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J L Innis - One of the best experts on this subject based on the ideXlab platform.
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characterization of acoustic gravity waves in the upper thermosphere using dynamics explorer 2 Wind and temperature spectrometer wats and neutral atmosphere composition spectrometer nacs data
Journal of Geophysical Research, 2002Co-Authors: J L Innis, M CondeAbstract:[1] Data obtained by the Neutral Atmosphere Composition Spectrometer (NACS) and the Wind and Temperature Spectrometer (WATS) instruments on Dynamics Explorer 2 (DE 2) show examples of large wave-like events in composition, vertical Wind, and temperature, particularly (perhaps almost exclusively) at high geomagnetic latitudes. These events are believed to arise due to atmospheric gravity waves (AGWs). If so, the various perturbation quantities of mass density, pressure, temperature, Horizontal Wind, and vertical Wind should be related in a manner consistent with the AGW theory. An analysis of a subset of the WATS (vertical and Horizontal Wind and temperature) and NACS data (number density and, hence, mass density) and pressure (as a derived quantity, from number density and temperature) was performed to investigate whether such perturbations could be clearly shown to be due to AGWs by comparing quantitatively the various simultaneous data sets with AGW theory. Seven examples of wave-like events in the vertical Wind were studied, together with the accompanying variations in mass density, pressure, temperature, and Horizontal Wind. The pressure (acoustic) component of the density variation was calculated and then subtracted from the total density variation, allowing the wave-induced vertical displacement amplitude to be found. This was compared to the vertical Wind amplitude, via a spectral analysis, to yield estimates of the possible AGW frequency. The observed variation in the ratio of O/N2 number densities during the course of the oscillations was found to be consistent with the calculated altitude displacements. Phase lags in the number density perturbations between different species also appeared consistent with the AGW theory. Horizontal velocity perturbations in phase with the pressure perturbations were also seen. It is concluded that the oscillations are consistent with acoustic–gravity waves, where the pressure perturbation is nonnegligible. Phase relationships between the various observables can define the direction of wave travel to within 90° of azimuth, relative to the direction of spacecraft motion. For the seven cases detailed here, the derived (intrinsic) wave frequencies are close to, but slightly less than, the estimated local Brunt–Vaisala frequency, while the vertical displacement amplitudes were typically around ±25 km. All of the wave events studied in this work were located at high latitudes, poleward of the nominal location of the auroral oval.
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characterization of acoustic gravity waves in the upper thermosphere using dynamics explorer 2 Wind and temperature spectrometer wats and neutral atmosphere composition spectrometer nacs data
Journal of Geophysical Research, 2002Co-Authors: J L Innis, M CondeAbstract:[1] Data obtained by the Neutral Atmosphere Composition Spectrometer (NACS) and the Wind and Temperature Spectrometer (WATS) instruments on Dynamics Explorer 2 (DE 2) show examples of large wave-like events in composition, vertical Wind, and temperature, particularly (perhaps almost exclusively) at high geomagnetic latitudes. These events are believed to arise due to atmospheric gravity waves (AGWs). If so, the various perturbation quantities of mass density, pressure, temperature, Horizontal Wind, and vertical Wind should be related in a manner consistent with the AGW theory. An analysis of a subset of the WATS (vertical and Horizontal Wind and temperature) and NACS data (number density and, hence, mass density) and pressure (as a derived quantity, from number density and temperature) was performed to investigate whether such perturbations could be clearly shown to be due to AGWs by comparing quantitatively the various simultaneous data sets with AGW theory. Seven examples of wave-like events in the vertical Wind were studied, together with the accompanying variations in mass density, pressure, temperature, and Horizontal Wind. The pressure (acoustic) component of the density variation was calculated and then subtracted from the total density variation, allowing the wave-induced vertical displacement amplitude to be found. This was compared to the vertical Wind amplitude, via a spectral analysis, to yield estimates of the possible AGW frequency. The observed variation in the ratio of O/N2 number densities during the course of the oscillations was found to be consistent with the calculated altitude displacements. Phase lags in the number density perturbations between different species also appeared consistent with the AGW theory. Horizontal velocity perturbations in phase with the pressure perturbations were also seen. It is concluded that the oscillations are consistent with acoustic–gravity waves, where the pressure perturbation is nonnegligible. Phase relationships between the various observables can define the direction of wave travel to within 90° of azimuth, relative to the direction of spacecraft motion. For the seven cases detailed here, the derived (intrinsic) wave frequencies are close to, but slightly less than, the estimated local Brunt–Vaisala frequency, while the vertical displacement amplitudes were typically around ±25 km. All of the wave events studied in this work were located at high latitudes, poleward of the nominal location of the auroral oval.
