In situ aerosol measurements taken during the 2007 COPS field campaign at the Hornisgrinde ground site

Copyright @ 2011 Royal Meteorological Society.The Convective and Orographically-induced Precipitation Study (COPS) campaign was conducted during the summer of 2007. A suite of instruments housed at the top of the Hornisgrinde Mountain (1156 m) in the Black Forest region of south-west Germany provided datasets that allow an investigation into the physical, chemical and hygroscopic properties of the aerosol particles sampled during COPS. Organic mass loadings were found to dominate the aerosol composition for the majority of the project, exceeding 8 µg m−3 during a period of high pressure, high temperature, and low wind speed. The ratio of organic:sulphate sub-micron mass concentration exceeds 10:1 during the same time period. Back trajectories show air from this time-frame passing slowly over the local forest and not passing over any local anthropogenic sources. Occasional peaks in nitrate mass loadings were associated with changes in the typical wind direction from south-westerly to north-westerly where air had passed over the Stuttgart region. Size distribution data shows a dominant accumulation-mode when the measurement site was free from precipitation events. A sharp increase in ultrafine particle number concentration was seen during most days commencing around noon. The apparent growth of these particles is associated with an increase in organic mass loading, suggesting condensational growth. For the most part, with the exception of the high pressure period, the aerosol properties recorded during COPS were comparable to previous studies of continental aerosol properties.NER

Long-term trends in rain and cloud chemistry in a region of complex topography

Rain and cloud water from a high-elevation site and an adjacent lower-level site in the northern Pennines of England were sampled and analysed between 1994 and 2008. The comparison of wet deposition and rainfall depth at the high and low-level sites has been used to estimate the additional deposition of pollutants arising from ‘seeder–feeder’ enhancement by washout of the orographic cap cloud that forms over the high-level site. The derived ‘orographic scavenging ratio’ for different ions is used to map the orographic enhancement of wet deposition across the U.K. The ratio of ion concentrations in cloud and in rain at the high-level site is also important for estimating the input of pollutants through the direct capture of cloud water droplets at high elevation sites. Long-term trends in ion concentrations in cloud and rain showed significant downward trends in non-sea sulphate, and a weaker downward trend in nitrate, but no trend in other ions. There was also no trend in the orographic scavenging ratios, implying that the methods used to estimate orographic enhancement across the U.K. are robust over time

CLIMATE RISK AND FOOD SECURITY IN MALI

We combine socioeconomic data from a large‐scale household survey with historical climate data to map the climate sensitivity of availability and access dimensions of food security in Mali, and infer the ways in which at‐risk communities may have been impacted by persistent climatic shift. Thirty years after 1982–1984, the period of most intense drought during the protracted late 20th century drying of the Sahel, the impact of drought on livelihoods and food security is still recognizable in the Sahelian center of Mali. This impact is expressed in the larger fraction of households in this Sahelian center of the country—the agro‐ecological transition between pastoralism in the north, and sedentary agriculture in the south—who practice agriculture but not livestock raising, despite environmental conditions that are suitable to their combination. These households have lower food security and rely more frequently on detrimental nutrition‐based coping strategies, such as reducing the quantity or quality of meals. In contrast, the more food secure households show a clear tendency toward livelihood diversification away from subsistence agriculture. These households produce less of what they consume, yet spend less on food in proportion. The analysis points to the value of interdisciplinary research—in this case bridging climate science and vulnerability analysis—to gain a dynamical understanding of complex systems, understanding which may be exploited to address real‐world challenges, offering lessons about food security and local adaptation strategies in places among the most vulnerable to climate

Evaluating the effects of microphysical complexity in idealised simulations of trade wind cumulus using the Factorial Method

The effect of microphysical and environmental factors on the development of precipitation in warm idealised cloud is explored using a kinematic modelling framework. A simple one-dimensional column model is used to drive a suite of microphysics schemes including a flexible multi-moment bulk scheme (including both single and dual moment cloud liquid water) and a state-of-the-art bin-resolved scheme with explicit treatments of liquid and aerosol. The Factorial Method is employed to quantify and compare the sensitivities of each scheme under a set of controlled conditions, in order to isolate the effect of additional microphysical complexity in terms of the impact on surface precipitation. At relatively low updraught speeds, the sensitivity of the bulk schemes was found to depend on the assumptions made with regards the treatment of droplet activation. It was possible to achieve a much closer agreement between the single and dual moment bulk schemes by tuning the specified droplet number concentration in the single moment scheme, suggesting that a diagnostic representation of droplet number may be an acceptable alternative to the more expensive prognostic option. However the effect of changes in CCN concentration were found to produce a relatively stronger effect on precipitation in the bulk schemes compared to the bin scheme; this is believed to be a consequence of differences in the treatment of drop growth by collision and coalescence. Collectively, these results demonstrate the usefulness of the Factorial Method as a model development tool for quantitatively comparing and contrasting the behaviour of microphysics schemes of differing levels of complexity within a specified parameter space

Factors influencing ice formation and growth in simulations of a mixed-phase wave cloud

In this paper, numerical simulations of an orographically induced wave cloud sampled in-situ during the ICE-L (Ice in Clouds Experiment - Layer clouds) field campaign are performed and compared directly against the available observations along various straight and level flight paths. The simulations are based on a detailed mixed-phase bin microphysics model embedded within a 1-D column framework with the latest parameterizations for heterogeneous ice nucleation and an adaptive treatment of ice crystal growth based on the evolution of crystal habit. The study focuses on the second of two clouds sampled on 16th November 2007, the in-situ data from which exhibits some interesting and more complex microphysics than other flights from the campaign. The model is used to demonstrate the importance of both heterogeneous and homogeneous nucleation in explaining the in-situ observations of ice crystal concentration and habit, and how the ability to isolate the influence of both nucleation mechanisms helps when quantifying active IN concentrations. The aspect ratio and density of the simulated ice crystals is shown to evolve in a manner consistent with the in-situ observations along the flight track, particularly during the transition from the mixed-phase region of the cloud to the ice tail dominated by homogeneous nucleation. Some additional model runs are also performed to explore how changes in IN concentration and the value of the deposition coefficient for ice affect the competition between heterogeneous and homogeneous ice formation in the wave cloud, where the Factorial Method is used to isolate and quantify the effect of such non-linear interactions. The findings from this analysis show that the effect on homogeneous freezing rates is small, suggesting that any competition between the microphysical variables is largely overshadowed by the strong dynamical forcing of the cloud in the early stages of ice formation

Anatomy of Cirrus Clouds: Results from the Emerald Airborne Campaigns

2000 FLORIDA AVE NW, WASHINGTON, USA, DC, 2000

Index insurance for managing climate-related agricultural risk: toward a strategic research agenda

In October 2011, the CGIAR program on Climate Change, Agriculture and Food Security (CCAFS) and the Index Insurance Innovation Initiative (I4) organized a joint workshop hosted by the International Food Policy Research Institute (IFPRI). The workshop was designed to identify and address issues surrounding index‐based insurance for smallholder farmers and the rural poor in the developing world. Emphasis was placed on identifying key areas of research and learning for the academic and policy community to pursue. The workshop took as its starting point the idea that there is large potential in using indices to insure smallholder farmers. However, in practice, the costs of providing and scaling up index insurance have not been insubstantial. In view of this potential and these constraints, workshop participants identified key areas of research and learning aimed at increasing the benefits of index‐based insurance to smallholder farmers and the rural poor in the developing world. This report summarizes the findings of the two‐day workshop

Climate risk and food security in Nepal—analysis of climate impacts on food security and livelihoods

Food security in Nepal is highly sensitive to climate risks. Recent climate-related events, such as the floods of 2008 and the winter drought of 2008/2009, have highlighted the potential impacts of climate on food production, access to markets and income from agricultural activities. However, the ways in which livelihoods and other vulnerabilities are linked to climate have not been well studied. The purpose of this analysis is to quantitatively and qualitatively assess climate (including climate variability, change and extremes) impacts on food security and livelihoods. The analytical method carried out for this research consisted of three components: (i) a dynamic analysis to evaluate the relationship between historic and current climatic variability and food security indicators, using long-term historical data; (ii) a descriptive analysis to establish a baseline against which vulnerability to future risks can be assessed, using household data from the Nepal Living Standards Survey 2010/2011 (NLSS-III); and (iii) a workshop with national stakeholders to validate the results and identify priority adaptation interventions