Climate change impacts on spatial patterns in drought risk in the Willamette River Basin, Oregon, USA     

Il Won Jung  Heejun Chang 《Theoretical and Applied Climatology》2012,108(3-4):355-371

Climate change is likely to lead more frequent droughts in the Pacific Northwest (PNW) of America. Rising air temperature will reduce winter snowfall and increase earlier snowmelt, subsequently reducing summer flows. Longer crop-growing season caused by higher temperatures will lead to increases in evapotranspiration and irrigation water demand, which could exacerbate drought damage. However, the impacts of climate change on drought risk will vary over space and time. Thus, spatially explicit drought assessment can help water resource managers and planners to better cope with risk. This study seeks to identify possible drought-vulnerable regions in the Willamette River Basin of the PNW. In order to estimate drought risk in a spatially explicit way, relative Standardized Precipitation Index (rSPI) and relative Standardized Runoff Index (rSRI) were employed. Statistically downscaled climate simulations forcing two greenhouse gas emission scenarios, A1B and B1, were used to investigate the possible changes in drought frequency with 3-, 6-, 12-, and 24-month time scales. The results of rSPI and rSRI showed an increase in the short-term frequency of drought due to decreases in summer precipitation and snowmelt. However, long-term drought showed no change or a slight decreasing pattern due to increases in winter precipitation and runoff. According to the local index of spatial autocorrelation analysis, the Willamette Valley region was more vulnerable (hot spot) to drought risk than the mountainous regions of the Western Cascades and the High Cascades (cold spot). Although the hydrology of the Western Cascades and the High Cascades will be affected by climate change, these regions will remain relatively water-rich. This suggests that improving the water transfer system could be a reasonable climate adaptation option. Additionally, these results showed that the spatial patterns of drought risk change were affected by drought indices, such that appropriate drought index selection will be important in future studies of climate impacts on spatial drought risk.  相似文献   

Terrigenous zircon of archean greenstone belts as a source of information on the early earth’s crust: Azov and Dnieper domains,Ukrainian shield     

E. V. Bibikova  S. Claesson  A. A. Fedotova  G. V. Artemenko  L. Il’inskii 《Geochemistry International》2010,48(9):845-861

Zircons from the metasedimentary rocks of the Mesoarchean greenstone belts of the Azov and Middle Dnieper blocks of the Ukrainian shield were studied and dated by U-Pb method on a NORDSIM secondary-ion mass spectrometer. Detrital zircons from the metasediments of the Belozerskaya Formation of the greenstone belts of the Middle Dnieper block are usually dated within 3000–3100 Ma, while individual grains have an age of 3200–3300 Ma. This indicates that the sediments were derived mainly from proximal volcanic source with minor contribution of the basement material (Aul’skaya Group). The metasediments of the Soroki greenstone structure of the Azov block contain mainly zircons with ages within 3500–3600 Ma, except for scarce grains having the ages older than 3700 Ma. Zircon cores are overgrown by granulitic rims dated at approximately 3300 Ma. A wide scatter in ages and Th/U ratios in the zircons indicate that they were derived from rocks of different composition and age. Obtained data suggest significantly wider distribution of the Paleoarchean crust within the Azov block of the Ukrainian shield than was previously assumed.  相似文献   

Hydrologo-morphological approach to regionalization of the Selenga river basin     

L. M. Korytny  E. A. Il’icheva  M. V. Pavlov  I. Yu. Amosova 《Geography and Natural Resources》2012,33(3):212-217

We examine the evolutionary stages of scientific views on the formation history of the delta plain of the Selenga river and adjacent territories, based on cartographic material and national investigations spanning the period 1701?C2009. We suggest the regionalization of the Selenga river from hydromorphometric attributes of erosion-accumulation, abrasion-accumulation and neotectonic processes. The study is based on comparing topographic maps, guides for navigation and space images (1898?C2009) as well as on experimental data obtained by the authors.  相似文献   

