Ideas and perspectives: on the emission of amines from terrestrial vegetation in the context of new atmospheric particle formation Biogeosciences DOI 10.5194/bg-12-3225-2015 3 June 2015 In this article we summarise recent science which shows how airborne amines, specifically methylamines (MAs), play a key role in new atmospheric particle formation (NPF) by stabilising small molecule clusters. Read more
Snowfall in the Himalayas: an uncertain future from a little-known past The Cryosphere DOI 10.5194/tc-9-1147-2015 2 June 2015 Snow and ice provide large amounts of meltwater to the Indus, Ganges and Brahmaputra rivers. In this study we show that climate change will reduce the amount of snow falling in the Himalayas, Hindu Kush and Karakoram substantially. The limited number of observations in remote upper-level terrain makes it difficult to get a complete overview of the situation today, but our results indicate that by 2071–2100 snowfall may be reduced by 30–70% with the strongest anthropogenic forcing scenario. Read more
Reliable, robust and realistic: the three R’s of next-generation land-surface modelling Atmospheric Chemistry and Physics DOI 10.5194/acp-15-5987-2015 29 May 2015 Land surface models (LSMs) describe how carbon and water fluxes react to environmental change. They are key component of climate models, yet they differ enormously. Many perform poorly, despite having many parameters. We outline a development strategy emphasizing robustness, reliability and realism, none of which is guaranteed by complexity alone. We propose multiple constraints, benchmarking and data assimilation, and representing unresolved processes stochastically, as tools in this endeavour. Read more
Modelling glacier change in the Everest region, Nepal Himalaya The Cryosphere DOI 10.5194/tc-9-1105-2015 27 May 2015 A glacier mass balance and redistribution model that integrates field observations and downscaled climate fields is developed to examine glacier sensitivity to future climate in the Everest region of Nepal. The modelled sensitivity of glaciers to future climate change is high, and glacier mass loss is sustained through the 21st century for both middle- and high-emission scenarios. Projected temperature increases will expose large glacier areas to melt and reduce snow accumulations. Read more
Local and regional scale measurements of CH4, δ13CH4, and C2H6 in the Uintah Basin using a mobile stable isotope analyzer Atmospheric Measurement Techniques DOI 10.5194/amtd-8-4859-2015 13 May 2015 We describe an innovative instrument based on cavity ring down spectroscopy that analyzes the stable isotopes of methane in the ambient atmosphere. This instrument was used to study atmospheric emissions from oil and gas extraction activities in the Uintah Basin in Utah. These measurements suggest that 86 ± 7% of the total emissions in the basin are from natural gas production. The easy field deployment of this instrument can enable similar regional attribution studies across the world. Read more
Oceanic and atmospheric forcing of Larsen C Ice-Shelf thinning The Cryosphere DOI 10.5194/tc-9-1005-2015 13 May 2015 Antarctic Peninsula ice shelves have collapsed in recent decades. The surface of Larsen C Ice Shelf is lowering, but the cause of this has not been understood. This study uses eight radar surveys to show that the lowering is caused by both ice loss and a loss of air from the ice shelf’s snowpack. At least two different processes are causing the lowering. The stability of Larsen C may be at risk from an ungrounding of Bawden Ice Rise or ice-front retreat past a ‘compressive arch’ in strain rates. Read more
The GAMDAM glacier inventory: a quality-controlled inventory of Asian glaciers The Cryosphere DOI 10.5194/tc-9-849-2015 6 May 2015 We present a new glacier inventory for high-mountain Asia named Glacier Area Mapping for Discharge from the Asian Mountains (GAMDAM). Glacier outlines were delineated manually using 356 Landsat ETM+ scenes in 226 path-row sets from the period 1999–2003, in conjunction with a digital elevation model and high-resolution Google EarthTM imagery. Our GAMDAM Glacier Inventory includes 87,084 glaciers covering a total area of 91,263 ± 13,689 km2 throughout high-mountain Asia. Read more
Open ocean dead zones in the tropical North Atlantic Ocean Biogeosciences DOI 10.5194/bg-12-2597-2015 30 April 2015 This study is the first report of the formation of dead zones in the open ocean. A combination of multiple ocean observing system elements (mooring, floats, satellites, ships) allowed us to reconstruct the generation of the dead zones and to connect the formation to enhanced respiration within mesoscale ocean eddies. The dead zones present specific threats to the ecosystem, such as the interruption of the diurnal migration of zooplankters. Read more
Storm type effects on super Clausius–Clapeyron scaling of intense rainstorm properties with air temperature Hydrology and Earth System Sciences DOI 10.5194/hess-19-1753-2015 16 April 2015 We present an empirical study of the rates of increase in precipitation intensity with air temperature using high-resolution 10 min precipitation records in Switzerland. We estimated the scaling rates for lightning (convective) and non-lightning event subsets and show that scaling rates are between 7 and 14%/C for convective rain and that mixing of storm types exaggerates the relations to air temperature. Doubled CC rates reported by other studies are an exception in our data set. Read more
Field survey report and satellite image interpretation of the 2013 Super Typhoon Haiyan in the Philippines Natural Hazards and Earth System Sciences DOI 10.5194/nhess-15-805-2015 10 April 2015 Super Typhoon Haiyan devastated the Eastern Visayas islands of the Philippines on 8 November 2013. The International Research Institute of Disaster Science (IRIDeS) at Tohoku University in Sendai, Japan, deployed several teams for damage recognition, relief support and collaboration with regard to this event. In this paper, we summarize the rapid damage assessment from satellite imagery conducted days after the event and report on the inundation measurements and damage surveyed in the field. Read more
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