Sustainable Livelihoods Approach in tropical coastal and marine social–ecological systems: A review

Tropical coastal and marine social–ecological systems (CM-SESs) differ from other social–ecological systems through the higher degree of risk and uncertainty associated with coastal and marine resource extraction, the dynamic nature of aquatic and human resources, and often unclear tenure. CM-SES resource management and poverty-alleviation strategies must be adaptive and holistic. The Sustainable Livelihoods Approach (SLA) provides a framework for understanding and guiding policy-making in CM-SES. Case studies from the past 10 years analyze tropical coastal and marine-resource dependent livelihoods and/or to evaluate current CM-SES management using the SLA. These studies have shown that, despite the rounded and inclusive approach of projects such as the Sustainable Fisheries Livelihoods Programme, key challenges for researchers and practitioners remain including rights and access allocation, corruption, lack of local financial, intellectual and innovative capacity and centralized governance. Whilst the SLA may increase understanding of local-level dynamics within CM-SES, more consultation at interdisciplinary frontiers is needed in order to formulate practical solutions to the core problems of tropical CM-SES management.     

The 27-Day and 22-Year Cycles in Solar and Geomagnetic Activity

We study the evolution of the longitudinal asymmetry in solar activity through the wave packet technique applied to the period domain of 25 – 31 days (centered at the 27-day solar rotation period) for the sunspot number and geomagnetic aa index. We observe the occurrence of alternating smaller and larger amplitudes of the 11-year cycle, resulting in a 22-year periodicity in the 27-day signal. The evolution of the 22-year cycle shows a change of regime around the year 1912 when the 22-year period disappears from the sunspot number series and appears in the aa index. Other changes, such as a change in the correlation between solar and geomagnetic activity, took place at the same time. Splitting the 27-day frequency domain of aa index shows an 11-year cycle for higher frequencies and a pure22-year cycle for lower frequencies, which we attribute to higher latitude coronal holes. This evidence is particularly clear after 1940, which is another benchmark in the evolution of the aa index. We discuss briefly the mechanisms that could account for the observed features of the 22-year cycle evolution.     

The certification of small-scale fisheries

Eco-labeling is a market-driven mechanism to promote sustainable fisheries. The most widely used certification scheme for seafood eco-labeling is issued by the Marine Stewardship Council (MSC), but the MSC has been criticized for favoring large-scale industrial fisheries. The benefits from eco-labeling can potentially be significant, ranging from price premiums to enriched understanding of fisheries management among fishers; however, anecdotal evidence from MSC-certified fisheries across various countries highlights the struggle of many small-scale fisheries to meet the costs of certification. The lack of environmental awareness in domestic markets can impede the spread of MSC eco-labeling among small-scale fisheries. In the absence of consumer preferences for seafood sustainability, and without subsidies, the certification may not be an appropriate tool for small-scale seafood producers. Examination of the case of an MSC-certified small-scale fishery suggests some efforts to achieve economies of scale; multi-species fisheries can apply for MSC certification as a single unit of assessment, and fisheries can cooperate with neighboring fisheries that target the same fish stock to share assessment costs. In a market where no price premium has been generated, effective face-to-face marketing is pivotal. The MSC will need to be committed to pursuing price premiums in new markets if it is to extend its reach further to small-scale fisheries.     

Livelihood diversity and dynamism in Timor-Leste; insights for coastal resource governance and livelihood development

Coastal communities within small island developing states are typically highly dependent on fisheries and other natural resource-based livelihoods. However, specialisation as a ‘fisher’ is rare compared to diverse livelihoods that can be adapted as opportunities and challenges emerge. Understanding this dynamic “livelihood landscape” is important for improving governance and livelihood opportunities associated with natural resources. Using data from 495 households across 15 communities on Atauro Island, Timor-Leste, this study evaluates the importance of fisheries within a suite of livelihoods; the correlation of livelihoods structure with wellbeing; and the spatial and temporal variation of those livelihoods. Activities linked to primary production were nominated by 67% of households as their primary livelihood, 41% fished, and of those 54% considered fishing their primary livelihood. Almost all households (95%) owned livestock, and even respondents who considered themselves ‘fishers’ ranked livestock disease, rather than fisheries related concerns, as their most critical livelihood challenge. Engagement in fishing varied by location and time of year. Communities in more protected locales fished throughout the year, and had less diverse livelihoods. This study highlights that interventions focused on self-identified ‘fishers’ would only engage a fraction of the population that derive benefit from fisheries resources, would likely overlook the most prevalent challenges fishers face, and would focus on those with relatively high food security and income. Measures of wellbeing were better explained by geography and socio-cultural settings, rather than dominant income sources. The results emphasise the value of cross-sector development interventions informed by contextualised analysis of livelihoods and wellbeing outcomes.     

