limno ctd English utf8 dataset McMurdo Dry Valleys LTER Information Manager im@mcmlter.org pointOfContact 2014-11-04 ISO 19115-2 Geographic Information - North American Profile Metadata - Data with Biological Extensions ISO 19115-2:2009(E) Conductivity, temperature, and depth (CTD) vertical profiles collected from lakes in the McMurdo Dry Valleys, Antarctica (1993-2023, ongoing) 2014-11-04 publication John Priscu Montana State University http://www.montana.edu/ jpriscu@montana.edu pointOfContact documentDigital As part of the Long Term Ecological Research (LTER) project in the McMurdo Dry Valleys of Antarctica, a series of Taylor Valley lakes have been monitored for conductivity, temperature, and depth (CTD). A Seabird instrument was used to record CTD profiles in these perennial ice covered lakes. Name: Jade Lawrence Role: field technician Name: RenĂ©e F. Brown Role: data manager Name: Amy Chiuchiolo Role: former field crew Name: Inigo San Gil Role: former data manager completed McMurdo Dry Valleys LTER Information Manager im@mcmlter.org pointOfContact unknown 2023 - There is no conductivity data for the deep waters of ELB during the 19/20 and 22/23 season because Seabird messed up the conductivity calibrations.   2015 - Data and metadata migrated to the Drupal Ecological Information Management System.   Data underwent revision on the spring of 2012, new depths are offered (WIRE CORRECTED CTD DEPTH) to reflect a different reference system to account for some problems. Additional parameters that were included in 2006 were dropped -- can be derived from the conductivity, depth and temperature values.   2012 onwards - Amy Chiuchiolo provided the revised data, Inigo San Gil prepared for the database and public services.    disturbance theme LTER Core Areas English Lake Bonney is a saline lake with permanent ice cover at the western end of Taylor Valley in the McMurdo Dry Valleys of Victoria Land, Antarctica. It is 7 kilometres or 4.3 mi long and up to 900 metres or 3,000 ft wide. A narrow channel only 50 metres or 160 ft wide. Lake Bonney at Narrows separates the lake into East Lake Bonney 3.32 square kilometres or 1.28 sq mi and West Lake Bonney, 0.99 square kilometres or 0.38 sq mi. The west lobe is flanked by Taylor glacier. Valley: Taylor Distance to Sea : 25 Maximum Length (km): 4.8 Maximum Width (km): 0.9 Maximum Depth (m): 37 Surface Area (km^2): 3.32 Ice Thickness Average Surface (m): 3 - 4.5 Volume (m^3 * 10^6): 54.7 162.536209106445 162.353210449219 -77.724441528320 -77.697700500488 Lake Bonney is a saline lake with permanent ice cover at the western end of Taylor Valley in the McMurdo Dry Valleys of Victoria Land, Antarctica. It is 7 kilometres or 4.3 mi long and up to 900 metres or 3,000 ft wide. A narrow channel only 50 metres or 160 ft wide. Lake Bonney at Narrows separates the lake into East Lake Bonney 3.32 square kilometres or 1.28 sq mi and West Lake Bonney, 0.99 square kilometres or 0.38 sq mi. Valley: Taylor Distance to Sea : 28 Maximum Length (km): 2.6 Maximum Width (km): 0.9 Maximum Depth (m): 40 Surface Area (km^2): 0.99 Ice Thickness Average Surface (m): 2.8-4.5 Volume (m^3 * 10^6): 10.1 162.354934692383 162.269104003906 -77.727287292480 -77.714805603027 Lake Hoare occupies a narrower portion of the Taylor Valley, dammed by the Canada Glacier. It would drain almost completely without this dam. There are a number of islands which may be related to an old terminal of Canada Glacier. The lake is fed primarily from direct runoff from the glacier, as well as meltwater streams. (Lake level rose ~1.5 m between 1972 and 1996). There are no surface outflows; the only known water loss is through ice ablation (evaporation, sublimation and physical scouring). Valley: Taylor Distance to Sea : 15 Maximum Length (km): 4.2 Maximum Width (km): 1 Maximum Depth (m): 34 Surface Area (km^2): 1.94 Ice Thickness Average Surface (m): 3.1 - 5.5 Volume (m^3 * 10^6): 