Integrated Climate Data Center

Sea-Ice type from ship observations (Antarctic)

 

Pictures of various sea ice types / surface types for the exemplification of the different conditions encountered: from left to right: cake ice, brash ice & pancake ice close to the ice edge, new ice (here: grease ice), first-year ice with melt ponds & new ice (here: dark nilas) & open water, multiyear ice, thin ice (here: dark nilas), multiyear ice & fresh lead, thin ice (here: light nilas). Please see the tutorial for a much better selection of different ice types and how they look like.

 

Access

UNRESTRICTED

The data are available, e.g., via this link, and alternatively via http://www.aspect.aq

 

Description

This data set is a collection of visual ship-based sea-ice observations carried out from the ship's bridge while the ship cruises through the sea ice. These observations have been standardized according to the ASPeCt protocol. These observations contain the ship's position, the day and time of the observation (hourly, with an observation radius around the ship of about 1 km), the total sea ice concentration, the partial concentrations of the three thickest sea ice types, and for these, respectively, thickness, type, degree of deformation, floe size, and snow properties and depth.

For more information see: http://www.aspect.aq

A tutorial allows to learn how sea-ice observations are carried out according to the ASPeCt protocol.

The two pictures at the top illustrate how the sea ice thickness is estimated by looking at the tilted ice floe and a scale attached to the ship's hull (in this case the research icebreaker Polarstern).

 

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Parameters

Name Unit
Total sea ice concentration 1/10
Partial sea ice concentration (primary (=thickest) ice type) 1/10
Partial sea ice concentration (secondary ice type) 1/10
Partial sea ice concentration (tertiary ice type) 1/10
Sea ice type and floe size primary ice type coded, see tutorial
Sea ice type and floe size secondary ice type coded, see tutorial
Sea ice type and floe size tertiary ice type coded, see tutorial
Height and areal fraction of deformation primary ice type coded, see tutorial
Height and areal fraction of deformation secondary ice type coded, see tutorial
Height and areal fraction of deformation tertiary ice type coded, see tutorial

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Coverage, spatial and temporal resolution

Period and temporal resolution:

  • 1980 to 2005
  • irregular temporal resolution, often hourly, for different ship expeditions for different seasons

Coverage and spatial resolution:

  • Southern hemisphere, along ship expedition routes
  • Spatial resolution: irregular, depending on ships speed, 1 observation represents an area of 1 mile radius around the ships' position.
  • Geographic longitude: irregular, between 0° to 360°
  • Geographic latitude: irregular, between 50°S and 80°S
  • Dimension: irregular, depends on length of and observation interval during the ship expeditions
  • Altitude: 0.0 m

 Format:

  • ASCII

The header of the data files informs about the parameters included and in which column they are given in the data file. Data of different cruises are given in chronological order; the beginning of a new (cruise) data set is indicated at the first line of the respective data set (see references).

 

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Data quality

This data indicate the mean, typical sea ice type along the ship's cruise track; this data can not be recommended for a point validation.

This data is based on a visual estimation of the mentioned parameters and/or the parameters given in the data file and the tutorial.

The accuracy is therefore quite low: sea ice concentrations are given in 10% intervals; observation quality of sea ice type, degree of deformation, and floe size depend much more on the skills and experience of the observer, than estimates of ice thickness and snow depth.

Note that

  • a) the cruise track is often located in thinner and more easily to navigate  sea ice than would be typical for the region of the cruise --> bias
  • b) it takes about 10 minutes to carry out an ice observation according to the ASPeCt protocol; therefore the represented area is elliptic rather than circular due to the continued motion of the ship

 

 

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Contact

internal:

Name: Stefan Kern

Institute: CliSAP / KlimaCampus / ICDC

email: stefan.kern@we dont want spamzmaw.de

 

external:

Name: Anthony Worby

Institute: Australian Antarctic Division and ACE CRC, University of Tasmania

email: A.Worby@we dont want spamutas.edu.au

 

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References

 

Data citation

Should this data be used in a publication / report / presentation it is asked to cite as follows:

The ship-based sea ice and snow thickness data were provided by the SCAR Antarctic Sea Ice Processes and Climate (ASPeCt) program (www.aspect.aq)

 

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