The Meaning of Animals

This research examines the social construction of animals by a rural Allegheny culture using a linguistic approach based on estimating the set of attributes associated with the words they used to describe animals. We asked 268 respondents to free-associate with the nouns, chicken and deer when seen in a context of other words related to nature. Their responses were coded and the frequencies of of words and word groupings were tabulated for sub-samples of differing age, gender and occupation. Response words were categorized into seven typologies including two affective types. The results indicate that except for possibly the very young, the social meanings of chicken and deer did not vary with gender, age or occupation. The respondents interpretation of living chicken was indistinguishable from that of unprepared food. Their interpretation of deer was broader and primarily one of interaction with a lesser adversary

Interhemispheric differences in the chemical characteristics of the Indian Ocean aerosol during INDOEX

International audienceThe water soluble inorganic part of the sub-micrometer aerosol was measured from two research vessels over the Indian Ocean during the winter monsoon season (February and March) as part of the INDOEX project in 1998 and 1999. Additional measurements were made of gas phase SO2 from one of the vessels in 1999. All samples collected north of the ITCZ were clearly affected by continental, anthropogenic sources. A sharp transition occurred across the ITCZ with concentrations of nss-SO42, NH4+ and nss-K+ being lower by a factor of 7--15, >20 and >40, respectively, on the southern side of the ITCZ. The contribution from DMS to the sub-micrometer nss-SO42 was estimated to be up to 40% in clean air north of the ITCZ but less than 10% in polluted air originating from India. South of the ITCZ virtually all nss-SO42 was likely to be derived from oxidation of DMS. The concentration of \chem{SO_2} decreased rapidly with distance from the Indian coast, the ratio \SO2nss-SO42 reaching values below 5% after 35 h travel time over the ocean. Surprisingly, MSA, which is derived from DMS, also showed higher concentrations in the sub-micrometer aerosol north of the ITCZ than south of it. This could be explained by the larger sub-micrometer surface area available north of the ITCZ for the condensation of MSA. South of the ITCZ a major part of the MSA was found on the super-micrometer particles. The total amount of MSA, on both sub-micrometer and super-micrometer particles, varied little across the ITCZ. An analysis based on the air trajectories showed that systematic variation in the observed concentrations was associated with variations in the transport from source regions. For example, differences in time since air parcels left the Arabian or Indian coasts was shown to be an important factor for explaining the substantial differences in absolute concentrations

Differences across the ITCZ in the chemical characteristics of the Indian Ocean MBL aerosol during INDOEX

International audienceThe water soluble inorganic part of the sub-micrometer aerosol was measured from two research vessels over the Indian Ocean during the winter monsoon season (February and March) as part of the INDOEX project in 1998 and 1999. Additional measurements were made of gas phase SO2 from one of the vessels in 1999. All samples collected north of the Inter Tropical Convergence Zone, ITCZ, were clearly affected by continental, anthropogenic sources. A sharp transition occurred across the ITCZ with concentrations of nss-SO42-, NH4+ and nss-K+ being lower by a factor of 7-15, >20 and >40, respectively, on the southern side of the ITCZ. The contribution from DMS to the sub-micrometer nss-SO42- was estimated to be up to 40% in clean air north of the ITCZ but less than 10% in polluted air originating from India. South of the ITCZ virtually all nss-SO42- was likely to be derived from oxidation of DMS. The concentration of SO2 decreased rapidly with distance from the Indian coast, the molar ratio SO2/nss-SO42- reaching values below 5% after 35 h travel time over the ocean. Surprisingly, MSA, which is derived from DMS, also showed higher concentrations in the sub-micrometer aerosol north of the ITCZ than south of it. This could be explained by the larger sub-micrometer surface area available north of the ITCZ for the condensation of MSA. South of the ITCZ a major part of the MSA was found on the super-micrometer particles. An analysis based on the air trajectories showed that systematic variation in the observed concentrations was associated with variations in the transport from source regions. For example, differences in time since air parcels left the Arabian or Indian coasts was shown to be an important factor for explaining the substantial differences in absolute concentrations

