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Sensitivity of Iberian Upwelling to Climate Change: A Numerical Simulation with ROMS Forced by RACMO A2 Scenario

This study examines the sensitivity of the Iberian upwelling to climate change using a numerical simulation with ROMS forced by the RACMO A2 scenario. The results show an increase in the number and intensity of upwelling events under future climate conditions.

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Sensitivity of Iberian Upwelling to Climate Change: A Numerical Simulation with ROMS Forced by RACMO A2 Scenario

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  1. 2008 ROMS/TOMS European WorkshopSaint Martin d'Heres Campus Grenoble, France Sensitivity of Iberian upwelling to climate change: a numerical simulation with ROMS forced by RACMO A2 scenario (1) University of Lisbon, CGUL, IDL (2) University of Hamburg, Center for Marine and Atmospheric Research (ZMAW) José Alves (1) Pedro M A Miranda (1) Nuno Serra (2)

  2. Summary Detailed study during the year 2000 (U, V, W, SST, SSH) ECMWF – ERA 40 1960-2000 RACMO 1961-1990 2071-2100 ROMS

  3. Cape Carvoeiro Latitude: 39.35 N Longitude: 9.4 W ROMS domain

  4. ROMSRUTGERS version 3.0

  5. Surface forcing • Downward shortwave radiation (swrad) • Downward longwave radiation (lwrad) • 2m air temperature (Tair) • 10 m wind (Uwind, Vwind) • pressure (Pair) • relative humidity (Qair)

  6. Forcing (ERA 40) at Cape Carvoeiro Year 2000 Surface temperature Relative humidity 24°C 8°C Surface pressure

  7. Forcing (ERA 40) Cape Carvoeiro Year 2000 Surface wind Shortwave radiation

  8. Results: Summer 2000 at Cape Carvoeiro ROMS 1 2 3 1 July 31 August 1 July 31 August 1 July 1 July 31 August 31 August

  9. Sea surface height at cape Cape Carvoeiro 2000 ROMS 1 July 31 August

  10. Spatial variability (full year) Cape Finisterre Cape Carvoeiro Cape São Vicente Most of the events are verified simultaneously along the coast.

  11. Validation near Cape Carvoeiro Satellite AVHRR (1/4 AVHRR daily OI SST) vs ROMS AVHRR, NOAA Nearest points ROMS

  12. SST during the July and August 2000

  13. variable Upwelling Episodes SST sea surface temperature  decrease T < - 4 K U zonal current  westward U < 0.3 m/s V meridional current  southward V < 0.4 m/s W vertical component  upward W < 0.15 mm/s SSH sea surface height  lower values H < 0.06 m Results Summer 2000 episodes Upwelling near Iberia is episodic Episode duration ~1-2 weeks Extension < 50 km Intensity < 4 K

  14. Climate change impacts on upwelling 40 year simulation forced by ERA-40 Wind turned to more Northerly Implying more frequent (simulated) upwelling

  15. Number of events The upwelling episodes were identified through the analyses of sea surface temperature time series. The threshold considered to identify an upwelling event was a decrease in SST of at least 2C in less than 1 week, followed by an increase of the same magnitude in a similar time period.

  16. RACMO model surface winds at Cape Carvoeiro From 2001-2100, it is observed an increase in the wind intensity, although the mean direction has not changed.

  17. Atmospheric forcing variables TEMPERATURE (2071-2100) (1961-1990) 50% SURFACE PRESSURE Increase in the mean temperature of 2.2 C / slight increase in the variability Slight decrease in the pressure mean value / increase in the variabilty

  18. ROMS forced with RACMO

  19. ROMS forced with RACMO data (Regional Atmospheric Climate MOdel) RACMO control has no relevant decadal tendencies (unlike ERA-40) 10% more

  20. Horizontal displacement Number of days with westward current A2 CONTROL A2 CONTROL Increased interanual variability • Sligtly increase in the westward horizontal • displacement

  21. Upwelling duration CONTROL A2 Increase in the number of events of short duration (1 week) and long duration (4 weeks), decrease in the number of events of medium duration (3 and 4 weeks) , more interdecadal variability

  22. Upwelling intensity CAT I > 4 °C || 3 °C< CATII <4 °C|| 2 °C< CATIII < 3 °C Slight increase in the events intensity

  23. Conclusions • ROMS forced by ERA-40 • Increase in the decadal number of upwelling events from 1960 to 2000 • due to change in the mean wind direction. • ROMS forced by RACMO control run (1961-1990) • Number of upwelling events almost constant • RACMO fields do not include observed climate trends • ROMS A2 scenario (2071-2100) • 10% increase in the number of upwelling events (vs Control run) • due to an increase in the wind intensity • A2 2071-2100 simulated upwelling • Increased event duration variability (More long and short events) • Slight increase in mean event intensity • Increased interdecadal variability

  24. Future work Add Tagus estuary to the computational domain in order to study the circulation within the Tagus estuary – grid nesting Use atmospheric data with a higher spatial resolution Apply boundary conditions from a global ocean model Look at other upwelling diagnostics

  25. ROMS forced with RACMO

  26. Initial conditionsLevitus 1 January Surface salinity Surface temperature

  27. Climate change impacts on Iberian upwelling ROMS forced with ECMWF ERA 40 data

  28. ROMS forced with ERA 40 2K

  29. ROMS forced with RACMO Control vs ERA-40

  30. ERA 40 Vs RACMO ERA 40 reanalysis data RACMO data from a climate model

  31. Quando o modelo ROMS foi forçado com dados do ECMWF-ERA40, no período 1960-2000, verificou-se um aumento do número de episódios de upwelling, enquanto que quando se utilizou o forçamento do modelo RACMO, para o mesmo período, se verificou que o número de episódios de upwelling se manteve praticamente constante. • Nas projecções para o final do século XXI [2071-2100] (modelo RACMO) verificou-se um aumento do vento junto ao Cabo Carvoeiro e um consequente aumento do número de episódios de upwelling, cerca de 10 % em relação ao verificado no período 1961-1990. • No Cabo Carvoeiro a maioria dos episódios de upwelling eram e vão continuar a ser de longa duração (4 semanas ou mais) e de baixa intensidade (2<T<3), embora se tenha verificado um ligeiro aumento na intensidade dos episódios. • O número de dias de upwelling por ano praticamente não sofre alteração.

  32. Sea surface temperatureSST at layers 30-20-10

  33. Cape Vilano (lat= ???N/ lon=???W ) SST Vertical sections Cape Carvoeiro (lat= 39.35 N/lon=9.40 W ) Cape São Vicente (lat= ???N/lon=??? W)

  34. July and August 2000 SST; SSH; currents U and V

  35. 30 year temporal series Horizontal displacement (m) Number of days with U>0 and U<0

  36. U and SST 30 Year temporal series

  37. Currents (U, V and W)

  38. Sea surface heightSSH Lower values close to the coast during upwelling episodes due to …

  39. STATIONS Map with stations locations

  40. FLOATS Map with float trajectories

  41. Validate SST with satellite data

  42. Conclusions

  43. Problems Sea surface temperature values too low during the winter months

  44. Ver figura em Inglês

  45. 1961-1990 2071-2100

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