Glacier product

This product includes the glacier outlines as extracted from GLIMS together with additional data for each individual glacier.

Fig. 2 Example of the glacier product (light blue), with outlines in black.

Product files

In the following, file contents are explained using RGI region 01 (Alaska) as example:

RGI2000-v7.0-G-01_alaska.shp

RGI glacier outlines as a shapefile (with accompanying .dbf, .prj, .cpg and .shx files).

RGI2000-v7.0-G-01_alaska-attributes.csv

Glacier attributes in a .csv file. The attributes are strictly the same as those encountered in the shapefile. This file allows users to read glacier attributes without reading the entire shapefile.

RGI2000-v7.0-G-01_alaska-attributes_metadata.json

Description of the attributes in the glacier product shapefile: full name, description, units, etc. The content of this file is displayed in Full list of attributes below.

RGI2000-v7.0-G-01_alaska-submission_info.csv

Information about the data providers ordered by submission identifier (subm_id). Each glacier outline can be attributed to a specific submission via their subm_id attribute.

RGI2000-v7.0-G-01_alaska-submission_info_metadata.json

Description of the columns in the submission_info.csv file: full name, description, units, etc. The content of this file is displayed in Submission info table below.

RGI2000-v7.0-G-01_alaska-rgi6_links.csv

A list of overlapping outline pairs between RGI 7.0 and RGI 6.0 describing 1:1, 1:n, n:1 or n:n relationships as well as the overlapping area between them. For example, a perfect match between an RGI 7.0 and RGI 6.0 outline results in a 1:1 relation with 100% area match in both. If a single RGI 6.0 outline was divided into two glaciers for RGI 7.0, a 2:1 relationship (a cluster) would result with two lines in the table with twice 50% area match in RGI 6.0 and twice 100% match in RGI 7.0. In more complex cases the matches are not always perfect and the relationships less straightforward, for example when an outline was remapped.

RGI2000-v7.0-G-01_alaska-hypsometry.csv

Hypsometry for each glacier, preceded by copies of the glacier’s rgi_id and area_km2. The hypsometry data are given as a comma-separated series of elevation-band areas in the form of integer thousandths of the glacier’s total area in km² (area_km2). The sum of the elevation-band area values is constrained to be 1000. This means that an elevation band’s value divided by 10 represents the elevation band’s area as a percentage of total glacier area. For example, a value of 500 for a particular elevation bands means that it contains 50% of the total glacier area. The elevation bands are all 50 m in height and their central elevations are listed in the file header record. Within each hypsometry file the elevation bands extend from the lowest glacierized elevation up to the highest glacierized elevation band of the corresponding first-order region.

Full list of attributes

The following attributes are available in the RGI 7.0 shapefiles. For more details, see Additional information on glacier attributes.

rgi_id

long_name: RGI identifier
description: Unique identifier assigned to a single outline.
datatype: str
units:
source: RGI
rgi6_name: RGI_Id

o1region

long_name: First order region
description: The code of the first-order region to which the glacier belongs.
datatype: str
units:
source: RGI
rgi6_name: O1Region

o2region

long_name: Second order region
description: The code of the second-order region to which the glacier belongs.
datatype: str
units:
source: RGI
rgi6_name: O2Region

glims_id

long_name: GLIMS identifier
description: Non-unique identifier assigned to glaciers by the Global Land Ice Measurements from Space service at NSIDC.
datatype: str
units:
source: GLIMS
rgi6_name: GLIMS_Id

anlys_id

long_name: Analysis identifier
description: The unique identifier assigned within GLIMS for a particular outline of a glacier at a particular time.
datatype: int
units:
source: GLIMS
rgi6_name:

subm_id

long_name: Submission identifier
description: Unique identifier assigned by GLIMS to a specific data submission. Allows to obtain information about the analysts and data submitters.
datatype: int
units:
source: GLIMS
rgi6_name:

src_date

long_name: Outline source date
description: The as-of date for the outline (usually the acquisition date of the image), in the format ISO 8601.
datatype: str
units: date
source: GLIMS
rgi6_name: BgnDate

cenlon

long_name: Center longitude
description: Longitude of an approximately central point within the glacier outlines (not the centroid).
datatype: float
units: degrees
source: RGI
rgi6_name: CenLon

cenlat

long_name: Center latitude
description: Latitude of an approximately central point within the glacier outlines (not the centroid).
datatype: float
units: degrees
source: RGI
rgi6_name: CenLat

