Net precipitation over the Baltic Sea for one year using models and data-based methods   总被引：1，自引：0，他引：1  

BARBARA HENNEMUTH  ANNA RUTGERSSON  KARL BUMKE  MARCO CLEMENS  ERS OMSTEDT  DANIELA JACOB  ANN-SOFI SMEDMAN 《地球，A辑:动力气象学与海洋学》2003,55(4):352-367

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A catchment scale evaluation of the SIBERIA and CAESAR landscape evolution models     

GR Hancock  JBC Lowry  TJ Coulthard  KG Evans  DR Moliere 《地球表面变化过程与地形》2010,35(8):863-875

Landscape evolution models provide a way to determine erosion rates and landscape stability over times scales from tens to thousands of years. The SIBERIA and CAESAR landscape evolution models both have the capability to simulate catchment–wide erosion and deposition over these time scales. They are both cellular, operate over a digital elevation model of the landscape, and represent fluvial and slope processes. However, they were initially developed to solve research questions at different time and space scales and subsequently the perspective, detail and process representation vary considerably between the models. Notably, CAESAR simulates individual events with a greater emphasis on fluvial processes whereas SIBERIA averages erosion rates across annual time scales. This paper describes how both models are applied to Tin Camp Creek, Northern Territory, Australia, where soil erosion rates have been closely monitored over the last 10 years. Results simulating 10 000 years of erosion are similar, yet also pick up subtle differences that indicate the relative strengths and weaknesses of the two models. The results from both the SIBERIA and CAESAR models compare well with independent field data determined for the site over different time scales. Representative hillslope cross‐sections are very similar between the models. Geomorphologically there was little difference between the modelled catchments after 1000 years but significant differences were revealed at longer simulation times. Importantly, both models show that they are sensitive to input parameters and that hydrology and erosion parameter derivation has long‐term implications for sediment transport prediction. Therefore selection of input parameters is critical. This study also provides a good example of how different models may be better suited to different applications or research questions. Copyright © 2010 John Wiley & Sons, Ltd and Commonwealth of Australia  相似文献   

Palaeomagnetism of Pliocene-Pleistocene sediments and lava flows on Tjörnes and Flatey, North Iceland     

JÓN EIRÍKSSON  RÉS I. GUDMUNDSSON  LEÓ KRISTJÁNSSON  KARL GUNNARSSON 《Boreas: An International Journal of Quaternary Research》1990,19(1):39-55

Palaeomagnetic measurements have been carried out on lava flows and volcaniclastic sedimentary rocks of Upper Pliocene and Pleistocene age from sections on the Tjömes Peninsula and a core section from the island of Flatey off North Iceland. Earlier palaeomagnetic work in the area is reviewed, and new data on the stratigraphy of the Hoskuldsvik Group on Tjörnes are presented. A revised polarity column based on our resultsisset upfortheoutcropson Tjörnes, including twoadditionalnormalsubchronswithin the Matuyama. Our palaeomagnetic results indicate that the rocks penetrated by the Flatey drillhole accumulated during the Matuyama. Age estimates for the Upper Tjömes sequence are reviewed, and correlation alternatives indicate that the earliest glaciation of Tjörnes took place either at c.2 Ma or near the Gauss/Matuyama boundary at c. 2.5 Ma. Correlation of individual Matuyama subchrons remains uncertain. A comparison of the climatic evidence from the Tjörnes area with data on oxygen isotope and carbonate variations at DSDP site 552A is used to evaluate correlation alternatives.  相似文献   

Physiological adaptations in Coleoptera on Spitsbergen     

JOHN ALEXANDER STRøMME  THOMAS WANJOHI NGARI  KARL ERIK ZACHARIASSEN 《Polar research》1986,4(2):199-204

Metabolic rates and Q₁₀ values were determined for three species of Spitsbergen Coleoptera, Amara quenseli, Simplocaria metallica and Rhynchaenus flagellum . The beetles had metabolic rates which were elevated compared to values of Coleoptera from other regions. This is interpreted as an adaptation to the prevailing low temperatures and short activity period on Spitsbergen.
A. quenseli had rates of water loss comparable to values of beetles in temperate and tropical xeric habitats, indicating that the habitat of the beetles on Spitsbergen at least occasionally is xeric.
Determination of cold-hardiness parameters such as supercooling point and haemolymph melting point of A. quenseli beetles revealed that the beetles had values corresponding to those of active insects in the temperate and tropical region. They had no thermal hysteresis factors. Thus, during summer they show no physiological adaptations to cold.  相似文献   

Ecophysiological studies on arthropods from Spitsbergen     

TORE AUNAAS  JOHN G. BAUST  KARL ERIK ZACHARIASSEN 《Polar research》1983,1(3):235-240

The cold-hardiness, high temperature tolerance and metabolic activity of summer specimens of staphylinid beetles ( Atheta graminicola ), collembolans ( Onichiurus groenlandicus ), spiders ( Erigone arctica ), and prostigmatid mites ( Molgus littoralis ) from Spitsbergen were investigated. The animals displayed cold-hardiness and haemolymph melting points within the normal ranges for summer insects from temperate regions, but were less tolerant to high temperatures. Haemolymph from spiders and from one species of collembolans ( Isotoma sp.) was found to contain thermal hysteresis factors. The beetles, collembolans, and mites were found to have oxygen consumption rates above the values of their relatives in other climatic zones, whereas the spiders had values within the range of temperate arachnoids. The study supports the view that polar arthropods have activation energy values lower than those of temperate animals.  相似文献   

Thermal hysteresis antifreeze agents in fishes from Spitsbergen waters     

JOHN-PEDER DENSTAD  TORE AUNAAS  JAN FREDRIK BORSETH  ARNE VOLLAN AARSET  KARL ERIK ZACHARIASSEN 《Polar research》1987,5(2):171-174

The occurrence of macromolecular antifreeze agents (so-called Thermal Hysteresis Factors) in blood plasma of fishes from Spitsbergen waters was investigated in August 1983, October 1984, and January 1986.
Thermal hysteresis was found in the plasma of three species of Spitsbergen fishes: shorthorn sculpin (Myoxocephalus scorpius) , polar cod (Boreogadus saida) , and sea snail (Liparis liparis) . This is the first time thermal hysteresis is reported from the sea snail. Seasonal changes in the amount of thermal hysteresis were observed in blood plasma of the shorthorn sculpin and the sea snail.
With the exception of the polar cod, blood plasma of deep water fishes displays no thermal hysteresis. The reason for this is probably that the polar cod also occurs in shallow ice laden sea water, where an'antifreeze'would be needed to protect against inoculative freezing.
No thermal hysteresis was observed in blood plasma of the saithe (Pollachius virens) , despite the fact that the saithe was observed swimming in ice laden sea water at a temperature of -1 to – 1.5°C under natural conditions, and was rapidly killed when it came into contact with ice in the laboratory. It is not known how the saithe survives in ice laden water under natural conditions.  相似文献