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TS TRENDS IN THE WESTERN MEDITERRANEAN: WATER MASS CHANGES AND VERTICAL DISPLACEMENTS (HEAVING) Patricia Zunino Rodríguez Manolo Vargas Yáñez M. Carmen.

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Presentation on theme: "TS TRENDS IN THE WESTERN MEDITERRANEAN: WATER MASS CHANGES AND VERTICAL DISPLACEMENTS (HEAVING) Patricia Zunino Rodríguez Manolo Vargas Yáñez M. Carmen."— Presentation transcript:

1 TS TRENDS IN THE WESTERN MEDITERRANEAN: WATER MASS CHANGES AND VERTICAL DISPLACEMENTS (HEAVING) Patricia Zunino Rodríguez Manolo Vargas Yáñez M. Carmen García Martínez Francina Moya CLIVAR ESPAÑA febrero 2009

2 1. Trends in the Western Mediterranean: state of the art WMED deep waters have warmed and increased its salinity during the second half of the XX th century WMED intermediate waters have increased its salinity No robust results have been obtained related to temperature in the WMED intermediate waters CLIVAR ESPAÑA febrero 2009

3 2. How have these trends been estimated? CLIVAR ESPAÑA febrero 2009 Temperature and salinity profiles MEDAR database (2002) From 1943 to PRESSURE (dbar)

4 2. How have these trends been estimated? CLIVAR ESPAÑA febrero dbar 500 dbar anomaly + anomaly - TEMPERATURE SALINITY 1991

5 2. How have these trends been estimated? CLIVAR ESPAÑA febrero 2009 Temperature anomaly Time (year) ºC yr dbar Trends on isobaric surfaces don’t necessarily imply water mass changes

6 3. Contribution to trends in each pressure level Changes on isobaric surfaces can be decomposed into: a. Changes on isopycnal surfaces (changes in water masses) b. Vertical displacements (heaving, Bindoff & McDougall, 1994) Both effects could add or cancel, enhancing or masking possible water mass trends in a determined pressure level CLIVAR ESPAÑA febrero 2009

7 3. Contribution to trends in each isobaric level a)Changes on isopycnals (water mass changes): Related with the heat and freshwater exchange in the ocean- atmosphere interface CLIVAR ESPAÑA febrero dbar Q E - P T, S, =  CHANGE ON ISOBARIC SURFACES AND CHANGE ON ISOPYCNAL SURFACES

8 3. Contribution to trends in each pressure level b. Isopycnal vertical displacement: marine dynamics CLIVAR ESPAÑA febrero 2009 wind TT NO WATER MASS CHANGE

9 QE-P Outflow 1000 dbr 3. Contribution to trends in each pressure level b. Isopycnal vertical displacement: deep water formation CLIVAR ESPAÑA febrero 2009 T S T, S,  V Kg m -3 NO WATER MASS CHANGE T, S,  V

10 3. Contribution to trends in each pressure level How to estimate both contributions? Bindoff & McDougall [1994] CLIVAR ESPAÑA febrero 2009 dd dt z = dd  - dp dt  ∂θ ∂p isobaric surfaces isopycnal surfaces heaving This decomposition have never been applied in the WMED, but it is so common in other world´s ocean

11 HEAVINGISOPYCNAL SURFACESISOBARIC SURFACES CLIVAR ESPAÑA febrero Our results b) Results: Deep layer (600 dbar- bottom) TEMPERATURE ± ºC yr ± ºC yr ± ºC yr Kg m Kg m Kg m ± dbar yr -1

12 ISOPYNAL SURFACESHEAVING CLIVAR ESPAÑA febrero Our results b) Results: Deep layer (600 dbar- bottom) SALINITY ± yr ± yr ± yr Kg m Kg m Kg m ± yr ± yr ± yr -1 ISOBARIC SURFACES

13 ISOPYCNAL SURFACESISOBARIC SURFACES CLIVAR ESPAÑA febrero Our results b) Results: Intermediate layer ( dbar) TEMPERATURE No significative trend ± ºC yr ± ºC yr Kg m Kg m ± ºC yr ± ºC yr Kg m Kg m ± 3.45 dbar yr ± 9.12 dbar yr -1 HEAVING

14 4. Our results b) Results: Intermediate layer ( dbar) SALINITY ± yr ± yr ± yr ± yr -1 CLIVAR ESPAÑA febrero 2009 Pressure (dbar) - Salinity Kg m Kg m ± 3.45 dbar yr ± 9.12 dbar yr -1 increase decrease ISOPYCNAL SURFACESISOBARIC SURFACESHEAVING

15 5. CONCLUSION CLIVAR ESPAÑA febrero 2009 Subestimation of temperature and salinity trends of the deep waters masses when trends were estimated on isobaric surfaces Intermediate waters in the WMED were warming during the last half century, which wasn't clear before Upward displacement in the WMED during the second half of the XX th century, and this would be linked to the deep water formation rate in the Gulf of Lions and Levantine basin

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