Tab. 1: Direct beam solar radiation measurements for selected stations in Polar regions

As part of a larger experiment, atmospheric turbidity measurements were carried out during the austral summer 1985/86 in Adelie Land, Eastern Antarctica at 1560 m elevation. A comparison of our measurements of the solar beam with those of other areas in the Arctic and Antarctic was carried out. Our values were higher than all measurements from the Arctic. For Antarctica, Plateau and Mizuho Stations, both higher in altitude, had somewhat higher values, while the value of the coastal stations were lower. We calculated also turbidity indexes such as Unke's turbidity factor T and Angstrom's turbidity coefficient ß. Mean values of T were around 2.0, which are low values indeed. Beta values were around 0.04, a rather typical value for polar regions. No trend in turbidity could be observed for the time of observation. Further, it could be shown that the decrease in intensity with increasing optical air mass was less pronounced for larger wavelengths than for shorter ones.

Geological map of MONSRUDNABBEN, Heimefrontfjella, Antarctica (Scale 1:25,000)

Topographic data of this geological map were obtained through stereoscopic aerial photo interpretation. The photogrammetric photo flights were undertaken in 1986 by the Institut für Angewandte Geodäsie, Frankfurt. Horizontal ground control points required for aerial photo interpretation were determined by means of Doppler satellite observation during the 2nd German Neuschwabenland Expedition 1985/86. Vertical ground control points were taken from unpublished map drafts at 1:100 000 scale by Norsk Polarinstitutt, Oslo. The elevation above mean sea level was transferred to Heimefrontfjella barometrically. For this reason assertions concerning the absolute elevation (referred to sea level) are uncertain. Contours and spot heights presented on the map were obtained from the photogrammetric evaluation of the photography taken in 1986; relative elevation data (hight differences) are accurate to approximately ±10 m.

Halocarbons (water) measured during Maria S. Merian cruise MSM18/3

Halocarbons from oceanic sources contribute to halogens in the troposphere, and can be transported into the stratosphere where they take part in ozone depletion. This paper presents distribution and sources in the equatorial Atlantic from June and July 2011 of the four compounds bromoform (CHBr3), dibromomethane (CH2Br2), methyl iodide (CH3I) and diiodomethane (CH2I2). Enhanced biological production during the Atlantic Cold Tongue (ACT) season, indicated by phytoplankton pigment concentrations, led to elevated concentrations of CHBr3 of up to 44.7 and up to 9.2 pmol/L for CH2Br2 in surface water, which is comparable to other tropical upwelling systems. While both compounds correlated very well with each other in the surface water, CH2Br2 was often more elevated in greater depth than CHBr3, which showed maxima in the vicinity of the deep chlorophyll maximum. The deeper maximum of CH2Br2 indicates an additional source in comparison to CHBr3 or a slower degradation of CH2Br2. Concentrations of CH3I of up to 12.8 pmol/L in the surface water were measured. In contrary to expectations of a predominantly photochemical source in the tropical ocean, its distribution was mostly in agreement with biological parameters, indicating a biological source. CH2I2 was very low in the near surface water with maximum concentrations of only 3.7 pmol/L. CH2I2 showed distinct maxima in deeper waters similar to CH2Br2. For the first time, diapycnal fluxes of the four halocarbons from the upper thermocline into and out of the mixed layer were determined. These fluxes were low in comparison to the halocarbon sea-to-air fluxes. This indicates that despite the observed maximum concentrations at depth, production in the surface mixed layer is the main oceanic source for all four compounds and one of the main driving factors of their emissions into the atmosphere in the ACT-region. The calculated production rates of the compounds in the mixed layer are 34 ± 65 pmol/m**3/h for CHBr3, 10 ± 12 pmol/m**3/h for CH2Br2, 21 ± 24 pmol/m**3/h for CH3I and 384 ± 318 pmol/m**3/h for CH2I2 determined from 13 depth profiles.