Application of relative drought indices in assessing climate-change impacts on drought conditions in Czechia

The common versions (referred to as self-calibrated here) of the Standardized Precipitation Index (SPI) and the Palmer Drought Severity Index (PDSI) are calibrated and then applied to the same weather series. Therefore, the distribution of the index values is about the same for any weather series. We introduce here the relative SPI and PDSI, abbreviated as rSPI and rPDSI. These are calibrated using a reference weather series as a first step, which is then applied to the tested series. The reference series may result from either a different station to allow for the inter-station comparison or from a different period to allow for climate-change impact assessments. The PDSI and 1–24 month aggregations of the SPI are used here. In the first part, the relationships between the self-calibrated and relative indices are studied. The relative drought indices are then used to assess drought conditions for 45 Czech stations under present (1961–2000) and future (2060–2099) climates. In the present climate experiment, the drought indices are calibrated by using the reference station weather series. Of all drought indices, the PDSI exhibits the widest spectrum of drought conditions across Czechia, in part because it depends not only on precipitation (as does the SPI) but also on temperature. In our climate-change impact experiments, the future climate is represented by modifying the observed series according to scenarios based on five Global Climate Models (GCMs). Changes in the SPI-based drought risk closely follow the modeled changes in precipitation, which is predicted to decrease in summer and increase in both winter and spring. Changes in the PDSI indicate an increased drought risk at all stations under all climate-change scenarios, which relates to temperature increases predicted by all of the GCMs throughout the whole year. As drought depends on both precipitation and temperature, we conclude that the PDSI is more appropriate (when compared to the SPI) for use in assessing the potential impact of climate change on future droughts.     

Identifying potential marine pests--a deductive approach applied to Australia

Introduced marine organisms continue to threaten coastal resources around the world. Many agencies rely on lists of potentially harmful species for risk assessment and to prioritise management responses to an incursion. This study outlines a deductive hazard assessment technique to identify potential marine pests that may arrive via ballast water and/or hull fouling. This technique is then applied in an Australian context to identify potential "next pests" for this region. An extensive literature review identified 851 introduced marine species from around the world. The following selection criteria were then applied to develop a next pest list: (a) the species has been reported in a shipping vector or has a ship-mediated invasion history; (b) the vector still exists; (c) the species is responsible for economic or environmental harm; and, (d) it is exotic to Australia or present in Australia but subject to official control. The selection criteria are transparent and consistent with other international and national biosecurity initiatives. Thirty three of the species identified in the initial literature review satisfied all four selection criteria. These species are described here together with their associated vectors and impacts.     

美国国家级干旱监测业务产品介绍

美国需要改进干旱监测与评估方法。干旱是代价昂贵的自然灾害(联邦应急管理局(FEMA),1995;W ilhite,2000),但经常被评估和预报产品的开发者忽略。相比于其他灾害,干旱表现得更模糊并且不适合用传统的评估或预报方法,它相对缓慢的发生以及其影响的复杂性,需要有一套新的方法来对它进行评估。干旱监测和预报技术的提高会使我们为应对干旱灾害做更好的准备工作,进行更好的应对实践,从而减少社会对干旱及其影响的脆弱性。为追踪和展示全美国干旱的程度、空间范围以及其影响,开发了新的干旱监测工具,研发了每周发布的国家级干旱监测业务产品(th…     

Holocene atmosphere-ocean interactions: records from Greenland and the Aegean Sea

We compare paleoclimate proxy records from central Greenland and the Aegean Sea to offer new insights into the causes, timing, and mechanisms of Holocene atmosphere-ocean interactions. A direct atmospheric link is revealed between Aegean sea surface temperature (SST) and high-latitude climate. The major Holocene events in our proxies of Aegean SST and winter/spring intensity of the Siberian High (GISP2 K⁺ record) follow an ~2300 year spacing, recognised also in the (¹⁴C record and in worldwide Holocene glacier advance phases, suggesting a solar modulation of climate. We argue that the primary atmospheric response involved decadal-centennial fluctuations in the meridional pressure gradient, driving Aegean SST events via changes in the strength, duration, and/or frequency of northerly polar/continental air outbreaks over the basin. The observed natural variability should be accounted for in predictions of future climate change, and our timeframe for the Aegean climate events in addition provides an independent chronostratigraphic argument to Middle Eastern archaeological studies.     

Carbon isotope effects associated with autotrophic acetogenesis

The carbon kinetic isotope effects associated with synthesis of acetate from CO2 and H2 during autotrophic growth of Acetobacterium woodii at 30 degrees C have been measured by isotopic analyses of CO2, methyl-carbon, and total acetate. Closed systems allowing construction of complete mass balances at varying stages of growth were utilized, and the effects of the partitioning of carbon between CO2 and HCO3- were taken account. For the overall reaction, total carbonate --> total acetate, isotope effects measured in replicate experiments ranged from -59.0 +/- 0.9% to -57.2 +/- 2.3%. Taking into account all measurements, the weighted mean and standard deviation are -58.6 +/- 0.7%. There is no evidence for intramolecular ordering in the acetate. The carbon isotopic composition of sedimentary acetate, otherwise expected to be near that of sedimentary organic carbon, is likely to be depleted in environments in which autotrophic acetogenesis is occurring.     

Mesozoic magnetic lineations and the magnetic quiet zone off northwest Africa

An extensive compilation of recently acquired geophysical reconnaissance data has allowed the Mesozoic magnetic lineations (The Eastern Keathley sequence) to be identified and mapped in detail for the area off northwest Africa lying between Madeira and the Cape Verde Islands. These anomalies were generated as one limb of a symmetric spreading center (Paleo Mid-Atlantic Ridge) from about 107 to 153 m.y.B.P. Offsets in the lineation pattern serve to identify fracture zone traces whose trends are approximately east-west. The seaward boundary of the marginal quiet zone does not precisely define an isochron due to the presence of a variable width transition zone of intermediate amplitude magnetic anomalies. Crust underlying the marginal quiet zone was generated, at least in part, during the Jurassic, Graham normal polarity epoch. The quiet zone boundary is not offset significantly on opposite sides of the Canaries lineament as previously suggested. A possible counterpart of the U.S. east coast magnetic anomaly is observed in some areas near the shelf/slope break of Spanish Sahara and Mauritania. The presence of relatively high-amplitude (but not-correlatable) magnetic anomalies seaward of the Mesozoic sequence and presumably generated during the Cretaceous, Mercanton normal polarity epoch remains a paradox.     

Climatic change and grain corn yields in the North American Great Plains

A basic parametric crop yield model (YIELD) that uses climatic and environmental data to calculate yield and associated parameters for grain corn (maize) was applied to a transect through the North American Great Plains. This paper continues our examination of the impact of probable climatic change scenarios on crop evapotranspiration and irrigation requirements (Terjung et al., 1984), This study of grain corn yields showed highest yield for the first (or primary) harvest under full irrigation occurring under a sunny and cold scenario in Austin, TX, sunny and cool in Kansas City, KS, and sunny and warm in Bismarck, ND. Lowest irrigated yield was found with cloudy and hot and very dry climate change scenarios. Under rainfed-only conditions, minima were obtained under the sunny-hot and -warm scenarios and very dry conditions.J. T. Hayes is a professor at the Department of Geography and Regional Planning, State University of New York, Albany, NY, U.S.A.L. O. Mearns is also currently associated with the National Center for Atmospheric Research, funded by the National Science Foundation.Dr. Liverman is a professor at the Department of Geography, University of Wisconsin, Madison, Wis., U.S.A.