Inter‐annual variability in the effects of riparian woodland on micro‐climate,energy exchanges and water temperature of an upland Scottish stream          下载免费PDF全文

Grace Garner  Iain A. Malcolm  Jonathan P. Sadler  Colin P. Millar  David M. Hannah 《水文研究》2015,29(6):1080-1095

The influence of riparian woodland on stream temperature, micro‐climate and energy exchange was investigated over seven calendar years. Continuous data were collected from two reaches of the Girnock Burn (a tributary of the Aberdeenshire Dee, Scotland) with contrasting land use characteristics: (1) semi‐natural riparian forest and (2) open moorland. In the moorland reach, wind speed and energy fluxes (especially net radiation, latent heat and sensible heat) varied considerably between years because of variable riparian micro‐climate coupled strongly to prevailing meteorological conditions. In the forested reach, riparian vegetation sheltered the stream from meteorological conditions that produced a moderated micro‐climate and thus energy exchange conditions, which were relatively stable between years. Net energy gains (losses) in spring and summer (autumn and winter) were typically greater in the moorland than the forest. However, when particularly high latent heat loss or low net radiation gain occurred in the moorland, net energy gain (loss) was less than that in the forest during the spring and summer (autumn and winter) months. Spring and summer water temperature was typically cooler in the forest and characterised by less inter‐annual variability due to reduced, more inter‐annually stable energy gain in the forested reach. The effect of riparian vegetation on autumn and winter water temperature dynamics was less clear because of the confounding effects of reach‐scale inflows of thermally stable groundwater in the moorland reach, which strongly influenced the local heat budget. These findings provide new insights as to the hydrometeorological conditions under which semi‐natural riparian forest may be effective in mitigating river thermal variability, notably peaks, under present and future climates. © 2014 The Authors. Hydrological Processes published by John Wiley & Sons Ltd.  相似文献   

Carbon-Bearing Molecules in Oxygen-Rich Circumstellar Envelopes     

A.J. Markwick  T.J. Millar 《Astrophysics and Space Science》1997,251(1-2):255-258

We are currently conducting a search of oxygen-rich circumstellar envelopes for carbon-bearing molecules with the ISO SWS instrument. CH₄ is the molecule in which we are most interested, because it has been shown to be capable of providing the reactive carbon which is needed produce the carbon-bearing molecules in these envelopes (Willacy & Millar 1997). However, CO₂ and C₂H₂ are also possible candidates. The spectral ranges for our observations have been chosen specifically to include ro-vibrational bands in these molecules, but many other molecules, such as HCN, NH₃, OH and HO₂ have bands in these regions and hopefully there will be a few interesting surprises. To date we have received the observations of three of our objects, R Cas, IRC+10420 and the S-type star W Aql, which we are observing to study the effect of the C/O ratio on chemical composition. Preliminary results for W Aql show little evidence of CH₄, a tentative detection of CO₂, and clear evidence of OH and HCl. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   

Silicon chemistry in dense clouds     

T. J. Millar 《Astrophysics and Space Science》1980,72(2):509-517

The equilibrium chemistry of silicon in dense interstellar clouds is discussed in terms of both gas phase and grain surface reactions. Unless the metal depletion is very large, the gas phase scheme tends to over-produce SiO and/or SiS when compared to the observations of Sgr B2. The scheme also predicts SiC to be an abundant form of silicon. There is a great need for relevant laboratory data on the reactions used here—of the 35 rate coefficients adopted in the scheme, only three have been measured in the laboratory. Reactions between positively charged gas phase ions and small grains can lead to the formation of SiO and SiS. This type of reaction seems to offer a simple explanation for the observed differences between sulphur and silicon chemistry in dense clouds.  相似文献   

Large interstellar molecules     

T. J. Millar  D. A. Williams 《Astrophysics and Space Science》1977,48(2):243-248

We propose that photocycloaddition reactions in molecular complexes in normal interstellar clouds will create unusually large molecules. These may be sufficiently radiation stable to be circulated with the interstellar gas, and so provide convenient nucleation centres for growth of loosely bound grains in dark regions.  相似文献   

Bronfenbrenner’s bioecological theory for modelling community resilience to natural disasters   总被引：1，自引：1，他引：0  

Helen J. Boon  Alison Cottrell  David King  Robert B. Stevenson  Joanne Millar 《Natural Hazards》2012,60(2):381-408

This paper advocates the use of Bronfenbrenner’s bioecological theory as a framework to analyse resilience at diverse scales. Bronfenbrenner’s bioecological theory can be employed to (a) benchmark social resilience, (b) target the priority interventions required and (c) measure progress arising from these interventions to enhance resilience to natural disasters. First, the paper explores resilience to natural disasters in the context of climatic change as building resilience is seen as a way to mitigate impacts of natural disasters. Second, concepts of resilience are systematically examined and documented, outlining resilience as a trait and resilience as a process. Third, issues arising in relation to the measurement of resilience are discussed. Fourth, Bronfenbrenner’s bioecological systems theory is described and proffered to model and assess resilience at different scales. Fifth, studies are described which have supported the use of the bioecological systems theory for the study of resilience. Sixth, an example of the use of Bronfenbrenner’s theory is offered and the paper concludes with suggestions for future research using Bronfenbrenner’s theory.  相似文献