Large-Scale Synoptic Systems and Fog During the C-FOG Field Experiment     

Dorman  Clive E.  Hoch  Sebastian W.  Gultepe  Ismail  Wang  Qing  Yamaguchi  Ryan T.  Fernando  H. J. S.  Krishnamurthy  Raghavendra 《Boundary-Layer Meteorology》2021,181(2-3):171-202

Boundary-Layer Meteorology - The goal of this work is to summarize synoptic meteorological conditions during the Coastal Fog (C-FOG) field project that took place onshore and offshore of the Avalon...  相似文献   

A Review of Coastal Fog Microphysics During C-FOG     

Gultepe  I.  Heymsfield  A. J.  Fernando  H. J. S.  Pardyjak  E.  Dorman  C. E.  Wang  Q.  Creegan  E.  Hoch  S. W.  Flagg  D. D.  Yamaguchi  R.  Krishnamurthy  R.  Gaberšek  S.  Perrie  W.  Perelet  A.  Singh  D. K.  Chang  R.  Nagare  B.  Wagh  S.  Wang  S. 《Boundary-Layer Meteorology》2021,181(2-3):227-265

Boundary-Layer Meteorology - Our goal is to provide an overview of the microphysical measurements made during the C-FOG (Toward Improving Coastal Fog Prediction) field project. In addition, we...  相似文献   

全球增温1.5和2℃下中国东部极端高温风险预估          下载免费PDF全文

江晓菲  江志红  李伟 《大气科学学报》2020,43(6):1056-1064

2013年中国中东部地区经历了一次破纪录的极端高温,给社会经济及人民财产造成了严重损失。利用高分辨率的观测格点数据集以及参与CMIP5的17个全球气候模式数据,通过分位数映射的偏差订正方法对模式模拟的逐日最高温度数据进行订正;在此基础上,研究了2013年的破纪录极端高温以及多年（20、50和100 a）一遇极端高温在未来全球增温1.5和2℃下的风险。结果表明,在未来增温1.5℃（2℃）下,2013年极端高温强度的发生风险将会增加为历史时期（1986-2005年）的3.0倍（6.1倍）,极端高温日数增加为历史时期的5.6倍（12.6倍）。从1.5℃到2℃,额外的0.5℃的增温将会使2013年极端高温强度和日数在未来的发生风险分别增加到2.0倍和2.3倍。对于不同重现期的极端高温来说,越极端的极端高温在未来发生的风险越大,并且极端高温日数增加的风险要大于极端高温强度增加的风险。历史时期平均每20、50、100 a发生一次的极端高温日数在未来增温1.5℃下将会变为平均每4、8、15 a发生一次,在增温2℃下变为平均每2、3、6 a发生一次。历史时期20、50、100 a一遇的极端高温强度在未来增温1.5℃下将会变为7、14、27 a一遇,在未来增温2℃下变为4、6、8 a一遇。  相似文献   

Water and Soil Conservation from the Perspective of Stakeholders: Evidence from China and Policy Implications          下载免费PDF全文

Xinhua Qi  Yu Cheng  Yaoqi Zhang  Yecheng Xu  Linglin Xu 《洁净——土壤、空气、水》2014,42(7):956-962

  相似文献   

减化比值植被指数在城市热环境研究中的应用     

王伟  申双和  赵小艳  杨沈斌 《南京气象学院学报》2012,35(2):140-147

以南京市ETM＋影像为数据源,经嵌套于ERDAS IMAGINE9.1中的ATCOR2大气校正后,提取了南京城区地表温度（land surface temperature,LST）、归一化植被指数（normalized difference vegetation index,NDVI）和减化比值植被指数（reduced simple ratio,RSR）,基于实测值和同时相AS-TER数据反演结果的双重验证,拟合了两种植被指数与地表温度的定量关系,并进行对比分析。结果表明,除水体外,植被覆盖度高的区域地表温度明显低于植被稀少或无植被区;地表温度与NDVI呈显著线性负相关,与RSR呈显著幂函数负相关,后者的相关性高于前者;当RSR小于3.2时,地表温度随植被覆盖增加而锐减,当RSR大于3.2时,植被覆盖继续增加,地表温度却趋于恒定,呈现植被降温效应＂饱和＂现象;对比比值植被指数（ratio vegetation index,RVI）应用结果发现,近红外和红光比值的线性拉伸是导致NDVI和RSR表征城市热环境效应存在差异的主因,还与短波红外对水分敏感和能真实反映植被冠层结构有关。中国6大城市热环境案例研究均表明,RSR能直接解释对于不同下垫面,增加相同的植被覆盖度其降温效果存在差异的现象,而不进行土地利用分类,NDVI则无法揭示此现象。  相似文献   

