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Ken Moran Sergio Pezoa Chris Fairall Chris Williams Tom Ayers Alan Brewer Simon P. de Szoeke Virendra Ghate 《Boundary-Layer Meteorology》2012,143(1):3-24
Cloud radars at X, Ka and W-bands have been used in the past for ocean studies of clouds, but the lack of suitable stabilization
has limited their usefulness in obtaining accurate measurements of the velocity structure of cloud particles and the heights
of cloud features. A 94 GHz (W-band) radar suitable for use on shipboard studies of clouds has been developed that is small
and lightweight and can maintain the radar’s beam pointing in the vertical to reduce the affects of the pitch and roll of
the ship. A vertical velocity sensor on the platform allows the effects of the ship’s heave to be removed from the measured
cloud particle motions. Results from the VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-Rex) field program
on the NOAA vessel Ronald H. Brown demonstrate the improvements to the cloud measurements after the ship’s motion effects are removed. The compact design of
the radar also makes it suitable for use in aircraft studies. The radar is being repackaged to fit in an aft bay of a NOAA
P3 aircraft to observe sea-spray profiles during ocean storms. 相似文献
43.
Amandine Bordon Odile Peyron Anne-Marie Lzine Simon Brewer Eric Fouache 《Quaternary International》2009,200(1-2):19
High-temporal resolution analysis of pollen records from Lake Maliq (Albania) provides quantitative estimates of monthly temperature and precipitation changes since the last deglaciation. The climate parameters were estimated using the best modern analogue technique with an updated modern pollen-climate database composed of 2748 surface samples. The record shows two main cooling phases in the Maliq area (the Oldest and Younger Dryas) and a cooling event around 8200 years, which suggests that the forcing factors driving climate variations in the North Atlantic area since the Last Glacial period also extended their influence into the Mediterranean area. The Oldest and Younger Dryas are also characterized by an arid climate and a change in the seasonality of precipitation: the summer precipitation tends to be greater during the cooling phases than during the temperate periods. The Holocene climate is relatively stable and the values of each parameter reach their modern levels, except for an arid event between 8300 and 8100 cal BP. 相似文献
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Cynthia A. Brewer 《The Professional geographer》1997,49(3):280-294
Perceptions of colors of individual map symbols are affected by simultaneous contrast, or induction, from surrounding colors. In an experiment with human subjects, reaction times were significantly slower, with significantly more errors, for test maps on which an induction model predicted that colors would be misinterpreted. Reaction times and error rates improved significantly with map color adjustments that the model predicted would remove induced confusions. These results represent progress toward establishing objective guidance for the design of effective color schemes in computer-assisted mapping environments common in cartography, geographic information systems, and scientific visualization. 相似文献
47.
Multiple sedimentary units from floodplain reaches at Welshpool on the upper River Severn and at the confluence of the Afon Tanat and Afon Vyrnwy (mid‐Wales, UK) were examined to ascertain if they have distinctive particle size characteristics. Changes in particle size characteristics and their possible relationship to known human and climatic impacts are also discussed. Ellipse plots of particle size characteristics from the River Severn floodplain at Welshpool show that coarse‐grained outwash deposits can be clearly discriminated from channel margin or palaeochannel sediments. In contrast, at the Afon Tanat–Vyrnwy study reach, this discrimination is not seen so clearly. The relationships between age and particle size characteristics from the most sampled sedimentary environment, palaeochannel infills, were also examined. The data from the River Severn floodplain at Welshpool show that palaeochannel sediments reveal a gradual but clear increase in particle size from the mid‐ to late Holocene towards the present day. Sediments deposited in the period 90–160 years BP are markedly coarser. It is suggested that these changes may be related to the combined effect of land‐use changes, metal mining impacts and changes in flood frequency and magnitude that occurred at this time within the upper Severn basin. In contrast, the particle size characteristics of post Late Devensian/Early Holocene units from Tanat–Vyrnwy palaeochannels were random with no discernible age–size patterns. It is suggested that the non‐systematic grain size distribution may be due to the steeper valley gradients of the Tanat–Vyrnwy system (and by inference higher stream powers) and its relatively narrow valley form enabling more effective coupling between coarser outwash deposits found on and at the edges of hillslopes and the valley floor. Although the two study reaches have undergone comparable environmental change during the Holocene and lie in the piedmont zone of their catchments, palaeochannel units of the same age possess distinctly different characteristics. Intrinsic reach‐scale geomorphic factors would appear to preclude the uniform application of particle size characteristics to determine alluvial response to environmental change. Consequently, care needs to be applied to the use of such data for environmental discrimination because the phenomenon of equifinality means that a specific set of sediment characteristics is not necessarily exclusive to specific fluvial environments in either space or time. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
48.
