Island Climate Research Articles

High-resolution continuous-flow analysis setup for water isotopic measurement from ice cores using laser spectroscopy

Abstract. Here we present an experimental setup for water stable isotope (δ18O and δD) continuous-flow measurements and provide metrics defining the performance of the setup during a major ice core measurement campaign (Roosevelt Island Climate Evolution; RICE). We also use the metrics to compare alternate systems. Our setup is the first continuous-flow laser spectroscopy system that is using off-axis integrated cavity output spectroscopy (OA-ICOS; analyzer manufactured by Los Gatos Research, LGR) in combination with an evaporation unit to continuously analyze water samples from an ice core. A Water Vapor Isotope Standard Source (WVISS) calibration unit, manufactured by LGR, was modified to (1) enable measurements on several water standards, (2) increase the temporal resolution by reducing the response time and (3) reduce the influence from memory effects. While this setup was designed for the continuous-flow analysis (CFA) of ice cores, it can also continuously analyze other liquid or vapor sources. The custom setups provide a shorter response time (~ 54 and 18 s for 2013 and 2014 setup, respectively) compared to the original WVISS unit (~ 62 s), which is an improvement in measurement resolution. Another improvement compared to the original WVISS is that the custom setups have a reduced memory effect. Stability tests comparing the custom and WVISS setups were performed and Allan deviations (σAllan) were calculated to determine precision at different averaging times. For the custom 2013 setup the precision after integration times of 103 s is 0.060 and 0.070 ‰ for δ18O and δD, respectively. The corresponding σAllan values for the custom 2014 setup are 0.030, 0.060 and 0.043 ‰ for δ18O, δD and δ17O, respectively. For the WVISS setup the precision is 0.035, 0.070 and 0.042 ‰ after 103 s for δ18O, δD and δ17O, respectively. Both the custom setups and WVISS setup are influenced by instrumental drift with δ18O being more drift sensitive than δD. The σAllan values for δ18O are 0.30 and 0.18 ‰ for the custom 2013 and WVISS setup, respectively, after averaging times of 104 s (2.78 h). Using response time tests and stability tests, we show that the custom setups are more responsive (shorter response time), whereas the University of Copenhagen (UC) setup is more stable. More broadly, comparisons of different setups address the challenge of integrating vaporizer/spectrometer isotope measurement systems into a CFA campaign with many other analytical instruments.

Patterns of island treeline elevation – a global perspective

Treeline research has strongly focused on mountain systems on the mainland. However, island treelines offer the opportunity to contribute to the global framework on treeline elevation due to their island‐specific attributes such as isolation, small area, low species richness and relative youth. We hypothesize that, similar to the mainland, latitude‐driven temperature variation is the most important determinant of island treeline elevation on a global scale. To test this hypothesis, we compared mainland with island treeline elevations. Then we focused 1) on the global effects of latitude, 2) on the regional effects of island type (continental vs oceanic islands) and 3) the local effects of several specific island characteristics (age, area, maximum island elevation, isolation and plant species richness). We collected a global dataset of islands (n = 86) by applying a stratified design using GoogleEarth and the Global Island Database. For each island we extracted data on latitude and local characteristics. Treeline elevation decreased from the mainland through continental to oceanic islands. Island treeline elevation followed a hump‐shaped latitudinal distribution, which is fundamentally different from the mainland double‐hump. Higher maximum island elevation generated higher treeline elevation and was found the best single predictor of island treeline elevation, even better than latitude. Lower island treeline elevation may be the result of a low mass elevation effect (MEE) influencing island climates and an increasingly impoverished species pool but also trade wind inversion‐associated aridity. The maximum island elevation effect possibly results from an increasing mass elevation effect (MEE) with increasing island elevation but also range shifts during climatic fluctuations and the summit syndrome (i.e. high wind speeds and poor soils in peak regions). Investigating islands in treeline research has enabled disentangling the global effect of latitude from regional and local effects and, at least for islands, a comprehensive quantification of the MEE.

