Numerical Modeling of the Propagation Environment in the Atmospheric Boundary Layer over the Persian Gulf

B. W. Atkinson Department of Geography, Queen Mary and Westfield College, University of London, London, United Kingdom

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J-G. Li Department of Geography, Queen Mary and Westfield College, University of London, London, United Kingdom

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R. S. Plant Department of Geography, Queen Mary and Westfield College, University of London, London, United Kingdom

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Abstract

Strong vertical gradients at the top of the atmospheric boundary layer affect the propagation of electromagnetic waves and can produce radar ducts. A three-dimensional, time-dependent, nonhydrostatic numerical model was used to simulate the propagation environment in the atmosphere over the Persian Gulf when aircraft observations of ducting had been made. A division of the observations into high- and low-wind cases was used as a framework for the simulations. Three sets of simulations were conducted with initial conditions of varying degrees of idealization and were compared with the observations taken in the Ship Antisubmarine Warfare Readiness/Effectiveness Measuring (SHAREM-115) program. The best results occurred with the initialization based on a sounding taken over the coast modified by the inclusion of data on low-level atmospheric conditions over the Gulf waters. The development of moist, cool, stable marine internal boundary layers (MIBL) in air flowing from land over the waters of the Gulf was simulated. The MIBLs were capped by temperature inversions and associated lapses of humidity and refractivity. The low-wind MIBL was shallower and the gradients at its top were sharper than in the high-wind case, in agreement with the observations. Because it is also forced by land–sea contrasts, a sea-breeze circulation frequently occurs in association with the MIBL. The size, location, and internal structure of the sea-breeze circulation were realistically simulated. The gradients of temperature and humidity that bound the MIBL cause perturbations in the refractivity distribution that, in turn, lead to trapping layers and ducts. The existence, location, and surface character of the ducts were well captured. Horizontal variations in duct characteristics due to the sea-breeze circulation were also evident. The simulations successfully distinguished between high- and low-wind occasions, a notable feature of the SHAREM-115 observations. The modeled magnitudes of duct depth and strength, although leaving scope for improvement, were most encouraging.

Corresponding author address: B. W. Atkinson, Dept. of Geography, Queen Mary and Westfield College, University of London, London E1 4NS, United Kingdom.

b.w.atkinson@qmw.ac.uk

Abstract

Strong vertical gradients at the top of the atmospheric boundary layer affect the propagation of electromagnetic waves and can produce radar ducts. A three-dimensional, time-dependent, nonhydrostatic numerical model was used to simulate the propagation environment in the atmosphere over the Persian Gulf when aircraft observations of ducting had been made. A division of the observations into high- and low-wind cases was used as a framework for the simulations. Three sets of simulations were conducted with initial conditions of varying degrees of idealization and were compared with the observations taken in the Ship Antisubmarine Warfare Readiness/Effectiveness Measuring (SHAREM-115) program. The best results occurred with the initialization based on a sounding taken over the coast modified by the inclusion of data on low-level atmospheric conditions over the Gulf waters. The development of moist, cool, stable marine internal boundary layers (MIBL) in air flowing from land over the waters of the Gulf was simulated. The MIBLs were capped by temperature inversions and associated lapses of humidity and refractivity. The low-wind MIBL was shallower and the gradients at its top were sharper than in the high-wind case, in agreement with the observations. Because it is also forced by land–sea contrasts, a sea-breeze circulation frequently occurs in association with the MIBL. The size, location, and internal structure of the sea-breeze circulation were realistically simulated. The gradients of temperature and humidity that bound the MIBL cause perturbations in the refractivity distribution that, in turn, lead to trapping layers and ducts. The existence, location, and surface character of the ducts were well captured. Horizontal variations in duct characteristics due to the sea-breeze circulation were also evident. The simulations successfully distinguished between high- and low-wind occasions, a notable feature of the SHAREM-115 observations. The modeled magnitudes of duct depth and strength, although leaving scope for improvement, were most encouraging.

Corresponding author address: B. W. Atkinson, Dept. of Geography, Queen Mary and Westfield College, University of London, London E1 4NS, United Kingdom.

b.w.atkinson@qmw.ac.uk

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  • André, J. C., and L. Mahrt, 1982: The nocturnal surface inversion and influence of clear-air radiative cooling. J. Atmos. Sci.,39, 864–878.

  • Arritt, R. W., 1993: Effects of the large-scale flow on characteristic features of the sea breeze. J. Appl. Meteor.,32, 116–125.

  • Atkinson, B. W., 1981: Mesoscale Atmospheric Circulations. Academic Press, 495 pp.

  • Atkinson, B. W., 1995: Orographic and stability effects on valley-side drainage flows. Bound.-Layer Meteor.,75, 403–428.

  • Atkinson, B. W., and A. N. Shahub, 1994: Orographic and stability effects on day-time, valley-side slope flows. Bound.-Layer Meteor.,68, 275–300.

  • Babin, S. M., 1995: A case study of subrefractive conditions at Wallops Island, Virginia. J. Appl. Meteor.,34, 1028–1038.

  • Babin, S. M., 1996: Surface duct height distributions for Wallops Island, 1985–1994. J. Appl. Meteor.,35, 86–93.

  • Babin, S. M., and J. R. Rowland, 1992: Observation of a strong surface radar duct using helicopter acquired fine-scale radio refractivity measurements. Geophys. Res. Lett.,19, 917–920.

  • Babin, S. M., G. S. Young, and J. A. Carton, 1997: A new model for the oceanic evaporation duct. J. Appl. Meteor.,36, 193–204.

  • Ballard, S. P., B. W. Golding, and R. N. B. Smith, 1991: Mesoscale model experimental forecasts of the Haar of northeast Scotland. Mon. Wea. Rev.,119, 2107–2123.

