TITLE

Improving Ocean Model Initialization for Coupled Tropical Cyclone Forecast Models Using GODAE Nowcasts

AUTHOR(S)
Halliwell Jr., G. R.; Shay, L. K.; Jacob, S. D.; Smedstad, O. M.; Uhlhorn, E. W.
PUB. DATE
July 2008
SOURCE
Monthly Weather Review;Jul2008, Vol. 136 Issue 7, p2576
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
To simulate tropical cyclone (TC) intensification, coupled ocean–atmosphere prediction models must realistically reproduce the magnitude and pattern of storm-forced sea surface temperature (SST) cooling. The potential for the ocean to support intensification depends on the thermal energy available to the storm, which in turn depends on both the temperature and thickness of the upper-ocean warm layer. The ocean heat content (OHC) is used as an index of this potential. Large differences in available thermal energy associated with energetic boundary currents and ocean eddies require their accurate initialization in ocean models. Two generations of the experimental U.S. Navy ocean nowcast–forecast system based on the Hybrid Coordinate Ocean Model (HYCOM) are evaluated for this purpose in the NW Caribbean Sea and Gulf of Mexico prior to Hurricanes Isidore and Lili (2002), Ivan (2004), and Katrina (2005). Evaluations are conducted by comparison to in situ measurements, the navy’s three-dimensional Modular Ocean Data Assimilation System (MODAS) temperature and salinity analyses, microwave satellite SST, and fields of OHC and 26°C isotherm depth derived from satellite altimetry. Both nowcast–forecast systems represent the position of important oceanographic features with reasonable accuracy. Initial fields provided by the first-generation product had a large upper-ocean cold bias because the nowcast was initialized from a biased older-model run. SST response in a free-running Isidore simulation is improved by using initial and boundary fields with reduced cold bias generated from a HYCOM nowcast that relaxed model fields to MODAS analyses. A new climatological initialization procedure used for the second-generation nowcast system tended to reduce the cold bias, but the nowcast still could not adequately reproduce anomalously warm conditions present before all storms within the first few months following nowcast initialization. The initial cold biases in both nowcast products tended to decrease with time. A realistic free-running HYCOM simulation of the ocean response to Ivan illustrates the critical importance of correctly initializing both warm-core rings and cold-core eddies to correctly simulate the magnitude and pattern of SST cooling.
ACCESSION #
33327951

 

Related Articles

  • Below-Average Hurricane Season Predicted For Atlantic Basin. Wilmsen, Emily Narvaes // Beef Expert Blog;5/17/2012, p6 

    A weather forecast is presented for the Atlantic basin hurricane season in 2012.

  • Medium-Range Prediction of an Extratropical Oceanic Cyclone: Impact of Initial State. Zou, X.; Kuo, Y. -H.; Low-Nam, S. // Monthly Weather Review;Nov98, Vol. 126 Issue 11, p2737 

    Significant progress has been made in the short-range (1--2 days) prediction of east coast cyclogenesis over the past decade. This is the result of improved model resolution, physical parameterization, and good analysis of the upstream conditions often well sampled by the high-density North...

  • Tropical Cyclone Formation in Environments with Cool SST and High Wind Shear over the Northeastern Atlantic Ocean. MAUK, RACHEL G.; HOBGOOD, JAY S. // Weather & Forecasting;Dec2012, Vol. 27 Issue 6, p1433 

    Tropical cyclones with nontropical characteristics are being identified more frequently over the North Atlantic Ocean in recent years. These systems present forecasting challenges because of their hybrid struc-ture. The authors analyze environmental conditions preceding the formation of 20...

  • Sensitivity of different convective parameterization schemes on tropical cyclone prediction using a mesoscale model. Mohandas, Saji; Ashrit, Raghavendra // Natural Hazards;Sep2014, Vol. 73 Issue 2, p213 

    This study presents an intercomparison of four cumulus parameterization schemes (CPS) in the prediction of three cases of tropical cyclones in the north Indian Ocean. The study makes use of the Weather Research and Forecasting model of Non-hydrostatic Mesoscale Model version with a horizontal...

  • Hindcast of the Hércules winter storm in the North Atlantic. Ponce de León, Sonia; Guedes Soares, C. // Natural Hazards;Sep2015, Vol. 78 Issue 3, p1883 

    The study describes the Hércules storm hindcast performed with the WAM model during one of the major cyclones that occurred in the North Atlantic in the last several years. A description of the development of a peculiar winter season in which a number of consecutive storms took place severely...

  • Comments on `The Meandering Nature of Tropical Cyclone Tracks'. Khandekar, M.L. // Journal of the Atmospheric Sciences;1/15/95, Vol. 52 Issue 2, p286 

    Argues that the oscillatory movement in tropical cyclone tracks could be forecast using the concept of a tilted or sloping vortex. Why the concept of tilted vortex is superior to explanations based on the theories of Yeh (1950), Kuo (1969), Syono (1955) and Futi (1956); Importance of the...

  • Reply. Holland, Greg J.; Wang, Yuqing // Journal of the Atmospheric Sciences;1/15/95, Vol. 52 Issue 2, p289 

    Rebuts the contention of Khandekar (1994) that typhoon meandering can be explained by self-interaction of a tilted vortex. Factors affecting typhoon meandering; Mesoscale convective system.

  • Performance of the Navy's Tropical Cyclone Prediction Model in the Western North Pacific Basin during 1996. Rennick, M.A. // Weather & Forecasting;Jun99, Vol. 14 Issue 3, p297 

    The U.S. Navy's operational implementation of the hurricane prediction system developed at the National Oceanographic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory is described, and the performance of the model during the 1996 western North Pacific tropical cyclone...

  • The Joint Hurricane Test Bed: Its First Decade of Tropical Cyclone Research-To-Operations Activities Reviewed. Rappaport, Edward N.; Jiing, Jiann-Gwo; Landsea, Christopher W.; Murillo, Shirley T.; Franklin, James L. // Bulletin of the American Meteorological Society;Mar2012, Vol. 93 Issue 3, p371 

    The Joint Hurricane Testbed (JHT) is reviewed at the completion of its first decade. Views of the program by hurricane forecasters at the National Hurricane Center, the test bed's impact on forecast accuracy, and highlights of the top-rated projects are presented. Key concerns encountered by the...

Share

Read the Article

Courtesy of THE LIBRARY OF VIRGINIA

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics