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Occurrence of lower cloud albedo in ship tracks

The concept of geoengineering by marine cloud brightening is based on seeding marine stratocumulus clouds with sub-micrometer sea-salt particles to enhance the cloud droplet number concentration and cloud albedo, thereby producing a climate cooling effect. The efficacy of this as a strategy for global cooling rests on the extent to which aerosol-perturbed marine clouds will respond with increased albedo. It is found that the sign (increase or decrease) and magnitude of the albedo response in ship tracks depends on the mesoscale cloud structure, the free tropospheric humidity, and cloud top height.

Improving the active involvement of stakeholders and the public in flood risk management – tools of an involvement strategy and case study results from Austria, Germany and Italy

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-12-2785-2012
11 September 2012

This paper presents basic elements and the application of two innovative approaches as a part of an “involvement strategy” that aims at the active involvement of all interested parties (stakeholders) for assessing, reviewing and updating flood risk management plans, as formulated in the EU Flood Risk Management Directive 2007/60/EC.

The carbon budget of terrestrial ecosystems in East Asia over the last two decades

Biogeosciences
DOI 10.5194/bg-9-3571-2012
7 September 2012

We estimate the current terrestrial carbon balance of East Asia and its driving mechanisms during 1990–2009 using three different approaches: inventories combined with satellite greenness measurements, terrestrial ecosystem carbon cycle models and atmospheric inversion models.

The “step feature” of suprathermal ion distributions: a discriminator between acceleration processes?

With this study, we draw the attention to the so-called “step feature” of the velocity distributions of suprathermal particles in the solar wind and offer a criterion that allows one to distinguish between those scenarios that employ velocity diffusion, i.e. second-order Fermi processes, which are prime candidates in the present debate.

Water resources trends in Middle East and North Africa towards 2050

Changes in water resources availability can be expected as consequences of climate change, population growth, economic development and environmental considerations. A two-stage modeling approach is used to explore the impact of these changes in the Middle East and North Africa region.

Tree height integrated into pantropical forest biomass estimates

Aboveground tropical tree biomass and carbon storage estimates commonly ignore tree height (H). We estimate the effect of incorporating H on tropics-wide forest biomass estimates in 327 plots across four continents using 42 656 H and diameter measurements and harvested trees from 20 sites to answer various questions.

A synthesis of carbon in international trade

In a globalised world, the transfer of carbon between regions, either physically or embodied in production, represents a substantial fraction of global carbon emissions. The resulting emission transfers are important for balancing regional carbon budgets and for understanding the drivers of emissions.

The scientific basis for a satellite mission to retrieve CCN concentrations and their impacts on convective clouds

The cloud-mediated aerosol radiative forcing is widely recognized as the main source of uncertainty in our knowledge of the anthropogenic forcing on climate. Here, we present a new conceptual framework to help us overcome the challenges for improving our understanding, using relatively simple passive satellite measurements in the visible and infared (IR).

Summer ammonia measurements in a densely populated Mediterranean city

Real-time measurements of ambient concentrations of gas-phase ammonia (NH₃) were performed in Barcelona (NE Spain) in summer between May and September 2011. Two measurement sites were selected: one in an urban background traffic-influenced area (UB) and the other in the historical city centre (CC).

Value of medium range weather forecasts in the improvement of seasonal hydrologic prediction skill

We investigated the contribution of medium range weather forecasts with lead times of up to 14 days to seasonal hydrologic prediction skill over the conterminous United States (CONUS).

Photoproduction of ammonium in the southeastern Beaufort Sea and its biogeochemical implications

During the August 2009 Mackenzie Light and Carbon (MALINA) Program, the absorbed photon-based efficiency spectra of NH₄⁺photoproduction (i.e. photoammonification) were determined using water samples from the SE Beaufort Sea, including the Mackenzie River estuary, shelf, and Canada Basin.

Assessing climate model software quality: a defect density analysis of three models

We found that the climate models all have very low defect densities compared to well-known, similarly sized open-source projects. We discuss the implications of our findings for the assessment of climate model software trustworthiness.

Effects of business-as-usual anthropogenic emissions on air quality

The atmospheric chemistry general circulation model EMAC has been used to estimate the impact of anthropogenic emission changes on global and regional air quality in recent and future years (2005, 2010, 2025 and 2050). The emission scenario assumes that population and economic growth largely determine energy and food consumption and consequent pollution sources with the current technologies (“business as usual”).

Aerosol information content analysis of multi-angle high spectral resolution measurements and its benefit for high accuracy greenhouse gas retrievals

In this paper, we investigate the combined aerosol and greenhouse gas retrieval using multiple satellite viewing angles simultaneously. We find that this method greatly enhances the ability to retrieve aerosol properties by 2–3 degrees of freedom.

Statistical adaptation of ALADIN RCM outputs over the French Alps – application to future climate and snow cover

In this study, snowpack scenarios are modelled across the French Alps using dynamically downscaled variables from the ALADIN Regional Climate Model (RCM) for the control period (1961–1990) and three emission scenarios (SRES B1, A1B and A2) for the mid- and late 21st century (2021–2050 and 2071–2100).

Climatic and geologic controls on suspended sediment flux in the Sutlej River Valley, western Himalaya

Here, we present a comprehensive analysis of the spatiotemporal trends in suspended sediment flux based on daily data during the past decade (2001–2009) from four sites along the Sutlej River and from four of its main tributaries.

Enhancing flood resilience through improved risk communications

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-12-2271-2012
20 July 2012

A framework of guiding recommendations for effective pre-flood and flood warning communications derived from the URFlood project (2nd ERA-Net CRUE Research Funding Initiative) from extensive quantitative and qualitative research in Finland, Ireland, Italy and Scotland is presented.

Risk perception – issues for flood management in Europe

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-12-2299-2012
20 July 2012

Public perception of flood risk and flood risk information is often overlooked when developing flood risk management plans. As scientists and the public at large perceive risk in very different ways, flood risk management strategies are known to have failed in the past due to this disconnect between authorities and the public. This paper uses a novel approach in exploring the role of public perception in developing flood risk communication strategies in Europe.

Detecting anthropogenic carbon dioxide uptake and ocean acidification in the North Atlantic Ocean

Fossil fuel use, cement manufacture and land-use changes are the primary sources of anthropogenic carbon dioxide (CO₂) to the atmosphere, with the ocean absorbing approximately 30% (Sabine et al., 2004). Ocean uptake and chemical equilibration of anthropogenic CO₂ with seawater results in a gradual reduction in seawater pH and saturation states (Ω) for calcium carbonate (CaCO₃) minerals in a process termed ocean acidification.

Comparison of OH concentration measurements by DOAS and LIF during SAPHIR chamber experiments at high OH reactivity and low NO concentration

During recent field campaigns, hydroxyl radical (OH) concentrations that were measured by laser-induced fluorescence (LIF) were up to a factor of ten larger than predicted by current chemical models for conditions of high OH reactivity and low NO concentration. These discrepancies, which were observed in forests and urban-influenced rural environments, are so far not entirely understood.