1 | TROPFLUX DATA README |
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2 | ==================== |
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3 | |
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4 | Complete information about the TropFlux project and data can be found at: |
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5 | http://www.locean-ipsl.upmc.fr/tropflux/ |
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6 | |
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7 | Short description of TropFlux |
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8 | ----------------------------- |
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9 | |
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10 | The TropFlux project aims at providing daily, timely, accurate air-sea heat and momentum flux data for the entire 30°N-30°S region. Wind stresses and the four components of net surface heat flux are currently available for the entire 1979 to September 2011 period. We are currently working on a regular (~monthly) update of the TropFlux product until 3-4 months behind realtime, which should be available in 2012. |
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12 | TropFlux is largely derived from a combination of ERA-I re-analysis data for turbulent and longwave fluxes, and ISCCP surface radiation data for shortwave flux. All input products are bias- and amplitude-corrected on the basis of Global Tropical Moored Buoy Array data, before surface net heat flux and wind stresses are computed using the COARE v3 bulk algorithm. A precise description of the flux computation procedure, as well as a detailed evaluation against other timely, daily air-sea heat flux alternatives (OAFLUX, NCEP, NCEP2, ERA-I) is provided in Praveen Kumar et al. 2011. The wind stress product is described, evaluated and compared against other widely used products (QuikSCAT, NCEP, NCEP2, ERA-I) in Praveen Kumar et al. submitted |
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14 | We believe that this product offers the following advantages: |
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15 | |
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16 | - better variability and less biases than re-analysis fluxes (and equivalent or slightly better than the best performing products: OAFLUX for heat fluxes and ERA-I for wind stresses) , |
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17 | - available until Septempber 2011, and soon updated every month, lagging realtime by ~3 months, |
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18 | - a simple estimate of surface shortwave radiation is provided from OLR data, as a near-realtime alternative to the more accurate but irregularly updated ISCCP data. |
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20 | The TropFlux product has been developed under a collaboration between the Laboratoire d'Océanographie: Expérimentation et Approches Numériques (LOCEAN) from Institut Pierre Simon Laplace, France and National Institute of Oceanography/CSIR, India. Bilateral scientific visits to France and India have been supported by Institut de Recherche pour le Développement, France. |
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21 | |
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22 | Data format |
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23 | ----------- |
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24 | |
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25 | The following variables are provided: |
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26 | |
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27 | - surface net short wave radiation (swr, W/m^2, positive downward) |
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28 | - surface net longwave radiation (lwr, W/m^2, positive downward) |
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29 | - latent heat flux (lhf, W/m^2, positive downward) |
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30 | - sensible heat flux (shf, W/m^2, positive downward) |
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31 | - net air-sea flux (netflux, W/m^2, positive downward) |
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32 | - zonal wind stress (taux, N/m^2, positive eastward) |
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33 | - meridional wind stress (tauy, N/m^2, positive eastward) |
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34 | - wind stress module (tau, N/m^2, positive) |
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35 | - wind module at 10m height (ws, m/s, positive) |
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36 | - Specific humidity at 2m height (q2m, g/kg, positive) |
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37 | - Air temperature at 2m height (t2m, degC) |
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38 | - Bulk sea surface temperature (sst, degC) |
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39 | |
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40 | The data is provided in netcdf format, with one file per variable for the complete dataset. |
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41 | Daily (almost 1Gb per file) and monthly (32Mb per file) average data are proposed. |
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42 | The data is provided on a 1° resolution grid (with the same land-sea mask than for the OAFLUX project, http://oaflux.whoi.edu/ ). |
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43 | There are 60 points in latidude at -29.5, -28.5, ..., 28.5 (positive north of the equator). |
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44 | There are 350 points in longitude at 30.5, 31.5, ..., 379.5 (eastward of the Greenwhich meridian). |
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45 | This choice on longitude has been made: to avoid including points with only land (in central Africa)and to avoid cutting through a tropical ocean. |
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46 | |
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47 | References |
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48 | ---------- |
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49 | |
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50 | Praveen Kumar, B., J. Vialard, M. Lengaigne, V. S. N. Murty, M. J. McPhaden, 2011: TropFlux: Air-Sea Fluxes for the Global Tropical Oceans - Description and evaluation, Climate Dynamics, on line, doi:10.1007/s00382-011-1115-0 |
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52 | Praveen Kumar, B., J. Vialard, M. Lengaigne, V.S.N. Murty, M. J. McPhaden, M.F. Cronin and F. Pinsard and K. Gopala Reddy, 2012: TropFlux wind stresses over the tropical oceans: evaluation and comparison with other products, submitted to Climate Dynamics |
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