Hydrogeomorphic processes of thermokarst lakes with grounded‐ice and floating‐ice regimes on the Arctic coastal plain,Alaska

Thermokarst lakes cover > 20% of the landscape throughout much of the Alaskan Arctic Coastal Plain (ACP) with shallow lakes freezing solid (grounded ice) and deeper lakes maintaining perennial liquid water (floating ice). Thus, lake depth relative to maximum ice thickness (1·5–2·0 m) represents an important threshold that impacts permafrost, aquatic habitat, and potentially geomorphic and hydrologic behaviour. We studied coupled hydrogeomorphic processes of 13 lakes representing a depth gradient across this threshold of maximum ice thickness by analysing remotely sensed, water quality, and climatic data over a 35‐year period. Shoreline erosion rates due to permafrost degradation ranged from < 0·2 m/year in very shallow lakes (0·4 m) up to 1·8 m/year in the deepest lakes (2·6 m). This pattern of thermokarst expansion masked detection of lake hydrologic change using remotely sensed imagery except for the shallowest lakes with stable shorelines. Changes in the surface area of these shallow lakes tracked interannual variation in precipitation minus evaporation (P ? E_L) with periods of full and nearly dry basins. Shorter‐term (2004–2008) specific conductance data indicated a drying pattern across lakes of all depths consistent with the long‐term record for only shallow lakes. Our analysis suggests that grounded‐ice lakes are ice‐free on average 37 days longer than floating‐ice lakes resulting in a longer period of evaporative loss and more frequent negative P ? E_L. These results suggest divergent hydrogeomorphic responses to a changing Arctic climate depending on the threshold created by water depth relative to maximum ice thickness in ACP lakes. Copyright © 2011 John Wiley & Sons, Ltd.     

Modular development of an inline monitoring system for waterborne pathogens in raw and drinking water

The state-of-the-art monitoring of drinking water hygiene is based on the cultivation and enumeration of indicator bacteria. Despite its proven reliability, this approach has the disadvantages of being (a) relatively slow and (b) limited to a small number of indicator bacteria. Ideally, alternative methods would be less time-consuming while providing information about a larger set of hygienically relevant microorganisms including viruses. In this paper, we present insights into the design of a modular concentration and detection system for bacteria, bacteriophages and viruses. Following further validation, this or similar techniques have the potential to extend and speed up the monitoring of raw and drinking water hygiene in the future. The system consists of different modules for the concentration of microorganisms, an amplification and detection unit that includes a module for the differentiation between live and dead microorganisms, and an automated system for decision support and self-diagnosis. The ongoing testing under controlled laboratory conditions and real-life conditions in the water supply industry yields further system improvements. Moreover, the increased sensitivity and broader range of microbiological parameters emphasize the need for a reconsideration of the currently used criteria for the assessment of (drinking) water hygiene.     

Spatial interpretation of high-resolution environmental proxy data of the Middle Pleistocene Palaeolithic faunal kill site Schöningen 13 II-4, Germany

To spatially characterize the palaeolakeshore environment at the archaeological kill site Schöningen 13 II-4 of the Middle Pleistocene Reinsdorf sequence, in-depth palynological, geochemical, aquatic microfossil and archaeological analyses were undertaken on sediment sections with an average thickness of about 15 cm, concordantly overlain by faunal remains, dominated by horse, from the unique ‘Spear Horizon’ layers of the 1995 excavation campaign. The data reveal a distinctive lake level drop, documented by the change from a carbonate-rich lake marl to a carbonate-free organic mud with increased carbon content and decreasing C/N, Si/Al, Si/K and Fe/Al ratios, indicating a higher pedogenic supply of organic matter and drier conditions at the site. Compared with older, similar transitional phases of lake level changes occurring within the Reinsdorf sequence, it is important that these youngest sediments are undisturbed, indicating continuous development. Ostracod and diatom analyses indicate a lowering water level with higher salinities and rich aquatic vegetation. Mesorheophilic ostracod species along with tychoplanktic diatom taxa point to flowing waters and turbulence at the lakeshore, presumably related to spring-fed streams originating from nearby highlands. Palynological results reveal a very diverse zonal vegetation pattern around the palaeolakeshore considering an area of investigation of approximately 50 × 75 m and a tessellated type of regional vegetation during the formation of the archaeological horizons. On topographically lower elevated areas, birch groves and taxa favouring wet, marshy conditions such as Cyperaceae, indicative of terrestrialization, were predominating, while other stands of this transitional phase reveal a very dry, grass-dominated steppe woodland favouring a rich wildlife with a striking number of megaherbivores. Our results suggest that the lithological differences of the ‘Spear Horizon’ layers containing the archaeological finds were due to their respective topographical situation and that the layers were deposited almost simultaneously during the beginning of the lake level drop. Human activities seem to have concentrated in sparsely vegetated areas along the palaeolakeshore, rather than in areas of adjacent denser birch swamp forest stands.     

Sunshine duration and its variability in the main ridge of the Karkonosze Mountains in relation to with atmospheric circulation

Theoretical and Applied Climatology - Sunshine duration analysis was based on a series of measurements spanning the period from 1901 to 2014 for Śnieżka (1603&nbsp;m&nbsp;a.s.l.)...     

