Climate change risks for severe storms in developing countries in the context of poverty and inequality in Cambodia     

Kirsten Halsnæs  Morten Andreas Dahl Larsen  Per Skougaard Kaspersen 《Natural Hazards》2018,94(1):261-278

Least developed countries are generally regarded as particularly sensitive to climate change due to among other vulnerable locations and low adaptation capabilities. In the present study, we address climate change hazards in least developed countries by presenting a methodological framework, which is suitable for the estimation damage costs as a function of risk aversion, equality, income distribution and climate scenario using state-of-the-art climate model projections. As a case study, the methodology is applied to study severe storms in Cambodia based on two future climate scenarios and data on historical damages from storm events, which are used as a proxy in performing a sensitivity analysis on all input parameters. For the assumptions and parameter ranges used here, the study shows a high sensitivity to the income distribution (reflected by discount rates) and risk aversion and smaller effects from equality measures and extreme wind climate scenario. We emphasize that the assumptions on risk aversion reflecting consumption smoothing possibilities of low-income households clearly depicts that climate risks can be particularly high as a consequence of poverty and therefore recommend that context-specific vulnerabilities and equity concerns in climate risk studies should be included when making assessments for least developed countries.  相似文献   

Monitoring of the plume from the basaltic phreatomagmatic 2004 Grímsv?tn eruption—application of weather radar and comparison with plume models     

Bj?rn Oddsson  Magnús T. Gudmundsson  Guerún Larsen  Sigrún Karlsdóttir 《Bulletin of Volcanology》2012,74(6):1395-1407

The Grímsv?tn eruption in November 2004 belongs to a class of small- to medium-sized phreatomagmatic eruptions which are common in Iceland. The eruption lasted 6?days, but the main phase, producing most of the 0.02?km³ of magma erupted, was visible for 33?h on the C-band weather radar of the Icelandic Meteorological Office located in Keflavík, 260?km to the west of the volcano. The plume rose to 8–12?km high over sea level during 33?h. The long distance between radar and source severely reduces the accuracy of the plume height determinations, causing 3.5-km steps in recorded heights. Moreover, an apparent height overestimate of ~1.5?km in the uncorrected radar records occurs, possibly caused by wave ducting or super-refraction in the atmosphere. The stepping and the height overestimate can be partly overcome by averaging the plume heights and by applying a height adjustment based on direct aircraft measurements. Adjusted weather radar data on plume height are used to estimate the total mass erupted using empirical plume models mostly based on magmatic eruptions and to compare it with detailed in situ measurements of the mass of erupted tephra. The errors arising because of the large radar plume distance limit the applicability of the data for detailed comparisons. However, the results indicate that the models overestimate the mass erupted by a factor of three to four. This supports theoretical models indicating that high steam content of phreatomagmatic (wet) plumes enhances their height compared to dry plumes.  相似文献   

Gully catchments as a sediment sink,not just a source: Results from a long‐term (~12 500 year) sediment budget          下载免费PDF全文

Annegret Larsen  Tobias Heckmann  Joshua R. Larsen  Hans‐Rudolf Bork 《地球表面变化过程与地形》2016,41(4):486-498

Sediment delivery from hillslopes to trunk streams represents a significant pathway of mass transfer in the landscape, with a large fraction facilitated by gully systems. The internal gully geomorphic dynamics represent a considerable gap in many landscape and empirical erosion models, therefore a better understanding of these processes over longer timescales (10–10⁴ years) is needed. This study analyses the sediment mass balance and storage dynamics within a headwater gully catchment in central Europe over the last ~12 500 years. Human induced erosion resulted in hillslope erosion rates ~2.3 times higher than under naturally de‐vegetated conditions (during the Younger Dryas), however the total sediment inputs to the gully system (and therefore gully aggradation), were similar. Net gully storage has consistently increased to become the second largest term in the sediment budget after hillslope erosion (storage is ~45% and ~73% of inputs during two separate erosion and aggradation cycles). In terms of the depletion of gully sediment storage, the sediment mass balance shows that export beyond the gully fan was not significant until the last ~500 years, due to reduced gully fan accommodation space. The significance of storage effects on the gully sediment mass balance, particularly the export terms, means that it would be difficult to determine the influences of human impact and/or climatic changes from floodplain or lake sedimentary archives alone and that the sediment budgets of the headwater catchments from which they drain are more likely to provide these mechanistic links. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Recent changes in diatom-inferred pH, heavy metals, and spheroidal carbonaceous particles in lake sediments near an oil refinery at Mongstad, Western Norway     