Cloud and boundary layer interactions over the Arctic sea ice in late summer

Observations from the Arctic Summer Cloud Ocean Study (ASCOS), in the central Arctic sea-ice pack in late summer 2008, provide a detailed view of cloud- atmosphere-surface interactions and vertical mixing processes over the sea-ice environment. Measurements from a suite of ground-based remote sensors, near-surface meteorological and aerosol instruments, and profiles from radiosondes and a helicopter are combined to characterize a weeklong period dominated by low-level, mixed-phase, stratocumulus clouds. Detailed case studies and statistical analyses are used to develop a conceptual model for the cloud and atmosphere structure and their interactions in this environment. Clouds were persistent during the period of study, having qualities that suggest they were sustained through a combination of advective influences and in-cloud processes, with little contribution from the surface. Radiative cooling near cloud top produced buoyancy-driven, turbulent eddies that contributed to cloud formation and created a cloud-driven mixed layer. The depth of this mixed layer was related to the amount of turbulence and condensed cloud water. Coupling of this cloud-driven mixed layer to the surface boundary layer was primarily determined by proximity. For 75%of the period of study, the primary stratocumulus cloud-driven mixed layer was decoupled from the surface and typically at a warmer potential temperature. Since the near-surface temperature was constrained by the ocean-ice mixture, warm temperatures aloft suggest that these air masses had not significantly interacted with the sea-ice surface. Instead, backtrajectory analyses suggest that these warm air masses advected into the central Arctic Basin from lower latitudes. Moisture and aerosol particles likely accompanied these air masses, providing necessary support for cloud formation. On the occasions when cloud-surface coupling did occur, back trajectories indicated that these air masses advected at low levels, while mixing processes kept the mixed layer in equilibrium with the near-surface environment. Rather than contributing buoyancy forcing for the mixed-layer dynamics, the surface instead simply appeared to respond to the mixedlayer processes aloft. Clouds in these cases often contained slightly higher condensed water amounts, potentially due to additional moisture sources from below

Near-surface profiles of aerosol number concentration and temperature over the Arctic Ocean

Temperature and particle number concentration profiles were measured at small height intervals above open and frozen leads and snow surfaces in the central Arctic. The device used was a gradient pole designed to investigate potential particle sources over the central Arctic Ocean. The collected data were fitted according to basic logarithmic flux-profile relationships to calculate the sensible heat flux and particle deposition velocity. Independent measurements by the eddy covariance technique were conducted at the same location. General agreement was observed between the two methods when logarithmic profiles could be fitted to the gradient pole data. In general, snow surfaces behaved as weak particle sinks with a maximum deposition velocity vd = 1.3 mm s−1 measured with the gradient pole. The lead surface behaved as a weak particle source before freeze-up with an upward flux Fc = 5.7 × 104 particles m−2 s−1, and as a relatively strong heat source after freeze-up, with an upward maximum sensible heat flux H = 13.1 W m−2. Over the frozen lead, however, we were unable to resolve any significant aerosol profiles

Near-surface profiles of aerosol number concentration and temperature over the Arctic Ocean

Temperature and particle number concentration profiles were measured at small height intervals above open and frozen leads and snow surfaces in the central Arctic. The device used was a gradient pole designed to investigate potential particle sources over the central Arctic Ocean. The collected data were fitted according to basic logarithmic flux-profile relationships to calculate the sensible heat flux and particle deposition velocity. Independent measurements by the eddy covariance technique were conducted at the same location. General agreement was observed between the two methods when logarithmic profiles could be fitted to the gradient pole data. In general, snow surfaces behaved as weak particle sinks with a maximum deposition velocity <i>v</i><sub>d</sub> = 1.3 mm s<sup>−1</sup> measured with the gradient pole. The lead surface behaved as a weak particle source before freeze-up with an upward flux <i>F</i><sub>c</sub> = 5.7 × 10<sup>4</sup> particles m<sup>−2</sup> s<sup>−1</sup>, and as a relatively strong heat source after freeze-up, with an upward maximum sensible heat flux <i>H</i> = 13.1 W m<sup>−2</sup>. Over the frozen lead, however, we were unable to resolve any significant aerosol profiles