utm_zone

long_name: UTM zone
description: Number of the UTM zone for this glacier, based on its representative point. Note that this attribute is for information only, the geometries are all in WGS84.
datatype: int
units:
source: RGI
rgi6_name:

area_km2

long_name: Glacier area
description: Area of the glacier.
datatype: float
units: km2
source: RGI
rgi6_name: Area

primeclass

long_name: Primary classification
description: WGMS primary classification of the glacier. For a categories description, see user guide.
datatype: int
units:
source: GLIMS
rgi6_name:

conn_lvl

long_name: Connectivity level
description: Level of connection to the Greenland Icesheet (0: no connection; 1: weak connection).
datatype: int
units:
source: GLIMS
rgi6_name: Connect

surge_type

long_name: Evidence for surging
description: Flag indicating if surging behavior has been documented for this glacier. For a categories description, see user guide.
datatype: int
units:
source: GLIMS
rgi6_name: Surging

term_type

long_name: Glacier terminus type
description: Flag indicating the terminus type of the glacier. For a categories description, see user guide.
datatype: int
units:
source: GLIMS
rgi6_name: TermType

glac_name

long_name: Glacier name
description: Glacier name (when available).
datatype: str
units:
source: GLIMS
rgi6_name: Name

is_rgi6

long_name: Same as RGI 6.0 outline
description: Flag indicating if the outline is the same as in RGI 6.0 (1) or was remapped (0). Note that it does not guarantee strict equivalence of the polygon (in most of the cases it does).
datatype: int
units:
source: RGI
rgi6_name:

termlon

long_name: Terminus longitude
description: Longitude of the lowest elevation point on the glacier outline.
datatype: float
units: degrees
source: RGI
rgi6_name:

termlat

long_name: Terminus latitude
description: Latitude of the lowest elevation point on the glacier outline.
datatype: float
units: degrees
source: RGI
rgi6_name:

zmin_m

long_name: Minimum elevation
description: Minimum elevation (m above sea level) of the glacier.
datatype: float
units: m
source: RGI
rgi6_name: Zmin

zmax_m

long_name: Maximum elevation
description: Maximum elevation (m above sea level) of the glacier.
datatype: float
units: m
source: RGI
rgi6_name: Zmax

zmed_m

long_name: Median elevation
description: Median elevation (m above sea level) of the glacier.
datatype: float
units: m
source: RGI
rgi6_name: Zmed

zmean_m

long_name: Mean elevation
description: Mean elevation (m above sea level) of the glacier.
datatype: float
units: m
source: RGI
rgi6_name:

slope_deg

long_name: Mean slope
description: Mean slope of the glacier surface.
datatype: float
units: degrees
source: RGI
rgi6_name: Slope

aspect_deg

long_name: Aspect
description: The aspect (orientation) of the glacier surface presented as an azimuth relative to 0° at due north.
datatype: float
units: degrees
source: RGI
rgi6_name: Aspect

aspect_sec

long_name: Aspect sector
description: The aspect (orientation) of the glacier surface presented as a category. For a categories description, see user guide.
datatype: int
units:
source: RGI
rgi6_name:

dem_source

long_name: DEM data source
description: The name of the dataset that was used to compute the topography attributes.
datatype: str
units:
source: RGI
rgi6_name:

lmax_m

long_name: Maximum length
description: Length (m) of the longest surface centerline of the glacier.
datatype: int
units: m
source: RGI
rgi6_name: Lmax

geometry

long_name: Geometry
description: Glacier geometry (Polygon)
datatype:
units: deg
source: GLIMS
rgi6_name: geometry

Additional information on glacier attributes

Glacier identifiers

One RGI outline in the glacier product corresponds to one glacier. Glaciers are identified with the following attributes:

rgi_id

Unique identifier attributed by the RGI when constructing the files. These ids are generated automatically (in order of distance to the westernmost outline in a region) and follow the file naming convention described below. These ids are different from RGI 6.0 and likely to change in future RGI versions.

glims_id

Non-unique identifier assigned to glaciers by the Global Land Ice Measurements from Space service at NSIDC. A single glims_id can have multiple outlines, for example at different dates or when a glacier disintegrates.

anlys_id

Unique identifier assigned within GLIMS for a particular outline of a glacier at a particular time and for a particular submission. These ids allow to unambiguously trace an outline back to the GLIMS database, and will not change between future RGI versions if the outline does not change.

