uid=MCM,o=EDI,dc=edirepository,dc=org all public read GLACIER_GSC Alex Mass alex.mass@colorado.edu https://orcid.org/0000-0002-6343-5568 Diane McKnight diane.mcknight@colorado.edu https://orcid.org/0000-0002-4171-1533 McMurdo Dry Valleys LTER http://mcmlter.org/ Renée Brown rfbrown@unm.edu https://orcid.org/0000-0002-4986-7663 data manager 2021-03-26 English

This data package includes measurements pertaining to the spatial distribution and multi-annual persistence of cryoconite holes on Canada and Commonwealth Glaciers in Taylor Valley, Antarctica during two consecutive austral summers (2013-14 and 2014-15). Four circular sampling zones were established on each glacier and multiple measurements of the surface shape and absolute location of all cryoconite holes within the sampling zones were recorded. These measurements can be used to generate spatial maps and analyze the persistence of cryoconite holes from one summer to the next by tracking individual holes and identifying the number lost, gained, and persistent on a multiannual scale. The physical state of each cryoconite hole (liquid-filled, fully frozen, or drained/dry) was also recorded in order to assess the capacity for drained columns to re-initiate downward melting later in the austral summer or during the following year. The glacial surface coverage (GSC) of liquid-filled cryoconite holes can be used in order to assess the contribution of these columns to total glacial melt and drainage. A detailed description for how to use these data in subsequent analyses to spatially map and ‘track’ cryoconite holes over time is available in Water Resources Research: A.Q. Mass and D.M. McKnight (2021) The inter-annual persistence and contribution of cryoconite holes in Taylor Valley, Antarctica to the hydrologic cycle of the McMurdo Dry Valleys under a new climate regime. 

Antarctica cryoconite glacier hydrology ice LTER McMurdo Dry Valleys Taylor Valley Station Keywords hydrologic processes hydrology ice runoff water LTER Controlled Vocabulary

This data package is released under the Creative Commons Attribution 4.0 International License (CC BY 4.0; http://creativecommons.org/licenses/by/4.0/), which allows consumers (hereinafter referred to as “Data Users”) to freely reuse, redistribute, transform, or build on this work (even commercially) so long as appropriate credit is provided. Accordingly, Data Users are required to properly cite this data package in any publications or in the metadata of any derived products that result from its use (in whole or in part). A recommended citation is provided on the summary metadata page associated with this data package in the McMurdo Dry Valleys LTER Data Catalog (https://mcmlter.org/data), and a generic citation may be found on the summary metadata page in the repository where this data package was obtained. When these data contribute significantly to the contents of a publication, Data Users must also acknowledge that data were provided by the NSF-supported McMurdo Dry Valleys Long Term Ecological Research program (OPP-2224760). This data package has been released in the spirit of open scientific collaboration. Hence, Data Users are strongly encouraged to consider consultation, collaboration, and/or co-authorship (as appropriate) with the data package creator(s). Data Users should be aware these data may be actively used by others for ongoing research; thus, coordination may be necessary to prevent duplicate publication. Data Users should also recognize that misinterpretation of data may occur if they are used outside the context of the original study. Hence, Data Users are urged to contact the data package creator(s) if they have any questions regarding methodology or results. While substantial efforts are made to ensure the accuracy of this data package (with all its components), complete accuracy cannot be guaranteed. Periodic updates to this data package may occur, and it is the responsibility of Data Users to check for new versions. This data package is made available “as is” and comes with no warranty of accuracy or fitness for use. The creator(s) of this data package and the repository where these data were obtained shall not be liable for any damages resulting from misinterpretation, use, or misuse of these data. Finally, as a professional courtesy, we kindly request Data Users notify the primary contact referenced in the metadata when these data are used in the production of any derivative work or publication. Notification should include an explanation of how the data were used, along with a digital copy of the derived product(s). Thank you.

https://mcm.lternet.edu/content/spatial-coverage-and-inter-annual-persistence-cryoconite-holes-canada-and-commonwealth The Canada Glacier a small glacier flowing south-east into the northern side of Taylor Valley.  The glacier receives less than 10 cm of snowfall annually. Its seasonal melting feeds Lake Hoare to the west and Lake Fryxell to the east. 162.894287109375 163.057708740234 -77.598403930664 -77.632133483887 The Commonwealth glacier flows in a southeasterly direction and enters the northern side of Taylor Valley immediately west of Mount Coleman. Named by the British Antarctic Expedition for the Commonwealth of Australia in the early 1900s.   163.197784423828 163.373565673828 -77.545059204102 -77.589111328125 286 286 meter 2014-01-20 2015-01-20 McMurdo Dry Valleys LTER Information Manager im@mcmlter.org McMurdo Dry Valleys LTER http://mcmlter.org/ McMurdo Dry Valleys LTER

