Model Runs

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Cycle 25r5

Atlantic anomaly runs

Relaxation experiments

• b067 Control run 0 W/m2 SST relaxation - analysis only, no forecast
• b068 Control run 20 W/m2 SST relaxation - analysis only, no forecast
• b069 Control run 400 W/m2 SST relaxation - analysis only, no forecast

Forcing experiment - taux

• b06b Control run 20 W/m2 SST relaxation - full forecast (in realtime, run ended 5/6/03)
• b06d TropAnom run 20 W/m2 SST relaxation - analysis only, no forecast . (Anom: taux_forcing.grib)

  Click here for image of anomaly created in the potential temperature field (b06d-b06b)

• b06e Forecast run starting from end of b06d - two member ensemble. Designed to check if ocean thermocline anomalies develop into surface SSTA's.

  Theory suggests that as winter develops and the mixed layer deepens, the latter may interact with the heat stored at depth and increase the temperature of the ML (and the surface).

  Forecast SST (T2m) anomalies for two members: member 1 member 2

  Values are Anom member - control (ensmean). Data only shown if outside +/- 2*stdev of control run.

  Initial Thoughts: Significant surface anomaly has not really developed

Forcing experiment - heat flux and combined

• b06f TropAnom run 20 W/m2 SST relaxation - analysis only, no forecast (Anom: flux_anom_forcing.grib)
  

  Anomaly has slightly longer extent in longitude, and has a 2-D gaussian type profile

• b06g TropAnom run 20 W/m2 SST relaxation - analysis only, no forecast (Anom: taux + heatflux)

  Click here for potential temperature anomalies created by the combined forcing patterns

• b06h Forecast run starting from end of b06g - two member ensemble.

  Forecast SST (T2m) anomalies for two members: member 1 member 2

New Approach

Some background on the wind-stress curls associated with anomaly can be found here.

New Control run

• b080 Analyis period
• b088 40 member ensemble forecast (starting from end of b080)

Forcing experiment - wind stress only

• b07x : plus 15% average taux/tauy forcing
  The forcing pattern can be seen here.
  Click here for image of anomaly created in the potential temperature field (b07x-b080)

• b089 : plus 30% average taux/tauy forcing
  The forcing pattern can be seen here.
  Click here for image of anomaly created in the potential temperature field (b089-b080)

• b08a : plus 100% average taux/tauy forcing
  Click here for image of anomaly created in the potential temperature field (b08a-b080)
  Note: The scale is different to the b089 plot
  The wind-stress anomaly creates a maximum surface anomaly of ~0.5° C and minimum of ~-1.5° C.
  Here you will find an animation of the anomaly development in the 20° isotherm.Note: Requires Java.

  update: Monthly average, Atlantic zonal average ptemp with depth here.

• b08h : 5 member ensemble forecast (starting from end of b08a)

Forcing experiment - ATL heat flux

• b08p (A) - CONTROL 12 months control run.
  • b090 (F9) - CONTROL 6 month forecast from b08p.
  • b09n (F20) - CONTROL 6 month forecast from b08p. Increased diagnostic output.

• b08m (A) 12 months forcing with above pattern. Assuming a constant 100m mixed depth, a 20W/m2 forcing would give a mixed layer depth temp rise of 1.5K (after 12 months). Spatially this results in this. The actual temperature rise for the the top 10m and averaged over the mixed layer can be seen here. (This being for October 1990). It should be noted that the relaxation term (towards Reynolds OI SST fields) is -20W/m2 per degree difference in the calculated SST wrt to the Reynolds Obs.

  Assuming a simple column model of the ocean (as above), the consequence of applying various ocean relaxation terms can be seen here.

• b08q (A) 12 month forcing as in b08m. Anomaly field increased in magnitude. 25-50 W/m2 (0-73N). The average potential temperature anomaly created in the top 100m can be seen here
  • b091 (F9) 6 month forecast from b08q. The combined 2m temp anomalies and MSLP can be seen for the six month forecast here.
  • b09z (F20) 6 month forecast from b08q. Increased diagnostics.

• b094 (A) As per b08q, but with negative forcing. Anomaly field increased in (absolute) magnitude -25 to -50 W/m2 (0-73N). A nine member forecast ensemble is then started from Nov 1990 (so this is the negative form of b08q and b091 combined.
  The average potential temperature anomaly created in the top 100m can be seen here.
  The combined 2m temp anomalies and MSLP can be seen for the six month forecast here.
  • b094 (F9) Forecast and analysis combined.
  • b0a5 (F20) From end of b094 analysis period.

• b09v (A) As per b08m, but forcing only applied for first six months (Nov-Apr inclusive) The average potential temperature anomaly created in the top 100m can be seen here.
  It can be seen that the anomaly survives over the summer period (below the mixed layer in theory), and re-emerges in the following winter. The anomaly is damped (compared to the anomaly that survives with all year forcing here), and it must be remembered that the model has a surface relaxation of 20 W/m2 towards observed SST.
  • b0a6 (F20) 6 month forecast from b09v (20 members) Global potential temp (10m) anomalies.
    Atlantic precipitation anomalies. Right hand column indicates control run intra-ensemble stdev.

• b0a0 (A) As per b09v, but with 75-100W/m**2 forcing.
  • b0ac (F20) From end of b0a0.