The Experts below are selected from a list of 57 Experts worldwide ranked by ideXlab platform
Steven P. Anderson - One of the best experts on this subject based on the ideXlab platform.
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surface meteorology and air sea fluxes in the western equatorial pacific warm pool during the toga coupled ocean atmosphere response experiment
Journal of Climate, 1996Co-Authors: Robert. A. Weller, Steven P. AndersonAbstract:Abstract A major goal of the Coupled Ocean-Atmosphere Response Experiment (COARE) was to achieve significantly more accurate and complete descriptions of the surface meteorology and air-sea fluxes in the western equatorial warm pool region. Time series of near-surface meteorology from a buoy moored near the center of the COARE Intensive Flux Array (IFA) are described here. The accuracies of the measurements and the derived fluxes are quantified; agreement between average net heat fluxes at the buoy and two nearby Research Ships is better than 10 W m−2 during three intercomparisons. Variability in the surface meteorology and fluxes associated with westerly wind bursts, periods of low winds, and short-lived, deep convective events characteristic of the region was large compared to the 4-month means. The ECMWF (European Centre for Medium-Range Weather Forecasts) analysis and prediction fields differed most from the buoy data during periods of short-lived, deep convective events, when several day averages of ...
M J Yelland - One of the best experts on this subject based on the ideXlab platform.
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cfd model estimates of the airflow distortion over Research Ships and the impact on momentum flux measurements
Journal of Atmospheric and Oceanic Technology, 2002Co-Authors: M J Yelland, B I Moat, R W Pascal, David I BerryAbstract:Abstract Wind velocity and air–sea turbulent flux measurements made from shipborne instruments are biased due to the effect of the ship on the flow of air to the instruments. The presence of the ship causes the airflow to a particular instrument site to be either accelerated or decelerated, displaced vertically, and sometimes deflected slightly in the horizontal. Although recognized for some time, it is only recently that the problem has been addressed using three-dimensional computational fluid dynamics (CFD) models to simulate the flow over particular Ships, quantify the effects of flow distortion, and hence correct the ship-based measurements. It has previously been shown that this improves the calculated momentum fluxes by removing disparities between data from different Ships, or from instruments in different locations on the same ship. This paper provides validation of the CFD model simulations. Two Research Ships were instrumented with multiple anemometers located in both well-exposed and badly exp...
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wind stress measurements from the open ocean corrected for airflow distortion by the ship
Journal of Physical Oceanography, 1998Co-Authors: M J Yelland, R W Pascal, Bengamin I Moat, Peter K Taylor, J Hutchings, V C CornellAbstract:A large dataset of wind stress estimates, covering a wide range of wind speed and stability conditions, was obtained during three cruises of the RRS Discovery in the Southern Ocean. These data were used by Yelland and Taylor to determine the relationship between 10-m height, neutral stability values for the drag coefficient, and the wind speed, and to devise a new formulation for the nondimensional dissipation function under diabatic conditions. These results have been reevaluated allowing for the airflow distortion caused by the ship. The acceleration and vertical displacement of the flow have been modeled in three dimensions using computational fluid dynamics (CFD). The CFD modeling was tested, first by comparison with wind tunnel measurements on models of two Canadian Research Ships and second, by analysis of data from four anemometers on the foremast of the RRS Charles Darwin. Originally, the four anemometers gave drag coefficient values that differed by up to 20% from one to another and were all unexpectedly high. The CFD results showed that the airflow had been decelerated by 4%‐14% and displaced vertically by about 1 m. These effects caused the original drag coefficient results to be overestimated by up to 60%. After correcting for flow distortion effects, the results from the different anemometers became consistent, which gave confidence in the quantitative CFD-derived corrections. The CFD modeling showed that the anemometer position on the RRS Discovery was much less affected by airflow distortion. For a given wind speed the CFD corrections reduced the drag coefficient by about 6%. The resulting mean drag coefficient to wind speed relationship confirmed that suggested by Smith from a more limited set of open ocean data. The effects of flow distortion are sensitive to changes in the relative wind direction. It is shown that much of the scatter in drag coefficient estimates may be due to variations in airflow distortion rather than to the effect of changing sea states. The Discovery wind stress data is examined for evidence of a sea-state dependence: none is found. It is concluded that a wave-age-dependent wind stress formulation is not applicable to open ocean conditions.
V C Cornell - One of the best experts on this subject based on the ideXlab platform.
