Responding to change: Using scenarios to understand how socioeconomic factors may influence amplifying or dampening exploitation feedbacks among Tanzanian fishers

Environmental change often requires societies to adapt. In some instances, these adaptations can create feedbacks that amplify the change. Alternatively, other adaptations may dampen the change. We used semi-structured interviews with 240 fishers from nine Tanzanian coastal communities to explore responses to four hypothetical scenarios of increasingly severe declines in their average catch (10%, 20%, 30% and 50%). Overall, a higher proportion of fishers said they would respond to decline using amplifying adaptations (such as fishing harder) than dampening adaptations (such as reducing effort), particularly in the scenarios with lower levels of decline. We used a redundancy analysis to explore whether certain types of responses were related to the fishers’ socioeconomic characteristics. Fishers that would employ amplifying responses had greater economic wealth but lacked options. Fishers who would adopt dampening responses possessed characteristics associated with having livelihood options. Fishers who would adopt neither amplifying nor dampening responses were less likely to belong to community groups and sold the largest proportion of their catch. This study provides novel contributions by differentiating aspects of adaptive capacity that will amplify versus dampen environmental change and by highlighting what the resource users’ themselves say regarding responding to environmental change. Although direct policy application is limited by the study's hypothetical scenario nature, it provides a good beginning to incorporating resource users’ voices into such policy discussions.     

MJO对2018年华北夏季降水的影响

本文基于华北夏季降水资料和热带大气季节内振荡（Madden–Julian Oscillation，简称MJO）指数、NCEP/NCAR（美国国家环境预报中心/美国国家大气研究中心）再分析环流资料，采用多种统计方法分析MJO与2018年华北夏季降水的关系及影响机制。结果表明:（1）MJO与华北夏季降水有密切的联系。虽然MJO不能移到较高纬度直接影响华北夏季降水，但MJO对流区的气旋会在其北侧激发出反气旋环流，这对“气旋—反气旋对”在缓慢东移过程中，处于较高纬度的反气旋会直接影响华北夏季降水。即MJO会间接影响华北夏季降水，表现为当夏季MJO进入5、6位相时，华北地区夏季会出现明显降水过程，但降水强弱与MJO振幅大小有关。（2）影响机制方面。在850 hPa，伴随MJO的“气旋—反气旋对”的东移，它会造成华北夏季偏南风水汽输送加强（对应RMM1）或东南风水汽输送加强（对应RMM2），从而有利于降水过程发生。在500 hPa层，MJO通过中层扰动向中高纬的传播，诱导副热带高压移到朝鲜半岛附近并加强，对西来高空槽形成阻挡作用，有利于华北地区产生上升运动，从而有利于华北夏季降水过程发生。（3）可以用MJO制作华北夏季延伸期降水过程预报。     

Observations of the evolution of the aerosol, cloud and boundary‐layer characteristics during the 1st ACE‐2 Lagrangian experiment

During the 1st Lagrangian experiment of the North Atlantic Regional Aerosol Characterisation Experiment (ACE‐2), a parcel of air was tagged by releasing a smart, constant level balloon into it from the Research Vessel Vodyanitskiy . The Meteorological Research Flight's C‐130 aircraft then followed this parcel over a period of 30 h characterising the marine boundary layer (MBL), the cloud and the physical and chemical aerosol evolution. The air mass had originated over the northern North Atlantic and thus was clean and had low aerosol concentrations. At the beginning of the experiment the MBL was over 1500 m deep and made up of a surface mixed layer (SML) underlying a layer containing cloud beneath a subsidence inversion. Subsidence in the free troposphere caused the depth of the MBL to almost halve during the experiment and, after 26 h, the MBL became well mixed throughout its whole depth. Salt particle mass in the MBL increased as the surface wind speed increased from 8 m s⁻¹ to 16 m s⁻¹ and the accumulation mode (0.1μm to 3.0 μm) aerosol concentrations quadrupled from 50 cm⁻³ to 200 cm⁻³. However, at the same time the total condensation nuclei (>3 nm) decreased from over 1000 cm⁻³ to 750 cm⁻³. The changes in the accumulation mode aerosol concentrations had a significant effect on the observed cloud microphysics. Observational evidence suggests that the important processes in controlling the Aitken mode concentration which, dominated the total CN concentration, included, scavenging of interstitial aerosol by cloud droplets, enhanced coagulation of Aitken mode aerosol and accumulation mode aerosol due to the increased sea salt aerosol surface area, and dilution of the MBL by free tropospheric air.     

CONNECTION OF THE SOUTH CHINA SEA SUMMER MONSOON TO MARITIME CONTINENT CONVECTION AND ENSO

The relationship between the intensity of the South China Sea summer monsoon (SCSSM) and the Nino3.4 index and anomalous atmospheric circulation patterns associated with a strong and weak SCSSM are investigated using the NCEP/NCAR reanalysis data, Extended Reconstructed Sea Surface Temperature (ERSST) data and Climate Prediction Center Merged Analysis of Precipitation (CMAP) data. The SCSSM is significantly positively correlated with the Nino3.4 index in the succeeding northern autumn and winter. In the strong minus weak SCSSM composite, a positive East Asia-Pacific teleconnection (EAP) pattern and a negative Europe-Asian-Pacific teleconnection (EUP) pattern appear in the 500 hPa height difference field; low-level cross-equatorial flows are strengthened over the Maritime Continent (MC) region; positive (negative) precipitation anomalies occur in the South China Sea and western north Pacific (MC). A possible mechanism through which SCSSM affects ENSO is proposed. A strong (weak) SCSSM strengthens (weakens) cross-equatorial flows over the MC. The anomalous cross-equatorial flows cool (warm) the SST around the MC through enhanced (reduced) surface latent heat fluxes. The cooling (warming) further leads to suppressed (enhanced) convection over the MC, and causes the anomalous westerly (easterly) in the equatorial western Pacific, which favors the onset of El Ni?o (La Ni?a) through modulating the positive air-sea feedback process.     

淮河流域夏季极端降水频次空间分布的客观分类及其形成机理

本文基于1961～2016年淮河流域四省（江苏、安徽、河南、山东）逐日降水观测资料及全球大气再分析资料,利用K均值聚类、旋转经验正交函数分解对淮河流域夏季极端降水频次分布进行了客观分类,利用统计诊断和数值模拟的手段讨论了其相关环流异常和形成机理。结果表明:（1）淮河流域夏季极端降水频次的空间分布可客观分为以极端降水主要发生在淮河流域33°N以南地区的南部型,主要发生在32°～36°N之间的中部型,和主要发生在34°N以北的北部型这三种分布类型;（2）南部型极端降水频次分布与西北太平洋副热带高压异常偏西偏南有关,西北太平洋异常反气旋北侧的异常气旋性环流使得水汽输送停留在淮河流域南部,导致南部极端降水频次偏多。中部型对应淮河流域受鞍型场环流结构控制,导致中部极端降水频次偏多。北部型极端降水频次分布时,淮河流域处于反气旋性环流异常西南侧,偏南风将水汽输送至淮河流域北部,导致北部极端降水频次偏多;（3）南部型和北部型的极端降水频次分布相关环流异常分别受厄尔尼诺和拉尼娜相关海表温度异常所影响,而中部型极端降水频次分布的相关环流异常是巴伦支海/喀拉海海冰异常在欧亚大陆上空激发的自西北向东南传播的准定常罗斯贝波所导致的。