Lithium and the 6Li-7Li isotope ratio in the atmospheres of some sharp-lined roAp stars     

A. V. Shavrina  N. S. Polosukhina  S. Khan  Ya. V. Pavlenko  D. O. Kudryavtsev  V. R. Khalack  N. G. Mikhaĭlitskaya  Yu. P. Lyubchik  A. V. Yushchenko  A. Hatzes  D. E. Mkrtichian  I. V. Il’in 《Astronomy Reports》2006,50(6):500-511

The λ 6708 Å and 6103 Å lithium lines in the high-resolution spectra of some sharp-lined roAp stars are analyzed using three spectral-synthesis codes STARSP, ZEEMAN2, and SYNTHM. The lines from the VALD database were supplemented with lines of rare-earth elements from the DREAM database and new lines calculated using the NIST energy levels. Our synthetic-spectrum calculations take into account magnetic splitting and other line-broadening effects. Lithium overabundances were found in the atmospheres of the stars based on our analysis of both lithium lines, along with high values of the ⁶Li-⁷Li isotope ratio (0.2–0.5). This can be explained if lithium is produced in spallation reactions and the surface ⁶Li and ⁷Li is preserved by strong magnetic fields in the upper layers of the stellar atmospheres, around the poles of the dipole field. The asymmetry of lithium lines to the red may be due to the action of shocks in the optically thin upper atmosphere, with the shocked material subsequently falling onto the star.  相似文献   

Search for spatial and spectral fluctuations of the cosmic microwave background radiation using the RATAN-600 radio telescope     

I. V. Gosachinskij  V. K. Dubrovich  S. R. Zhelenkov  G. N. Il’in  V. A. Prozorov 《Astronomy Reports》2002,46(7):543-550

We report the results of a search for spatial and spectral fluctuations of the cosmic microwave background in the region of the North celestial pole carried out at 6.2 cm using the RATAN-600 radio telescope in 1999–2000. The spatial spectrum is flat and has no features exceeding ΔT/T =10^?3 in a ～1 MHz frequency band for spatial periods from 0.5′ to 16′. If this estimate is adopted as an upper limit for emission associated with the first rotational transition of primordial LiH at z=90.7, we obtain an upper limit for the LiH abundance of about 3×10^?14 for protocluster masses of about 10¹³ M _⊙.  相似文献   

Retraction of “Advance of the outlet glaciers during regional warming as inferred from Late Holocene massive diamicton in the King George Island fjords, the South Shetland Islands, West Antarctica” [Quaternary Research 65 (2006) 57–69]     

Kyu-Cheul Yoo  Ho Il Yoon  Byong-Kwon Park  Yeadong Kim 《Quaternary Research》2008,69(3):57

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Analysis of the structure of disk galaxies in the NGC 2300 group     

M. A. Il’ina  O. K. Sil’chenko 《Astronomy Reports》2016,60(10):894-903

Data from the 6-m telescope of the Special Astrophysical Observatory obtained using the SCORPIO instrument in imaging mode are used to study member galaxies of the NGC 2300 group. Surface photometry has been carried out for the five largest galaxies in the group, whose isophotal parameters and the parameters of their large-scale structural components (disks and bulges) have been determined. The morphological type of the central galaxy in the group has been refined, and shown to be elliptical. Studies of structural features in non-central disk galaxies have revealed an enhanced percent of bars: bars were found in all disk galaxies of this group, with all of these being compact structures. The similarity of the structural features of the disks of the group galaxies suggests that these disksmay be being restructured in the process of the current merger of the two X-ray subgroups comprising NGC 2300: the group NGC 2300 itself and the group NGC 2276.  相似文献   

Methane emission from West Siberian forest-steppe and subtaiga reed fens     

A. F. Sabrekov  I. V. Filippov  M. V. Glagolev  D. V. Il’yasov  O. R. Kotsyurbenko  Sh. Sh. Maksyutov 《Russian Meteorology and Hydrology》2016,41(1):37-42

