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Original Research Papers

Vapor flux associated with return flow over the Gulf of Mexico: a sensitivity study using adjoint modeling

Authors:

J. M. Lewis ,

National Severe Storms Laboratory, Norman, OK, 73069, and Desert Research Institute, Reno, NV, US
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K. D. Raeder,

National Center for Atmospheric Research, Boulder, Colorado, 80305, US
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R. M. Errico

National Center for Atmospheric Research, Boulder, Colorado, 80305, US
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Abstract

The moisture flux associated with a return-flow event in the Gulf of Mexico is studied with the aid of a regional forecast model and its adjoint. The adjoint model allows us to determine the derivatives of some aspect of the model output (a scalar, J) with respect to elements of the control vector (initial and boundary conditions). We choose J to be the northward moisture flux through a vertical cross section in the northwestern corner of the Gulf at the time when the moisture surge in the US is a maximum. The sensitivities (VJ) are used in conjunction with a set of optimal perturbations to estimate the impact of each of the perturbations on the moisture flux. The perturbations are chosen to have the structure of the sensitivities (making them optimal as described in the text), with magnitudes based on the (assumed) uncertainties in the model’s initial and boundary conditions. The linear impact estimate is simply the projection of the perturbation onto the sensitivity fields. In complementary fashion, we introduce perturbations into the nonlinear forecast model and decompose the actual impact on J into thermodynamic and dynamic components, in order to better understand the nature of the sensitivity. From this numerical experiment we conclude the following. J is more sensitive to the temperature field than to the other prognostic variables, roughly by a factor of 3 or 4, based on the optimal perturbations used here. The sensitivity to each of the 3-D prognostic variables peaks in the lower atmosphere near 85 kPa. The sensitivity of J to the sea surface temperature (Ts, a fixed boundary condition) increases with forecast length. More than 30 h before the verification time, the impact of an optimal perturbation to Ts is comparable to the impact of an optimal perturbation to the whole 3-D air temperature field. The zones of sensitivity to the Ts are intimately tied to the trajectories of low-level air which terminate at the cross section. The impact of an optimal perturbation to the topography along the Sierra Madre Oriental mountains is comparable to the impact of optimal perturbations in each of the 3-Dprognostic variables (except T ).

How to Cite: Lewis, J.M., Raeder, K.D. and Errico, R.M., 2001. Vapor flux associated with return flow over the Gulf of Mexico: a sensitivity study using adjoint modeling. Tellus A: Dynamic Meteorology and Oceanography, 53(1), pp.74–93. DOI: http://doi.org/10.3402/tellusa.v53i1.12177
  Published on 01 Jan 2001
 Accepted on 17 May 2000            Submitted on 23 Jun 1999

References

  1. Anthes , R. A. , Hsie , E-Y. and Kuo , Y.-H . 1987 . Descrip-tion of the Penn StateINCAR Mesoscale model version 4 (MM4). NCAR Technical Note, NCAR/TN-282 + STR , 66 pp. ( Available from the National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307, USA ).  

  2. Arakawa , A. and Lamb , V. R . 1977 . Computational design of the basic dynamical processes of the UCLA general circulation model . Methods in Computational Physics 17 ( Julius Chang , ed.). Academic Press , pp. 174 – 264 .  

  3. Asselin , R . 1972 . Frequency filter for time integration. Mon. Wea. Re v . 100 , 487 – 490 .  

  4. Bourke , W. and McGregor , J. L . 1983 . A nonlinear ver-tical mode initialization scheme for a limited area prediction model. Mon. Wea. Rev. 111 , 2285 - 2297. Davies , H. C. and Turner , R. E. 1977. Updating predic-tion models by dynamical relaxation: An examination of the technique . Quart. J. Roy. Meteor. Soc . 103 , 225 – 245 .  

  5. Deardorff , J. W . 1972 . Parameterization of the planetary boundary layer for use in general circulation models. Mon. Wea. Re v . 100 , 93 – 106 .  

  6. Djuric , D. and Ladwig , D . 1983 . Southerly low-level jets in the winter cyclones of the Southwestern Great Plains. Mon. Wea. Re v . 111 , 2275 – 2281 .  

