http://bolin.su.se/data/tarfala-kirchner-2017-bathymetry-2 Nina Kirchner, Jakob Kuttenkeuler, Riko Noormets, Elias Strandell Erstorp Bolin Centre Database 2019 Datafile Lacustrine Bathymetry Autonomous Bathymetry Lake Tarfala Glacial landforms Glacial lake Earth science > Terrestrial hydrosphere > Surface water > Lakes Nina Kirchner 2019-04-25T06:46:00+00:00 English 2 None, but please cite Kirchner et al. (2019) This data has been acquired by Nina Kirchner, Jakob Kuttenkeuler, Elias Strandell Erstorp, and the autonomous surface vessel (ASV) "ANKA" in 2016. ANKA is equipped with an echosounder of type AIRMAR® EchoRange™ Smart™ Sensor, operated at 200kHz.</p> <p>Data are provided in four xlsx files. </p> <p>kirchner-2019-ANKA-all.xlsx contains 39581 raw soundings performed by ANKA, recorded with LON (column A) and LAT (column B) and depth (columns C and D). Mapping was carried out with an assumed sound velocity of 1500 m/s (column C) and corrected for the sound velocity in fresh water (1430 m/s) in column D.</p> <p>kirchner-2019-ANKA-cleaned.xlsx contains 38598 soundings, resulting from a cleaning of the orginal ANKA dataset. Of the original 39581 ANKA soundings, 983 (approximately 2%) were disregard because they stem from positions already visited earlier by ANKA during the survey (to a seven place decimal accuracy in the decimal-degrees (lon/lat)). Therefore, the entire data set comprises soundings taken at the first visit of a spatial coordinate pairleaving a total of 38598 valid data-points, listed in column C.</p> <p>For comparsion with the bathymetric chart available until 2016, data published 1960 by Larje and Nyberger was digitized. The file kirchner-2019-LN-all.xlsx contains 257 geo-referenced depth values corresponding to Larje and Nyberger's soundings. In kirchner-2019-LN-cropped.xlsx, 12 soundings have been removed because of no overlap with the ANKA data. The ANKA dataset, containing more that 38000 depth-soundings, replaces the previously best-available bathymetric dataset of Lake Tarfala, derived from 257 depth-soundings conducted in 1959 and published in Larje and Nyberger (1960). A comparison of the two datasets shows that the map constructed from the 1960 data is surprisingly accurate despite it lacks exact GPS positioning, but that it was too coarse to reveal the glacial landforms at the bottom of the Lake which, however, become clearly visible in the high-resolution bathymetric data.</p> <p>Literature reference:<br /> Larje, R., Nyberger, L. (1960): Kartering av bottentopografien i Tarfalasjön (Mapping of bottom topography in Lake Tarfala). Naturgeografiska proseminariet, Stockholms Högskola.</p> <p>The data files in Dataset Version 2 are commented in slightly more detail than in Version 1.</p> <p><a href="https://www.youtube.com/watch?v=la8HCtpZRK8">Video from mapping campaign </a>