hyDRaCAT Spectral Reflectance Library: Hyperspectral Field Spectroscopy and Field Spectro-Goniometry of Siberian and Alaskan Tundra

hyDRaCAT Spectral Reflectance Library for tundra provides the surface reflectance data and the bidirectional reflectance distribution function (BRDF) of important Arctic tundra vegetation communities at representative Siberian and Alaskan tundra sites. The aim of this dataset is the hyperspectral and spectro-directional reflectance characterization as basis for the extraction of vegetation parameters, and the normalization of BRDF effects in off-nadir and multi-temporal remote sensing data. The spectroscopic and field spectro-goniometric measurements were undertaken on the YAMAL2011 expedition of representative Siberian vegetation fields and on the North American Arctic Transect NAAT2012 expedition of Alaskan vegetation fields both belonging to the Greening-of-the-Arctic (GOA) program. For the field spectroscopy each 100 m2 vegetation study grid was divided into quadrats of 1 × 1 m. The averaged reflectance of all quadrats represents the spectral reflectance at the scale of the whole grid at the 10 × 10 m scale. For the surface radiometric measurements two GER1500 portable field spectroradiometers (Spectra Vista Corporation, Poughkeepsie, NY, USA) were used. The GER1500 measures radiance across the wavelength range of 350-1,050 nm, with sampling intervals of 1.5 nm and a radiance accuracy of 1.2 × 10**-1 W/cm**2/nm/sr. In order to increase the signal-to-noise ratio, 32 individual measurements were averaged per one target scan. To minimize variations in the target reflectance due to sun zenith angle changes, all measurements at one study location have been performed under similar sun zenith angles and during clear-sky conditions. The field spectrometer measurements were carried out with a GER1500 UV-VIS spectrometer The spectrogoniometer measurements were carried out with a self-designed spectro-goniometer: the Manual Transportable Instrument platform for ground-based Spectro-directional observations (ManTIS, patent publication number: DE 10 2011 117 713.A1). The ManTIS was equipped with the GER1500 spectrometer allowing spectro-directional measurements with up to 30° viewing zenith angle by full 360° viewing azimuth angles. Measurements in central Yamal (Siberia) at the research site 'Vaskiny Dachi' were carried out in the late summer phenological state from August 12 2011 to August 28 2011. All measurements in Alaska along the North South transect on the North Slope were taken between 29 June and 11 July 2012, ensuring that the vegetation was in the same phenological state near peak growing season.

Documentation of Graf-Wilczek-Knoll

During Leg ANT-XXIII/9 on the 31st March 2007 the German research vessel Polarstern mapped a significant bathymetric feature with its swath sonar system at the north-west margin of the Kerguelen Plateau. Due to the fact, that the feature was discovered just a month after the third IPY 2007/2008 has started, it was named after Graf Wilczek who, together with Carl Weyprecht, had promoted the first IPY. The undersea feature name proposal was officialy accepted by the GEBCO Sub-Committee on Undersea Feature Names (SCUFN) at its 20th meeting in late July and was added to the GEBCO Gazetteer of UFN (http://www.iho.shom.fr/COMMITTEES/GEBCO/SCUFN/scufn_intro.htm). ______________ Graf Hans Wilczek (Notation of the name from the book of Wilczek's daughter Elisabeth Kinsky- Wilczek). The Austrian naval hero Tegetthoff in 1871 planned an expedition to the southern hemisphere. The geophysicist G. Neumayer (1826-1909) already was selected as its chief scientist. Also the naval officer Carl Weyprecht (1838-1881) and the mountaineer Julius Payer (1841-1915) were to participate. Because of the sudden death of Tegettoff the project came to a halt and eventually was cancelled. By support of the well known geographer August Petermann (1822-1878) Weyprecht and Payer made a voyage into the Barents Sea which made them believe having seen the "open polar sea". An additional undertaking to confirm and to extend the find was obvious. At this stage of the affair count Hans Wilczek (1837-1922) got involved. He not only fostered a new expedition with a considerable sum of money, but he participated in commanding a support vessel to Novaya Zemlya. Wilczek managed to get home but the expedition vessel under Weyprecht's command became imprisoned in the pack for two years and at least had to be abandoned. After an adventurous trip back to civilisation Weyprecht changed his mind in what he considered the best way of polar research. Together with Wilczek in 1875 he started the promotion of international station-based polar exploration - the IPY was born. Wilczek guaranteed the constitution of an Austrian station on Novaya Zemlya and was ready to winter over there personally. Because of several political and other obstructions the beginning of the IPY was delayed till 1882. Wilczek's friend Weyprecht had passed away already. The command of the Austrian station, eventually erected on Jan Mayen, was given to Emil v. Wohlgemuth (1843-1896). Wilczek financed the main part of the Austrian IPY participation. Wilczek is described as honest and popular. On the one hand acquainted with the most prominent persons of his days, he respected everybody and had many relationships with scientists and artists. There is a kind of autobiography under the title: Hans Wilczek erzählt seinen Enkeln Erinnerungen aus seinem Leben (Hans Wilczek tells his grandchildren reminiscences from his life); edited by his daughter Elisabeth Kinsky-Wilczek, Graz 1933, 502 p. The book is available in an English version: Happy Retrospect - the Reminiscences of Count Wilczek 1837-1922, Bell and Sons, London 1934, 295 p.