ESA-CCI_Phase2_Standardized_Manual_Visual_Ship-Based_SeaIceObservations_v01

Polar regions are data sparse regions. Research ships operating in polar regions often record sea-ice conditions during their transects through ice infested waters. Such observations of the sea-ice conditions are often the only information that can be provided in addition to satellite-based estimates of the sea-ice conditions, such as sea-ice concentration or sea-ice thickness.


Such observations have been carried out and gathered using two protocols. For the Antarctic, this is the so-called ASPeCt protocol [Worby and Allison, 1999; Worby and Dirita, 1999; Worby et al., 2008]. For the Arctic, this is the so-called ASSIST/IceWatch protocol [Hutchings et al., 2018]. The latter builds on the ASPeCt protocol, incorporating surface melt conditions being more ubiquitous in the Arctic.

Ship-based observations of the sea-ice conditions are conducted manually, visually, i.e. by eye, regularly every hour taking into account an area around the ship of about one kilometer radius. Note that this area distorts to an elliptically shaped area as a function of observers' experience, ships' cruising speed and ice and visibility conditions.


Each observation comprises the total sea-ice concentration, and the concentration, level ice thickness, level ice snow depth, fraction and height of ridges, ice type, snow type, and floe size for the up to three thickest ice types. For the Arctic, melt-pond fraction and stage-of-melt are also part of the observables. In addition to the ships' position often auxiliary parameters such as visibility, wind speed and direction, or air and water temperature are recorded.


For development and evaluation of satellite-based sea-ice products, such ship-based observations are of great value. Because of this, within the ESA-CCI sea-ice ECV project (ESA-SICCI), phase 2, a standardized data set of such ship-based observations was generated for both polar regions. It comprises data from June 2002 through December 2015. This time period is motivated by the purpose to evaluate sea-ice concentration data retrieved from AMSR-E and AMSR2 brightness temperature measurements which, at the time the project was initiated, were planned to be retrieved until the end of 2015.


The data set incorporates observational data from various collections, e.g. a part of the original ASPeCt collection [Worby et al., 2008], which ended in May 2005. More information about all data sources is given below.


All data have been manually standardized to the same format (i.e., number of decimals, unit), using the same value to describe missing data, using the same temporal ordering, and filling gaps with the respective missing-data value. Double data entries have been removed. The data set is split into two ascii text files, one for the Arctic, one for the Antarctic. It has been successfully used to evaluate sea-ice concentration and thickness products of the ESA-SICCI phase 2 project.

Simple

Date (Publication)
2019-11-01
Edition

1
Citation identifier
ESACCIPSMVSBSIO
Citation identifier
doi:10.26050/WDCC/ESACCIPSMVSBSIO
Principal investigator
  University of Hamburg - Dr. Stefan Kern
http://www.cen.uni-hamburg.de/
Author
  University of Hamburg - Dr. Stefan Kern
http://www.cen.uni-hamburg.de/
Publisher
  WDC Climate at DKRZ
Point of contact
  University of Hamburg - Dr. Stefan Kern
http://www.cen.uni-hamburg.de/
Name

GZ
Keywords

  • Aurora Australis
Keywords

  • CCGS Louis St. Laurent
Keywords

  • CCGS Sir Wilfried Laurier
Keywords

  • Icebreaker 50 Let Pobedy
Keywords

  • Icebreaker Oden
Keywords

  • RRS James Clark Ross
Keywords

  • RV Lance
Keywords

  • RV Laurence M. Gould
Keywords

  • RV Nathaniel B. Palmer
Keywords

  • RV Polarstern DBLK
Keywords

  • RV Sikuliaq
Keywords

  • USCGC Healy
Keywords

  • USCGC PolarSea
Keywords

  • sea ice
Keywords

  • ship
Use limitation

CC-BY-4.0: Creative Commons Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/

Language

eng; USA
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Begin date
2002-05-08
End date
2016-02-08
Distribution format
  • GZ ()

Transfer size
0
OnLine resource
https://www.wdc-climate.de/ui/entry?acronym=ESACCIPSMVSBSIO
Hierarchy level
collection

Completeness commission

Name of measure

n/a
Measure description

None

Non quantitative attribute accuracy

Name of measure

n/a
Measure description

None
Attribute description
sea_ice_ridges_thickness_at_top_of_sea_ice
Descriptor

not filled; unit: not filled
Attribute description
sea_ice_thickness
Descriptor

sea_ice_thickness [CF-Standard Name]; unit: not filled
Attribute description
sea_ice_area_fraction
Descriptor

sea_ice_area_fraction [CF-Standard Name]; unit: not filled
Attribute description
wind_speed
Descriptor