17.5 162.935836791992 162.784423828125 -77.639259338379 -77.623085021973 The Lake Fryxell basin is formed by a moraine depression in a wider portion of the Taylor Valley. It has a number of moraine islands and shallower areas, as well as several relatively well developed deltas. The lake is fed by at least 10 meltwater streams with a total drainage catchment of 230 km2. The lake is dammed to the southwest by the Canada Glacier and is topographically closed. It is perennially ice covered; during summer months, an ice-free moat generally forms around much of the lake margin. Lake levels have risen ~2 m between 1971 and 1996. There are no surface outflows; the only known water loss is through ice ablation (evaporation, sublimation and physical scouring). Valley: Taylor Distance to Sea : 9 Maximum Length (km): 5.8 Maximum Width (km): 2.1 Maximum Depth (m): 20 Surface Area (km^2): 7.08 Ice Thickness Average Surface (m): 3.3 - 4.5 Volume (m^3 * 10^6): 25.2 163.259582519531 163.048782348633 -77.622711181641 -77.597076416016 Lake Vanda is located in the Wright Valley, adjacent to the Taylor Valley. It is fed primarily by the Onyx River, which has its origin at Lake Brownworth, and ultimately at the Lower Wright Glacier located ~27 km east of the lake. The lake has no outflow. Valley: Wright Distance to Sea : 47 Maximum Length (km): 8 Maximum Width (km): 2 Maximum Depth (m): 75 Surface Area (km^2): 5.2 Ice Thickness Average Surface (m): 2.8 - 4.2 Volume (m^3 * 10^6): 160 161.691970825195 161.391906738281 -77.542304992676 -77.518882751465 Lake Joyce lies in the Pearse Valley against the Taylor Glacier.  Valley: Pearse  Distance to Sea : 44  Maximum Length (km): 1  Maximum Width (km): 1  Maximum Depth (m): 35  Surface Area (km^2): 0.83  Ice Thickness Average Surface (m): 3.9 - 5.6  Volume (m^3 * 10^6): 4.9 161.662445068359 161.608886718750 -77.726486206055 -77.715972900391 Lake Miers lies in the Miers Valley. Valley: Miers Distance to Sea : 20 Maximum Length (km): 1.5 Maximum Width (km): 0.7 Maximum Depth (m): 21 Surface Area (km^2): 1.3 Ice Thickness Average Surface (m): 3.4 - 6 Volume (m^3 * 10^6): 2.9 163.886840820313 163.812332153320 -78.101478576660 -78.094047546387 ground condition 1993-12-06 2023-01-07 https://mcm.lternet.edu/sites/default/files/data/mcmlter-lake-ctd-20231023.csv LIMNO_CTD eng; US McMurdo Dry Valleys LTER LIMNO_CTD Record Delimiter : \n Number of Header Lines : 1 Number of Footer Lines : 1 Orientation : Column Quote Character : "Field Delimiter : , false DATASET_CODE Code to identify the table - used by the data query system LIMNO_RUN Code for lake's sampling location and date LOCATION NAME Name of lake where measurement was made LOCATION CODE Code for site where measurement was made, a database integrity constraint too DEPTH (m) Depth (below the piezometric water level) derived from pressure using the Seabird software (d = p * 1.019716). Note: The upper 3-6 meters of each CTD cast, depending upon ice thickness for each lake, represents conditions within the ice melt hole and is not representative of actual lake water. It is advised that users of the data review the Lake Ice Thickness dataset in the MCM Database to find where the liquid water column starts for each cast. CTD CONDUCTIVITY (mS/cm) Conductivity measured at lake depth CTD TEMP (C) Temperature measured at lake depth CTD COMMENTS Helpful hints about the CTD measurements FILE_NAME Name of file in which data was submitted DATE_TIME Date on which sample was gathered Date Time Format: MM/DD/YYYY WIRE CORRECTED DEPTH (m) CTD Depth (see DEPTH) corrected with lake specific equations based on the relationship between CTD measured depths, and depths measured by a calibrated winch cable. These corrections are necessary because of the high density of the bottom waters of East and West Lake Bonney, and the offset in the pressure sensor output compared to the winch measured depth at the surface