Cycle 24r3 summary of changes

22 January 2002 Introduction of Cycle 24r3. This version includes the following important changes that together will affect all components of the system (Data assimilation, atmospheric and oceanic waves forecasts, EPS):

  1. More data are activated (SeaWinds data from QUIKSCAT, less thinning of aircraft observations, more intelligent thinning and better scan correction of ATOVS radiances);
  2. Pre-processing (bias correction) of SSMI data and redundancy checks for SYNOP, SHIP, DRIBU, AIREP, TEMP and PILOT observation are refined;
  3. 4D-var analysis algorithms are upgraded:
    • pre-conditioning is added to the minimisation, resulting in a 40% reduction of the number of adiabatic iterations;
    • correlation functions slightly revised (compacted);
    • the radiative transfer model used to assimilate satellite radiances has been completely re-written;
    • the observation timeslot has been reduced from 1 hour to 30 minutes;
  4. Model changes include a new finite-element vertical discretization, small changes in the convective precipitation scheme and supersaturation checks, and an improved temporal scheme for oceanic waves generation;
  5. Initial EPS perturbations in the tropics are included. The perturbations are generated for a maximum of four target areas by Gaussian sampling of the 5 leading diabatic singular vectors for each area. The Caribbean (0°-25°N and 100°-60°W) is always target area, as is every tropical storm of category larger than 1 between 25°N and 25°S. (In the event that these criteria produce more than four target areas, the closest areas are merged.)


Cycle changes

Please note

Prior to 2006 information on cycle upgrades has been migrated from the old website to the new website "as is". The information has not been reviewed during the migration.