M Conde - One of the best experts on this subject based on the ideXlab platform.
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an update to the Horizontal Wind model hwm the quiet time thermosphere
Earth and Space Science, 2015Co-Authors: D P Drob, M Conde, G. Hernandez, Jonathan J. Makela, John Noto, John T Emmert, J W Meriwether, Eelco Doornbos, K A Zawdie, S E McdonaldAbstract:The Horizontal Wind Model (HWM) has been updated in the thermosphere with new observations and formulation changes. These new data are ground-based 630 nm Fabry-Perot Interferometer (FPI) measurements in the equatorial and polar regions, as well as cross-track Winds from the Gravity Field and Steady State Ocean Circulation Explorer (GOCE) satellite. The GOCE Wind observations provide valuable Wind data in the twilight regions. The ground-based FPI measurements fill latitudinal data gaps in the prior observational database. Construction of this reference model also provides the opportunity to compare these new measurements. The resulting update (HWM14) provides an improved time-dependent, observationally based, global empirical specification of the upper atmospheric general circulation patterns and migrating tides. In basic agreement with existing accepted theoretical knowledge of the thermosphere general circulation, additional calculations indicate that the empirical Wind specifications are self-consistent with climatological ionosphere plasma distribution and electric field patterns.
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characterization of acoustic gravity waves in the upper thermosphere using dynamics explorer 2 Wind and temperature spectrometer wats and neutral atmosphere composition spectrometer nacs data
Journal of Geophysical Research, 2002Co-Authors: J L Innis, M CondeAbstract:[1] Data obtained by the Neutral Atmosphere Composition Spectrometer (NACS) and the Wind and Temperature Spectrometer (WATS) instruments on Dynamics Explorer 2 (DE 2) show examples of large wave-like events in composition, vertical Wind, and temperature, particularly (perhaps almost exclusively) at high geomagnetic latitudes. These events are believed to arise due to atmospheric gravity waves (AGWs). If so, the various perturbation quantities of mass density, pressure, temperature, Horizontal Wind, and vertical Wind should be related in a manner consistent with the AGW theory. An analysis of a subset of the WATS (vertical and Horizontal Wind and temperature) and NACS data (number density and, hence, mass density) and pressure (as a derived quantity, from number density and temperature) was performed to investigate whether such perturbations could be clearly shown to be due to AGWs by comparing quantitatively the various simultaneous data sets with AGW theory. Seven examples of wave-like events in the vertical Wind were studied, together with the accompanying variations in mass density, pressure, temperature, and Horizontal Wind. The pressure (acoustic) component of the density variation was calculated and then subtracted from the total density variation, allowing the wave-induced vertical displacement amplitude to be found. This was compared to the vertical Wind amplitude, via a spectral analysis, to yield estimates of the possible AGW frequency. The observed variation in the ratio of O/N2 number densities during the course of the oscillations was found to be consistent with the calculated altitude displacements. Phase lags in the number density perturbations between different species also appeared consistent with the AGW theory. Horizontal velocity perturbations in phase with the pressure perturbations were also seen. It is concluded that the oscillations are consistent with acoustic–gravity waves, where the pressure perturbation is nonnegligible. Phase relationships between the various observables can define the direction of wave travel to within 90° of azimuth, relative to the direction of spacecraft motion. For the seven cases detailed here, the derived (intrinsic) wave frequencies are close to, but slightly less than, the estimated local Brunt–Vaisala frequency, while the vertical displacement amplitudes were typically around ±25 km. All of the wave events studied in this work were located at high latitudes, poleward of the nominal location of the auroral oval.
