共查询到19条相似文献，搜索用时 171 毫秒
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控制分蘖角度对群体温度、群体相对湿度、群体CO2浓度和光合有效辐射均会产生一定影响。选用2006年水稻有关研究数据,分析水稻分蘖角度对群体生态特征的影响。结果表明：各生育时期群体温度在07:00－19:00处理大于CK。分蘖高峰期到孕穗期CK白天群体相对湿度大于处理,齐穗期到灌浆期处理群体相对湿度大于CK。群体CO2浓度在拔节期和孕穗期均为处理大于CK,其他生育期差异不显著。光合有效辐射垂直分布是处理前期和后期上层截获的光能均小于CK,群体内消光系数小。控制分蘖角度形成了有较高温度、较低湿度、高CO2浓度和适宜光分布的群体,可为获得高产奠定基础。 相似文献
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采用中川１９８５～１９９４年资料统计分析中川机场雷暴的气候特征：中川雷暴强度较弱、风小、雨少、时间短;雷暴集中出现在５～９月;雷暴日变化明显,以午后到０３时居多;雷暴大风移过本站前多为偏南风,后多为偏北风;雷暴可带来降水,大风、扬沙、冰雹等天气,雷暴时能见度一般大于１０ｋｍ。 相似文献
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利用湖北省2007—2013年雷电定位系统(Lightning Location System,LLS)监测的雷电流相关参数资料,采用数理统计方法,对雷电流波头时间的年、季、月、日变化以及累积概率和概率密度分布进行了统计分析。结果表明,正闪电平均波头时间为4.8μs,负闪和总闪电为3.6μs;一年中,正闪电7月波头时间最短,月变化特征大致呈"V"形;负闪和总闪电5—7月波头时间比其他月份短,月变化特征大致呈"U"形。正闪电波头时间季节、日变化明显,负闪和总闪电季节、日变化不明显。波头时间小于等于10μs时,正闪、负闪和总闪电的波头时间累积概率分别为95.5%、99.7%和99.6%,总闪电95%的波头时间大于1.5μs,50%的大于3.1μs,5%的大于6.0μs。波头时间在2~3μs时,正闪、负闪和总闪电的概率密度最大。气温较低月份,波头时间相对较长,反之,波头时间相对较短,其原因可能与雷电流幅值大小有关,具体原因有待进一步研究。 相似文献
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近年来,我省两系水稻的选育取得了较大的进展,在产量和品质上显出一定优势,正在由试验转向应用。省委、省政府提出我省“九五”期间要推广种植两系水稻１００万公顷,因此,两系水稻种子的需求量将大大增加。两系水稻是指光温敏两用核不育系水稻,它具有在长日高温下不育和短日低温下可育的特性,因此可用其不育性进行制种,用其可育性进行繁种,从而达到一系两用的目的。两系水稻可分为光敏型、温敏型和光温互作三大类型,目前广东生产和科研中应用的主要为温敏型（临界温度一般为２３℃）。因此,两系水稻的繁殖对气象条件有特殊要求,… 相似文献
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光敏感核不育水稻研究中,杂交稻不育系不育和育性转换需要一定强度(勒克斯)的光长和温度光长互作影响.光敏感核不育和育性转换的临界光长:≥501xl3时45分、温度≥25℃.武汉地区临界光长出现时间平均为8月5日,最早7月30日,最迟8月11日.此刻以前为长光照时段,以后为短光照时段,梅雨明显、凉夏年份,常出现短光照、低温互作影响,因此,武汉地区引种、培育耐低温的两系法杂交稻光敏型不育系对生产是十分必要的. 相似文献
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水稻光敏核不育系的育性气象模型及其机理 总被引：4，自引：4，他引：4
光敏核不育水稻的育性转换主要是抽穗前５￣２０天的光温条件综合影响的结果。其数量关系可由结实率量化模型表达。温敏型不育系的育性由温度主控；光敏型不育系的育性在日长大于最适日长时由日长主控，日长短于最适日长时由温度主控。温光对育性的影响存在互补效应，在最适温度以下，不育临界日长随温度升高延长；在最适温度以上，不育临界日长随温度升高缩短。温光当量可作为比较温度和日长对育性影响大小的具体量值。根据结实率量 相似文献
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The role of phase locking in a simple model for glacial dynamics 总被引：1，自引：1，他引：1
Yosef Ashkenazy 《Climate Dynamics》2006,27(4):421-431
Glacial–interglacial oscillations are often described by simple conceptual models. Relatively few models, however, are accompanied by analytical solutions, though detailed analytical investigation of climate models often leads to deeper understanding of the climate system. Here we study a simple conceptual model for glacial dynamics, a simplified version of the sea-ice-switch mechanism of Gildor and Tziperman (Paleoceanography 15:605–615, 2000), and provide a detailed analytical treatment for this model. We show that when the model is forced by a simplified insolation forcing it exhibits rich dynamics and passes through a series of bifurcations before being completely phase-locked to the insolation forcing. Our model suggests that even when the glacial cycles are self-sustained, insolation forcing has a major role on the complexity of glacial cycles: (1) it is possible to obtain glacial–interglacial oscillations for a wider parameters range when the amplitude of the insolation forcing is larger; (2) in addition, the ice-volume becomes more periodic; (3) when the period of the ice-volume is minimal the ice-volume is symmetric and for larger period is more asymmetric; (4) the ice-volume can be either periodic, higher order periodic, or quasi-periodic. 相似文献
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Variations in terrestrial insolation, induced by perturbations of the earth's orbital parameters, are calculated for different
geographical latitudes for ±100000 yr and in detail for the modern period between A.D. 1800–2100. The calculations show that
short-period insolation variations occur against a background of secular variation, with an amplitude which can be comparable
in magnitude to that of the 300-yr secular trend. For comparison we calculate the secular trends of insolation for Milankovich's
caloric half-years for the period ±100000 yr with high time resolution. The nature of secular and short-term insolation changes
is discussed for different latitudinal circles during future centuries. We conclude that orbitally-induced variations of insolation
with periods of 18.6, 11.9, 5.9, 4.0, and 2.7 yr will perturb the radiation regime at the upper atmospheric boundary. 相似文献
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H.-S. Liu 《Theoretical and Applied Climatology》1998,61(3-4):217-229
Summary For astronomical seasons, Rubincam insolation deviations at latitude 65° N varied from 218.50 Wm−2 to 225.75 Wm−2 (3%). The periodicity of the insolation cycles varied from 36.7 Kyr to 44.7 Kyr (20%) due to phase shift. Phase shift of
insolation variations can induce asymmetry of the insolation cycles, permitting rapid melting and prolonged glaciation of
ice sheets to occur. For instance, an abnormal decrease of the insolation frequency during the longer period of glacial interval
