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Climate Indices (climate + index)
Selected AbstractsProjecting the risk of future climate shiftsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 7 2006David B. Enfield Abstract Recent research has shown that decadal-to-multidecadal (D2M) climate variability is associated with environmental changes that have important consequences for human activities, such as public health, water availability, frequency of hurricanes, and so forth. As scientists, how do we convert these relationships into decision support products useful to water managers, insurance actuaries, and others, whose principal interest lies in knowing when future climate regime shifts will likely occur that affect long-horizon decisions? Unfortunately, numerical models are far from being able to make deterministic predictions for future D2M climate shifts. However, the recent development of paleoclimate reconstructions of the Atlantic Multidecadal Oscillation (AMO) (Gray et al., 2004) and Pacific Decadal Oscillation (PDO); (MacDonald and Case, 2005) give us a viable alternative: to estimate probability distribution functions from long climate index series that allow us to calculate the probability of future D2M regime shifts. In this paper, we show how probabilistic projections can be developed for a specific climate mode,the AMO as represented by the Gray et al. (2004) tree-ring reconstruction. The methods are robust and can be applied to any D2M climate mode for which a sufficiently long index series exists, as well as to the growing body of paleo-proxy reconstructions that have become available. The target index need not be a paleo-proxy calibrated against a climate index; it may profitably be calibrated against a specific resource of interest, such as stream flow or lake levels. Copyright © 2006 Royal Meteorological Society [source] Decadal-scale variability in the Kuroshio marine ecosystem in winterFISHERIES OCEANOGRAPHY, Issue 4-5 2003Kaoru Nakata Abstract Interannual variation of winter copepod biomass during the last three decades of the twentieth century was examined in the Kuroshio, off central Japan in relation to climate regime shifts. The biomass levels of large copepods in the period before 1977 and in 1999 and 2000 were higher than those in the period between 1977 and 1998. The biomass of large copepods was positively related with the Southern Oscillation Index (SOI), in winter in the Northern Hemisphere, which also showed steplike shifts in 1976/77 and 1998/99. The biomass of large copepods was largely influenced by abundance of Calanus sinicus that has high rates of production compared with small copepods under food satiated conditions. Accordingly, the climatic regime shift accompanied by the climatic change in the tropical region seems to regulate interannual variation of winter biomass of large copepods in the Kuroshio through effects on food supply. There is less decadal variablity in the small copepod (SC) biomass than large copepod (LC) biomass, but more variablity in SC than in LC at periods 2,4 years. In contrast to the large copepods, the biomass of small copepods was not related to global climate indices but with the local climate factors such as SST in the Kuroshio and variability in the Kuroshio flow path. Causes for the differences in the biomass trends between large and small copepods are discussed. [source] Detecting the impact of oceano-climatic changes on marine ecosystems using a multivariate index: The case of the Bay of Biscay (North Atlantic-European Ocean)GLOBAL CHANGE BIOLOGY, Issue 1 2008GEORGES HEMERY Abstract Large-scale univariate climate indices (such as NAO) are thought to outperform local weather variables in the explanation of trends in animal numbers but are not always suitable to describe regional scale patterns. We advocate the use of a Multivariate Oceanic and Climatic index (MOCI), derived from ,synthetic' and independent variables from a linear combination of the total initial variables objectively obtained from Principal Component Analysis. We test the efficacy of the index using long-term data from marine animal populations. The study area is the southern half of the Bay of Biscay (43°,47°N; western Europe). Between 1974 and 2000 we monitored cetaceans and seabirds along 131000 standardized line transects from ships. Fish abundance was derived from commercial fishery landings. We used 44 initial variables describing the oceanic and atmospheric conditions and characterizing the four annual seasons in the Bay of Biscay. The first principal component of our MOCI is called the South Biscay Climate (SBC) index. The winter NAO index was correlated to this SBC index. Inter-annual fluctuations for most seabird, cetacean and fish populations were significant. Boreal species (e.g. gadiformes fish species, European storm petrel and Razorbill ,) with affinities to cold temperate waters declined significantly over time while two (Puffin and Killer Whale) totally disappeared from the area during the study period. Meridional species with affinities to hotter waters increased in population size. Those medium-term demographic trends may reveal a regime shift for this part of the Atlantic Ocean. Most of the specific observed trends were highly correlated to the SBC index and not to the NAO. Between 40% and 60% of temporal variations in species abundance were explained by the multivariate SBC index suggesting that the whole marine ecosystem is strongly affected by a limited number of physical parameters revealed by the multivariate SBC index. Aside the statistical error of the field measurements, the remaining variation unexplained by the physical characteristics of the environment correspond to the impact of anthropogenic activities such overfishing and oil-spills. [source] Hydroclimatic teleconnection between global