-------------------------------------------------------------------------------- Tropical Cyclone Heat Potential V2.1 www.aoml.noaa.gov/phod/cyclone -------------------------------------------------------------------------------- Daily maps available online at http://www.aoml.noaa.gov/phod/cyclone/data/gl.html -------------------------------------------------------------------------------- TCHP DATA -------------------------------------------------------------------------------- RT directory contains real-time fields, updated daily with 1-day delayed real-time AVISO SHA gridded fields. Daily resolution. NRT directory contains near real-time fields, updated monthly with 1-month delayed near real-time AVISO SHA gridded fields. Daily resolution. RT directory, contains delayed-time fields, updated monthly with 6-month delayed delayed-time AVISO SHA gridded fields. Weekly resolution. The date of each field is in the file name with name YYYYMMDD. For the weekly fields, the date in the filename corresponds to the Wednesday of the week of data used to produce the AVISO gridded file. The files are ascii with data formated in columns: col# field units range ---------------------------------------- 1 Longitude deg -180/180 2 Latitude deg -40/40 3 TCHP kJ cm^2 4 D26 m -------------------------------------------------------------------------------- How to acknowledge data from NOAA/AOML Tropical Cyclone Heat Potential -------------------------------------------------------------------------------- We would appreciate it if you added the following acknowledgment to any publications that use this data: "The Tropical Cyclone Heat Potential (TCHP) is made freely available by the Atlantic Oceanographic and Meteorological Laboratory (www.aoml.noaa.gov/phod/cyclone) and has been funded by the NASA and NOAA at different stages of the project. The sea surface height and temperature products incorporated in the TCHP are supplied by the CLS Space Oceanography Division, France (www.cls.fr) and Remote Sensing, USA (www.remss.com/tmi/) respectively." The project scientists would also appreciate it if you informed us of any publications or presentations that you prepare using this data. Continued funding of this project depends on us being able to justify to NOAA the usefulness of this data. -------------------------------------------------------------------------------- METHODOLOGY V2.1 -------------------------------------------------------------------------------- Sea surface temperature (SST) provides a measure of the surface ocean conditions, however no information about the subsurface ocean thermal structure (approximately the upper 50 m of the ocean) can be derived from SST alone. For instance, it is known that the oceanic skin temperature erodes when the sea surface is affected by strong winds, creating a well-mixed layer that can reach depths of several tens of meters. Moreover, warm ocean features, mainly anticyclonic rings and eddies, are characterized by a deepening of the isotherms towards their centers with a markedly different temperature and salinity structure than the surrounding waters. Several studies have shown that observations of sea surface height (SSH) are strongly correlated with the thermal structure of the upper ocean (e.g. Goni et al. 1996; Gilson et al. 1998; Mayer et al. 2001; Willis et al. 2004). Based in this virtually ubiquitous relationship, we developed a methodology to estimate fields of isotherm depth from the SHA fields derived from satellite observations. The Tropical Cyclone Heat Potential (TCHP), is defined as a measure of the integrated vertical temperature from the sea surface to the depth of the 26°C isotherm. This parameter is computed globally from the altimeter-derived vertical temperature profiles estimates in the upper ocean (Shay et al., 2000). Different methods have been developed to calculate this vertical thermal structure of the upper ocean. The current methodology (version 2.1) to estimate the TCHP consists of the following steps: * In-situ temperature profiles obtained mostly from eXpendable BathyThermograph and profiling-float observations from 1992 to 2006 are grouped in 3°×3° bins with a 1°×1° resolution. * The depth of the 26°C to 28°C isotherms is estimated from each profile. * The weekly SHA gridded fields derived by AVISO are interpolated into the location and time of the temperature profiles. * In each 1°×1° bin the depth of each isotherm is linearly regressed onto the corresponding SHA value. * Only regression parameters that are statistically significant within a 1-sigma level are considered. Any small gaps in the resulting fields of regression parameters are interpolated. * The regression coefficients are interpolated in a 1/4°×1/4° grid. * A synthetic temperature profile is derived from the regression parameters and the daily real-time SHA fields distributed by AVISO, which have 1/4°×1/4° resolution that allows to identify mesoscale features. * The altimetry-derived synthetic profiles (ASTEP) are completed with global TMI-AMSR-E SST fields for the z = 0 temperature. * The TCHP is compued as the anomalous heat storage associated with temperatures larger than 26°C in each grid-point. The SHA fields are: Merged Ssalto/Duacs Gridded Sea level anomalies (1/3°x1/3° on a Mercator grid) (http://www.aviso.oceanobs.com/en/data/products/sea-surface-height-products/global/index.html) NRT ftp://ftp.cls.fr/pub/oceano/AVISO/SSH/duacs/global/nrt/msla/merged/h/ DT ftp://ftp.cls.fr/pub/oceano/AVISO/SSH/duacs/global/dt/ref/msla/merged/h/ The SST fields are: TMI Sea Surface Temperature (SST) (http://www.remss.com/tmi/tmi_browse.html) RT ftp://ftp.ssmi.com/tmi For technical questions, please contact Joaquin Triananes (joaquin.trinanes@noaa.gov) or Pedro DiNezio (pedro.dinezio@noaa.gov). For scientific questions, contact Gustavo Goni (gustavo.goni@noaa.gov). -------------------------------------------------------------------------------- REFERENCES -------------------------------------------------------------------------------- Gilson, J., D. Roemmich, B. Cornuelle, and L.-L. Fu, Relationship of TOPEX/Poseidon altimetric height to steric height and circulation of the North Pacific, J. Geophys. Res., 103 (27),947.27,965, 1998. Goni, G., S. Kamholz, S. Garzoli, and D. Olson, Dynamics of the Brazil-Malvinas Confluence based on inverted echo sounders and altimetry, J. Geophys. Res., 101(C7), 16,273.16,289, 1996. Goni, G. J., S. L. Garzoli, A. J. Roubicek, D. B. Olson and O. B. Brown. Agulhas ring dynamics from TOPEX/POSEIDON satellite altimeter data, J.Mar. Res., 55, 861-883, 1997. Leipper, D. and D. Volgenau. Hurricane heat potential of the Gulf of Mexico, J. Phys. Oceanogr., 2, 218-224, 1972. Mainelli M., M. DeMaria, L. Shay, and G. Goni, Application of Oceanic Heat Content Estimation to Operational Forecasting of Recent Atlantic Category 5 Hurricanes, Weather Forecast., in press, 2008. Shay L. K., G. J. Goni and P. G. Black. Effect of a warm ocean ring on hurricane Opal. Mon. Weath. Rev., 128, 1366-1383, 2000. Willis, J. K., D. Roemmich, and B. Cornuelle, Interannual variability in upper-ocean heat content, temperature and thermosteric expansion on global scales, J. Geophys. Res., 109 (C12036), 2004.