Topography attributes

The zmin_m, zmax_m, zmed_m, zmean_m attributes are computed from a Digital Elevation Model (DEM) reprojected onto a locally defined grid for each glacier. The gridded dataset used to compute these attributes (RGI-TOPO) is documented and available on the OGGM documentation.

Each glacier grid is defined in the locally valid UTM zone (utm_zone attribute) and with a grid spacing \(dx\) depending on the glacier size: \(dx = 14 \sqrt{A} + 10\), with \(dx\) the grid spacing in meters and \(A\) the glacier area in km² [Maussion et al., 2019]. If a grid spacing chosen by this formula exceeds 100 m, the grid spacing is fixed to a maximum of 100 m. Effectively, this means that a glacier of the minimum area of 0.01 km² will have a grid spacing of 11.4 m, a 8 km² glacier a grid spacing of 50 m, and all glaciers above 42 km² a grid spacing of 100 m. The chosen DEM product (dem_source attribute) is reprojected onto the local glacier grid and interpolated using cubic resampling with the rasterio library.

The main DEM product used for RGI 7.0 is the Copernicus DEM [Copernicus, 2019] (used for all but 128 glaciers). The COP-DEM products are available at 30 m and 90 m resolution. For all glaciers which grid size is below 60 m we use the 30 m COP-DEM product as source, and use the 90 m COP-DEM product for all other glaciers. If the COP-DEM product is not available for a glacier, we use one of the alternative products RAMP (21 glaciers), DEM3 (20 glaciers), ASTER (14 glaciers), or TANDEM (73 glaciers). We ask our users to refer to the original data sources in their publications if the topography attributes derived from RGI 7.0 play a significant role: refer to DEM products citations for a full reference.

For each glacier, a glacier mask is computed from the outlines and then applied to compute the glacier statistics.

Slope attributes

The slope_deg, aspect_deg, aspect_sec attributes are computed from the same DEM and grid as for the topography attributes described above (RGI-TOPO).

slope_deg and aspect_deg are computed using a standard trigonometric functions in python. The aspect_sec attribute contains information on the orientation of the glacier, classified into the following categories:

Value	Aspect sector	Aspect range
1	North	[337.5°; 22.5°]
2	North-east	[22.5°; 67.5°]
3	East	[67.5°; 112.5°]
4	South-east	[112.5°; 157.5°]
5	South	[157.5°; 202.5°]
6	South-west	[202.5; 247.5°]
7	West	[247.5°; 292.5°]
8	North-west	[292.5°; 337.5°]
9	Not assigned

Terminus location

The termlon, termlat attributes mark the longitude and latitude of the last point of the main centerline, guaranteed to be on the glacier outline. It represents (approximately) the location of lowest elevation along the glacier outline. Knowing the terminus location is useful to assign a glacier to a hydrological basin, for example.

Fig. 3 Example of the glacier terminus location (red dots) plotted with the centerlines product (purple) drawn over the glacier product (light blue).

Glacier length

The maximum length (lmax_m, in meters) is computed from the main centerline in the RGI 7.0 glacier centerline product. Absolute glacier length is a subjective measure, and principally depends on the chosen “head” of the glacier. The head is distinct from the maximum elevation of the glacier. The centerline algorithm from Kienholz et al. [2014] selects potential heads by searching for local maxima along the glacier outline, and then computes all the centerlines joining all heads to the single terminus. The longest of them is selected as the main centerline, which implies that the computed glacier length is often longer than the shortest route from the highest to the lowest point of the glacier.

Surge type

The surge_type attribute contains information on evidence for surging, and is based on the following datasets:

• All glaciers marked as surge-type in RGI 6.0;

• The global inventory of Sevestre and Benn [2015];

• An inventory of surge-type glaciers in the Karakoram from Bhambri et al. [2017] (region 14);

• An inventory of observed glacier surges in the Pamirs from Goerlich et al. [2020] (region 13);

• An inventory of High Mountain Asia surge-type glaciers from Guillet et al. [2022] (regions 13, 14, 15);

• Additional inventories compiled by Ruth Krembel, Andreas Kääb, and Frank Paul.

Each inventory was intersected with the RGI 7.0 outlines. For inventories with glacier outlines, intersections smaller than 5% by area were discarded. For inventories with point data, where no intersection was found, the closest glacier to the point was manually chosen based on a comparison with the metadata provided with each inventory. Finally, each glacier in the RGI 7.0 was then assigned the category corresponding to the highest level of confidence based on each inventory (i.e., “observed” > “probable” > “possible” > “not assigned”).