sea surface temperature and rainfall over India at subdivisional monthly scaleHYDROLOGICAL PROCESSES, Issue 14 2007Rajib Maity Abstract It is well established that sea surface temperature (SST) plays a significant role in the hydrologic cycle in which precipitation is the most important part. In this study, the influence of SST on Indian subdivisional monthly rainfall is investigated. Both spatial and temporal influences are investigated. The most influencing regions of sea surface are identified for different subdivisions and for different overlapping seasons in the year. The relative importance of SST, land surface temperature (LST) and ocean,land temperature contrast (OLTC) and their variation from subdivision to subdivision and from season to season are also studied. It is observed that LST does not show much similarity with rainfall series, but, in general, OLTC shows relatively higher influence in the pre-monsoon and early monsoon periods, whereas SST plays a more important role in late- and post-monsoon periods. The influence of OLTC is seen to be mostly confined to the Indian Ocean region, whereas the effect of SST indicates the climatic teleconnection between Indian regional rainfall and climate indices in Pacific and Atlantic Oceans. Copyright © 2006 John Wiley & Sons, Ltd. [source] Variability of southeastern Queensland rainfall and climate indicesINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 6 2004Bradley F. Murphy Abstract The variability of climate indices and rainfall in southeastern (SE) Queensland (Qld) is studied. Using high-resolution gridded rainfall data for all of Australia and global sea-surface temperatures (SSTs), the relationship between Australia-wide rainfall (and in SE Qld in particular) and SST indices and the southern oscillation index (SOI) have been investigated. It is found that SE Qld is more subject to the breakdown of correlations between the SOI and rainfall than any other part of Australia. Model predictions suggest that this is probable in the future. Considering only time scales longer than interannual, it was found that SSTs in the central tropical Pacific Ocean (TPO; represented by the Niño-4 index) correlated best with SE Qld rainfall. Eastern TPO (Niño-3) SSTs and the SOI produced successively weaker correlations. The time series of the second modes of variability of SSTs over the Pacific and Indian Oceans were shown to have limited impact on SE Qld rainfall variability. The data were split into periods before and after 1946, when Australian mean rainfall changed. Whereas the SOI correlations with rainfall in SE Australia were similar in both periods, in SE Qld the correlations were very weak in the earlier period (0.06) but very strong in the later period (0.72). The Niño-4 index correlated better than the Niño-3 index in both periods, but both indexes showed smaller changes from the earlier to the later periods than the SOI. Copyright © 2004 Royal Meteorological Society. [source] Weather packages: finding the right scale and composition of climate in ecologyJOURNAL OF ANIMAL ECOLOGY, Issue 6 2005NILS CHR. Summary 1Animals are affected by local weather variables such as temperature, rainfall and snow. However, large-scale climate indices such as the North Atlantic Oscillation (NAO) often outperform local weather variables when it comes to explain climate-related variation in life history traits or animal numbers. 2In a recent paper, Hallet et al. (2004, Nature, 430, 71,75) document convincingly why this may happen. In this perspective, we identify from the literature three mechanisms why this is so: (1) the time window; (2) the spatial window; and (3) the weather composition component of climate. 3Such an understanding may be used to derive even better ,weather packages' than the NAO. [source] Spatial analysis of climate in winegrape-growing regions in AustraliaAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 3 2010A. HALL Abstract Background and Aims:, Temperature-based indices are commonly used to indicate long-term suitability of climate for commercially viable winegrape production of different grapevine cultivars, but their calculation has been inconsistent and often inconsiderate of within-region spatial variability. This paper (i) investigates and quantifies differences between four such indices; and (ii) quantifies the within-region spatial variability for each Australian wine region. Methods and Results:, Four commonly used indices describing winegrape growing suitability were calculated for each Australian geographic indication (GI) using temperature data from 1971 to 2000. Within-region spatial variability was determined for each index using a geographic information system. The sets of indices were compared with each other using first- and second-order polynomial regression. Heat-sum temperature indices were strongly related to the simple measure of mean growing season temperature, but variation resulted in some differences between indices. Conclusion:, Temperature regime differences between the same region pairs varied depending upon which index was employed. Spatial variability of the climate indices within some regions led to significant overlap with other regions; knowledge of the climate distribution provides a better understanding of the range of cultivar suitability within each region. Significance of the Study:, Within-region spatial variability and the use of different indices over inconsistent time periods to describe temperature regimes have, before now, made comparisons of climates between viticulture regions difficult. Consistent calculations of indices, and quantification of spatial variability, enabled comparisons of Australian GIs to be made both within Australia and with American Viticultural Areas in the western United States. 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