Diurnal warming in the Arctic Ocean: Observations at CMS
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Diurnal warming in the Arctic Ocean: Observations at CMS Sonia Péré Centre de Météorologie Spatiale, Météo-France, Lannion, France
description
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) - PowerPoint PPT Presentation
Transcript of Diurnal warming in the Arctic Ocean: Observations at CMS
Diurnal warming in the Arctic Ocean:Observations at CMS
Sonia Péré
Centre de Météorologie Spatiale, Météo-France, Lannion, France
Arctic SST workshop, Exeter 18-19 December 2013
2Outline
Introduction : How to quantify DW in the Arctic ?
Reference: Previous « night » vs foundation SST?– Buoy observations (drifters)
– Application to satellite data
Modelling
Conclusion
Arctic SST workshop, Exeter 18-19 December 2013
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Buoys observations : drifters DW vs lst in arctic
DW latitude >66 with drifters
DW = sst -ref_sst
Ref_sst= previous « night » SST: the mean SST value between 20 lst the day before and 10 lst the same day
What is DW ?
Previous night SST is DW contaminated(most of the time)
Can we use foundation SST as a reference ?
Arctic SST workshop, Exeter 18-19 December 2013
4How to determine foundation SST ?
Reference SST? Threshold on wind speed?
Time series for drifter 62926: lat 70.6 lon 41
Arctic SST workshop, Exeter 18-19 December 2013
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Residual DW after 21 lst
WIN
D
Wind threshold ?
Summer 2012
How to determine foundation SST
Which Wind value leads to close the cycle ?
Wind above 5m/s
Arctic SST workshop, Exeter 18-19 December 2013
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We adopt a wind threshold > 7m/s and 10 day centered averages.
How to determine foundation SST
Arctic SST workshop, Exeter 18-19 December 2013
7Satellite observations
Buoy 62926
Metop SST Buoy 62926
Time serie from 16 to 19 of july
Arctic SST workshop, Exeter 18-19 December 2013
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Foundation sst :Wind > 7 m/s+- 5 days
Dw =sst-Foundation sst
Previous night vs foundation SST
Arctic SST workshop, Exeter 18-19 December 2013
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Daily reference :The previous « night » SST
Dw =SST-daily reference
Previous night vs foundation SST
22/04/23
Reference vs foundation SST
22/04/23
Previous night vs foundation SST
Arctic SST workshop, Exeter 18-19 December 2013
12Relative number of clear sky cases with wind
> 7ms-1
July 2012
Arctic SST workshop, Exeter 18-19 December 2013
13Modelling :
Buoy :62926swr
wind
Non solar fluxes
Arctic SST workshop, Exeter 18-19 December 2013
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Wind =0 on 20120717 from 00h to 19h
Modelling
Arctic SST workshop, Exeter 18-19 December 2013
15Modelling
Wind =0 on 20120717 from 00h to 19h+ Non solar fluxes=0
Arctic SST workshop, Exeter 18-19 December 2013
16Modelling
Wind =0 on 20120717 from 00h to 19h+ Non solar fluxes=0+ surface salinity =0
Arctic SST workshop, Exeter 18-19 December 2013
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Salinity assumption?
Arctic SST workshop, Exeter 18-19 December 2013
18Conclusion
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