  7. Errico , R. and Raeder , K . 1999 . An examination of the accuracy of the linearization of a mesoscale model with moist physics . Quart. J. Roy. Meteor. Soc . 125 , 169 – 195 .  

  8. Errico , R . 1997 . What is an adjoint model? Bull. Amer. Meteor. Soc . 78 , 2577 – 2591 .  

  9. Errico , R. , Vukicevic , T. and Raeder , K . 1993 : Examina-tion of the accuracy of a tangent linear model . Tellus 45A , 462 – 497 .  

  10. Errico , R. and Vukicevic , T . 1992 : Sensitivity analysis using an adjoint of the PSU-NCAR mesoscale model . Mon. Wea. Rev . 120 , 1644 – 1660 .  

  11. Hack , J. J. , Boville , B. A. Briegleb , B. A. , Kiehl , J. T. , Rasch , P. J. and Williamson , D. L. 1993 . Description of the NCAR Community Climate Model (CCM2). NCAR Technical Note, NCAR/TN-382 + STR , 160 pp. ( Available from NCAR, PO Box 3000, Boul-der, CO 80307-3000, USA ).  

  12. Hall , M. , Cacuci , D. and Schlesinger , M. 1982 . Sensitivity analysis of a radiative convective model by the adjoint method. J. Atmos. Sci . 39 , 2050 – 2083.  

  13. Janish , P. and Lyons , S . 1992 . NGM performance during cold-air outbreaks and periods of return flow over the Gulf of Mexico with emphasis on moisture field evolu-tion . J. Appl. Meteor . 31 , 995 – 1017 .  

  14. J. Applied Meteorology , 1992 . Air—Sea Interaction and Airmass Modification over the Gulf of Mexico (Special Issue) . J. Appl. Meteor . 31 , 819 – 1017 .  

  15. Kiehl , J. T. , Hack , J. J. , Bonan , G. B. , Boville , B. A. , Briegleb , B. A. , Williamson , D. L. and Rasch , P. J. 1996 . Description of the NCAR Community Climate Model (CCM3) . NCAR Technical Note, NCAR/TN-420 + STR, 160pp. (Available from NCAR, PO Box 3000, Boulder, CO 80307-3000, USA).  

  16. Langland , R. H. , Elsberry , R. L. and Errico , R. M . 1995 . Evaluation of physical processes in an idealized extra-tropical cyclone using adjoint sensitivity . Quart. J. Roy. Meteor. Soc . 121 , 1349 – 1386 .  

  17. Lewis , J. , Martin , W. and Guinasso , N . 1997 . Bowen ratio estimates in return flow over the Gulf of Mexico . J. of Geophys. Res . 102 , 10535 – 10544 .  

  18. Lewis , J. and Crisp , C . 1992 . Return flow in the Gulf of Mexico. Part II: variability in return-flow thermodyn-amics inferred from trajectories over the Gulf . J. Appl. Meteor . 31 , 882 – 898 .  

  19. Lewis , J. , Hayden , C. , Merrill , R. and Schneider , J . 1989 : GUFMEX: a study of return flow in the Gulf of Mexico . Bull. Amer. Meteor. Soc . 70 , 24 – 29 .  

  20. Madala , R. V . 1981 . Efficient time integration schemes for atmosphere and ocean models. Finite-difference techniques for vectorized fluid dynamics calculations , D. L. Book , Ed., Springer , pp. 56 - 74 .  

  21. Merrill , R . 1992 . Synoptic analysis of the GUFMEX return-flow event of 10-12 March 1988 . J. Appl. Meteor . 31 , 849 – 867 .  

  22. Moorthi , S. and Suarez , M. J . 1992 . Relaxed Arakawa—Schubert: a parameterization of moist convection for general circulation models . Mon. Wea. Rev . 120 , 978 – 1002 .  

  23. Reynolds , R. W. and Smith , T. S . 1994 . Improved global sea surface temperature analyses . J. Climate 7 , 929 – 948 .  

  24. Weiss , S . 1992 . Some aspects of forecasting severe thun-derstorms during cool-season return-flow episodes . J. Appl. Meteor . 31 , 964 – 982 .  

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