Large-eddy simulation of a two-layer boundary-layer cloud system from the Arctic Ocean 2018 expedition

Climate change is particularly noticeable in the Arctic. The most common type of cloud at these latitudes is mixed-phase stratocumulus. These clouds occur frequently and persistently during all seasons and play a critical role in the Arctic energy budget. Previous observations in the central (north of 80&deg; N) Arctic have shown a high occurrence of prolonged periods of a shallow, single-layer mixed-phase stratocumulus at the top of the boundary layer (BL; altitudes ~300 to 400 m). However, recent observations from the summer of 2018 instead showed a prevalence of a two-layer boundary-layer cloud system. Here we use large-eddy simulation to examine the maintenance of one of the cloud systems observed in the summer of 2018 as well as the sensitivity of the cloud layers to different micro- and macro-scale parameters. We find that the model generally reproduces the observed thermodynamic structure well, with two near-neutrally stratified layers in the BL caused by a low cloud (located within the first few hundred meters) capped by a lower temperature inversion, and an upper cloud layer (based around one km or slightly higher) capped by the main temperature inversion of the BL. The investigated cloud structure is persistent unless there are low aerosol number concentrations (&le; 5 cm-3), which cause the upper cloud layer to dissipate, or high large-scale wind speeds (greater than or equal 8.5 m s-1), which erode the lower inversion and the related cloud layer. These types of changes in cloud structure lead to a substantial reduction of the net longwave radiation at the surface due to a lower emissivity or higher altitude of the remaining cloud layer. The findings highlight the importance of better understanding and representing aerosol sources and sinks over the central Arctic Ocean. Furthermore, they underline the significance of meteorological parameters, such as the large-scale wind speed, for maintaining the two-layer boundary-layer cloud structure encountered in the lower atmosphere of the central Arctic.</p

Communicating risk from the frontline: projecting community voices into disaster risk management policies across scales, in: Urban Ark Briefing No 19. October 2018

Research carried out in Dar es Salaam, Tanzania on cross-scalar risk communication and disaster risk governance reveals that, while there is considerable potential for communities to measure and communicate risk and to prioritise actions, there is little scope for them to influence disaster risk governance at this point in time. This is partly because, although disaster risk management (DRM) is devolved in Tanzania, it has not gone far enough to give adequate powers and financing to the lowest level of government at the sub-wards, which are at the frontline of managing the biggest everyday risks that people face. The effective communication of risks upwards from communities to governments, and of DRM policies and opportunities downwards to communities and across sectors is crucial to overcome these gaps. When communication is participatory and collaborative, there is scope for local city actors to reflect on the need for action to be joined across governance scales, and to ensure communication plays a key role at and between all levels

Florivory Shapes both Leaf and Floral Interactions

Florivory, or the consumption of flowers, is a ubiquitous interaction that can reduce plant reproduction directly by damaging reproductive tissues and indirectly by deterring pollinators. However, we know surprisingly little about how florivory alters plant traits or the larger community of species interactions. Although leaf damage is known to affect floral traits and interactions in many systems, the consequences of floral damage for leaf traits and interactions are unknown. We manipulated floral damage in Impatiens capensisand measured effects on floral attractive traits and secondary chemicals, leaf secondary chemicals, floral interactions, leaf herbivory, and plant reproduction. We also examined relationships between early season floral traits and floral interactions, to explore which traits structure floral interactions. Moderate but not high florivory significantly increased relative selfed reproduction, leading to a shift in mating system away from outcrossing. Florivory increased leaf secondary compounds and decreased leaf herbivory, although mechanisms other than leaf chemistry may be responsible for some of the reduced leaf damage. Florivory altered four of seven measured interactions, including increased subsequent florivory and reduced flower spiders, although only leaf damage effects were significant after correcting for multiple tests. Pretreatment concentrations of floral anthocyanins and condensed tannins were associated with reduced levels of many floral antagonisms, including florivory, nectar larceny, and flower spider abundance, suggesting these traits play a role in floral resistance. Overall, our results indicate a broad range of community and potential evolutionary consequences of florivory through structuring subsequent floral interactions, altering leaf secondary chemicals, and shaping leaf herbivory