ESSO - Indian National Centre for Ocean Information Services

(An Autonomous Body under the Ministry of Earth Sciences, Govt. of India)


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 March 2013 period. We are currently working on a regular (~monthly) update of the TropFlux product until 3-4 months behind realtime.

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. 2012. The wind stress product is described, evaluated and compared against other widely used products (QuikSCAT, NCEP, NCEP2, ERA-I) in Praveen Kumar et al. 2013

We believe that this product offers the following advantages:

  • 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) ,
  • available until August 2013, and soon updated every month, lagging realtime by ~3 months,
  • 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.

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 and distributed through Indian National Centre for Ocean Information Services, India. Bilateral scientific visits to France and India have been supported by Institut de Recherche pour le Développement, France.