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1.
H.B. Kruger 《大气与海洋》2013,51(2):61-65
A wide set of size‐distribution models of haze and fog droplets expressed in terms of the modified gamma distribution function have been used for evaluating the proportionality coefficient b in the empirical relationship between visibility V and liquid water content LWC, that is V=b (LWC)‐ 2/3, as proposed by Eldridge (1966). The evaluations of b turn out to be consistent with the values proposed in the literature and give evidence for its close dependence on the shape‐parameters of the droplet size distribution, especially as regards the mode radius and the width of the larger‐droplet wing. Three average relationship curves are proposed respectively for dense haze, “dry and cold” fog and “wet and warm” fog. Corresponding to these cases, three correlation lines are presented between b and the ratio of the volume extinction coefficient at 3.70 μm wavelength to that at 0.55 μm, evaluated for the same uniform path in hazy and foggy atmospheres. Applied to measurements of infrared and visible transmission such correlation lines give the possibility of estimating the most proper value of b to be used in Eldridge's relationship for different atmospheric conditions. 相似文献
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During the 1974 growing season, a micrometeorological measurement program was conducted at Simcoe, Ontario, Canada to study atmospheric and surface control on hourly and daytime evaporation from soybeans. For days when leaf area index exceeded unity, daytime evaporation varied linearly with volumetric soil moisture content when the latter was less than 0.12. At larger volumetric soil moisture contents, evaporation proceeded at a potential rate. The data confirm the usefulness of the Priestley and Taylor model with a proportionality constant of 1.26. 相似文献
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Information from a variety of sources, including an airborne field expedition in November 1985, is used to produce estimates of the annual emissions of some hydrocarbons from bushfires, and isoprene from trees, in tropical Australia. For the continent north of 23° S the annual bushfires (biomass burning) input was estimated, in units of Tg carbon, to be 2 TgC (uncertainty range 0.8–5 TgC), emitted predominantly during the May to October dryseason. Isoprene emissions during this period were estimated also to be 2 TgC (uncertainty range 0.5–8 TgC), but were estimated to be an order of magnitude higher during the November to April wet season, at a level of 23 TgC (uncertainty range 6–100 TgC).The large annual emission of isoprene over the tropical part of the Australian continent yields ppbv levels of isoprene measured at the surface in summertime. Isoprene reactivity with hydroxyl radical is such that at these concentrations isoprene must be a dominant factor in controlling the concentration of OH radical in the convective boundary layer. Simple arguments based on the convective velocity scale suggest that the shape of the isoprene vertical profile in November 1985 would be consistent with available data on the OH-isoprene reaction rate if OH concentration in the boundary layer averaged about 2.5×106 cm-3 over the middle part of the day.Temporarily at the International Meteorological Institute, Stockholm University, S-106 91, Stockholm, Sweden. 相似文献
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The first 1,000 year long Carpathian tree-ring width chronology was established based on living and subfossil stone pine (Pinus cembra L.) samples from an upper timberline forest located in Calimani Mts. (Romania). Tree-ring data were standardized using the regional curve standardization method in order to preserve the low and medium frequency climate signals. The de-trended index strongly correlates with summer mean temperature both at annual and decadal scales. The Calimani summer mean temperature anomalies were reconstructed for the period ad 1163-2005 applying the rescaling method. This new climate proxy from the Carpathians shows similar fluctuations to other North Hemispheric temperature reconstructions, but with periods of distinct differences. The fingerprint of Little Ice Age in the Calimani area is visible between ad 1370 and 1630 followed by lagged cold decades in ad 1820 and 1840. The recent warming is evident only after the 1980s in our reconstruction. 相似文献
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Annual methane emission from Finnish mires estimated from eddy covariance campaign measurements 总被引：4，自引：0，他引：4
K. J. Hargreaves D. Fowler C. E. R. Pitcairn M. Aurela 《Theoretical and Applied Climatology》2001,70(1-4):203-213
Summary Measurements of landscape-scale methane emission were made over an aapa mire near Kaamanen in Finnish Lapland (69° 8′ N,
27° 16′ E, 155 m ASL). Emissions were measured during the spring thaw, in summer and in autumn. No effect of water table position
on CH4 emission was found as the water table remained at or above the surface of the peat. Methane emission fluxes increased with
surface temperature from which an activation energy of −99 kJ mol−1 was obtained. Annual emission from the site, modelled from temperature regression and short-term flux measurements made in
three separate years, was calculated to be 5.5 ± 0.4 g CH4 m−2 y−1 of which 0.6 ± 0.1 g CH4 m−2 y−1 (11%) was released during the spring thaw which lasted 20 to 30 days.