Speed is the magnitude of velocity. Wind is defined as a two-dimensional (horizontal) air velocity vector, with no vertical component. (Vertical motion in the atmosphere has the standard name upward_air_velocity.) The wind speed is the magnitude of the wind velocity.[CF-Standard Name]; unit: not filled
Attribute description
sea_ice_area_fraction
Descriptor

sea_ice_area_fraction [CF-Standard Name]; unit: not filled
Attribute description
sea_water_temperature
Descriptor

Sea water temperature is the in situ temperature of the sea water. To specify the depth at which the temperature applies use a vertical coordinate variable or scalar coordinate variable. There are standard names for sea_surface_temperature, sea_surface_skin_temperature, sea_surface_subskin_temperature and sea_surface_foundation_temperature which can be used to describe data located at the specified surfaces. For observed data, depending on the period during which the observation was made, the measured in situ temperature was recorded against standard "scales". These historical scales include the International Practical Temperature Scale of 1948 (IPTS-48; 1948-1967), the International Practical Temperature Scale of 1968 (IPTS-68, Barber, 1969; 1968-1989) and the International Temperature Scale of 1990 (ITS-90, Saunders 1990; 1990 onwards). Conversion of data between these scales follows t68 = t48 - (4.4 x 10e-6) * t48(100 - t - 48); t90 = 0.99976 * t68. Observations made prior to 1948 (IPTS-48) have not been documented and therefore a conversion cannot be certain. Differences between t90 and t68 can be up to 0.01 at temperatures of 40 C and above; differences of 0.002-0.007 occur across the standard range of ocean temperatures (-10 - 30 C). The International Equation of State of Seawater 1980 (EOS-80, UNESCO, 1981) and the Practical Salinity Scale (PSS-78) were both based on IPTS-68, while the Thermodynamic Equation of Seawater 2010 (TEOS-10) is based on ITS-90. References: Barber, 1969, doi: 10.1088/0026-1394/5/2/001; UNESCO, 1981; Saunders, 1990, WOCE Newsletter, 10, September 1990. [CF-Standard Name]; unit: not filled
Attribute description
melt_pond_area_fraction_at_top_of_sea_ice
Descriptor

melt pond area fraction at top of sea ice [CF-Guidelines for construction]; unit: not filled
Attribute description
area_type-where_lake_ice_or_sea_ice
Descriptor

alias: land_cover

alias: surface_cover

A variable with the standard name of area_type contains strings which indicate the nature of the surface e.g. land, sea, sea_ice. These strings are standardised. Values must be taken from the area_type table. [CF-Standard Name where cell method]; unit: not filled
Attribute description
area_type_at_top_of_sea_ice
Descriptor

not filled; unit: not filled
Attribute description
sea_ice_ridges_thickness_at_top_of_sea_ice
Descriptor

not filled; unit: not filled
Attribute description
area_type-where_lake_ice_or_sea_ice
Descriptor

alias: land_cover

alias: surface_cover

A variable with the standard name of area_type contains strings which indicate the nature of the surface e.g. land, sea, sea_ice. These strings are standardised. Values must be taken from the area_type table. [CF-Standard Name where cell method]; unit: not filled
Attribute description
surface_snow_thickness
Descriptor

surface_snow_thickness [CF-Standard Name]; unit: not filled
Attribute description
cloud_area_fraction
Descriptor

"X_area_fraction" means the fraction of horizontal area occupied by X. "X_area" means the horizontal area occupied by X within the grid cell. Cloud area fraction is also called "cloud amount" and "cloud cover". The cloud area fraction is for the whole atmosphere column, as seen from the surface or the top of the atmosphere. The cloud area fraction in a layer of the atmosphere has the standard name cloud_area_fraction_in_atmosphere_layer. [CF-Standard Name]; unit: not filled
Attribute description
wind_speed
Descriptor

Speed is the magnitude of velocity. Wind is defined as a two-dimensional (horizontal) air velocity vector, with no vertical component. (Vertical motion in the atmosphere has the standard name upward_air_velocity.) The wind speed is the magnitude of the wind velocity.[CF-Standard Name]; unit: not filled
Attribute description
relative_humidity
Descriptor

relative_humidity [CF-Standard Name]; unit: not filled
Attribute description
sea_ice_thickness
Descriptor

sea_ice_thickness [CF-Standard Name]; unit: not filled
Attribute description
wind_from_direction
Descriptor

Wind is defined as a two-dimensional (horizontal) air velocity vector, with no vertical component. (Vertical motion in the atmosphere has the standard name upward_air_velocity.) In meteorological reports, the direction of the wind vector is usually (but not always) given as the direction from which it is blowing (wind_from_direction) (westerly, northerly, etc.). In other contexts, such as atmospheric modelling, it is often natural to give the direction in the usual manner of vectors as the heading or the direction to which it is blowing (wind_to_direction) (eastward, southward, etc.) "from_direction" is used in the construction X_from_direction and indicates the direction from which the velocity vector of X is coming. [CF-Standard Name]; unit: not filled
Attribute description
sea_ice_ridges_area_fraction
Descriptor

not filled; unit: not filled
Attribute description
cloud_area_fraction
Descriptor