紫外辐射对菹草(Potamogeton crispus)成株快速光响应曲线的影响   总被引：1，自引：0，他引：1  

王锦旗  宋玉芝  薛艳 《湖泊科学》2015,27(3):451-458

将菹草(Potamogeton crispus)成株置于50、100、150、200μW/cm2剂量的UV-B辐射下,利用调制叶绿素荧光仪测定紫外辐射对菹草成株PSⅡ系统的损伤程度.结果表明:急性辐射初期叶片最大光合速率、耐强光能力、叶片捕光能力均随辐射剂量增大而减少;16 d后,UV-B辐射剂量小于100μW/cm2的实验组,辐射促进其叶片光能利用效率、最大光合速率、耐强光能力,而高于100μW/cm2的实验组,随辐射时间延长,其抑制作用持续,最终高于100μW/cm2剂量组植株均死亡,而低于100μW/cm2剂量组差异不大.结果表明辐射剂量小于100μW/cm2时,UV-B辐射对叶片最大光合速率、耐强光能力、叶片捕光能力的影响较小,而高于100μW/cm2时,UV-B辐射对植株叶片PSⅡ系统构成的损伤,降低了植株叶片的光合作用能力.春末夏初陆上紫外辐射逐渐增加,对菹草伤害程度加剧,因此,紫外辐射可能是促进菹草春末夏初大批衰亡的重要原因.  相似文献   

Dissolved inorganic carbon,alkalinity, nutrient and oxygen seasonal and interannual variations at the Antarctic Ocean JGOFS-KERFIX site     

《Deep Sea Research Part I: Oceanographic Research Papers》2001,48(7):1581-1603

JGOFS-KERFIX (KERguelen point FIXe) time-series station, located south of the polar front in the Indian sector of the Antarctic Ocean, was occupied monthly between January 1990 and March 1995. Annual cycles of dissolved inorganic carbon (DIC), total alkalinity (TALK), oxygen (O₂) and nutrients (nitrate, silicate, phosphate and ammonia) in the upper ocean are presented for this site. From seasonal drawdown of nutrients and DIC, we estimate a spring–summer net community production of 3.2±0.5 mol m⁻² and C/N/P ratios of 100/16/1. The Si/N ratio varies between 1.8 and 3, suggesting low iron concentrations. The spring–summer biogenic silicon export derived from silicate drawdown is 1.18 mol m⁻², consistent with model estimates of silicate export at this site. Seasonal and interannual variations of oxygen, nitrate and DIC due to physical and biological processes are quantified using a simple month-to-month budget formulation. From these budgets, an annual net community production of 5.7±3.3 mol m⁻² yr⁻¹ is estimated, about twice the averaged spring–summer production, indicating that, at KERFIX, there is a positive net community production throughout the year. Air–sea CO₂ fluxes show that KERFIX is a strong CO₂ sink for the atmosphere of 2.4–5.1 mol m⁻² yr⁻¹ in 1993, depending on the gas exchange formulation used. A 2.1–3.3 mol m⁻² yr⁻¹ outgassing of O₂ is observed at KERFIX except in 1993 and 1994 where a decreasing trend of temperature induces an increase of O₂ solubility.  相似文献   

Peculiar transient events in the Schumann resonance band and their possible explanation     

《Journal of Atmospheric and Solar》2008,70(6):937-946

Superimposed on the continuous Schumann resonance (SR) background in the extremely low frequency (ELF) band, transient signals (e.g. bursts) can be observed, which originate from intense lightning discharges occurring at different locations on the globe. From the many transients that were observed at the Astronomical and Geophysical Observatory (AGO) of Comenius University near Modra, western Slovakia, in the vertical electric field component mainly during May and June of 2006, a peculiar group of events could be recognized. According to the waveform analysis, these peculiar events in most cases consist of two overlapping transients with a characteristic time difference of 0.13–0.15 s between the onsets. On the other hand, the spectrum of these peculiar transients showed discernible SR peaks for higher modes as well (n>7). The same events could be found in the records of the Széchenyi István Geophysical Observatory of the Geodetic and Geophysical Research Institute of the Hungarian Academy of Sciences near Nagycenk, Hungary (NCK). The natural origin of the peculiar events was verified from the NCK data and the source location was determined from the second transient. The results suggest that the two consecutive transients originated in the same thunderstorm. Furthermore, the phase spectrum analysis indicates that the sources have coherently excited the Earth-ionosphere cavity. These findings seem to support the idea that electromagnetic waves orbiting the Earth might trigger lightning discharges. The possibility that electromagnetic waves may trigger discharges was first considered by Nikola Tesla.  相似文献   

Meso-scale perturbations and thermohaline fronts in the south atlantic ocean     

《Dynamics of Atmospheres and Oceans》1999,30(1):1-24

A linear quasi-geostrophic model and a non-linear balanced model are used to study the properties of the oceanic baroclinic waves. From a linear point of view, the oceanic meso-scale (200–400 km) disturbances found near the Brazil and Falkland currents confluence zone seem to be generated by baroclinic instability. Non-geostrophic and non-linear effects due to a single original wave are superimposed on the linear fields associated with the most unstable wave. Characteristics very similar to observations are obtained in the evolution to finite amplitude. The evolution of oceanic thermal rings is very well reproduced by the non-linear model. However, the stage of saturation is not reached in the model results since the feedback to the thermal basic state is not included.  相似文献   

The spectral indices of X-ray and radio producing electrons in solar flares     

《Chinese Astronomy and Astrophysics》1999,23(2):229-236

In the homogeneous model of solar radio burst model, the spectral index of the optically thick part of the spectrum is almost independent of the spectral index of the electron energy, while from the optically thin part, the derived electron index δ_R is far smaller than that derived from the X-ray emission, δ_X. An inhomogeneous model is proposed, in which, by adjusting two parameters within reasonable limits, we can make δ_R, derived from both the optically thick and thin parts, to equal δ_X. The model is exemplified by the 1981 April 27 0800 UT burst.  相似文献