  • Barrios, A. E., 1995: Terrain and refractivity effects in a coastal environment. Conf. on Propagation Assessment in Coastal Environment, Bremerhaven, Germany, AGARD/NATO, 9.1–9.5.

  • Bean, B. R., and E. J. Dutton, 1968: Radio Meteorology. Dover, 435 pp.

  • Bechtold, P., J.-P. Pinty, and P. Mascart, 1991: A numerical investigation of the influence of large-scale winds on sea-breeze- and inland-breeze-type circulations. J. Appl. Meteor.,30, 1268–1279.

  • Brooks, I. M., and D. P. Rogers, 2000: Aircraft observations of the mean and turbulent structure of a shallow boundary layer over the Persian Gulf. Bound.-Layer Meteor.,95, 189–210.

  • Brooks, I. M., A. K. Goroch, and D. P. Rogers, 1999: Observations of strong surface radar ducts over the Persian Gulf. J. Appl. Meteor.,38, 1293–1310.

  • Burk, S. D., and W. T. Thompson, 1995: Mesoscale modeling of refractive conditions in a complex coastal environment. Conf. on Propagation Assessment in Coastal Environment, Bremerhaven, Germany, AGARD/NATO, 40.1–40.7.

  • Burk, S. D., and W. T. Thompson, 1997: Mesoscale modeling of summertime refractive conditions in the Southern California Bight. J. Appl. Meteor.,36, 23–31.

  • Carpenter, K. M., 1979: An experimental forecast using a non-hydrostatic mesoscale model. Quart. J. Roy. Meteor. Soc.,105, 629–656.

  • Christophe, F., N. Douchin, Y. Hurtaud, D. Dion, R. Makaruschka, H. Heemskert, and K. Anderson, 1995: Overview of NATO/AC 243/Panel 3 activities concerning radio wave propagation in coastal environments. Conf. on Propagation Assessment in Coastal Environment, Bremerhaven, Germany, AGARD/NATO, 27.1–27.9.

  • Cook, J., G. Vogel, and G. Love, 1995: Operational support for a range-dependent radio propagation model. Conf. on Propagation Assessment in Coastal Environment, Bremerhaven, Germany, AGARD/NATO, 13.1–13.7.

  • Craig, K. H., 1988: Propagation modelling in the troposphere: Parabolic equation method. Electr. Lett.,24, 1136–1139.

  • Craig, K. H., and T. G. Hayton, 1995: Climatic mapping of refractivity parameters from radiosonde data. Conf. on Propagation Assessment in Coastal Environment, Bremerhaven, Germany, AGARD/NATO, 43.1–43.12.

  • Dare, R. A., and B. W. Atkinson, 1999: Numerical modeling of atmospheric response to polynyas in the Southern Ocean sea ice zone. J. Geophys. Res.,104, 16 691–16 708.

  • Dockery, G. D., and J. Goldhirsh, 1995: Atmospheric data resolution requirements for propagation assessment: Case studies of range-dependent coastal environments. Conf. on Propagation Assessment in Coastal Environment, Bremerhaven, Germany, AGARD/NATO, 7.1–7.12.

  • Finkele, K., J. M. Hacker, H. Kraus, and R. A. D. Byron-Scott, 1995:A complete sea-breeze circulation cell derived from aircraft observations. Bound.-Layer Meteor.,73, 299–317.

  • Garratt, J. R., 1990: The internal boundary layer—a review. Bound.-Layer Meteor.,50, 171–203.

  • Garratt, J. R., and B. F. Ryan, 1989: The structure of the stably stratified internal boundary layer in offshore flow over the sea. Bound.-Layer Meteor.,47, 17–40.

  • Golding, B. W., 1987: The U.K. Meteorological Office mesoscale model. Bound.-Layer Meteor.,41, 91–107.

  • Golding, B. W., 1990: The Meteorological Office mesoscale model. Meteor. Mag.,119, 81–96.

  • Levy, M. F., 1995: Fast PE models for mixed environments. Conf. on Propagation Assessment in Coastal Environment, Bremerhaven, Germany, AGARD/NATO, 8.1–8.6.

  • Levy, M. F., and K. H. Craig, 1992: Use of mesoscale models for refractivity forecasting. Conf. on Remote Sensing of the Propagation Environment, Cesme, Turkey, AGARD/NATO, 7.1–7.11.

  • Li, J.-G., and B. W. Atkinson, 1999: Transition regimes in valley airflows. Bound.-Layer Meteor.,91, 385–411.

  • Lystad, S., and T. Tjelta, 1995: High-resolution meteorological grid for clear air propagation modelling in northern coastal regions. Conf. on Propagation Assessment in Coastal Environment, Bremerhaven, Germany, AGARD/NATO, 41.1–41.12.

  • Rogers, D. P., D. W. Johnson, and C. A. Friehe, 1995: The stable internal boundary layer over a coastal sea. Part I: Airborne measurements of the mean and turbulence structure. J. Atmos. Sci.,52, 667–683.

  • Rogers, L. T., 1995: Effects of spatial and temporal variability of atmospheric refractivity on the accuracy of propagation assessments. Conf. on Propagation Assessment in Coastal Environment, Bremerhaven, Germany, AGARD/NATO, 31.1–31.9.

  • Tapp, M. C., and P. W. White, 1976: A non-hydrostatic mesoscale model. Quart. J. Roy. Meteor. Soc.,102, 277–296.

  • Turton, J. D., D. A. Bennetts, and S. F. G. Farmer, 1988: An introduction to radio ducting. Meteor. Mag.117, 245–254.

  • Wu, J., 1982: Wind stress coefficients over sea surface from breeze to hurricane. J. Geophys. Res.87, 277–296.

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