Value	Surging
0	No evidence
1	Possible
2	Probable
3	Observed
9	Not assigned

Visit Global attributes statistics for glacier counts/area of this attribute in RGI 7.0 and RGI 6.0.

Terminus type

The term_type attribute contains information on terminus type. All glaciers in RGI 7.0 have been assigned the “Not assigned” category, except for the marine-terminating glaciers in the northern hemisphere (after Kochtitzky et al. [2022]) and in region 17 - Southern Andes (same methodology).

The marine-terminating term_type attribute is valid for approximately the year 2000. The only region missing classification for marine-terminating glaciers is RGI 19 (Antarctic and Subantarctic), thus all glaciers that are “not assigned” outside of RGI 19 can be assumed to be land- or lake-terminating for the mapped year.

As of RGI 7.0, no region or glacier has any attributes available for lake-terminating or shelf-terminating glaciers. We aim to add this information in a future update of the RGI.

Value	Terminus type
0	Land-terminating
1	Marine-terminating
2	Lake-terminating
3	Shelf-terminating
9	Not assigned

Visit Global attributes statistics for glacier counts/area of this attribute in RGI 7.0 and RGI 6.0.

WGMS primary classification

The WGMS primary classification of the glacier (primeclass) is directly fetched from the GLIMS database. It is currently poorly populated, with only few submissions to GLIMS having provided this information.

Digit	Class	Description
0	Miscellaneous	Any type not listed below (please explain)
1	Continental ice sheet	Inundates areas of continental size
2	Icefield	Ice masses of sheet or blanket type of a thickness that is insufficient to obscure the subsurface topography
3	Ice cap	Dome-shaped ice masses with radial flow
4	Outlet glacier	Drains an ice sheet, icefield or ice cap, usually of valley glacier form; the catchment area may not be easily defined
5	Valley glacier	Flows down a valley; the catchment area is well defined
6	Mountain glacier	Cirque, niche or crater type, hanging glacier; includes ice aprons and groups of small units
7	Glacieret and snowfield	Small ice masses of indefinite shape in hollows, river beds and on protected slopes, which has developed from snow drifting, avalanching, and/or particularly heavy accumulation in certain years; usually no marked flow pattern is visible; in existence for at least two consecutive years.
8	Ice shelf	Floating ice sheet of considerable thickness attached to a coast nourished by a glacier(s); snow accumulation on its surface or bottom freezing
9	Rock glacier	Lava-stream-like debris mass containing ice in several possible forms and moving slowly downslope

Submission info table

Each glacier region folder contains a csv file containing information about provenance of the glacier outlines. This file is available for the glacier product only, and allows to associate each outline’s subm_id (submission identifier) to a specific entry in the GLIMS database. The table contains the following columns:

subm_id

long_name: submission_id
description: Unique identifier assigned by GLIMS to a specific data submission. Allows to obtain information about the analysts and data submitters.
datatype: int
units:
source: GLIMS
rgi6_name:

n_outlines

long_name: number_of_outlines
description: Number of outlines from this submission used in RGI 7.0.
datatype: int
units:
source: RGI
rgi6_name:

area_km2

long_name: total_area_of_outlines
description: Total area of the outlines from this submission used in RGI 7.0.
datatype: float
units: km2
source: RGI
rgi6_name:

anlys_time

long_name: analysis_time
description: Representative time the outline analysis was carried out.
datatype: str
units: date
source: GLIMS
rgi6_name:

release_dt

long_name: release_date
description: Date at which the submission was realeased on GLIMS.
datatype: str
units: date
source: GLIMS
rgi6_name:

proc_desc

long_name: processing_description
description: Description of the processing done to create the glacier outlines.
datatype: str
units:
source: GLIMS
rgi6_name:

chief_affl

long_name: chief_affiliation
description: Affiliation of the chief of the regional center or the person(s) who submitted the data.
datatype: str
units:
source: GLIMS
rgi6_name:

submitters

long_name: submitters
description: Person(s) who submitted the data.
datatype: str
units:
source: GLIMS
rgi6_name:

analysts

long_name: analysts
description: Person(s) who created the data.
datatype: str
units:
source: GLIMS
rgi6_name:

rc_id

long_name: regional_center_id
description: GLIMS ID for the regional center.
datatype: int
units:
source: GLIMS
rgi6_name: