On producing sea ice deformation data sets from SAR-derived sea ice motion The Cryosphere DOI 10.5194/tc-9-663-2015 9 April 2015 We present a new method to compute sea ice deformation fields from satellite-derived motion. The method particularly reduces the artificial noise that arises along discontinuities in the sea ice motion field. We estimate that this artificial noise may cause an overestimation of about 60% of sea ice opening and closing. The constant overestimation of the opening and closing could have led in previous studies to a large overestimation of freezing in leads, salt rejection and sea ice ridging. Read more
Rapid transport of East Asian pollution to the deep tropics Atmospheric Chemistry and Physics DOI 10.5194/acp-15-3565-2015 31 March 2015 We use observations and model calculations to show that “cold surges” occurring during Northern Hemisphere winter can rapidly transport East Asian pollution to equatorial Southeast Asia. As well as affecting atmospheric composition near the surface, we argue that strong convection can subsequently lift the polluted air masses to the tropical upper troposphere. This suggests a potentially important connection between midlatitude pollution sources and the lower stratosphere. Read more
Intercomparison of vertically resolved merged satellite ozone data sets: interannual variability and long-term trends Atmospheric Chemistry and Physics DOI 10.5194/acp-15-3021-2015 17 March 2015 Understanding ozone trends in the vertical are vital in terms of assessing the success of the Montreal Protocol. This paper compares and analyses the long-term trends in stratospheric ozone from seven new merged satellite data sets. The data sets largely agree well with each other, particularly for the negative trends seen in the early period 1984-1997. For the 1998-2011 period there is less agreement, but a clear shift from negative to mostly positive trends. Read more
Continuous and discontinuous variation in ecosystem carbon stocks with elevation across a treeline ecotone Biogeosciences DOI 10.5194/bg-12-1615-2015 12 March 2015 Here we investigate how ecosystem carbon stocks vary with elevation shifting from the closed forest to open alpine tundra, in the mountains of southern Norway. Above-ground carbon stocks decreased with elevation, with a clear breakpoint at the forest line, while the organic horizon soil carbon stocks increased linearly with elevation. Overall, ecosystem carbon stocks increased with elevation above the treeline and decreased with elevation below, demonstrating the importance of the treeline. Read more
A novel algorithm for detection of precipitation in tropical regions using PMW radiometers Atmospheric Measurement Techniques DOI 10.5194/amt-8-1217-2015 12 March 2015 The CCA algorithm is applicable to any modern passive microwave radiometer on board polar orbiting satellites; it has been developed using a data set of co-located SSMIS and TRMM-PR measurements and AMSU-MHS and TRMM-PR measurements. The algorithm shows a small rate of false alarms and superior detection capability and can efficiently detect (POD between 0.55 and 0.71) minimum rain rate varying from 0.14 mm/h (AMSU over ocean) to 0.41 (SSMIS over coast). Read more
The soil N cycle: new insights and key challenges SOIL DOI 10.5194/soil-1-235-2015 11 March 2015 Here, we review important insights with respect to the soil N cycle that have been made over the last decade, and present a personal view on the key challenges of future research. Read more
Improved routines to model the ocean carbonate system: mocsy 2.0 Geoscientific Model Development DOI 10.5194/gmd-8-485-2015 9 March 2015 We provide improved routines to model the ocean carbonate system, i.e., to compute ocean pH and related variables from dissolved inorganic carbon and total alkalinity. These routines (1) rely on the fastest available algorithm to solve the alkalinity-pH equation, which converges even under extreme conditions; (2) avoid common model approximations that lead to errors of 3% or more in computed variables; and (3) account for large pressure effects on subsurface pCO2, unlike other packages. Read more
Use of Ra isotopes to deduce rapid transfer of sediment-derived inputs off Kerguelen Biogeosciences DOI 10.5194/bg-12-1415-2015 5 March 2015 We investigated the origin and mechanisms of the natural iron fertilization that sustains a phytoplankton bloom downstream of the Kerguelen Islands. We used radium isotopes to trace the fate of shelf waters that may transport iron and other micronutrients towards offshore waters. We show that shelf waters are rapidly transferred offshore and may be transported across the polar front (PF). The PF may thus not be a strong physical barrier for chemical elements released by the shelf sediments. Read more
Using results from the PlioMIP ensemble to investigate the Greenland Ice Sheet during the mid-Pliocene Warm Period Climate of the Past DOI 10.5194/cp-11-403-2015 5 March 2015 Climate and ice sheet models are often used to predict the nature of ice sheets in Earth history. It is important to understand if such predictions are consistent between different models, especially in warm periods of relevance to the future. We use input from 15 different climate models to run one ice sheet model and compare the predictions over Greenland. We find that there are large differences between the predicted ice sheets for the warm Pliocene (c. 3 million years ago). Read more
Evaluation of coral reef carbonate production models at a global scale Biogeosciences DOI 10.5194/bg-12-1339-2015 4 March 2015 Production of calcium carbonate by coral reefs is important in the global carbon cycle. Using a global framework we evaluate four models of reef calcification against observed values. The temperature-only model showed significant skill in reproducing coral calcification rates. The absence of any predictive power for whole reef systems highlights the importance of coral cover and the need for an ecosystem modelling approach accounting for population dynamics in terms of mortality and recruitment. Read more
