Wind-driven oscillations of an enclosed basin with bottom friction     

Prof. Dr. W. Krauss 《Ocean Dynamics》1973,26(1):1-9

  相似文献   

Assessing stand water use in four coastal wetland forests using sapflow techniques: annual estimates,errors and associated uncertainties          下载免费PDF全文

Ken W. Krauss  Jamie A. Duberstein  William H. Conner 《水文研究》2015,29(1):112-127

Forests comprise approximately 37% of the terrestrial land surface and influence global water cycling. However, very little attention has been directed towards understanding environmental impacts on stand water use (S) or in identifying rates of S from specific forested wetlands. Here, we use sapflow techniques to address two separate but linked objectives: (1) determine S in four, hydrologically distinctive South Carolina (USA) wetland forests from 2009–2010 and (2) describe potential error, uncertainty and stand‐level variation associated with these assessments. Sapflow measurements were made from a number of tree species for approximately 2–8 months over 2 years to initiate the model, which was applied to canopy trees (DBH > 10–20 cm). We determined that S in three healthy forested wetlands varied from 1.97–3.97 mm day^?1 or 355–687 mm year^?1 when scaled. In contrast, saltwater intrusion impacted individual tree physiology and size class distributions on a fourth site, which decreased S to 0.61–1.13 mm day^?1 or 110–196 mm year^?1. The primary sources of error in estimations using sapflow probes would relate to calibration of probes and standardization relative to no flow periods and accounting for accurate sapflow attenuation with radial depth into the sapwood by species and site. Such inherent variation in water use among wetland forest stands makes small differences in S (<200 mm year^?1) difficult to detect statistically through modelling, even though small differences may be important to local water cycling. These data also represent some of the first assessments of S from temperate, coastal forested wetlands along the Atlantic coast of the USA. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Coupling near-surface geomorphology with mangrove community diversity at the estuarine scale: A case study at Dongzhaigang Bay,China     

Guogui Chen  Wei Hong  Xuan Gu  Ken W. Krauss  Kaiyuan Zhao  Haifeng Fu  Luzhen Chen  Mao Wang  Wenqing Wang 《Sedimentology》2023,70(1):31-47

Coastal wetlands are key features of the Earth's surface and are characterized by a diverse array of coupled geomorphological and biological processes. However, the links between the distribution of biodiversity (for example, species and structural diversity) and the formation of coastal geomorphology are not well-understood on a landscape scale most useful to coastal zone managers. This study describes the relationship between select geomorphological and biological mangrove community features (i.e. species composition and functional root type) in a landscape-distributed coastal zone of Dongzhaigang Bay, north-eastern Hainan Island, China. A total of 11 mangrove species and five functional aerial root types were encountered, with the location of species by root types being controlled by the elevation of the soil surface. Plank roots, prop roots and pneumatophores occupied the lowest intertidal elevations, while knee roots and fibrous roots of the mangrove fern, Acrostichum aureum, preferred the highest intertidal elevations. Surface sediment deposition in areas with mangroves was greater than deposition in non-mangrove forest zones, establishing an important biological mechanism for this large-area response because surface erosion/compaction was also more prominent within mangrove roots. Indeed, functional root type influenced the magnitude of deposition, erosion and compaction, with knee roots and pneumatophores being more effective in promoting deposition and preventing surface erosion/compaction than prop roots. These results indicate a potential role for vegetation type (especially functional root type) to influence coastal geomorphological processes at large landscape scales. While soil surface elevation is correlated to the distribution of mangrove species and functional root types, a significant feedback exists between elevation change and the capacity of those root types to influence coastal geomorphological differentiation within sustainable intertidal elevations. An enhanced understanding of geomorphological development, mangrove species distribution and functional root type may improve management to support nature-based solutions that adjust more effectively to sea-level rise through feedbacks.  相似文献   

Investigation of the impact of dynamic factors on Cb cloud development in Saudi Arabia     

T. W. Krauss  A. A. Sin’kevich  R. Burger  N. E. Veremei  Yu. A. Dovgalyuk  V. D. Stepanenko 《Russian Meteorology and Hydrology》2011,36(10):643-652

Changes are analyzed of a Cb cloud characteristics due to its merging with feeder clouds, on the data on a long-living Cb cloud in Saudi Arabia on July 4, 2008. Continuous radar and satellite observations of the cloud are carried out during 6 h. The Cb cloud development is also numerically simulated using a nonstationary 1½ model. It is found that the processes of Cb cloud merging with feeder clouds developing in its vicinities affect significantly the Cb cloud development. This impact demonstrates itself in longer duration of the Cb cloud life span, increasing top height, reflectivity, precipitation duration and intensity. Modification of the feeder clouds can accelerate their development, which eventually can affect notably the Cb cloud.  相似文献   

Periodicity in Stem Growth and Litterfall in Tidal Freshwater Forested Wetlands: Influence of Salinity and Drought on Nitrogen Recycling     

Nicole Cormier  Ken W. Krauss  William H. Conner 《Estuaries and Coasts》2013,36(3):533-546

Many tidally influenced freshwater forested wetlands (tidal swamps) along the south Atlantic coast of the USA are currently undergoing dieback and decline. Salinity often drives conversion of tidal swamps to marsh, especially under conditions of regional drought. During this change, alterations in nitrogen (N) uptake from dominant vegetation or timing of N recycling from the canopy during annual litter senescence may help to facilitate marsh encroachment by providing for greater bioavailable N with small increases in salinity. To monitor these changes along with shifts in stand productivity, we established sites along two tidal swamp landscape transects on the lower reaches of the Waccamaw River (South Carolina) and Savannah River (Georgia) representing freshwater (≤0.1 psu), low oligohaline (1.1–1.6 psu), and high oligohaline (2.6–4.1 psu) stands; the latter stands have active marsh encroachment. Aboveground tree productivity was monitored on all sites through monthly litterfall collection and dendrometer band measurements from 2005 to 2009. Litterfall samples were pooled by season and analyzed for total N and carbon (C). On average between the two rivers, freshwater, low oligohaline, and high oligohaline tidal swamps returned 8,126, 3,831, and 1,471 mg N?m^?2 year^?1, respectively, to the forest floor through litterfall, with differences related to total litterfall volume rather than foliar N concentrations. High oligohaline sites were most inconsistent in patterns of foliar N concentrations and N loading from the canopy. Leaf N content generally decreased and foliar C/N generally increased with salinization (excepting one site), with all sites being fairly inefficient in resorbing N from leaves prior to senescence. Stands with higher salinity also had greater flood frequency and duration, lower basal area increments, lower tree densities, higher numbers of dead or dying trees, and much reduced leaf litter fall (103 vs. 624 g?m^?2 year^?1) over the five study years. Our data suggest that alternative processes, such as the rate of decomposition and potential for N mineralization, on tidal swamp sites undergoing salinity-induced state change may be more important for controlling N biogeochemical cycling in soils than differences among sites in N loading via litterfall.  相似文献   

Influence of the hot oxygen corona on the satellite drag in the Earth’s upper atmosphere     

V. I. Shematovich  D. V. Bisikalo  S. Krauss  W. Hausleitner  H. Lammer 《Solar System Research》2011,45(3):231-239

Calculation results on the possible influence of the hot oxygen fraction on the satellite drag in the Earth’s upper atmosphere on the basis of the previously developed theoretical model of the hot oxygen geocorona are presented. Calculations have shown that for satellites with orbits above 500 km, the contribution from the corona is extremely important. Even for the energy flux Q ₀ = 1 erg cm⁻² s⁻¹, the contribution of the hot oxygen can reach tens of percent; and considering that real energy fluxes are usually higher, one can suggest that for extreme solar events, the contribution of hot oxygen to the atmospheric drag of the satellite will be dominant. For lower altitudes, the contribution of hot oxygen is, to a considerable degree, defined by the solar activity level. The calculations imply that for the daytime polar atmosphere, the change of the solar activity level from F _10.7 ∼ 200 to F _10.7 ∼ 70 leads to an increase in the ratio of the hot oxygen partial pressure to the thermal oxygen partial pressure by a factor of almost 30, from 0.85 to 25%. The transition from daytime conditions to nighttime conditions almost does not change the contribution from suprathermal particles. The decrease of the characteristic energy of precipitating particles, i.e., for the case of charged particles with a softer energy spectrum, leads to a noticeable increase of the contribution of the suprathermal fraction, by a factor of 1.5–2. It has been ascertained that electrons make the main contribution to the formation of the suprathermal fraction; and with the increase of the energy of precipitating electrons, the contribution of hot oxygen to the satellite drag also increases proportionally. Thus, for a typical burst, the contribution of the suprathermal fraction is 30% even at relatively high solar activity F _10.7 = 135.  相似文献   

Granulite sulphides as tracers of lower crustal origin and evolution: An example from the Slave craton, Canada     

Sonja Aulbach  Cristen Krauss  Robert A. Creaser  Thomas Stachel  Larry M. Heaman  Sergei Matveev  Thomas Chacko 《Geochimica et cosmochimica acta》2010,74(18):5368-5381

We carried out a detailed study of sulphide minerals, a ubiquitous mineral group in lower crustal mafic to peraluminous granulite xenoliths from the Diavik kimberlites, to assess their use in constraining the origin and tectonothermal evolution of the deep crust, and to obtain additional data on the composition of lower crust beneath ancient continents. Sulphides are overwhelmingly pyrrhotite with minor Ni (0.7-3.9 at.%), Co (0.1-0.7 at.%), and Cu contents (0.4-3.9 at.%). Sulphide modes in mafic granulites range from 0.14 to 0.55 vol%, translating into bulk rock S contents from ∼600 to 2000 ppm, similar to S contents in other mafic igneous rocks and indicating preservation of primary igneous S contents. In mafic granulites, Re and Os abundances in sulphides range from 42.5 to 726 ppb and 3.2 to 180 ppb, respectively, whereas those in peraluminous granulites are distinctly lower (36.1-282 ppb and 1.8-7.2 ppb, respectively), suggestive of Re and Os loss to fractionating sulphides in the more evolved precursors of these rocks.The significant within-sample variability of ¹⁸⁷Os/¹⁸⁸Os and correlation with ¹⁸⁷Re/¹⁸⁸Os indicates the preservation of primary Re-Os isotope systematics and time-integrated decay of the measured ¹⁸⁷Re. Within the large uncertainties inherent in the nature of the samples and technique, sulphides in some granulites may record major tectonothermal events in the central Slave craton spanning several billion years of evolution. Multiple generations of sulphide can occur in a single sample. These data attest to the heterogeneous composition and complex history of the Slave craton lower crust.  相似文献   

Radar investigations of cloud merger     

T. W. Krauss  A. A. Sin’kevich  A. S. Ghulam 《Russian Meteorology and Hydrology》2012,37(9):604-614

Presented are the results of radar investigations of cloud merger during their natural cycle of development and after the seeding. The observations were carried out in the southwest of the Kingdom of Saudi Arabia in 2008. It is revealed that the merging was observed under conditions of very unstable atmosphere, when the convective available potential energy exceeded 3000 J/kg. The cloud merger impacts significantly their development. The most considerable changes due to the cloud merging were observed for the cloud mass and precipitation flow increased as a result of this process by two or three times. It is discovered that the impact of the merger of clouds on their characteristics exceeds significantly the effect of seeding carried out for the feeder clouds.  相似文献   

On the energy of the wind stress required to produce internal and inertial waves     

Prof. Dr. W. Krauss 《Ocean Dynamics》1978,31(2):31-49

  相似文献   

A semispectral model on the β-plane     

Wolfgang Krauss  Professor Dr. Chresten Wübber 《Ocean Dynamics》1982,35(5):187-201

  相似文献