The effect of global warming on the CH4 budget of the site was estimated using the central scenario of the SILMU (Finnish Research Programme on Climate Change) model
which predicts annual mean temperature increases of 1.2, 2.4 and 4.4 °C in 2020, 2050 and 2100, respectively. Maximum enhancements
in CH4 emission due to warming were calculated to be 18, 40 and 84% for 2020, 2050 and 2100, respectively. Actual increases may
be smaller because prediction of changes in water table are highly uncertain.
Received September 17, 1999 Revised October 16, 2000 相似文献
6.
《中国气象科学研究院年报》1999,(1)
Withtheadventofthe21stcentury,thedevelopmentofthehumansocietyfacilitatestheprogressandprosperity,inthemeanwhile,italsoproducessuchmomentousproblemsasexplodingpopulation,resourcesshortage,environmentdegradationandincreasingnaturaldisasters,whichseriouslysu… 相似文献
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Prior research shows that public opinion on climate politics sorts along partisan lines. However, they leave open the question of whether climate politics and other politically salient issues exhibit tendencies for issue alignment, which the political polarization literature identifies as among the most deleterious aspects of polarization. Using a network approach and social media data from the Twitter platform, we study polarization of public opinion toward climate politics and ten other politically salient topics during the 2019 Finnish elections as the emergence of opposing groups in a public forum. We find that while climate politics is not particularly polarized compared to the other topics, it is subject to partisan sorting and issue alignment within the universalist-communitarian dimension of European politics that arose following the growth of right-wing populism. Notably, climate politics is consistently aligned with the immigration issue, and temporal trends indicate that this phenomenon will likely persist. 相似文献
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张人禾 《中国气象科学研究院年报》2001,(1)
刚刚走过的2001年,是新世纪的开局之年,也是我们祖国大事连连、喜事频频的一年,北京的申办奥运成功、中国的成功入世、中国足球的如愿出线、APEC会议的成功举办……,在给全国人民带来无比喜悦的同时,也给正处于科技体制改革的中国气象科 相似文献
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《热带气象学报(英文版)》2017,(1)
正To mark the 40th anniversary of Guangzhou Institute of Tropical and Marine Meteorology,China Meteorological Administration(1976-2016),the publisher of this journal,our readers sent us their congratulations,which are presented with profound gratitude as follows:"Stuive to lecame a first-class international research institution in the field of trapical and mauine metarology!""Wish the Trapical Jnstitute ever-thriving in its coarse!" 相似文献
15.
Evidence for recent warming from perturbed geothermal gradients: examples from eastern Canada 总被引：1，自引：0，他引：1
Recent variations of the surface temperature of the Earth can be inferred from borehole temperature measurements. Generalized inversion is used to extract the information from the data; the potential of the method is evaluated. Tests were performed with synthetic data to demonstrate the effectiveness of the inversion to recover the gross features of the surface temperature history even when the data are affected by noise and errors. The tests show that it is possible to reconstruct the long term changes in ground temperature during the past 300 years; the resolution decreases with time, in particular if noise and errors must be filtered. Temperature logs, obtained in eastern Canada, and not suspected of being affected by non-climatic factors, have been inverted. The analysis confirms that eastern Canada has experienced warming by 1 to 2°C over the past 100–200 years. The relationship between air and ground temperatures has been examined. In eastern Canada ground temperature follows air temperature closely in summer but stays well above air temperature in winter. The number of days with snow on the ground correlates with the difference between annual mean ground and air temperature.Contribution to Clima Locarno — Past and Present Climate Dynamics; Conference September 1990, Swiss Academy of Sciences — National Climate-Program 相似文献
16.