Many upland river catchments in the UK have been historically mined for metals such as lead (Pb) and zinc (Zn), and as part of the mining process large quantities of metal contaminated sediment were released into the river system. The levels of sediment associated heavy metal contamination in river systems are largely controlled by the volumes of contaminated sediment released into the river and fluvial processes (e.g. erosion and deposition). As a consequence, the contamination patterns are often highly variable, which can make it difficult to create accurate assessments of the volumes of contaminated sediment remaining within the system. This paper uses a combination of techniques to establish the volumes of metal contaminated sediment remaining within the River Swale, UK. Firstly, using detailed field sampling and a geographical information system (GIS), it estimates the volumes of sediment remaining within one formerly mined tributary (Gunnerside Beck) which is then extrapolated to represent the contaminant volumes on other tributaries of the River Swale. Secondly, combining fresh field data with a range of existing data, volumes of contaminated sediment on the main stream of the River Swale are established. This two tier approach shows that significant volumes of contaminated sediment remain within the River Swale, with over 32 000 tonnes of Pb within the mined tributaries and 123 000 tonnes within the main channel belt of the River Swale itself. This represents approximately 28% of the Pb produced in the Swale catchment. Given these volumes and present day rates of removal, it may take over 5000 years for all of the metal rich sediment to be removed from the catchment. If the contaminated sediment is used as a tracer, present day rates of reworking of floodplain sediment can be calculated to be 0·02% per year. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
49.
Pavel E. Tarasov Rachid Cheddadi Joel Guiot Sytze Bottema Odile Peyron Jordina Belmonte Vittoria Ruiz-Sanchez Fatima Saadi Simon Brewer 《第四纪科学杂志》1998,13(4):335-344
An objective method for the assignment of pollen spectra to appropriate biomes has been published recently. The aim of this paper is to improve the distinction between warm and cool steppes, thus refining vegetation and climate reconstruction, particularly during the Last Glacial Maximum. A set of modern pollen spectra from the Mediterranean and Kazakhstan regions, dominated today by open vegetation types, has been analysed statistically in order to relate pollen taxa abundances to warm and cool grass/shrub plant functional types (PFTs). A statistical test using modern pollen data shows that the method is able to distinguish between cool and warm steppe biomes with a high degree of confidence. The method has been applied to two fossil pollen records. The results of this exercise showed that cool steppe dominated in central Greece between 18 000 and 13 000 yr BP, while in western Iran the vegetation was at the boundary between cool and warm steppes. These vegetation types were replaced by warm mixed forest in Greece and warm steppe in Iran after that time span. © 1998 John Wiley & Sons, Ltd. 相似文献
50.
Thomas L. Brewer 《Climate Policy》2013,13(4):329-341
This article addresses concerns that the multilateral trade regime centered in the WTO and the emerging climate regime may conflict in ways that could be damaging to either or both. The article discusses the institutional and diplomatic context of these concerns, and it identifies the kinds of issues that are in question. The analysis suggests that there are opportunities for win—win outcomes in the interactions of the two regimes, for instance in the possibility of reducing fossil fuel subsidies. However, there are also problematic areas where they intersect. A core issue—and as yet an unresolved one—is whether and how emission credit trading and other activities envisioned by the Kyoto Protocolwould be subject toWTOrules. The resolution of this issue will affect many other issues as well. Additional specific issues about the interactions of particular provisions inWTOagreements and theKyoto Protocol are analyzed in a subsequent companion article in Climate Policy. 相似文献