"X_area_fraction" means the fraction of horizontal area occupied by X. "X_area" means the horizontal area occupied by X within the grid cell. Cloud area fraction is also called "cloud amount" and "cloud cover". The cloud area fraction is for the whole atmosphere column, as seen from the surface or the top of the atmosphere. The cloud area fraction in a layer of the atmosphere has the standard name cloud_area_fraction_in_atmosphere_layer. [CF-Standard Name]; unit: not filled
Attribute description
area_type_due_to_melting-where_lake_ice_or_sea_ice
Descriptor

not filled; unit: not filled
Attribute description
air_temperature
Descriptor

Air temperature is the bulk temperature of the air, not the surface (skin) temperature. [CF-Standard Name]; unit: not filled
Attribute description
sea_ice_ridges_area_fraction
Descriptor

not filled; unit: not filled
Attribute description
sea_water_temperature
Descriptor

Sea water temperature is the in situ temperature of the sea water. To specify the depth at which the temperature applies use a vertical coordinate variable or scalar coordinate variable. There are standard names for sea_surface_temperature, sea_surface_skin_temperature, sea_surface_subskin_temperature and sea_surface_foundation_temperature which can be used to describe data located at the specified surfaces. For observed data, depending on the period during which the observation was made, the measured in situ temperature was recorded against standard "scales". These historical scales include the International Practical Temperature Scale of 1948 (IPTS-48; 1948-1967), the International Practical Temperature Scale of 1968 (IPTS-68, Barber, 1969; 1968-1989) and the International Temperature Scale of 1990 (ITS-90, Saunders 1990; 1990 onwards). Conversion of data between these scales follows t68 = t48 - (4.4 x 10e-6) * t48(100 - t - 48); t90 = 0.99976 * t68. Observations made prior to 1948 (IPTS-48) have not been documented and therefore a conversion cannot be certain. Differences between t90 and t68 can be up to 0.01 at temperatures of 40 C and above; differences of 0.002-0.007 occur across the standard range of ocean temperatures (-10 - 30 C). The International Equation of State of Seawater 1980 (EOS-80, UNESCO, 1981) and the Practical Salinity Scale (PSS-78) were both based on IPTS-68, while the Thermodynamic Equation of Seawater 2010 (TEOS-10) is based on ITS-90. References: Barber, 1969, doi: 10.1088/0026-1394/5/2/001; UNESCO, 1981; Saunders, 1990, WOCE Newsletter, 10, September 1990. [CF-Standard Name]; unit: not filled
Attribute description
surface_snow_thickness
Descriptor

surface_snow_thickness [CF-Standard Name]; unit: not filled
Attribute description
area_type-where_snow
Descriptor

alias: land_cover

alias: surface_cover

A variable with the standard name of area_type contains strings which indicate the nature of the surface e.g. land, sea, sea_ice. These strings are standardised. Values must be taken from the area_type table. [CF-Standard Name where cell method]; unit: not filled
Attribute description
wind_from_direction
Descriptor

Wind is defined as a two-dimensional (horizontal) air velocity vector, with no vertical component. (Vertical motion in the atmosphere has the standard name upward_air_velocity.) In meteorological reports, the direction of the wind vector is usually (but not always) given as the direction from which it is blowing (wind_from_direction) (westerly, northerly, etc.). In other contexts, such as atmospheric modelling, it is often natural to give the direction in the usual manner of vectors as the heading or the direction to which it is blowing (wind_to_direction) (eastward, southward, etc.) "from_direction" is used in the construction X_from_direction and indicates the direction from which the velocity vector of X is coming. [CF-Standard Name]; unit: not filled
Attribute description
air_temperature
Descriptor

Air temperature is the bulk temperature of the air, not the surface (skin) temperature. [CF-Standard Name]; unit: not filled
Attribute description
air_pressure
Descriptor

air_pressure [CF-Standard Name]; unit: not filled
File identifier
wdc-climate.de:3859062 XML
Metadata language

eng; USA
Hierarchy level
collection
Hierarchy level name

ESACCIPSMVSBSIO
Date stamp
2019-07-23T16:52:19
Metadata standard name

ISO 19115
Metadata standard version

ISO 19115-2:2009
Point of contact
  University of Hamburg - Dr. Stefan Kern
http://www.cen.uni-hamburg.de/
Point of contact
  University of Hamburg - Dr. Stefan Kern
http://www.cen.uni-hamburg.de/
 
 

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