Posts Tagged ‘DMI’

Arctic summer relatively short and ice melt-rate slow this year

August 9, 2013

The Arctic ice extent usually reaches a maximum in the 2nd week of March and its minimum during the 2nd week of September.

This year the Arctic summer started later than usual (long winter, late spring all over the Northern hemisphere). Now as Arctic temperatures have already dropped below freezing it could turn out to be a rather short. cool summer. Temperatures rose to above freezing about 3 weeks later than the average and seem to have dropped below zero about 2 weeks ahead of the average. In consequence the ice melt-rates have been much lower than for some time (but not unprecedented by a long way).

Arctic Temperatures North of 80° ( from DMI – Danish Centre for Ocean and Ice)

Daily mean temperatures for the Arctic area north of the 80th northern parallel, plotted with daily climate values calculated from the period 1958-2002.

Calculation of the Arctic Mean Temperature

The daily mean temperature of the Arctic area north of the 80th northern parallel is estimated from the average of the 00z and 12z analysis for all model grid points inside that area. The ERA40 reanalysis data set from ECMWF, has been applied to calculate daily mean temperatures for the period from 1958 to 2002, from 2002 to 2006 data from the global NWP model T511 is used and from 2006 to 2010 T799 data are used and from 2010 to present the T1279 model data are used. 

The ERA40 reanalysis data, has been applied to calculation of daily climate values that are plotted along with the daily analysis values in all plots. The data used to determine climate values is the full ERA40 data set, from 1958 to 2002.
More information can be found here.

Daily mean temperature and climate north of the 80th northern parallel, as a function of the day of year. DMI

Daily mean temperature and climate north of the 80th northern parallel, as a function of the day of year. DMI

Not surprisingly the ice melt-rate this year has been relatively low and the ice extent relatively high.

Total sea ice extent on the northern hemisphere during the past years, including climate mean; plus/minus 1 standard deviation. The ice extent values are calculated from the ice type data from theOcean and Sea Ice, Satellite Application Facility (OSISAF), where areas with ice concentration higher than 15% are classified as ice.

The total area of sea ice is the sum of First Year Ice (FYI), Multi Year Ice (MYI) and the area of ambiguous ice types, from the OSISAF ice type product.

Sea ice extent in recent years for the northern hemisphere.                        The grey shaded area corresponds to the climate mean                       plus/minus 1 standard deviation.

Sea ice extent in recent years for the northern hemisphere.
The grey shaded area corresponds to the climate mean plus/minus 1 standard deviation.

It looks probable that the ice extent minimum for 2013 will be within one standard deviation of the mean 1979-2000 value.

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