ALBERT

Description: The datasets present measurements of cDOM absorption of lakes located in Central Yamal regularly from the summer periods of 2011 on. The study region is in the central part of Yamal peninsula (Western Siberia, Russia) with the long-term research station Vaskiny Dachi. Vaskiny Dachi has been established in 1988 as permafrost monitoring site, since 1996 it is run by the Earth Cryosphere Institute (ECI), Siberian Branch of Russian Academy of Sciences and an established site for the international Global Terrestrial Network for Permafrost (GTN-P) program. Water samples were collected in calm weather conditions with bottle sampling from the upper 30 cm of water column close to the shore or in the center of lakes from boat. The coastal rim of several lakes on the high plains is affected by recent activation of thermocirques. The samples for CDOM were filtrated directly in the field after sampling. Filtrates for CDOM were prepared by filtrating through 0.7µm pore size glass fiber filters (Whatman) and were stored in cold and dark conditions to avoid the photodegradation of CDOM. CDOM filtrates have been measured after the expedition using the dual-beam Specord 200 laboratory spectrometer (Jena Analytik) at the Otto Schmidt Laboratory OSL, Arctic and Antarctic Research Institute, St. Petersburg, Russia. The OSL CDOM protocol (Heim and Roessler, 2016) prescribes 3 Absorbance (A) measurements per sample from UV to 750 nm against ultra-pure water. The absorption coefficient, a, is calculated by a = 2.303A/L, where L is the pathlength of the cuvette [m], and the factor 2.303 converts log10 to loge. The output of the calculation is a continuous spectrum of a. The CDOM a spectra are used to determine the exponential slope value for specific wavelength ranges, S by fitting the data between min and max wavelength to an exponential function. We provide CDOM absorption coefficients for the wavelengths 254, 260, 350, 375, 400, 412, 440, 443 nm [1/m] and Slope values for three different UV, VIS, wavelength ranges: 275 to 295 nm, 350 to 400 nm, 300 to 500 nm [1/nm]. All data sampling and processing were carried out by scientists from Earth Cryosphere Institute and Alfred Wegener Institute.