest augments the Automated Surface Observing System (ASOS) network maintained by the NWS, Federal Aviation Administration, and Department of Defense. MesoWest increases the coverage of observations in remote locations and helps capture many of the local and mesoscale weather phenomena that impact the public.
The primary goal of MesoWest is to improve timely access to automated observations for NWS forecasters at offices throughout the western United States. In addition, integration of the observations into analyses of surface conditions at high spatial and temporal resolution provides additional tools for nowcasts and forecast verification. MesoWest observations are being used for many other applications, including input to operational and research models and research and education on weather processes in the western United States.
Meteorological data from over 2800 automated environmental monitoring stations in the western United States are collected, processed, archived, integrated, and disseminated as part of the MesoWest program. MesoWest depends upon voluntary access to provisional observations from environmental monitoring stations installed and maintained by federal, state, and local agencies and commercial firms. In many cases, collection and transmission of these observations are facilitated by NWS forecast offices, government laboratories, and universities. MesoWest augments the Automated Surface Observing System (ASOS) network maintained by the NWS, Federal Aviation Administration, and Department of Defense. MesoWest increases the coverage of observations in remote locations and helps capture many of the local and mesoscale weather phenomena that impact the public.
The primary goal of MesoWest is to improve timely access to automated observations for NWS forecasters at offices throughout the western United States. In addition, integration of the observations into analyses of surface conditions at high spatial and temporal resolution provides additional tools for nowcasts and forecast verification. MesoWest observations are being used for many other applications, including input to operational and research models and research and education on weather processes in the western United States.
Abstract
Detailed information on the four-channel Airborne Chromatograph for Atmospheric Trace Species (ACATS-IV), used to measure long-lived atmospheric trace gases, is presented. Since ACATS-IV was last described in the literature, the temporal resolution of some measurements was tripled during 1997–99, chromatography was significantly changed, and data processing improved. ACATS-IV presently measures CCl3F [chlorofluorocarbon (CFC)-11], CCl2FCClF2 (CFC-113), CH3CCl3 (methyl chloroform), CCl4 (carbon tetrachloride), CH4 (methane), H2 (hydrogen), and CHCl3 (chloroform) every 140 s, and N2O (nitrous oxide), CCl2F2 (CFC-12), CBrClF2 (halon-1211), and SF6 (sulfur hexafluoride) every 70 s. An in-depth description of the instrument operation, standardization, calibration, and data processing is provided, along with a discussion of precision and uncertainties of ambient air measurements for several airborne missions.
Abstract
Detailed information on the four-channel Airborne Chromatograph for Atmospheric Trace Species (ACATS-IV), used to measure long-lived atmospheric trace gases, is presented. Since ACATS-IV was last described in the literature, the temporal resolution of some measurements was tripled during 1997–99, chromatography was significantly changed, and data processing improved. ACATS-IV presently measures CCl3F [chlorofluorocarbon (CFC)-11], CCl2FCClF2 (CFC-113), CH3CCl3 (methyl chloroform), CCl4 (carbon tetrachloride), CH4 (methane), H2 (hydrogen), and CHCl3 (chloroform) every 140 s, and N2O (nitrous oxide), CCl2F2 (CFC-12), CBrClF2 (halon-1211), and SF6 (sulfur hexafluoride) every 70 s. An in-depth description of the instrument operation, standardization, calibration, and data processing is provided, along with a discussion of precision and uncertainties of ambient air measurements for several airborne missions.
Abstract
Observations are the foundation for understanding the climate system. Yet, currently available land meteorological data are highly fractured into various global, regional, and national holdings for different variables and time scales, from a variety of sources, and in a mixture of formats. Added to this, many data are still inaccessible for analysis and usage. To meet modern scientific and societal demands as well as emerging needs such as the provision of climate services, it is essential that we improve the management and curation of available land-based meteorological holdings. We need a comprehensive global set of data holdings, of known provenance, that is truly integrated both across essential climate variables (ECVs) and across time scales to meet the broad range of stakeholder needs. These holdings must be easily discoverable, made available in accessible formats, and backed up by multitiered user support. The present paper provides a high-level overview, based upon broad community input, of the steps that are required to bring about this integration. The significant challenge is to find a sustained means to realize this vision. This requires a long-term international program. The database that results will transform our collective ability to provide societally relevant research, analysis, and predictions in many weather- and climate-related application areas across much of the globe.
Abstract
Observations are the foundation for understanding the climate system. Yet, currently available land meteorological data are highly fractured into various global, regional, and national holdings for different variables and time scales, from a variety of sources, and in a mixture of formats. Added to this, many data are still inaccessible for analysis and usage. To meet modern scientific and societal demands as well as emerging needs such as the provision of climate services, it is essential that we improve the management and curation of available land-based meteorological holdings. We need a comprehensive global set of data holdings, of known provenance, that is truly integrated both across essential climate variables (ECVs) and across time scales to meet the broad range of stakeholder needs. These holdings must be easily discoverable, made available in accessible formats, and backed up by multitiered user support. The present paper provides a high-level overview, based upon broad community input, of the steps that are required to bring about this integration. The significant challenge is to find a sustained means to realize this vision. This requires a long-term international program. The database that results will transform our collective ability to provide societally relevant research, analysis, and predictions in many weather- and climate-related application areas across much of the globe.