Improved representation of ocean heat content in energy balance models

Climatic Change - Anomaly-diffusing energy balance models (AD-EBMs) are routinely employed to analyze and emulate the warming response of both observed and simulated Earth systems. We demonstrate a...     

喜马拉雅山佩枯岗日冰川地貌的年代学、平衡线高度和气候研究

喜马拉雅山珠穆朗玛峰-希夏邦马峰地区是青藏高原南部现代冰川集中发育区之一,古冰川遗迹亦十分丰富,是研究第四纪青藏高原冰川形成和演化的关键区,一直备受地貌和第四纪环境研究者的关注.应用原地宇宙核素10Be暴露年龄测试技术,对采自希夏邦马峰西北佩枯岗日拉曲谷地冰碛垄上的冰川漂砾进行年代学研究;结合冰川地貌分析方法,对古冰川...     

长白山地区全新世泥炭剖面地球化学特征及其古环境意义

长白山地区是中国泥炭分布集中地区之一。本文选择长白山地区典型的泥炭剖面--大桥剖面,探讨其沉积物常量元素和微量元素的垂直分布规律及其对全新世气候变化的指示作用,并与该区另一代表剖面--金川泥炭剖面进行对比。结果表明,泥炭中常量元素含量最大值出现在195 cm,向上、向下都减少,铁含量与灰分、容重在剖面上的变化规律基本一致,说明它主要来源于灰分;由于泥炭和砂土的基本性质,如容重、灰分、pH值有很大的区别,泥炭层微量元素大于下部砂土的含量,亚表层微量元素含量最高,这与灰分、纤维含量正好相反,与pH值剖面变化一致;沉积物容重、灰分、pH值、Ca/ Mg以及元素的富集因子、泥炭中总碳含量在剖面上的变化,显示很强的一致性,据此反映该区经历了早11880～7600aBP)、中(7 600～480aBP)、晚(2480～0aBP)全新世三个环境阶段,其结论与前人通过孢粉、同位素手段分析得到的金川泥炭剖面环境变迁规律相同,从而说明它们可以作为研究环境变迁的敏感指标。     

Estimating traveler populations at airport and cruise terminals for population distribution and dynamics

In recent years, uses of high-resolution population distribution databases are increasing steadily for environmental, socioeconomic, public health, and disaster-related research and operations. With the development of daytime population distribution, temporal resolution of such databases has been improved. However, the lack of incorporation of transitional population, namely business and leisure travelers, leaves a significant population unaccounted for within the critical infrastructure networks, such as at transportation hubs. This paper presents two general methodologies for estimating passenger populations in airport and cruise port terminals at a high temporal resolution which can be incorporated into existing population distribution models. The methodologies are geographically scalable and are based on, and demonstrate how, two different transportation hubs with disparate temporal population dynamics can be modeled utilizing publicly available databases including novel data sources of flight activity from the Internet which are updated in near-real time. The airport population estimation model shows great potential for rapid implementation for a large collection of airports on a national scale, and the results suggest reasonable accuracy in the estimated passenger traffic. By incorporating population dynamics at high temporal resolutions into population distribution models, we hope to improve the estimates of populations exposed to or at risk to disasters, thereby improving emergency planning and response, and leading to more informed policy decisions.     

Predictions of magnetic fields for Uranus and Neptune

Summary The magnetic moments of Uranus and Neptune have been predicted using different scaling laws of planetary magnetism. The predictions for Uranus cover a broad band of values from very weak magnetic fields (tidal relations) to moderate fields (thermal convection hypothesis). Therefore, the direct measurements of this field by Voyager 2 (January 1986) will be very important for testing the individual hapotheses.

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Presented at the Fifth Scientific Assembly of IAGA in Prague 1985.     

Calibration and Verification of Jason-1 Using Global Along-Track Residuals with TOPEX

It is demonstrated that the Jason-1 measurements of sea surface height (SSH), wet path delay, and ionosphere path delay are within required accuracies, via a global cross-calibration with similar measurements made by TOPEX/Poseidon (T/P) over a 6-month period. Since the two satellites were on the same groundtrack separated in time by only 70 s, measurements were recorded at approximately the same location and time. The variations in the wet path delay measured by Jason-1 compared to T/P are only 5 mm RMS, well within the required performance of 1.2 cm RMS. The RMS of the ionosphere differences is also well within the expected values, with a mean RMS of 1.2 cm. The largest difference is that the Jason-1 SSH is biased high relative to T/P SSH by 144 mm after the T/P and Jason-1 data are both corrected with improved sea state bias (SSB) models. However, the bias will change if a different SSB model is used, so the user should be cautious that the bias used matches the SSB models. The bias is generally constant within ± 10 mm in the open ocean, but appears to be higher or lower in some regions. Additionally, the SSH has been verified by comparison with 36 island tide gauges over the same period. After removing the global relative bias, the Jason-1 SSH data agree with tide gauges within 3.7 cm RMS and with T/P data within about 3.5 cm RMS on average for 1-s measurements, meeting the required accuracy of 4.2 cm RMS.