Notes for data users: Information such as population density, mean diameter, circularity, and the fraction of glacial surface area covered by cryoconite holes at each sampling site can all be calculated directly from the raw data in this package. However, the transect number, CRYO_ORDER, and PERP_DISTANCE_C are relative, date-dependent notes and should not be compared across different sampling dates. The same cryoconite hole may have a different CRYO_ORDER code the following year due to subtle variation in transect placement and the gain/loss of other cryoconite holes (which would in turn affect measurement order). The location-based data in this package can be used to graphically reconstruct each site into a 2-D map of cryoconite holes on the glacial surface. Due to measurement drift (variation in the absolute orientation of transect lines when sites are remeasured), location-based data should not be compared across sampling dates without running a spatial mapping analysis (such as described by Mass and McKnight 2021) in order to align maps from separate measurement periods into the same absolute positioning with a reasonable degree of statistical confidence. Whole dataset comments: Cryoconite holes with a circular surface area (diametric circularity measured as minor/ major axis ratio >0.8) were recorded using measurements A through E (all in centimeters). Conical point F (cm) was only measured for cryoconite holes with an eccentric or oval surface shape (circularity <0.8). Note that ICE_LID_PRESENT is a numeric code for the absence (0) or presence (1) of ice lids and does not count the specific number of lids in multistratified holes. Four sampling locations were established on each glacier in mid-January 2014. Sites 1-4 were established and measured on Commonwealth Glacier on 1/20/14, followed by sites 5-8 on Canada Glacier on 1/21/14. Three sites on Commonwealth Glacier (CW-1, CW-2, and CW-4) were located 5-10 m downslope from a randomly chosen subset of pre-existing mass balance stakes used as reference locations throughout the ablation zone. The remaining site on Commonwealth Glacier (CW-3) was located 200 m upslope from a meteorological station. Locations on Canada Glacier were determined by a randomization function for both up/downslope and transverse directions 60-1500 m from a central reference site on the glacier. These randomization factors were used in order to prevent sampling bias towards regions with a high number of holes. The site locations were recorded by a handheld GPS and the center of each sampling zone was marked by a 3-m long bamboo post (the ‘center post’) drilled 0.5 m into the ice. A second bamboo post (the ‘reference post’) was installed 3 m upslope from the center post. Each site consisted of a circular area with a 3 m radius from the center post, encompassing a 28.27 square meter area of the glacial surface. The sampling zone was subdivided into a series of transect ‘wedges’ and the location, size, and physical state of all cryoconite holes within the transect were recorded. Care was taken not to tread on cryoconite holes or other surface features during site installation and measurements. The first transect was conducted by clipping two weight-reinforced 3 m measuring tapes to the center post, orienting the first towards the upslope reference post, and aligning the second tape one meter away following the outer circumference of the site (see Figure 5 in Mass and McKnight 2021). Consecutive transects were then conducted clockwise in 1-meter intervals around the circumference until the full 28.27 square meter circular area was measured. A metal ice screw was drilled into the surface at the circumferential border of transect nine and served as a secondary reference for transect locations midway through the sampling of each site. Six measurements were collected for each cryoconite hole in the sampling zone, each represented by an alphabetical code in the dataset. These included (A) the distance from the center post to the closest border of the cryoconite hole, (B) distance from the center post to the farthest border of the hole, (C) the perpendicular distance from the lesser transect tape to the closest edge of the hole, (D) the diameter of the major axis, and (E) the diameter of the minor axis. For holes with an eccentric shape, measurement (F) is the distance between the center post and the conical point angled towards (rather than away from) the lesser transect tape. This is a rough measure of the angular orientation of an oval on the glacial surface. A conical point midway between the start/end boundaries (measurements A and B) denotes an oval with a major axis directly perpendicular to the transect line, while a conical point above/below this midway point indicates a major axis tilted towards/away from the transect line with increasing distance from the center post, respectively. Circularity was calculated as the ratio of the minor:major diameter of the hole. Measurement (F) was not recorded for cryoconite holes with circularity >0.8 since the diameter is relatively equal from all angles. (Measurements A through F may be more easily described with diagrams for spatial reference. Multiple figures are available in the Water Resources Research article by Mass and McKnight (2021) and its associated Supporting Information.) Holes bisected by a transect line were measured during the first of the two intervals. Additionally, holes were characterized as either liquid-filled, frozen (filled with re-frozen meltwater), or fully drained. Liquid-filled holes were subcategorized as ice-lidded or open to the surface. Fully-drained ‘hollow’ cryoconite columns were included in spatial mapping on order to see if any sediment would initiate new melting later in the summer or during the following year. The seasonal timing for transect sampling was kept relatively consistent in the peak of each summer to accurately represent changes over the course of a full year. Measurements were repeated on January 18 and 20, 2015 on Canada and Commonwealth Glaciers, respectively.