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wind stress measurements from the open ocean corrected for airflow distortion by the ship
Journal of Physical Oceanography, 1998Co-Authors: M J Yelland, R W Pascal, Bengamin I Moat, Peter K Taylor, J Hutchings, V C CornellAbstract:A large dataset of wind stress estimates, covering a wide range of wind speed and stability conditions, was obtained during three cruises of the RRS Discovery in the Southern Ocean. These data were used by Yelland and Taylor to determine the relationship between 10-m height, neutral stability values for the drag coefficient, and the wind speed, and to devise a new formulation for the nondimensional dissipation function under diabatic conditions. These results have been reevaluated allowing for the airflow distortion caused by the ship. The acceleration and vertical displacement of the flow have been modeled in three dimensions using computational fluid dynamics (CFD). The CFD modeling was tested, first by comparison with wind tunnel measurements on models of two Canadian Research Ships and second, by analysis of data from four anemometers on the foremast of the RRS Charles Darwin. Originally, the four anemometers gave drag coefficient values that differed by up to 20% from one to another and were all unexpectedly high. The CFD results showed that the airflow had been decelerated by 4%‐14% and displaced vertically by about 1 m. These effects caused the original drag coefficient results to be overestimated by up to 60%. After correcting for flow distortion effects, the results from the different anemometers became consistent, which gave confidence in the quantitative CFD-derived corrections. The CFD modeling showed that the anemometer position on the RRS Discovery was much less affected by airflow distortion. For a given wind speed the CFD corrections reduced the drag coefficient by about 6%. The resulting mean drag coefficient to wind speed relationship confirmed that suggested by Smith from a more limited set of open ocean data. The effects of flow distortion are sensitive to changes in the relative wind direction. It is shown that much of the scatter in drag coefficient estimates may be due to variations in airflow distortion rather than to the effect of changing sea states. The Discovery wind stress data is examined for evidence of a sea-state dependence: none is found. It is concluded that a wave-age-dependent wind stress formulation is not applicable to open ocean conditions.
R W Pascal - One of the best experts on this subject based on the ideXlab platform.
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cfd model estimates of the airflow distortion over Research Ships and the impact on momentum flux measurements
Journal of Atmospheric and Oceanic Technology, 2002Co-Authors: M J Yelland, B I Moat, R W Pascal, David I BerryAbstract:Abstract Wind velocity and air–sea turbulent flux measurements made from shipborne instruments are biased due to the effect of the ship on the flow of air to the instruments. The presence of the ship causes the airflow to a particular instrument site to be either accelerated or decelerated, displaced vertically, and sometimes deflected slightly in the horizontal. Although recognized for some time, it is only recently that the problem has been addressed using three-dimensional computational fluid dynamics (CFD) models to simulate the flow over particular Ships, quantify the effects of flow distortion, and hence correct the ship-based measurements. It has previously been shown that this improves the calculated momentum fluxes by removing disparities between data from different Ships, or from instruments in different locations on the same ship. This paper provides validation of the CFD model simulations. Two Research Ships were instrumented with multiple anemometers located in both well-exposed and badly exp...
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wind stress measurements from the open ocean corrected for airflow distortion by the ship
Journal of Physical Oceanography, 1998Co-Authors: M J Yelland, R W Pascal, Bengamin I Moat, Peter K Taylor, J Hutchings, V C CornellAbstract:A large dataset of wind stress estimates, covering a wide range of wind speed and stability conditions, was obtained during three cruises of the RRS Discovery in the Southern Ocean. These data were used by Yelland and Taylor to determine the relationship between 10-m height, neutral stability values for the drag coefficient, and the wind speed, and to devise a new formulation for the nondimensional dissipation function under diabatic conditions. These results have been reevaluated allowing for the airflow distortion caused by the ship. The acceleration and vertical displacement of the flow have been modeled in three dimensions using computational fluid dynamics (CFD). The CFD modeling was tested, first by comparison with wind tunnel measurements on models of two Canadian Research Ships and second, by analysis of data from four anemometers on the foremast of the RRS Charles Darwin. Originally, the four anemometers gave drag coefficient values that differed by up to 20% from one to another and were all unexpectedly high. The CFD results showed that the airflow had been decelerated by 4%‐14% and displaced vertically by about 1 m. These effects caused the original drag coefficient results to be overestimated by up to 60%. After correcting for flow distortion effects, the results from the different anemometers became consistent, which gave confidence in the quantitative CFD-derived corrections. The CFD modeling showed that the anemometer position on the RRS Discovery was much less affected by airflow distortion. For a given wind speed the CFD corrections reduced the drag coefficient by about 6%. The resulting mean drag coefficient to wind speed relationship confirmed that suggested by Smith from a more limited set of open ocean data. The effects of flow distortion are sensitive to changes in the relative wind direction. It is shown that much of the scatter in drag coefficient estimates may be due to variations in airflow distortion rather than to the effect of changing sea states. The Discovery wind stress data is examined for evidence of a sea-state dependence: none is found. It is concluded that a wave-age-dependent wind stress formulation is not applicable to open ocean conditions.
Robert. A. Weller - One of the best experts on this subject based on the ideXlab platform.
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surface meteorology and air sea fluxes in the western equatorial pacific warm pool during the toga coupled ocean atmosphere response experiment
Journal of Climate, 1996Co-Authors: Robert. A. Weller, Steven P. AndersonAbstract:Abstract A major goal of the Coupled Ocean-Atmosphere Response Experiment (COARE) was to achieve significantly more accurate and complete descriptions of the surface meteorology and air-sea fluxes in the western equatorial warm pool region. Time series of near-surface meteorology from a buoy moored near the center of the COARE Intensive Flux Array (IFA) are described here. The accuracies of the measurements and the derived fluxes are quantified; agreement between average net heat fluxes at the buoy and two nearby Research Ships is better than 10 W m−2 during three intercomparisons. Variability in the surface meteorology and fluxes associated with westerly wind bursts, periods of low winds, and short-lived, deep convective events characteristic of the region was large compared to the 4-month means. The ECMWF (European Centre for Medium-Range Weather Forecasts) analysis and prediction fields differed most from the buoy data during periods of short-lived, deep convective events, when several day averages of ...