The Varied Impacts of El Niño–Southern Oscillation on Pacific Island Climates

Abstract El Niño–Southern Oscillation (ENSO) drives interannual climate variability in many tropical Pacific island countries, but different El Niño events might be expected to produce varying rainfall impacts. To investigate these possible variations, El Niño events were divided into three categories based on where the largest September–February sea surface temperature (SST) anomalies occur: warm pool El Niño (WPE), cold tongue El Niño (CTE), and mixed El Niño (ME), between the other two. Large-scale SST and wind patterns for each type of El Niño show distinct and significant differences, as well as shifts in rainfall patterns in the main convergence zones. As a result, November to April rainfall in many Pacific island countries is significantly different among the El Niño types. In western equatorial Pacific islands, CTE events are associated with drier than normal conditions whereas ME and WPE events are associated with significantly wetter than normal conditions. This is due to the South Pacific convergence zone and intertropical convergence zone moving equatorward and merging in CTE events. Rainfall in the convergence zones is enhanced during ME and WPE and the displacement is smaller. La Niña events also show robust impacts that most closely mirror those of ME events. In the northwest and southwest Pacific strong CTE events have much larger impacts on rainfall than ME and WPE, as SST anomalies and correspondingly large-scale surface wind and rainfall changes are largest in CTE. While variations in rainfall exist between different types of El Niño and the significant impacts on Pacific countries of each event are different, the two extreme CTE events have produced the most atypical impacts.

Holocene Closure of Lib Pond, Marshall Islands

Well-preserved sediment from closed water bodies of atolls such as Lib Pond are rare opportunities to reconstruct the past regional climate, which pieced together across a latitude and longitude range identify the range of movement patterns of wider scale climate phenomena such as the Intertropical Convergence Zone (ITCZ) and El Niño Southern Oscillation (ENSO). We conducted the first physico-chemical survey of Lib Pond, a shallow, closed-water saline lake located on remote and difficult to access Lib Island in the Marshall Islands at 8° 18′ 48.99″ N, 167 22′ 51.90″ E in the Pacific Ocean, in July 2009. We performed a bathymetric survey, recorded salinity, dissolved oxygen, pH, and temperature profiles, monitored the tidal variability, and conducted a vegetation survey surrounding the lake. From bathymetric data we calculated the lake volume, which we used to estimate the lake's salt budget, and ultimately the residence time of water in the lake basin. We took a series of sediment cores from the lake, cores which indicate Lib Island's changing environment and climate. Radiocarbon measurements determined sediment age, and reveal significant mixing over the last 2 ka of deposition. We conclude that prior to 3 ka, Lib Island was an atoll with a central lagoon connected to the open ocean, which was then closed off from the open ocean to form the brackish system that exists today. We predict that the sediment accumulation in Lib Pond evident today will continue. As seawater is inhibited from exchanging with fresh water, Lib Pond will become a shallower lake with increasingly fresh water.

Turks and Caicos Islands Climate and Its Impacts

AbstractThe Turks and Caicos Islands (TCI) climate is described using mesoscale ocean and atmosphere datasets with a focus on thermodynamic versus kinematic controls, the influence of the nearby island of Hispaniola, and factors affecting early colonization and fluctuations of marine resources. The key findings include the following: trade winds accelerate to 7 m s−1 north of Hispaniola and enhance anticyclonic subsidence; there is a dry-south/wet-north pattern of rainfall that opposes surface temperature and salinity fields; ocean currents near TCI are northwestward but there is a counterclockwise gyre near Haiti that guided colonization; conch catch increases when trade winds strengthen and SST declines; TCI's dry climate limits groundwater resources, food production, and population density; and Caicos Island sheds a wind wake that boosts SST and local convection, as evident in Quick Scatterometer (QuikSCAT) observations and operational model products. Further studies of small island climates will benefit from an ever-increasing stream of mesoscale datasets.

Eco-Efficiency Model for Green Building Material in a Subtropical Climate

Taiwan has a unique subtropical island climate. In the development of a green building material (GBM) evaluation system for Taiwan, evaluation criteria should differ from those in the frigid or temperate zones of the world. We aimed to provide academia and industry with an appropriate GBM evaluation method and to enhance the effectiveness of GBM. It means GBM should be concerned with creating more value with less impact to achieve “eco-efficiency”. Eco-efficiency is the balance of competitively priced goods and services that satisfy human needs and quality of life, while progressively reducing ecological impacts and resource intensity throughout the life-cycle within the Earth's estimated carrying capacity. We applied this method (eco-efficiency=quality/load) to comprehensively consider the efficiency of GBM. The first step was to review the literature to summarize GBM evaluation factors. Second, we conducted a two-stage survey by the fuzzy Delphi method to analyze the evaluation indicators' eco-efficiency dimension (quality or load) and the importance of evaluation factors for establishing the GBM Eco-Efficiency Evaluation System. Third, we analyzed the priority vector of the evaluation indicators by an analytic hierarchy process method before finally achieving the goal of constructing the GBM Eco-Efficiency Model. The achievement was the creation of the Taiwan GBM Eco-Efficiency Evaluation System and the GBM Eco-Efficiency Model. For academia, industry, and users, it could lead to the enhancement of GBM quality as well as provide feedback to modify the process in advance, reduce adverse environmental loads, and minimize the negative impact on the global environment. This method responds positively to human health and global sustainable development.