would prolong glaciation into deep ice age. In this study, we apply Rubincam’s insolation equations to investigate the phase
shift effect of insolation variations on climate change. Using complex transforms of the changing insolation, we have detected
a phase modulation signal in the insolation variations. As a result, an especially new and interesting series of the phase-related
insolation pulsation is established. The phase modulated insolation is then introduced as a forcing function into energy balance
climate models. Results of model computations shed new insights into the spectrum of the paleoclimatic proxy-data. It is shown
that phase modulation of the insolation may provide an appropriate and complete external forcing mechanism to which the climate
system would respond. The 100 Kyr cycle of the frequency modulation of the Rubincam’s insolation variations does seem adequate
to change the climate.
Received July 16, 1997 Revised May 18, 1998 相似文献
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Jaya Naithani H. N. Dutta P. K. Pasricha B. M. Reddy K. M. Aggarwal 《Boundary-Layer Meteorology》1995,74(1-2):195-208
Turbulent fluxes have been evaluated for clear sunny days over the Indian Antarctic station, Maitri, using the basic meteorological data recorded at four levels of a 28 m tower. The data are supplemented with radiation data. The surface layer over Maitri remains thermally stratified during the hours of minimum solar insolation, the so-called nighttime period. The surface winds during this period are generally very strong resulting in high momentum fluxes. In particular, for high winds (>12 m s–1), the temperature gradient is found to be less positive than for moderate winds (4 to 7 m s–1). Solar insolation provided the daytime heating necessary for the diurnal variation of atmospheric stability, and hence, for the turbulent fluxes. Thus, on clear days daytime conditions are marked by upward transport of heat with reduced momentum flux, while stable nighttime conditions are marked by a downward heat flux with increased momentum fluxes. 相似文献
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A. Kh. Degterev 《Russian Meteorology and Hydrology》2007,32(7):461-464
The sea roughness effect on insolation and sun rays reflection for different sun heights above the horizon and unclouded sky is considered. Numerical assessments for albedo, insolation, and absorbed radiation are received for Stokes waves. Normal ray falling at the wave crest is suggested. The ray trace approach is used that allowed to take into account such effects as the dependence of albedo on the wave tilt, double light reflection from neighboring wave crests and the trough shading by the crest. It is concluded that the main roughness effect on the radiative balance is the insolation increasing and albedo diminishing at large wave steepness when the sun height above the horizon is less than 40°. 相似文献
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The effect of orbitally induced insolation changes on Antarctic sea-ice cover are examined by means of a dynamic-thermodynamic seaice model. Results are compared with modified CLIMAP 18 000 B.P. sea-ice reconstructions. Calculations suggest that changes in insolation receipt had only a minor influence on Pleistocene sea-ice distributions. The small response can be explained by a number of factors: albedo effects reduce the insolation perturbation at the surface; some of the shortwave radiation entering the ocean contributes to bottom ablation rather than lateral melting; the radiation perturbation at the upper surface of the ice must go to warming the surface to the melting point before melting ensues; and, finally, the relatively high heat capacity of open water dampens the surface temperature response to altered seasonal insolation perturbations. 相似文献
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Summary ?For the LITFASS-98 experiment, from June 1 until June 30, 1998, the spatially resolved insolation at surface could be computed
from NOAA-14 AVHRR data applying the modular analysis scheme SESAT (Strahlungs- und Energiebilanzen aus Satellitendaten). The satellite inferred insolation for this period shows for clear-sky regions a good agreement with surface
based observations with a rms error of 76 Wm−2. For cloudy conditions the insolation is overestimated with respect to ground based observations, with a rms error between
83 and 118 Wm−2, depending on the cloud optical thickness. This overestimation can be explained by the surface heterogeneity, leading to
underestimated cloud optical thickness, and also by a fixed relative humidity below clouds (55%, dry atmosphere) and a fixed
horizontal visibility (50 km, clear atmosphere). A detailed study of comparable scales in space and time, considering the
different observation geometries and sampling intervals, shows that a 30 min ground based observation can be compared with
a 8 × 8 km2 mean by the satellite data.