Methane emission from West Siberian forest-steppe and subtaiga reed fens (that is, fens dominated by Phragmites australis) observed in summer 2013, is considered using the static chamber method. The obtained medians of CH₄ fluxes varied from -0.08 to 2.7 mg CH₄/m² per hour. Eenvironmental factors affecting methane emission are analyzed. It was found that CH₄ emissions from the reed fens correlate only with the concentration of salt ions in the wetland water and with the plant community structure. The latter probably also depends on water salinity. It was revealed that in fens the ratio between fluxes of CH₄ and CO₂ does not depend on the water table level that contradicts the general pattern simulated by mathematical models of CH₄ emission. It was found that Phragmites australis fens and similar ecosystems should be considered as a separate wetland class from the point of view of methane emission study.  相似文献   

Factors Affecting the Wintering Habitat of Major Fishery Resources in Southwestern Korean Waters     

Jin Yeong Kim  Il Su Choi  Joo Il Kim  Seok Gwan Choi  Young Yull Chun 《Ocean Science Journal》2007,42(1):41-48

We investigated the temperature and salinity effects on the major fish species in the wintering grounds based on trawl surveys and oceanographic observations in the southwestern waters of Korea during March-early April in 2002-2003. The influence area of warm Kuroshio water was limited to the southwestern area of Korea in 2003 with a range of 7.7-16.3°C, 32.54-34.70 of salinity, wider than that of 2002. The number of fish species and density of major fish species in 2003 were higher than in 2002. Geographical estimation showed high proportions of species number and catches in the areas around Jeju Islands, southwestern waters and the southeastern coast of Korea. Five species; silver pomfret (Pampus echinogaster), hairtail (Trichiurus lepturus), anchovy (Engraulis japonicus), small yellow croaker (Larimichthys polyactis) and yellow goosefish (Lophius litulon) were most abundant, composing above 60% of the total catch in 2002 and 2003. More than 50% of catch in the major fish species were mostly distributed in the range of 9.5-11.0°C of temperature and 33.1-33.9 of salinity. Non-parametric estimation for the major species showed the 1st mode around 10°C and the 2nd mode at 8-9°C in 2002 and 11-14°C in 2003. A m o n g major fish species, hairtail was principally composed of juveniles, and larger individuals were caught in southeastern waters. These results are considered to be helpful for the areabased fishery management strategy for the wintering grounds of the Yellow Sea and coastal waters of Korea.  相似文献   

Late Quaternary stable isotope record and meltwater discharge anomaly events to the south of the Antarctic Polar Front,Drake Passage     

Sung?Ho?BaeEmail author  Ho?Il?Yoon  Byong-Kwon?Park  Yeadong?Kim 《Geo-Marine Letters》2003,23(2):110-116

Marine isotope stages (MISs) 1 to 5 were identified in the planktonic ¹⁸O record in sediment core DP00-02 just south of the Antarctic Polar Front in the Drake Passage, Antarctica. The oxygen isotope record, based on Neogloboquadrina pachyderma sinistral, is correlated with the contemporaneous global ¹⁸O stratigraphy. Marked deviations from the global climate curve suggest a local/regional overprint, particularly during MIS 3 which is considered a colder time period in the ocean record than MIS 1 and MIS 5 during the last interglacial. The comparison shows that negative ¹⁸O shifts in core DP00-02 during MIS 3 are larger than mean global changes which show a shift equal to or smaller than 0.5. The isotope shift, exceeding the glacial-interglacial ice volume effect, probably resulted from changes in the isotope composition of seawater, which is linearly related to decreases in salinity rather than to increases in sea-surface temperature. Increased ice-rafted debris (IRD) content during this interval indicates a strong influx of IRD from melting ice shelves and icebergs, which may be related to upwelling of warmer circumpolar deep water.  相似文献