Impact of climatic conditions on the thermal effectiveness of an extensive green roof

The density of urban development has been the source of a number of environmental issues, and in urban areas with large quantities of stereoscopic space, roof greening has become an important strategy for land compensation and environmental quality improvement. In particular, with the intensification of urban heat island and the global warming phenomena, the effective regulation of the microclimate by building a green roof becomes more attractive. Because a green roof is closely related to the climate and the environment, the main purpose of this study is to explore the impact of climatic conditions on the thermal effectiveness of an extensive green roof. The experimental cases of an extensive green roof were individually established in urban areas with both sub-tropical and tropical island climates, and synchronous observations were made. The research results show that it can reduce the increase of outdoor temperature by approximately 42% and the increase of the indoor temperature by 8% during the daytime. During the night, it can maintain 17% of the temperature in the outdoor environment, stabilizing the temperature change. The thermal effectiveness of an extensive green roof is closely related to the climate. The daytime cooling effectiveness was relatively high in the tropical island climate in summer, and the nighttime insulation effectiveness was more pronounced in the sub-tropical climate. Rainfall reduced the thermal effectiveness of an extensive green roof.

Performance Evaluation of Biomass Fired Dryer for Copra Drying: A Comparison with Traditional Drying in Subtropical Climate

In tropical and sub-tropical Island climate, adverse effect of heavy rainfall (2800-3500 mm), temperature (25-35°C) and relative humidity (75-95%) year round render high microbial infection to the copra produced by farming communities using traditional methods, causing low quality of copra leading to lower income to the producers. Keeping in view, a biomass fired copra dryer has been designed, developed and tested in Andaman Islands. The aim was to increase in employment generation to the rural households who are engaged with traditional method of copra production. The results indicated that biomass fired copra took 22 hours to reduce initial moisture content from 57.4% (w.b) to 6.8% (w.b) which saved 40% and 47% of total drying time compared to two traditional methods e.g. Machan drying and sun drying. Coconut shell of 80-85 kg is used as fuel. Two persons are required to feed the fuel and maintain the constant temperature to obtain better quality copra. The copra obtained was graded as 82% MCG1, 13% MCG2 and 5% MCG3. The cost benefit ratio and payback period was found to be 1.4 and 1.5 month respectively. The coconut shell may be used for fuel which saves manpower and energy, thereby enhancing net return to the farmers.

Data assimilation of Island climate observations with large‐scale re‐analysis data to high‐resolution grids

AbstractData assimilation is important for the spatial analysis of small regions with complex terrain and diverse climates and for interpolation among observations. A data assimilation method incorporating observations, coarse‐grid re‐analysis data and physiographical features is demonstrated to generate high‐resolution temperature data for small islands such as Taiwan. The method is also able to weigh physiographic and anthropogenic factors. Among the spatial factors, the orographic effect is the dominating factor and the lapse rate varies seasonally. Population density is significantly related to temperature, which may correspond to the urban heat‐island (UHI) effect. It is also shown that an anthropogenic factor could be used with this interpolation method to explain the details of the temperature variation. The data assimilation model provides an opportunity to assess the extent to which simple statistical regression equations, calibrated from natural variability, can reproduce climate changes driven by land effects without considering a complex climate model. Copyright © 2012 Royal Meteorological Society

