Composition of airborne material from yellow snow fallen in the Russian North

Large amounts of dust responsible for bright colors of atmospheric precipitation in the temperate, subpolar and polar zones of the northern hemisphere have been rarely observed. In the twentieth century and in the beginning of the twenty first century in the Northern European Russia such events were not registered up to March 25-26, 2008. At that time in some parts of the Arkhangel'sk region, Komi Republic, and Nenets Autonomous Area atmospheric precipitation as sleet and rain responsible for sand- and saffron colors of ice crust formation on the snow surface was observed. During detailed mineralogical, geochemical, pollen, diatom and meteorological investigations it was established that semidesert and steppe regions of the Northwest Kazakhstan, Volgograd and Astrakhan' regions, and Kalmykia are the main sources of the yellow dust.

On the Southern Ocean CO2 uptake and the role of the biological carbon pump in the 21st century, links to supplementary material

We use a suite of eight ocean biogeochemical/ecological general circulation models from the MAREMIP and CMIP5 archives to explore the relative roles of changes in winds (positive trend of Southern Annular Mode, SAM) and in warming- and freshening-driven trends of upper ocean stratification in altering export production and CO2 uptake in the Southern Ocean at the end of the 21st century. The investigated models simulate a broad range of responses to climate change, with no agreement ona dominance of either the SAM or the warming signal south of 44° S. In the southernmost zone, i.e., south of 58° S, they concur on an increase of biological export production, while between 44 and 58° S the models lack consensus on the sign of change in export. Yet, in both regions, the models show an enhanced CO2 uptake during spring and summer. This is due to a larger CO 2 (aq) drawdown by the same amount of summer export production at a higher Revelle factor at the end of the 21st century. This strongly increases the importance of the biological carbon pump in the entire Southern Ocean. In the temperate zone, between 30 and 44° S all models show a predominance of the warming signal and a nutrient-driven reduction of export production. As a consequence, the share of the regions south of 44° S to the total uptake of the Southern Ocean south of 30° S is projected to increase at the end of the 21st century from 47 to 66% with a commensurable decrease to the north. Despite this major reorganization of the meridional distribution of the major regions of uptake, the total uptake increases largely in line with the rising atmospheric CO2. Simulations with the MITgcm-REcoM2 model show that this is mostly driven by the strong increase of atmospheric CO2, with the climate-driven changes of natural CO2 exchange offsetting that trend only to a limited degree (~10%) and with negligible impact of climate effects on anthropogenic CO2 uptake when integrated over a full annual cycle south of 30° S.