GLACIER_GSC mcmlter-glac-mass-gsc-20210326.csv 31490 1 1 column , " https://mcm.lternet.edu/sites/default/files/data/mcmlter-glac-mass-gsc-20210326.csv DATASET_CODE Dataset code Internal dataset code. string Internal dataset code. SAMPLING_DATE Sampling date Date when measurements were taken. date MM/DD/YYYY GLACIER Glacier name Name of the glacier (Canada or Commonwealth) where the measurement was taken. string Name of the glacier (Canada or Commonwealth) where the measurement was taken. SAMPLING_SITE Sampling site Code referring to the sampling site where measurements were taken. Sites 1-4 are located on Commonwealth Glacier and sites 5-8 are on Canada Glacier. string Code referring to the sampling site where measurements were taken. Sites 1-4 are located on Commonwealth Glacier and sites 5-8 are on Canada Glacier. CENTERPOST_LAT Centerpost latitude Latitude of the sampling site’s central post in decimal degrees. string Latitude of the sampling site’s central post in decimal degrees. CENTERPOST_LON Centerpost longitude Longitude of the sampling site’s central post in decimal degrees. string Longitude of the sampling site’s central post in decimal degrees. CRYO_ORDER Measurement order Consecutive order in which the cryoconite holes were measured. A code assigned to each cryoconite hole based on the transect wedge in which it was sampled (ordered numerically) and the consecutive order in which the holes were measured within that transect (labeled alphabetically). For example 05-C refers to the third (alphabetical) cryoconite hole measured in transect wedge #5. See methods for elaboration on this variable. string Consecutive order in which the cryoconite holes were measured. A code assigned to each cryoconite hole based on the transect wedge in which it was sampled (ordered numerically) and the consecutive order in which the holes were measured within that transect (labeled alphabetically). For example 05-C refers to the third (alphabetical) cryoconite hole measured in transect wedge #5. See methods for elaboration on this variable. START_DISTANCE_A Start Distance (A) Distance (cm) along the transect line from the center post to the closest border of the cryoconite hole. centimeter real END_DISTANCE_B End Distance (B) Distance (cm) along the transect line from the center post to the farthest border of the cryoconite hole. centimeter real PERP_DISTANCE_C Perpendicular Distance (C) Distance (perpendicular to the transect line; cm) between the transect line and the closest edge of the cryoconite hole. centimeter real MAJOR_DIAMETER_D Major Diameter (D) Diameter (cm) of the major axis of the cryoconite hole. centimeter real MINOR_DIAMETER_E Minor Diameter (E) Diameter (cm) of the minor axis of the cryoconite hole. centimeter real CIRCULARITY Circularity ratio Ratio of the minor to major axis (diameter of minor:major axes), used to determine if elliptical orientation should be measured. Holes with a circularity less than 0.8 were considered significantly oval or eccentric and required Ratio of the minor to major axis, used to determine if elliptical orientation should be measured. Holes with a circularity less than 0.8 were considered significantly oval or eccentric and required measuring conical distance F. string Ratio of the minor to major axis (diameter of minor:major axes), used to determine if elliptical orientation should be measured. Holes with a circularity less than 0.8 were considered significantly oval or eccentric and required Ratio of the minor to major axis, used to determine if elliptical orientation should be measured. Holes with a circularity less than 0.8 were considered significantly oval or eccentric and required measuring conical distance F. CONICAL_POINT_F Conical Point (F) For eccentric or oval-shaped cryoconite holes, this records the location (along the transect line; cm) of the conical point oriented towards, rather than away from, the lesser transect tape. This is a rough measure of the angular orientation of an oval on the glacial surface; see methods for elaboration. Blank cells indicate samples for which this measurement was not applicable. centimeter real MELTWATER_STATE Meltwater state Physical state of meltwater within the cryoconite hole. Classified as either “liquid” (liquid meltwater is present in the hole), “frozen” (column consists of refrozen meltwater) or “dry” (cryoconite hole is hollow/ fully drained). string Physical state of meltwater within the cryoconite hole. Classified as either “liquid” (liquid meltwater is present in the hole), “frozen” (column consists of refrozen meltwater) or “dry” (cryoconite hole is hollow/ fully drained). ICE_LID_PRESENT Ice Lid Presence Indicates whether a liquid-filled cryoconite hole was open to the surface (0) or contained at least one full-coverage ice lid between the liquid layer and glacial surface (1). Note that the numeric code only indicates absence/presence and holes containing multiple stratified ice lids are still indicated by (1). Ice lids are not applicable to fully frozen or dry columns since they do not contain underlying liquid melt. Blank cells indicate missing values. string Indicates whether a liquid-filled cryoconite hole was open to the surface (0) or contained at least one full-coverage ice lid between the liquid layer and glacial surface (1). Note that the numeric code only indicates absence/presence and holes containing multiple stratified ice lids are still indicated by (1). Ice lids are not applicable to fully frozen or dry columns since they do not contain underlying liquid melt. Blank cells indicate missing values. COMMENTS Comments Additional comments to describe the sampling site or cryoconite hole being measured. string Additional comments to describe the sampling site or cryoconite hole being measured.