Symposium summary: Island biogeography

ISSN 1948‐6596 news and update symposium summary Island biogeography A contributed session at the 5th International Biogeography Society Conference – Heraklion, Greece, 7–11 January 2011 It is now almost 50 years since the publication of Robert H. MacArthur and Edward O. Wilson’s 1963 paper, An Equilibrium Theory of Insular Zo‐ ogeography which led to their famous book, The Theory of Island Biogeography (MacArthur and Wilson 1967). These publications were instrumen‐ tal in a switch from a static, historically oriented biogeography, based in the direct interpretation of the data collected in the field, to a ‘dynamic’ equilibrium paradigm, based on a synthetic ap‐ proach to biogeographical processes. By their nature, the processes underlying biogeographic distributions and evolution on (remote) islands occur on large scales of time and space and remain among the most difficult to study and understand. Although some of the top‐ ics emphasized by MacArthur and Wilson still re‐ main relatively unexplored, recent advances in island theory demonstrate that we are moving towards a new synthesis, identifying and incorpo‐ rating aspects of the island systems that were not considered in the past. All the talks in the island biogeography session pointed in this direction. One of the first lessons taught to us by Wal‐ lace, decades before MacArthur and Wilson, is that comparisons among different archipelagos and biogeographic regions of the globe can offer significant insights and increase our understand‐ ing of the processes regulating biodiversity across time and space (see Wallace 1887). Daniel Car‐ stensen and colleagues compared the bio‐ geographical patterns of birds in Wallacea and the West Indies, adopting a network approach to detect biogeographical modules (i.e. sub‐regions of islands compartmentalized on the basis of a common avifauna) and the roles of each island according to its spatial location and the topology of the geographical network. They discussed the relative importance of island features and species richness on the local and regional fauna of the two biogeographical regions. Similarly, Silvia Aranda and co‐workers compared, within the framework of the Theory of Island Biogeography, the effects of area, isolation, geological age and climate on bryophyte species richness on Macaronesian Is‐ lands. They provided evidence that, in addition to area, it is necessary to quantify other variables that are also critical for the establishment of bio‐ diversity and at the same time have high explana‐ tory power (such as island age and climate), if we are to build up a more predictive science of spe‐ cies richness variation across island systems. However, island area remains the most powerful single variable in explaining variation in the number of species occupying an island and the species–area relationship (SAR) is one of ecology’s few laws. Even and Kathleen Tjorve showed that we should consider with caution the common assumption that the power law of Arrhenius is appropriate for both sample‐area (mainland) SARs and isolate (island) SARs. Especially regarding iso‐ late SARs, they argue that the form of the rela‐ tionship is actually sigmoid when the finest scales are included. Based on this assumption, they pro‐ posed a new species–area model and presented results from different archipelagos and taxa. Fifty years ago E.O Wilson, studying Mela‐ nesian ants, coined the term ‘taxon cycle’ to de‐ scribe ‘the inferred cyclical evolution of species [of Melanesian ants], from the ability to live in mar‐ ginal habitats and disperse widely, to preference for more central, species‐rich habitats with an as‐ sociated loss of dispersal ability, and back again’ (Wilson 1961). However, the taxon cycle has, until recently, been difficult to test (see Rick‐ lefs and Bermingham 2002). Evan Economo and Eli Sarnat evaluated taxon cycle predictions with a new dataset on habitat distributions of the entire Fijian ant fauna and a community phylogeny for one of the genera present in that archipelago. They provided evidence that as lineages progress to higher levels of endemism, they undergo shifts from marginal to interior primary habitats, from ecological generalism to specialization, and from frontiers of biogeography 3.1, 2011 — © 2011 the authors; journal compilation © 2011 The International Biogeography Society

Classification Tree Methods Provide a Multifactorial Approach to Predicting Insular Body Size Evolution in Rodents

Many hypotheses have been proposed to explain size changes in insular mammals, but no single variable suffices to explain the diversity of responses, particularly within Rodentia. Here in a data set on insular rodents, we observe strong consistency in the direction of size change within islands and within species but (outside of Heteromyidae) little consistency at broader taxonomic scales. Using traits of islands and of species in a classification tree analysis, we find the most important factor predicting direction of change to be mainland body mass (large rodents decrease, small ones increase); other variables (island climate, number of rodent species, and area) were significant, although their roles as revealed by the classification tree were context dependent. Ecological interactions appear relatively uninformative, and on any given island, the largest and smallest rodent species converged or diverged in size with equal frequency. Our approach provides a promising framework for continuing examination of insular body size evolution.

