Snow depth on sea ice from ship observations (Antarctic)

Pictures of ice floes tilted by the ship's hull for the illustration of the ship-based snow depth on sea ice estimation from, e.g., aboard the research icebreaker Polarstern.

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 snow depth on sea ice 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).

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
Snow depth primary ice type	m
Snow depth secondary ice type	m
Snow depth tertiary ice type	m

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).

Data quality

This data indicate the mean, typical sea ice thickness 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; the snow depth given in 10 cm intervals - unless the ice is thin.

Note that

a) the cruise track is often located in thinner sea ice than would be typical for the region of the cruise --> negative bias / zero snow depth
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

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

References

Webpage with detailed information about ASPeCt: http://www.aspect.aq
Tutorial to get to know the ASPeCt-Protocol
Worby et al., 2008

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)