• Nonlinear Processes in Geophysics
• DOI 10.5194/npg-22-645-2015
• 3 November 2015

The popular data assimilation technique known as the ensemble Kalman filter (EnKF) suffers from sampling errors due to the limited size of the ensemble. This deficiency is usually cured by inflating the sampled error covariances and by using localization. This paper further develops and discusses the finite-size EnKF, or EnKF-N, a variant of the EnKF that does not require inflation. It expands the use of the EnKF-N to a wider range of dynamical regimes.

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• Natural Hazards and Earth System Sciences
• DOI 10.5194/nhess-15-2201-2015
• 7 October 2015

While the debate is on the possibility that the 2012 Emilia quakes could have been triggered by human activity, we studied the inverse relationship between hydrocarbon and seismicity. Overlapping a data set of gas and oil wells with a database of seismic sources, we found that only 1/19 wells falling on the largest faults is currently productive, while the highest ratio of productive wells is found outside the seismogenic sources. In general, productive gas wells are anti-correlated with faults.

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• Geoscientific Model Development
• DOI 10.5194/gmd-8-3071-2015
• 6 October 2015

The ECCO v4 non-linear inverse modeling framework and its reference solution are made publicly available. The inverse estimate of ocean physics and atmospheric forcing yields a dynamically consistent and global state estimate without unidentified sources of heat and salt that closely fits in situ and satellite data. Any user can reproduce it accurately. Parametric and external model uncertainties are of comparable magnitudes and generally exceed structural model uncertainties.

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• Geoscientific Model Development
• DOI 10.5194/gmd-8-2815-2015
• 9 September 2015

Graphics processing units (GPUs) are an attractive solution in many scientific applications due to their high performance. However, most existing GPU conversions of climate models use GPUs for only a few computationally intensive regions. In the present study, we redesign the mpiPOM (a parallel version of the Princeton Ocean Model) with GPUs. We show that the performance of the new model on a workstation containing four GPUs is comparable to that on a powerful cluster with 408 standard CPU cores, and it reduces the energy consumption by a factor of 6.8.

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• Geoscientific Model Development
• DOI 10.5194/gmd-8-2231-2015
• 24 July 2015

Ecosystem models provide a powerful tool for simulating ocean biology. Care must be exercised when selecting appropriate equations and parameter values to represent chosen marine ecosystems. Here, we present an efficient plankton model testbed, using simplified physics and coded in the freely available language R. Multiple runs can be undertaken for different ocean sites, permitting thorough evaluation of ecosystem model performance. The testbed also serves as an excellent resource for teaching.

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• Biogeosciences
• DOI 10.5194/bg-12-4261-2015
• 22 July 2015

We investigated an unusual ice type, called hair ice. It grows on the surface of dead wood of broad-leaf trees at temperatures slightly below 0°C.We describe this phenomenon and present our biological, physical and chemical investigations to gain insight in the properties and processes related to hair ice: we found, that a winter-acive fungus in the wood is required. Ice segregation is the common mechanism. Chemical analyses show a complex mixture of several thousand lignin/tannin compounds.

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• Geoscientific Model Development
• DOI 10.5194/gmd-8-2079-2015
• 16 July 2015

The natural abundance of ¹⁴C in CO₂ dissolved in seawater is often used to evaluate circulation and age in the ocean and in ocean models. We study limitations of using natural ¹⁴C to determine the time elapsed since water had contact with the atmosphere. We find that, globally, bulk ¹⁴C age is dominated by two equally important components, (1) the time component of circulation and (2) the “preformed ¹⁴C-age”. Considering preformed ¹⁴C-age is critical for an assessment of circulation in models.

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• Earth System Dynamics
• DOI 10.5194/esd-6-435-2015
• 13 July 2015

Our MS focused on uncertainties terrestrial C cycling under newly developed scenarios with CMIP 5 experiment. This study is first results to figure out the relative uncertainties of projected terrestrial C cycling in multiple projection components. Only using our new model inter-comparison project datasets enables us to evaluate various uncertainty sources in projection periods. The information about relative uncertainties are useful for climate science and the climate change impact evaluation.

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• Natural Hazards and Earth System Sciences
• DOI 10.5194/nhess-15-1493-2015
• 3 July 2015

Human vulnerability indicators used by the scientific community are validated in light of past tsunamis (2011 Japan, 2010 Chile, 2009 Samoa, 2004 Indian Ocean). Temporal exposure depends on livelihoods, traditions and gender roles. Vulnerable age groups are the elderly (highest mortality rates) and children. Female mortality is not always higher. There is a high correlation between damaged buildings and victims; distance to the sea, building materials and water depths determine type of damage.

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• Natural Hazards and Earth System Sciences
• DOI 10.5194/nhess-15-1407-2015
• 30 June 2015

The authors of this study have developed a global database of daily, gridded Fire Weather Index System calculations beginning in 1980. Input data and two different estimates of precipitation from rain gauges were obtained from the NASA Modern Era Retrospective-Analysis for Research and Applications. This data set can be used for analyzing historical relationships between fire weather and fire activity, and in identifying large-scale atmosphere–ocean controls on fire weather.

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