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characterization of acoustic gravity waves in the upper thermosphere using dynamics explorer 2 Wind and temperature spectrometer wats and neutral atmosphere composition spectrometer nacs data
Journal of Geophysical Research, 2002Co-Authors: J L Innis, M CondeAbstract:[1] Data obtained by the Neutral Atmosphere Composition Spectrometer (NACS) and the Wind and Temperature Spectrometer (WATS) instruments on Dynamics Explorer 2 (DE 2) show examples of large wave-like events in composition, vertical Wind, and temperature, particularly (perhaps almost exclusively) at high geomagnetic latitudes. These events are believed to arise due to atmospheric gravity waves (AGWs). If so, the various perturbation quantities of mass density, pressure, temperature, Horizontal Wind, and vertical Wind should be related in a manner consistent with the AGW theory. An analysis of a subset of the WATS (vertical and Horizontal Wind and temperature) and NACS data (number density and, hence, mass density) and pressure (as a derived quantity, from number density and temperature) was performed to investigate whether such perturbations could be clearly shown to be due to AGWs by comparing quantitatively the various simultaneous data sets with AGW theory. Seven examples of wave-like events in the vertical Wind were studied, together with the accompanying variations in mass density, pressure, temperature, and Horizontal Wind. The pressure (acoustic) component of the density variation was calculated and then subtracted from the total density variation, allowing the wave-induced vertical displacement amplitude to be found. This was compared to the vertical Wind amplitude, via a spectral analysis, to yield estimates of the possible AGW frequency. The observed variation in the ratio of O/N2 number densities during the course of the oscillations was found to be consistent with the calculated altitude displacements. Phase lags in the number density perturbations between different species also appeared consistent with the AGW theory. Horizontal velocity perturbations in phase with the pressure perturbations were also seen. It is concluded that the oscillations are consistent with acoustic–gravity waves, where the pressure perturbation is nonnegligible. Phase relationships between the various observables can define the direction of wave travel to within 90° of azimuth, relative to the direction of spacecraft motion. For the seven cases detailed here, the derived (intrinsic) wave frequencies are close to, but slightly less than, the estimated local Brunt–Vaisala frequency, while the vertical displacement amplitudes were typically around ±25 km. All of the wave events studied in this work were located at high latitudes, poleward of the nominal location of the auroral oval.
Robert B Hurst - One of the best experts on this subject based on the ideXlab platform.
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level crossing statistics of the Horizontal Wind speed in the planetary surface boundary layer
Chaos, 2001Co-Authors: Paul J Edwards, Robert B HurstAbstract:The probability density of the times for which the Horizontal Wind remains above or below a given threshold speed is of some interest in the fields of renewable energy generation and pollutant dispersal. However there appear to be no analytic or conceptual models which account for the observed power law form of the distribution of these episode lengths over a range of over three decades, from a few tens of seconds to a day or more. We reanalyze high resolution Wind data and demonstrate the fractal character of the point process generated by the Wind speed level crossings. We simulate the fluctuating Wind speed by a Markov process which approximates the characteristics of the real (non-Markovian) Wind and successfully generates a power law distribution of episode lengths. However, fundamental questions concerning the physical basis for this behavior and the connection between the properties of a continuous-time stochastic process and the fractal statistics of the point process generated by its level crossi...
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level crossing statistics of the Horizontal Wind speed in the planetary surface boundary layer
Chaos, 2001Co-Authors: Paul J Edwards, Robert B HurstAbstract:The probability density of the times for which the Horizontal Wind remains above or below a given threshold speed is of some interest in the fields of renewable energygeneration and pollutant dispersal. However there appear to be no analytic or conceptual models which account for the observed power law form of the distribution of these episode lengths over a range of over three decades, from a few tens of seconds to a day or more. We reanalyze high resolution Wind data and demonstrate the fractal character of the point process generated by the Wind speed level crossings. We simulate the fluctuating Wind speed by a Markov process which approximates the characteristics of the real (non-Markovian) Wind and successfully generates a power law distribution of episode lengths. However, fundamental questions concerning the physical basis for this behavior and the connection between the properties of a continuous-time stochastic process and the fractal statistics of the point process generated by its level crossings remain unanswered.
