Summer and annual environmental variations of two polygons in the Indigirka-Kolyma lowland

• Main Authors: Schirrmeister, Lutz, Schneider, Andrea, Wetterich, Sebastian, Pestryakova, L. A.
• Format: Conference Object
• Language: unknown
• Published: University of Lisbon and the University of Évora 2014
• Subjects: Indigirka; Kolyma; Pokhodsk; permafrost; Thermokarst; Siberia
• Online Access: https://epic.awi.de/id/eprint/35769/; https://epic.awi.de/id/eprint/35769/3/Poster_EUCOP-IV_schirrmeister%282%29.pdf; http://www.eucop4.org/; https://hdl.handle.net/10013/epic.43694; https://hdl.handle.net/10013/epic.43694.d003

Environmental parameters of polygonal patterned ground were monitored near the Kytalyk Station (Indigirka-Lowland, 2011-2012) as well as near the fishing village Pokhodsk (Kolyma Delta, 2012-2013) in north-east Siberia. Both sites, located in a thermokarst depression (alas) and on a flood plain of a small river branch, respectively, are typical low-center polygons of about 20 m in diameter, enclosed by polygon walls and frost cracks. Sensors recorded ground temperature up to one meter depth and soil moisture conditions in the active layer down to the permafrost table. The air temperature was measured at 2 m height on the polygon rim. In polygon ponds, electrical conductivity, water level and water temperature were logged during field seasons from mid-July to the end of August. All data loggers measured every 30 minutes to record diurnal cycles. At both sites ground and air temperature records were collected for a complete year. Furthermore, soil moisture was recorded for a year at the Pokhodsk site, where the monitoring continues until 2015. The recorded air and water temperatures co-vary and show similar daily pattern during the monitored summer period, with a general cooling trend towards the end of the season. Both air and water temperatures seem to be related to water level changes and variations in electrical conductivity. Furthermore, a ground temperature differentiation in the active layer is present. Main peaks and dips follow air temperature patterns, even in the lowermost and coldest horizon of the active layer. Compared to the record from the enclosing polygon rim the temperature differentiation in the polygonal depression is more distinct in the lower horizon and shows a wider temperature range. Soil moisture sensors show mostly constant over time moisture contents in the active layer. Surface soil horizons were driest, interrupted by some short term events, which point to abruptly increasing surface moisture (rainfall) that were also registered as a weaker increase in moisture in the deeper sections. The lowest sensor, which was located close to the permafrost table, did not measure the highest soil water content. This was recorded by the second lowest sensor three centimeters higher and coincides with field observations. The records obtained from two sites in north-east Siberia demonstrate that environmental parameters of polygonal patterned ground are closely linked to local weather variations and climate conditions.