Jorunn Larsen 《Journal of Paleolimnology》2000,23(4):343-363

Sediments from two naturally acid lakes have been used to investigate whether there is any local impact of atmospheric pollution from an oil refinery at Mongstad in Western Norway. The refinery started production in 1975 and expanded in 1987. One lake was selected as a reference site as it only receives long-range transported air pollution, whereas a second lake was selected as it was expected to receive both long-range transported and local air pollution from the refinery. Heavy metal (Pb, Ni and Zn) and spheroidal carbonaceous particle (SCP) (> 5 µm in diameter) concentrations and accumulation rates have been estimated and lake-water pH has been reconstructed by weighted averaging and weighted averaging partial least squares regression and calibration from the fossil diatom assemblages.Heavy metals that are in the size range for which atmospheric residence time is greatest do not show any enhanced levels in the sediments after 1975 that could be associated with local impacts from the refinery. SCPs in the sediments that are in the size range thought to be effectively removed by dry deposition, and thus have a more local deposition pattern, show an increase after 1975 and an additional large increase after 1987 that can be explained by impacts from the local oil refinery. After 1975 the SCP diameter distribution changed from being dominated by SCPs with a small diameter in the range 5-10 µm to SCPs with larger diameters. The SO₂ emission from the oil refinery seems to have had no significant effect on lake pH. The reconstructed lake pH history is complex, possibly related to land-use changes and long-range transported air pollution.  相似文献   

Saalian to Weichselian stratigraphy and sedimentation along the Lågjæren – Høgjæren escarpment,southwest Norway     

Knut Stalsberg  Jon Y. Landvik  Eiliv Larsen  Hans Petter Sejrup 《第四纪科学杂志》1999,14(4):299-312

Quaternary sediments along a profile crossing the southern part of the Jæren escarpment, southwestern Norway, have been investigated with regard to their glacial history and sea-level variations. Deposits from at least three glaciations and two ice-free periods between Oxygen Isotope Stage 6 and the Late Weichselian have been identified. Subglacial till directly overlain by a glaciomarine regressional succession indicates a deglaciation, and amino acid ratios in Elphidium excavatum between 0.083 and 0.118 date this event to Oxygen Isotope Stage 6. Sea-level dropped from 130 to below 110 m a.s.l. Subsequently, a short-lived ice advance deposited a marginal moraine and a sandur locally on the escarpment. Stratigraphical position and luminescence dates around 148 ka BP suggest deposition during the final stage 6 deglaciation. A Late Weichselian till covers most of the surface of Jæren. In addition to a well documented westerly ice flow, glaciotectonic indications of ice flow towards the north have been found. Ice flow directions and a hiatus between Oxygen Isotope Stage 6 and the Weichselian indicate enhanced erosion along the escarpment and the influence of a Norwegian Channel ice-stream. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Late-glacial cirque glaciation in parts of western Norway     

Eiliv Larsen  John W. Attig  Asbjrn Rune Aa  Eivind Snstegaard 《第四纪科学杂志》1998,13(1):17-27

Younger Dryas cirque glaciers are known to have existed beyond the Scandinavian Ice Sheet in parts of western Norway. At Kråkenes, on the outermost coast, a cirque glacier formed and subsequently wasted away during the Younger Dryas. No glacier existed there during the Allerød. Large cirque moraines, some with marine deltas and associated fans, extend into the western part of Sykkylvsfjorden. Comparison with existing late-glacial sea-level curves shows that the uppermost marine sediment in these features was deposited well above Younger Dryas sea-level, demonstrating that the cirques were occupied by glaciers before the Younger Dryas. During the Younger Dryas the cirque glaciers expanded, and some advanced across the deltas, depositing till and supplying the sediment to form lower-level fans and deltas controlled by Younger Dryas sea level. The extent of the Younger Dryas advance of some of the glaciers was, at least in part, controlled by grounding on material deposited before the Younger Dryas. The depositional history of the glacial–marine deposits in the Sykkylven area indicates that cirque glaciers existed throughout Late-glacial time and only expanded during the Younger Dryas. The sediment sequence in glacial lakes beyond cirque moraines and reconstructions of glacier equilibrium lines indicate that this was true for most cirques in western Norway. Only on the outermost coast were new glaciers formed in response to Younger Dryas climate cooling. © 1998 John Wiley & Sons Ltd.  相似文献   