Schmale Julia - One of the best experts on this subject based on the ideXlab platform.
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One-minute average Horizontal Wind velocity data (which has been corrected for air-flow distortion) from the Antarctic Circumnavigation Expedition (ACE) 2016/2017 legs 0 to 4
2021Co-Authors: Landwehr Sebastian, Thomas Jenny, Schmale JuliaAbstract:Dataset abstract One-minute average Horizontal Wind velocity data from the Antarctic Circumnavigation Expedition (ACE) 2016/2017 legs 0 to 4. The data has been filtered for spurious observations and the true Wind correction has been redone using the quality checked one-minute ship track velocity data. The data has been corrected for air-flow distortion, which was caused by the ship's super structure. Dataset contents Wind-observations-stbd-corrected-1min-legs0-4.csv, data file, comma-separated values Wind-observations-port-corrected-1min-legs0-4.csv, data file, comma-separated values data_file_header, metadata, text format README.txt, metadata, text format Dataset license This one-minute averaged Wind velocity dataset is made available under the Creative Commons Attribution 4.0 International License (CC BY 4.0) whose full text can be found at https://creativecommons.org/licenses/by/4.0/ The Antarctic Circumnavigation Expedition was made possible by funding from the Swiss Polar Institute and Ferring Pharmaceuticals. SL received funding from the Swiss Data Science Center project c17-02. {"references": ["Landwehr, S., Thurnherr, I., Cassar, N., Gysel-Beer, M., and Schmale, J.: Using global reanalysis data to quantify and correct airflow distortion bias in shipborne Wind speed measurements, Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2019-366", "Smith, Shawn R., Mark A. Bourassa, and Ryan J. Sharp. 'Establishing More Truth in True Winds'. Journal of Atmospheric and Oceanic Technology 16 (1999): 14", "Python Software Foundation. Python Language Reference, version 3.7.3. Available at https://www.python.org"]
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One-minute average Horizontal Wind velocity data (not corrected for air-flow distortion) from the Antarctic Circumnavigation Expedition (ACE) 2016/2017 legs 0 to 4
2021Co-Authors: Landwehr Sebastian, Thomas Jenny, Schmale JuliaAbstract:Dataset abstract This dataset contains the one-minute average Horizontal Wind velocity data from the Antarctic Circumnavigation Expedition (ACE) 2016/2017 legs 0 to 4. The data has been filtered for spurious observations and the true Wind correction has been redone using the quality checked one-minute ship track velocity data. This data set has not been corrected for air-flow distortion, which was caused by the ship's super structure. The flow-distortion corrected data should be used for studies interested in the actual true Wind speed near the ship's location. Dataset contents Wind-observations-stbd-uncorrected-5min-legs0-4.csv, data file, comma-separated values Wind-observations-port-uncorrected-5min-legs0-4.csv, data file, comma-separated values data_file_header, metadata, text format README.txt, metadata, text format Dataset license This one-minute averaged Wind velocity dataset is made available under the Creative Commons Attribution 4.0 International License (CC BY 4.0) whose full text can be found at https://creativecommons.org/licenses/by/4.0/ The Antarctic Circumnavigation Expedition was made possible by funding from the Swiss Polar Institute and Ferring Pharmaceuticals. SL received funding from the Swiss Data Science Center project c17-02. {"references": ["Landwehr, S., Thurnherr, I., Cassar, N., Gysel-Beer, M., and Schmale, J.: Using global reanalysis data to quantify and correct airflow distortion bias in shipborne Wind speed measurements, Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2019-366", "Smith, Shawn R., Mark A. Bourassa, and Ryan J. Sharp. 'Establishing More Truth in True Winds'. Journal of Atmospheric and Oceanic Technology 16 (1999): 14", "Python Software Foundation. Python Language Reference, version 3.7.3. Available at https://www.python.org"]
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Five-minute average Horizontal Wind velocity data combined from both sensors (which has been corrected for air-flow distortion) from the Antarctic Circumnavigation Expedition (ACE) 2016/2017 legs 0 to 4
