A possible influence of the Great White Spot on Saturn kilometric radiation periodicity Annales Geophysicae DOI 10.5194/angeo-32-1463-2014 4 December 2014 In this paper we show that the large thunderstorm called Great White Spot, which raged for about 9 months in Saturn’s troposphere in 2010/2011, was accompanied by changes in the periodicity and phasing of auroral radio emissions. We suggest that the thunderstorm was a source of intense gravity waves causing a global change in Saturn’s ionospheric winds via energy and momentum deposition. This supports the theory that Saturn’s magnetospheric periodicities are driven by the upper atmosphere. Read more
Estimating degree-day factors from MODIS for snowmelt runoff modeling Hydrology and Earth System Sciences DOI 10.5194/hess-18-4773-2014 3 December 2014 In this paper, we propose a new method for estimating the snowmelt degree-day factor (DDFS) directly from MODIS snow covered area and ground-based snow depth data without calibration. Snow density is estimated as the ratio between observed precipitation and changes in the snow volume for days with snow accumulation. DDFS values are estimated as the ratio between changes in the snow water equivalent and difference between the daily temperature and a threshold value for days with snowmelt. Read more
Potential climate forcing of land use and land cover change Atmospheric Chemistry and Physics DOI 10.5194/acp-14-12701-2014 3 December 2014 While climate change mitigation policy often focuses on the energy sector, we find that 40% of the historical human-caused change in the Earth’s radiative balance can be attributed to land use activities, such as deforestation and agriculture. Since pressure on land resources is expected to increase, we compute a theoretical upper bound on the radiative balance impacts from future land use which suggests that not only energy policy but land policy is necessary to minimize future climate change. Read more
Estimated stocks of circumpolar permafrost carbon with quantified uncertainty ranges and identified data gaps Biogeosciences DOI 10.5194/bg-11-6573-2014 1 December 2014 This study provides an updated estimate of organic carbon stored in the northern permafrost region. The study includes estimates for carbon in soils (0 to 3 m depth) and deeper sediments in river deltas and the Yedoma region. We find that field-data is still scarce from many regions. Total estimated carbon storage is ~1300 Pg with an uncertainty range of between 1100 to 1500 Pg. Around 800 Pg carbon is perennially frozen, equivalent to all carbon dioxide currently in the Earths atmosphere. Read more
A comparison between VEGA 1, 2 and Giotto flybys of comet 1P/Halley: implications for Rosetta Annales Geophysicae DOI 10.5194/angeo-32-1441-2014 28 November 2014 We discuss three flybys (within a time span of 8 days) of comet 1P/Halley by VEGA 1, 2 and Giotto. Looking at two different plasma phenomena: mirror mode waves and field line draping; we study the differences in SW-comet interaction between these three flybys. We find that on this time scale (comparable to Rosetta’s orbits) there is a significant difference, both caused by changing outgassing rate of the comet and changes in the solar wind. We discuss implications for Rosetta RPC observations. Read more
Correlations between climate network and relief data Nonlinear Processes in Geophysics DOI 10.5194/npg-21-1127-2014 27 November 2014 In the past few years, complex networks have been extensively applied to climate sciences, yielding the new field of climate networks. Here, we generalize climate network analysis by investigating the influence of altitudes in network topology. More precisely, we verified that nodes group into different communities corresponding to geographical areas with similar relief properties. This new approach may contribute to obtaining more complete climate network models. Read more
Path independence of climate and carbon cycle response over a broad range of cumulative carbon emissions Earth System Dynamics DOI 10.5194/esd-5-409-2014 24 November 2014 Recent studies have identified an approximately proportional relationship between global warming and cumulative carbon emissions. This relationship – referred to as the transient climate response to cumulative carbon emissions (TCRE) – is useful for climate policy applications. We show that the TCRE is constant for cumulative emissions lower than ~1500 GtC, but declines for higher cumulative emissions. We also find the TCRE to decrease with increasing emission rate. Read more
Long-term trends at the Boknis Eck time series station (Baltic Sea), 1957–2013: does climate change counteract the decline in eutrophication? Biogeosciences DOI 10.5194/bg-11-6323-2014 24 November 2014 A time series of 9 oceanic parameters from the coastal time series station Boknis Eck (BE, South Western Baltic Sea) in the period of 1957-2013 is analysed with respect to seasonal cycles and longterm trends. Most striking was a paradoxical decreasing trend in oxygen with a simultaneous decline in eutrophication. Possible reasons for this paradox, e.g. processes related to warming temperatures such as increased decomposition of organic matter or altered ventilation, are discussed. Read more
Detailed ice loss pattern in the northern Antarctic Peninsula: widespread decline driven by ice front retreats The Cryosphere DOI 10.5194/tc-8-2135-2014 24 November 2014 This study of one of the most rapidly changing glacier regions on Earth – the Antarctic Peninsula – uses two types of satellite data to measure the rates of ice loss in detail for the individual glaciers. The satellite data is laser altimetry from ICESat and stereo image DEM differences. The results show that 24..9 ± 7.8 billion tons of ice are lost from the region north of 66°S on the Peninsula each year. The majority of the data cover 2003-2008. Read more