Received July 12, 2001; revised April 29, 2002; accepted June 7, 2002 相似文献
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Simulation of the evolutionary response of global summer monsoons to orbital forcing over the past 280,000 years 总被引：3，自引：2，他引：1
We describe the evolutionary response of northern and southern hemisphere summer monsoons to orbital forcing over the past
280,000 years using a fully coupled general circulation ocean-atmosphere model in which the orbital forcing is accelerated
by a factor of 100. We find a strong and positive response of northern (southern) summer monsoon precipitation to northern
(southern) summer insolation forcing. On average, July (January) precipitation maxima and JJA (DJF) precipitation maxima have
high coherence and are approximately in phase with June (December) insolation maxima, implying an average lag between forcing
and response of about 30° of phase at the precession period. The average lag increases to over 40° for 4-month precipitation
averages, JJAS (DJFM). The phase varies from region to region. The average JJA (DJF) land temperature maxima also lag the
June orbital forcing maxima by about 30° of phase, whereas ocean temperature maxima exhibit a lag of about 60° of phase at
the precession period. Using generalized measures of the thermal and hydrologic processes that produce monsoons, we find that
the summer monsoon precipitation indices for the six regions all fall within the phase limits of the process indices for the
respective hemispheres. Selected observational studies from four of the six monsoon regions report approximate in-phase relations
of summer monsoon proxies to summer insolation. However other observational studies report substantial phase lags of monsoon
proxies and a strong component of forcing associated with glacial-age boundary conditions or other factors. An important next
step will be to include glacial-age boundary condition forcing in long, transient paleoclimate simulations, along with orbital
forcing. 相似文献
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Individual contribution of insolation and CO2 to the interglacial climates of the past 800,000?years
The individual contributions of insolation and greenhouse gases (GHG) to the interglacial climates of the past 800,000?years are quantified through simulations with a model of intermediate complexity LOVECLIM and using the factor separation technique. The interglacials are compared in terms of their forcings and responses of surface air temperature, vegetation and sea ice. The results show that the relative magnitude of the simulated interglacials is in reasonable agreement with proxy data. GHG plays a dominant role on the variations of the annual mean temperature of both the Globe and the southern high latitudes, whereas, insolation plays a dominant role on the variations of tree fraction, precipitation and of the northern high latitude temperature and sea ice. The Mid-Brunhes Event (MBE) appears to be significant only in GHG and climate variables dominated by it. The results also show that the relative importance of GHG and insolation on the warmth intensity varies from one interglacial to another. For the warmest (MIS-9 and MIS-5) and coolest (MIS-17 and MIS-13) interglacials, GHG and insolation reinforce each other. MIS-11 (MIS-15) is a warm (cool) interglacial due to its high (low) GHG concentration, its insolation contributing to a cooling (warming). MIS-7, although with high GHG concentrations, can not be classified as a warm interglacial due to it large insolation-induced cooling. Related to these two forcings, MIS-19 appears to be the best analogue for MIS-1. In the response to insolation, the annual mean temperatures averaged over the globe and over southern high latitudes are highly linearly correlated with obliquity. However, precession becomes important in the temperature of the northern high latitudes and controls the tree fraction globally. Over the polar oceans, the response during the local winters, although the available energy is small, is larger than during the local summers due to the summer remnant effect. The sensitivity to double CO2 is the highest for the coolest interglacial. 相似文献