2021Co-Authors: Landwehr Sebastian, Thomas Jenny, Schmale JuliaAbstract:Dataset abstract The Horizontal Wind velocity data from the Antarctic Circumnavigation Expedition (ACE) 2016/2017 legs 0 to 4 has been corrected for air-flow distortion. The measurements from both the port and starboad side anemometer were averaged to five-minute resolution and have been combined via vector averaging of the data. The ten meter neutral Wind speed (U10N) has been estimated using ERA-5 surface heat fluxes, which were interpolated onto the ship's track, and the COARE 3.5 drag coefficient. This data set provides a continous and high-resolution record of the Wind speed and direction near to the ship's location. Dataset contents Wind-observations-port-stbd-corrected-combined-5min-legs0-4.csv, data file, comma-separated values data_file_header, metadata, text format README.txt, metadata, text format Dataset license This five-minute averaged Wind velocity dataset is made available under the Creative Commons Attribution 4.0 International License (CC BY 4.0) whose full text can be found at https://creativecommons.org/licenses/by/4.0/ The Antarctic Circumnavigation Expedition was made possible by funding from the Swiss Polar Institute and Ferring Pharmaceuticals. SL received funding from the Swiss Data Science Center project c17-02. {"references": ["Landwehr, S., Thurnherr, I., Cassar, N., Gysel-Beer, M., and Schmale, J.: Using global reanalysis data to quantify and correct airflow distortion bias in shipborne Wind speed measurements, Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2019-366", "Smith, Shawn R., Mark A. Bourassa, and Ryan J. Sharp. 'Establishing More Truth in True Winds'. Journal of Atmospheric and Oceanic Technology 16 (1999): 14", "Python Software Foundation. Python Language Reference, version 3.7.3. Available at https://www.python.org"]
Paul J Edwards - One of the best experts on this subject based on the ideXlab platform.
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level crossing statistics of the Horizontal Wind speed in the planetary surface boundary layer
Chaos, 2001Co-Authors: Paul J Edwards, Robert B HurstAbstract:The probability density of the times for which the Horizontal Wind remains above or below a given threshold speed is of some interest in the fields of renewable energy generation and pollutant dispersal. However there appear to be no analytic or conceptual models which account for the observed power law form of the distribution of these episode lengths over a range of over three decades, from a few tens of seconds to a day or more. We reanalyze high resolution Wind data and demonstrate the fractal character of the point process generated by the Wind speed level crossings. We simulate the fluctuating Wind speed by a Markov process which approximates the characteristics of the real (non-Markovian) Wind and successfully generates a power law distribution of episode lengths. However, fundamental questions concerning the physical basis for this behavior and the connection between the properties of a continuous-time stochastic process and the fractal statistics of the point process generated by its level crossi...
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level crossing statistics of the Horizontal Wind speed in the planetary surface boundary layer
Chaos, 2001Co-Authors: Paul J Edwards, Robert B HurstAbstract:The probability density of the times for which the Horizontal Wind remains above or below a given threshold speed is of some interest in the fields of renewable energygeneration and pollutant dispersal. However there appear to be no analytic or conceptual models which account for the observed power law form of the distribution of these episode lengths over a range of over three decades, from a few tens of seconds to a day or more. We reanalyze high resolution Wind data and demonstrate the fractal character of the point process generated by the Wind speed level crossings. We simulate the fluctuating Wind speed by a Markov process which approximates the characteristics of the real (non-Markovian) Wind and successfully generates a power law distribution of episode lengths. However, fundamental questions concerning the physical basis for this behavior and the connection between the properties of a continuous-time stochastic process and the fractal statistics of the point process generated by its level crossings remain unanswered.