Rotation of the solar core from BiSON and LOWL frequency observations     

W. J. Chaplin  J. Christensen-Dalsgaard  Y. Elsworth  R. Howe  G. R. Isaak  R. M. Larsen  R. New  J. Schou  M. J. Thompson  S. Tomczyk 《Monthly notices of the Royal Astronomical Society》1999,308(2):405-414

Determination of the rotation of the solar core requires very accurate data on splittings for the low-degree modes which penetrate to the core, as well as for modes of higher degree to suppress the contributions from the rest of the Sun to the splittings of the low-degree modes. Here we combine low-degree data based on 32 months of observations with the BiSON network and data from the LOWL instrument. The data are analysed with a technique that specifically aims at obtaining an inference of rotation that is localized to the core. Our analysis provides what we believe is the most stringent constraint to date on the rotation of the deep solar interior.  相似文献   

An Agricultural Package for MODFLOW 6 Using the Application Programming Interface     

Joshua D. Larsen  Christian D. Langevin  Joseph D. Hughes  Richard G. Niswonger 《Ground water》2024,62(1):157-166

An agricultural water use package has been developed for MODFLOW 6 using the MODFLOW Application Programming Interface (API). The MODFLOW API Agricultural Water Use Package (API-Ag) was based on the approach to simulate irrigation demand in the MODFLOW-NWT and GSFLOW Agricultural Water Use (AG) Package. The API-Ag Package differs from the previous approach by implementing new features and support for additional irrigation providers. New features include representation of deficit and over-irrigation, Multi-Aquifer Well and Lake Package irrigation providers, and support for structured, vertex, and unstructured grid models. Three example problems are presented that demonstrate how the API-Ag Package improves representation of highly managed systems and are further used to validate the irrigation demand and delivery formulations. Irrigation volumes simulated in the three example problems show excellent agreement with the MODFLOW-NWT AG Package.  相似文献   

Submarine Lateglacial lake deposits from the Kattegat,southern Scandinavia     

Peter Wiberg‐Larsen  Ole Bennike  Jrn Bo Jensen 《第四纪科学杂志》2019,34(2):165-171

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Glacial history of the Greenland Ice Sheet and a local ice cap in Qaanaaq,northwest Greenland     

Anne Sofie Sndergaard  Nicolaj Krog Larsen  Jesper Olsen  Astrid Strunk  Sarah Woodroffe 《第四纪科学杂志》2019,34(7):536-547

In this study, we present new information on the glacial history of the Greenland Ice Sheet (GrIS) and a local ice cap in Qaanaaq, northwest Greenland. We use geomorphological mapping, ¹⁰Be exposure dating of boulders, analysis of lake cores, and ¹⁴C dating of reworked marine molluscs and subfossil plants to constrain the glacial history. Our ¹⁴C ages of reworked marine molluscs reveal that the ice extent in the area was at or behind its present‐day position from 42.2 ± 0.4 to 30.6 ± 0.3k cal a BP after which the GrIS expanded to its maximum position during the Last Glacial Maximum. We find evidence of early ice retreat in the deep fjord (Inglefield Bredning) at 11.9 ± 0.6 ka whereas the Taserssuit Valley was deglaciated ~4 ka later at 7.8 ± 0.1k cal a BP. A proglacial lake record suggests that the local ice cap survived the Holocene Thermal Maximum but moss kill‐dates reveal that it was smaller than present for a period of time before 3.3 ± 0.1k until 0.9 ± 0.1k cal a BP, following which the ice in the area expanded towards its Little Ice Age extent. Copyright © 2019 John Wiley & Sons, Ltd.  相似文献