Methane emission from rice paddies 总被引：3，自引：0，他引：3
W. Seiler A. Holzapfel-Pschorn R. Conrad D. Scharffe 《Journal of Atmospheric Chemistry》1983,1(3):241-268
Methane release rates from rice paddies have been measured in Andalusia, Spain, during almost a complete vegetation period in 1982 using the static box system. The release rates ranged between 2 and 14 mg/m2/h and exhibited a strong seasonal variation with low values during the tillering stage and shortly before harvest, while maximum values were observed at the end of the flowering stage. The CH4 release rate, averaged over the complete vegetation period, accounted for 4 mg/m2/h which results in a worldwide CH4 emission from rice paddies of 35–59×1012 g/yr if we assume that the observed CH4 release rates are representative of global conditions. The CH4 release rates showed diurnal variations with higher values late in the afternoon which were most likely caused by temperature variations within the upper layers of the paddy soils. Approximately 95% of the CH4 emitted into the atmosphere by rice paddies was due to transport through the rice plants. Transport by bubbles or diffusion through the paddy water was of minor importance. Incubation experiments showed that CH4 was neither produced nor consumed in the paddy water. The relase of CH4 from rice paddies caused a diurnal variation of CH4 in ambient air within the rice-growing area with maximum values of up to 2.3 ppmv during the early morning, compared to average daytime values of 1.75 ppmv. 相似文献
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The midlatitude westerlies are one of the major components of the global atmospheric circulation. They play an important role in midlatitude weather and climate, and are particularly significant in interpreting aeolian sediments. In this study, we analyzed the behavior and the possible mechanism involved in the change of the westerlies, mainly in terms of the jet stream position, in the mid-Pliocene warm period(3.3 to 3.0 million years ago) using simulations of 15 climate models from the Pliocene Model Intercomparison Project(Plio MIP). Compared to the reference period, the mid-Pliocene midlatitude westerlies generally shifted poleward(approximately 3.6 of latitude in the Northern Hemisphere and 1.9 of latitude in the Southern Hemisphere at 850 h Pa level) with a dipole pattern. The dipole pattern of the tropospheric zonal wind anomalies was closely related to the change of the tropospheric meridional temperature gradient as a result of thermal structure adjustment.The poleward shift of the midlatitude westerly jet corresponded to the poleward shift of the mean meridional circulation.The sea surface temperatures and sea ice may have affected the simulated temperature structure and zonal winds, causing the spread of the westerly anomalies in the mid-Pliocene between the atmosphere-only and coupled atmosphere–ocean general circulation model simulations. 相似文献
18.
A. C. Heiden K. Kobel C. Langebartels G. Schuh-Thomas J. Wildt 《Journal of Atmospheric Chemistry》2003,45(2):143-172
Emissions of oxygenated volatile organic compounds (OVOC) from several plant species were measured in continuously stirred tank reactors (CSTR). High emission pulses of OVOCs were observed when plants were exposed to stress. Absolute emission rates were highly variable ranging up to 10–13 mol · cm–2 · s–1. The temporal shape of these emissions was described by a formalism similar to that of a consecutive reaction of pseudo first order kinetics. The main emitted OVOC was (Z)-3-hexenol together with other C6-aldehydes and alcohols, suggesting that lipoxygenase activity on linolenic acid was mainly responsible for OVOC production. Various stress factors induced lipoxygenase activity and subsequent emissions of OVOCs. These factors were exposure to high ozone concentrations, pathogen attack, and wounding. The pattern of OVOC emissions from tobacco was similar for different stress applications and the same products of lipoxygenase activity were emitted from all investigated plant species. Our results imply that these emissions occur as general response of the plants to stress. Since plants experience various abiotic or biotic stress factors in the environment, OVOC emissions as a response to stress are likely to be of significant importance for atmospheric chemistry.Now at 相似文献
19.
Pierre Welander 《Dynamics of Atmospheres and Oceans》1977,1(3):215-223
A theoretical discussion is given of the thermal transients and self-sustained oscillations in a fluid, heated at a constant rate below the surface, and cooled from the top strongly enough to allow freezing. Assuming that the fluid is well mixed and that the thickness of the ice is small compared to the fluid depth, it is shown that the system can have zero, one, or two steady states. The ice-covered steady state is stable for small perturbations; however, the ice-free steady state may be unstable with the impulsive addition of a thin ice sheet. Transient developments may include both ice-covered and ice-free states. In the case where no steady state exists the system exhibits periodic self-sustained oscillations. Application of the theory to a laboratory experiment is considered. 相似文献
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Detecting Aerosols over Land from Satellites by Measuring Far IR Radiation from the Earth-Atmospheric System 
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下载免费PDF全文 In this study, a special method is proposed for detecting aerosols over land by analyzing satellite-measured far IR radiation at three channels, 8.7, 11.5, and 12.5 um. Sensitivity tests revealed that the behavioral features of radiative brightness temperatures (BTs) at these three channels with increasing optical depth are different among different types of aerosols. Analyzing how BTs and their differences, xBT (BT11.5-BT12.5) and yBT (BT8.7-BT11.5), behave with varying optical depth can help to qualitatively distinguish among aerosols and semi-quantitatively estimate their optical thicknesses. In addition, the authors found that the vertical density profile of aerosols has little impact on this method. 相似文献