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Diurnal warming in the Arctic Ocean: Observations at CMS

Sonia Péré Centre de Météorologie Spatiale, Météo-France, Lannion, France. Diurnal warming in the Arctic Ocean: Observations at CMS. Outline. Introduction : How to quantify DW  in the Arctic  ? Reference: Previous « night » vs foundation SST? Buoy observations (drifters)

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Diurnal warming in the Arctic Ocean: Observations at CMS

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  1. Sonia Péré Centre deMétéorologie Spatiale, Météo-France, Lannion, France Diurnal warming in the Arctic Ocean:Observations at CMS

  2. Arctic SST workshop, Exeter 18-19 December 2013 Outline Introduction : How to quantify DW  in the Arctic  ? Reference: Previous « night » vs foundation SST? Buoy observations (drifters) Application to satellite data Modelling Conclusion

  3. Arctic SST workshop, Exeter 18-19 December 2013 Buoys observations : drifters DW vs lst in arctic What is DW ? DW = sst -ref_sst Ref_sst= previous « night » SST : the mean SST value between20 lst the day before and 10 lst the same day Previous night SST is DW contaminated (most of the time) DW latitude >66 with drifters Can we use foundation SST as a reference ?

  4. Arctic SST workshop, Exeter 18-19 December 2013 How to determine foundation SST ? Time series  for drifter 62926: lat 70.6 lon 41 Threshold on wind speed? Reference SST? 

  5. Arctic SST workshop, Exeter 18-19 December 2013 Wind threshold ? Wind above 5m/s WIND Residual DW after 21 lst How to determine foundation SST Which Wind value leads to close the cycle ? Summer 2012

  6. Arctic SST workshop, Exeter 18-19 December 2013 How to determine foundation SST We adopt a wind threshold > 7m/s and 10 day centered averages.

  7. Arctic SST workshop, Exeter 18-19 December 2013 Satellite observations Metop SST Buoy 62926 Time serie from 16 to 19 of july Buoy 62926

  8. Arctic SST workshop, Exeter 18-19 December 2013 Previous night vs foundation SST Foundation sst : Wind > 7 m/s +- 5 days Dw =sst-Foundation sst 

  9. Arctic SST workshop, Exeter 18-19 December 2013 Previous night vs foundation SST Daily reference : The previous « night » SST Dw =SST-daily reference

  10. Reference vs foundation SST

  11. Previous night vs foundation SST

  12. Arctic SST workshop, Exeter 18-19 December 2013 Relative number of clear sky cases with wind > 7ms-1 July 2012

  13. Arctic SST workshop, Exeter 18-19 December 2013 Modelling : swr Buoy :62926 wind Non solar fluxes

  14. Arctic SST workshop, Exeter 18-19 December 2013 Modelling Wind =0 on 20120717 from 00h to 19h

  15. Arctic SST workshop, Exeter 18-19 December 2013 Modelling Wind =0 on 20120717 from 00h to 19h + Non solar fluxes=0

  16. Arctic SST workshop, Exeter 18-19 December 2013 Modelling Wind =0 on 20120717 from 00h to 19h + Non solar fluxes=0 + surface salinity =0

  17. Arctic SST workshop, Exeter 18-19 December 2013 Salinity assumption?

  18. Arctic SST workshop, Exeter 18-19 December 2013 Conclusion • With drifter data, a « solar warming amplitude» over several days can be determined with SST foundation • With satellite data, the scarcity of wind >7m/s in clear sky does not permit to determine SST foundation (and solar warming events are difficult to quantify) • The use of daily reference permits to detect Diurnal Warming. • Localized amplitudes as large as 4 to 5 K are observed up to 80 North • It 's difficult to simulate such amplitudes unless we make extreme assumptions. • Further work : • understand the origin of such large amplitudes • contribute to the Lake Vanern paper

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