Analysis and modeling of spatial correlation structure in small-scale rainfall in Central Oklahoma

Spatial correlation structure in small-scale rainfall is analyzed based on a dense cluster of raingauges in Central Oklahoma. This cluster, called the EVAC PicoNet, consists of 53 gauges installed in 25 measurement stations covering an area of about 3 km by 3 km. Two raingauges are placed in 24 stations and five in the central station. Three aspects of the estimated spatial correlation functions are discussed: dependence on time-scale ranging from 1 min to 24 h, inter-storm variability, and dependence on rainfall intensity. The results show a regular dependence of the correlogram parameters on the averaging time-scale, large differences of the correlograms in the individual storms, and the dominance of storms with high spatial variability on the average large sample characteristics. The authors also demonstrate and discuss the ambiguities in correlation estimates conditioned on rainfall intensities. The findings of this study have implications for raingauge network design, rainfall modeling, and conclusive evaluation of radar and satellite estimates of rainfall.     

造山带下岩石圈地幔小尺度减薄的动力学成因

地质与地球物理观测数据表明青藏高原、安第斯山、以及帕米尔等典型造山高原之下均有明显的岩石圈地幔小尺度/分段式减薄现象.这些小尺度岩石圈减薄难以用经典的拆沉或对流减薄理论来解释,一方面,拆沉预示大尺度岩石圈地幔的剥离过程,而对流减薄则在黏度相对低的地幔岩石圈中发生,其主要以小尺度的局部增厚触发并仅减薄地幔岩石圈的底部区域.另一方面,拆沉或对流减薄模型都预测造山带尺度的地幔岩石圈拆离,都假设造山带岩石圈横向均一,然而实际的造山带岩石圈往往由多个不同的地块构成,块体之间岩性、物性、流变结构可能大有差别,即横向不均一性.这些造山带岩石圈地幔的横向不均一性,能否有效解释观测到的局部小尺度减薄现象？为此,我们构建了一系列高精度动力学数值模型,系统模拟了碰撞造山过程中岩石圈地幔的形变和不稳定性.结果表明,在塑性屈服强度很低的情况下,横向不均一的造山带岩石圈有发生分段式/小尺度减薄的可能性;其主要机理是由位错蠕变与强塑性作用所导致的应变集中使得地块间及壳幔间耦合弱化,从而使得较弱地块的岩石圈地幔在增厚时由于重力不稳定性而产生局部剥离,进而诱发小尺度软流圈上涌.模拟结果可以良好地解释发生在青藏高原东北缘、安第斯中部高原、以及帕米尔高原之下岩石圈的局部小尺度/分段式减薄现象.     

An introduction to quiet daily geomagnetic fields

On days that are quiet with respect to solar-terrestrial activity phenomena, the geomagnetic field has variations, tens of gamma in size, with major spectral components at about 24, 12, 8, and 6 hr in period. These quiet daily field variations are primarily due to the dynamo currents flowing in theE region of the earth's ionosphere, are driven by the global thermotidal wind systems, and are dependent upon the local tensor conductivity and main geomagnetic field vector. The highlights of the behavior and interpretation of these quiet field changes, from their discovery in 1634 until the present, are discussed as an introduction to the special journal issue on Quiet Daily Geomagnetic Fields.     

Meridional equatorial electrojet current in the American sector

Huancayo is the only equatorial electrojet station where the daytime increase of horizontal geomagnetic field (H) is associated with a simultaneous increase of eastward geomagnetic field (Y). It is shown that during the counter electrojet period when H is negative, Y also becomes negative. Thus, the diurnal variation of Y at equatorial latitudes is suggested to be a constituent part of the equatorial electrojet current system. Solar flares are known to increase the H field at an equatorial station during normal electrojet conditions (nej). At Huancayo, situated north of the magnetic equator, the solar flare effect, during nej, consists of positive impulses in H and Y and negative impulse in Z field. During counter electrojet periods (cej), a solar flare produces a negative impulse in H and Y and a positive impulse in Z at Huancayo. It is concluded that both the zonal and meridional components of the equatorial electrojet in American longitudes, as in Indian longitudes, flows in the same, E region of the ionosphere.