of all lakes. DEPTH MASL Depth referred to the Sea level. Distance below Mean Average Sea water level reference from which sample was drawn DBF https://mcm.lternet.edu/sites/default/files/data/mcmlter-lake-ctd-20231023.csv dataset The Seabird 25 CTD instrument (see below for updated instrument models) is cast in the Weatherport/Polar Haven sampling hole at locations where these structures are available (e.g., Fryxell, Hoare, East and West Lake Bonney), generally between 10 am and 2 pm on a day prior to or following limnological sampling; CTD profiles at lakes where these structures are not available are made from an outside hole. The CTD is deployed at all times using a depth calibrated wire on a manual winch. The instrument is lowered at a rate of 1 m sec-1 to a depth approximately 1 m above the bottom of the lake and retrieved at the same rate. Downcast data are compiled using SBE Data Processing software and current configuration files. Data are binned into 0.1 decibar intervals based on pressure, which equates to approximately 0.1 m intervals. Depth is derived using the freshwater derivation (d = p * 1.019716) using the SBE Data Processing software.       The thickness of the ice varies between 3 and 6 m among lake and year, and the CTD starts recording data at the surface of the water, which is about 30-50 cm beneath the ice surface. Hence, the top 3-6 meters of each cast (depending on ice thickness) are in the ice melt hole, and are not representative of the liquid water column. It is advised that users of the data review the Lake Ice Thickness data package to find where the liquid water column starts for each cast.   Because of the high density of the bottom waters of East and West Lake Bonney, and the offset in the pressure sensor output compared to the winch measured depth at the surface of all lakes, a correction equation for each lake is applied to the depth calculated from the CTD pressure sensor to obtain the wire-corrected depth. The equations below relate the pressure-depth output by the CTD to actual depth measured with a calibrated wire, where x = CTD measured depth (m), and y = wire corrected depth (m):   FRX: y = 0.9957x + 0.6774 HOR: y = 0.9987x + 0.7478 ELB: y = -0.003x2 + 1.0431x + 0.5737 WLB: y = -0.0019x2 + 1.0162x + 0.8106 MIE: y = -0.9968x + 0.6932 During the 16-17 season, new equations were determined for ELB and WLB to account for lake level rise. These equations were better able to correct the CTD measured depths at the deeper depths of these lakes. The equations are as follows: ELB: y = -0.0028x2 + 1.0437x + 0.5828WLB: y = -0.0017x2 + 1.0179x + 0.6418 Note that the depth calculated from the CTD pressure sensor can vary by up to 0.6 m depending on atmospheric pressure at the time of the cast. Note that no corrections have been determined for other lakes profiled. For more details on wire corrected data, see Spigel and Priscu 1996. 4 Graphs not inserted here, since this XML specification cannot describe nor carry them adequately. (to be revised -- now we can include images) A new CTD (Seabird 19plusV2) was purchased in 2019 and arrived halfway through the season. Some data from 2019 was collected with a Seabird SBE 19 CTD until the new instrument arrived. Depth correction equations (where x= CTD recorded depth in meters and y = wire corrected depth in meters) for both instruments are as follows: SBE 19: East Lobe Bonney: y = -0.0030x2 + 1.0593x + 0.6187 Hoare: y = 1.0045x + 0.7735 Seabird 19plusV2: Fryxell: y = 0.9975x + 0.4236 Hoare: y = 0.9989x + 0.3939 East Lobe Bonney: y = -0.0030x2 + 1.0567x + 0.1440 West Lobe Bonney: y = -0.0018x2 + 1.0198x + 0.3919 There is no conductivity data for the deep waters of ELB during the 19/20 and 22/23 season because Seabird messed up the conductivity calibrations.  Metadata Access Constraints: none Metadata Use Constraints: none annually McMurdo Dry Valleys LTER http://mcmlter.org/ pointOfContact