University leadership in island climate change mitigation

PurposeThe purpose of this paper is to present the University of Hawaii at Manoa's (UHM's) initiatives in achieving greenhouse gas (GHG) emissions reductions on campus and at the state level.Design/methodology/approachUHM has taken a “lead by example” approach to climate change mitigation in terms of working to meet the American College & University Presidents Climate Commitment, becoming a founding member of The Climate Registry, and providing university leadership in crafting the policy to meet Hawaii's Climate Change Solutions Act of 2007.FindingsUniversities are uniquely poised to play a role in not only climate change research, education, and community outreach, but also in the regional and national policy‐making arena. In the absence of federal legislation, states are paving the way to create binding US GHG reduction commitments – making crafting innovative and appropriate policy all the more important and meaningful at the state and regional levels.Practical implicationsThe paper discusses the multi‐prong approach UHM is taking in addressing the threats of climate change: from on‐campus GHG measurements and reductions to helping guide overarching state policy.Originality/valueIslands are particularly vulnerable to the effects of climate change. UHM has taken a comprehensive approach to addressing climate change, from forming strategic partnerships with the electric utility, to developing campus and state GHG reduction strategies, to helping mobilize planning for impacts like sea‐level rise. This paper presents the efforts of UHM, including faculty, student and administration‐led projects, specifically illustrating the role of Universities in meeting GHG reduction commitments through a “lead by example” approach at both the university and state levels.

Diversity and spatial distribution of Opuntia spp. in the Mediterranean Basin

This work offers a methodology based on statistical tools and GIS applications in a study of the adaptability of Opuntia to the environment, applied on the Mediterranean island of Sardinia. Detailed surveys of habitats containing naturalized populations of Opuntia spp. were made in order to select study sites. The topographic, soil and climatic features of these are described. The local biotypes are ascribed mainly to the spineless Opuntia ficus–indica (L.) Mill. and to the spiny Opuntia amyclaea Ten. Although introduced at different times, for different uses, they have adapted to the Sardinian environment and established in the wild. The distributions of the two species differed. The FloraMap ® modelling approach was used to simulate Opuntia distribution as a function of the island's climate and produced individual distribution maps using the accession points for the two species. Our analysis showed that environmental conditions at elevations above 800 m are the main limiting factors for the presence and abundance of Opuntia in Sardinia. Spatial representation developed by GIS software indicated temperatures below 2 °C as the threshold impairing the species naturalized distribution. The statistic results also show that variation in rainfall does not affect Opuntia spatial distribution in Sardinia.

Shoreline Impacts, Setback Policy, & Sea Level Rise

The Center for Island Climate Adaptation and Policy (ICAP), located within the University of Hawaii’s Sea Grant College Program, provides science-based policy and planning research for decision-makers in Hawai‘i and other island leaders. ICAP prepared this white paper at the request of Senator Shan Tsutsui, whose office sought a technical evaluation of Senate Bill 468 (relating to shoreline setbacks). ICAP finds that SB 468 as originally introduced would have a beneficial net impact on coastal resiliency for the State of Hawai‘i.

Coexistence of Feral Africanized and European Honey Bees (Hymenoptera: Apoidea: Apidae) on St. Croix Island

The first evaluation of the feral population of honey bees on the island of St. Croix, US Virgin Islands is performed. Since Africanized bees had been reported in 1994, we expected that, as in the neighboring island of Puerto Rico, the feral population of St. Croix would be strongly Africanized. We sampled worker bees of 13 colonies. Using a molecular technique that distinguishes European from Africanized bees we found that nine sampled colonies were Africanized and four were European by maternal descent. The lack of a complete genetic sweep by Africanized bees contrasts greatly with the population in Puerto Rico and populations studied in the mainland. Even though the presence of European bees on the island may be due to input from the apicultural sector, it is highly likely that other factors, such as island climate, the lack of a continuous influx of Africanized bees, and the absence of Varroa mites, a common pest of European bees has allowed their survival.

Lightning activity analyses with respect to the SPCZ location

The South Pacific Convergence Zone (SPCZ) stretches over the West Pacific warm pool Southeastward to French Polynesia. The Island Climate Update monthly publishes the mean location deduced from the total rainfall. On the other hand, the World Wide Lightning Location Network monthly provides data from which the lightning activity distribution in the 0°–30° South latitude and 150°–240° West longitude area can be drawn. Scanning this rectangle from West to East allows the spots of maximum lightning activity to be located versus the longitude. Fitting the location of these maxima with a polynomial function leads to a curve comparable with the monthly mean position of the SPCZ, showing that this band of cloudiness is one of the main sources of lightning in this whole area.