The global monsoon across timescales: coherent variability of regional monsoons Climate of the Past DOI 10.5194/cp-10-2007-2014 21 November 2014 It remains a debated issue as to what extent and at which timescales the global monsoon can be viewed as a major mode of climate variability. For this purpose, a PAGES (Past Global Changes) working group (WG) was set up to investigate the concept of the global monsoon and its future research directions. The WG’s synthesis is presented here. Read more
Complex networks for streamflow dynamics Hydrology and Earth System Sciences DOI 10.5194/hess-18-4565-2014 20 November 2014 This study introduces the theory of networks, and in particular complex networks, to examine connections in streamflow dynamics. Monthly streamflow data from a network of 639 stations in the United States are studied. The connections are examined primarily using the concept of clustering coefficient, which quantifies the network’s tendency to cluster. The clustering coefficient analysis is performed with several different threshold levels based on correlations in streamflow between the stations. Read more
Missing SO2 oxidant in the coastal atmosphere? – observations from high-resolution measurements of OH and atmospheric sulfur compounds Atmospheric Chemistry and Physics DOI 10.5194/acp-14-12209-2014 20 November 2014 Sulfuric acid plays a major role in the formation of aerosol particles and clouds. Measurements at the west coast of Ireland reveal that oxidation of SO2 by OH explains only 20%, on average, of H2SO4 formation in coastal marine air. Additional sources may be oxidation by Criegee intermediates produced photolytically and/or formation from SO3 instead of SO2 in the oxidation of dimethyl sulfide suggesting an important role of marine emissions in the self-cleaning power of the atmosphere. Read more
Historical impact of water infrastructure on water levels of the Mekong River and the Tonle Sap system Hydrology and Earth System Sciences DOI 10.5194/hess-18-4529-2014 17 November 2014 This paper analyses the historical water levels of the Mekong River and Tonle Sap system by comparing pre- and post-1991 daily observations from six stations along the Mekong mainstream from Chiang Saen (northern Thailand), to Stung Treng (Cambodia), and the Prek Kdam station on the Tonle Sap River. Read more
Changes in extreme regional sea surface height due to an abrupt weakening of the Atlantic meridional overturning circulation Ocean Science DOI 10.5194/os-10-881-2014 7 November 2014 As an extreme scenario of dynamical sea level changes, regional sea surface height (SSH) changes that occur in the North Atlantic due to an abrupt weakening of the Atlantic meridional overturning circulation (AMOC) are simulated. Two versions of the same ocean-only model are used to study the effect of ocean model resolution on these SSH changes. Read more
Gas emissions at the continental margin west of Svalbard: mapping, sampling, and quantification Biogeosciences DOI 10.5194/bg-11-6029-2014 6 November 2014 The authors mapped, sampled, and quantified gas emissions at the continental margin west of Svalbard in late summer 2012. They found that gas emissions occurred widespread between about 80 and 415 m water depth, which indicates that hydrate dissolution might only be one of several triggers for active hydrocarbon seepage in that area. Read more
Determining the focal mechanisms of the events in the Carpathian region of Ukraine Geoscientific Instrumentation, Methods and Data Systems DOI 10.5194/gi-3-229-2014 30 October 2014 The paper is devoted to mathematical modelling of propagation of seismic waves in inhomogeneous media. The trial and error method for determining the angles of orientation of fault plane and earthquake mechanism has been proposed. The graphic and trial and error approaches have been applied for determining the source parameters of earthquakes in seismically active region of Eastern Carpathian. Read more
Analytical approach for predicting fresh water discharge in an estuary based on tidal water level observations Hydrology and Earth System Sciences DOI 10.5194/hess-18-4153-2014 17 October 2014 In this study, the authors investigate the influence of river discharge on tidal wave propagation in the Yangtze estuary with specific attention to residual water level slope. Read more
An autonomous adaptive low-power instrument platform (AAL-PIP) for remote high-latitude geospace data collection Geoscientific Instrumentation, Methods and Data Systems DOI 10.5194/gi-3-211-2014 10 October 2014 This paper presents the development considerations and design for ground-based instrumentation that is being deployed on the East Antarctic Plateau along a 40° magnetic meridian chain to investigate interhemispheric magnetically conjugate geomagnetic coupling and other space-weather-related phenomena. Read more
Mapping the physico-chemical properties of mineral dust in western Africa: mineralogical composition Atmospheric Chemistry and Physics DOI 10.5194/acp-14-10663-2014 10 October 2014 In the last few years, several ground-based and airborne field campaigns have allowed the exploration of the properties and impacts of mineral dust in western Africa. This paper explores the synthesis of these observations to provide a large-scale quantitative view of the mineralogical composition and its variability according to source region and time after transport. Read more
Constraining CO2 emissions from open biomass burning by satellite observations of co-emitted species: a method and its application to wildfires in Siberia Atmospheric Chemistry and Physics DOI 10.5194/acp-14-10383-2014 1 October 2014 A method to constrain carbon dioxide (CO2) emissions from open biomass burning by using satellite observations of co-emitted species and a chemistry-transport model (CTM) is proposed and applied to the case of wildfires in Siberia. Read more