CMEMS Arctic MFC: Validation of near-surface drift

Validation based on data from drifting buoys

Validation of the CMEMS Arctic MFC results for near-surface drift is performed using data from drifting buoys, which are compiled by the CMEMS SST TAC. The drifters are equiped with a drogue which is centered at 15 meters beneath the surface. The purpose of the drogue is to obtain a measure of mixed layer currents in the upper ocean. Data are available with a temporal resolution of 3 hours. These data are converted to daily mean values to conform with the TOPAZ model results.

Scatter plots for model vs. observed daily drift have color coding to indicate a separation between buoys: Each buoy has up to 17 results for daily drift in the Best Estimate validation, so the same color is used for each of the (up to) 17 points in the scatter plot that corresponds to this buoy. However, the number of colors used is limited to 20. If there are more buoys (which is generally the case for the Extended Domain), the colors are recycled (i.e. the same color is used for buoys no.s 1 and 21 etc.).

Buoy data are available from CERSAT-IFREMER in collaboration with Coriolis. Additional information about the data is available from The Global Drifter Program at NOAA. On the NOAA web site there is also a schematic depiction of a drifter.

Results by bulletin date
January 2022
01-06
01-13
01-20
01-27

February 2022
02-03
02-10
02-17
02-24

March 2022
03-03
03-10
03-17
03-24
03-31

April 2022
04-07
04-14
04-21
04-28

May 2022
05-05
05-12
05-19

April 2021
04-01
04-08
04-15
04-22
04-29

May 2021
05-06
05-13
05-20
05-27

June 2021
06-03
06-10
06-17
06-24

July 2021
07-01
07-08
07-15
07-22
07-29

August 2021
08-05
08-12
08-19
08-26

September 2021
09-02
09-09
09-16
09-23
09-30

October 2021
10-07
10-14
10-21
10-28

November 2021
11-04
11-11
11-18
11-25

December 2021
12-02
12-09
12-16
12-23
12-30

Regions

The ocean circulation model used in CMEMS's Arctic MFC covers the Arctic Ocean, the North Atlantic Ocean and adjacent ocean regions. The northern part is depicted in the figure below. Validation of sea surface temperature from model results is performed for three domains:

  • an extended domain indicated by the blue, green and red regions in the figure
  • the Nordic Seas, shown as the green region
  • the Barents Sea, depicted in red

TOPAZ

The model results are produced with the TOPAZ ocean data assimilation model system. Presently, TOPAZ is run weekly with data assimillation one week prior to the bulletin date, followed by a one-week 100 member ensemble simulation ending on the bulletin date, and finally a 10 day deterministic forecast. TOPAZ was developed by the Nansen Center and is maintained jointly by the Nansen Center and MET Norway.

For the validation of near-surface drift, model results for ocean temperature at the 5 meter level are used. This is somewhat above the drift depth that is represented by the drifter data (15 meter level).