Personal Accounts: Invisible on Judgment Day

Personal Accounts: Invisible on Judgment Day

Transgenic Agrostis mongolica Roshev. with enhanced tolerance to drought and heat stresses obtained from Agrobacterium-mediated transformation

Efficient procedures for regeneration and Agrobacterium-mediated transformation were established for Agrostis mongolica Roshev. and generated transgenic plants tolerant to drought and heat stresses using a regulatory gene from Arabidopsis, ABF3, which controls the ABA-dependent adaptive responses. The identification and selection of regenerable and reproducible callus type was a key factor for successful transformation. The transformation efficiency was 49.2% and gfp expression was detected in hygromycin-resistant calli and stem of putative transgenic plants. The result of Southern blot analysis showed that the ABF3 transgene was stably integrated into the genome of transgenic plants. Of the five transgenic lines analyzed, single transgene integration was observed in two lines and two copy integration was observed in three transgenic lines. Northern blot analysis confirmed that ubi::ABF3 was expressed in all transgenic lines. Transgenic plants exhibited neither growth inhibition nor visible vegetative phenotypic alternations. However, both transgenic and wild-type plants were highly sterile and did not flower during 3 years of growth period in the open field under subtropical Jeju Island climate. The stomata of the transgenic plants opened less than did stomata of the wild-type plants, and water content of the transgenic leaves remained about 3–4 fold higher than observed for wild-type leaves under drought stress. The transgenic plants showed about 2 fold higher survival rates under drought stress and about 3 fold higher survival rates under heat stress when compared to wild-type plants. Thus, overexpression of the Arabidopsis ABF3 gene results in enhancement of both drought and heat stress tolerance in Agrostis mongolica Roshev.

Factors Limiting Convective Cloud-Top Height at the ARM Nauru Island Climate Research Facility

Abstract Cumulus congestus clouds, with moderate shortwave albedos and cloud-top temperatures near freezing, occur fairly often in the Tropics. These clouds may play an important role in the evolution of the Madden–Julian oscillation and the regulation of relative humidity in the midtroposphere. Despite this importance they are not necessarily simulated very well in global climate models. Surface remote sensing observations and soundings from the Atmospheric Radiation Measurement (ARM) climate research facility at Nauru Island are coupled with a simple parcel model in order to address the following questions about these cloud types: 1) Which environmental factors play a role in determining the depth of tropical convective clouds? 2) What environmental parameters are related to entrainment rate in cumulus congestus clouds? The results presented herein suggest that at Nauru Island a drying of the midtroposphere is more likely to be responsible for limiting congestus cloud-top heights than is a stabilizing of the freezing level. It is also found that low-level CAPE and the RH profile account for the largest portion of the variance in cumulus congestus entrainment rates, consistent with the idea that entrainment rate depends on the buoyant production of turbulent kinetic energy. If the analysis is limited to cases where there is a sounding during the hour preceding the cumulus congestus observations, it is found that the low-level CAPE accounts for 85% of the total variance in entrainment rate.

The winter St. Helena climate index and extreme Benguela upwelling

Climate changes in the subtropical South-east Atlantic turn out to be well described by the St. Helena Island Climate Index (HIX) and observed fluctuations are in good agreement with inter-decadal variability of the entire South Atlantic Ocean. Year-to-year variations of the averaged austral winter HIX (July–September), representative of the main upwelling season, were compared with (i) corresponding averages of the geostrophic alongshore component of the south-east trade wind (SET) between St. Helena Island in the south-west and Luanda/Angola in the north-east, (ii) the meridional distribution of surface waters colder than 13 °C to characterise intense Benguela upwelling (IBU), and (iii) the meridional position of the Angola-Benguela Frontal Zone (ABFZ) determined by means of sea surface temperature images for offshore distances between 50 and 400 km. Temporal changes of these parameters were investigated and showed that the frequency of consecutive years of strong and relaxed Benguela upwelling is characterised by a quasi-cycle of about 11–14 years. It is proposed that the index of the winter HIX may be used as a ‘surveyor’s rod' to describe interannual changes in the Benguela upwelling regime as well as those of the embedded marine ecosystem.