气象新闻图片拍摄技巧初探     

梁珊珊  朱雯雯 《广西气象》2013,(4):106-108

在气象灾害频发的今天,人们对获取气象信息的需求更为强烈.气象新闻图片,是把气象信息及时、直观地传送到读者面前的重要手段,是气象新闻中不可或缺的一部分.结合日常新闻摄影实践,探讨气象新闻图片拍摄技巧和手法,对如何拍摄好气象新闻图片提出几点建议,以期提升气象新闻摄影工作水平.  相似文献   

阶段性干旱胁迫对小麦光合生理特性及产量结构的影响          下载免费PDF全文

严韬  朱国良  葛非凡  蒋跃林  李威  吴文革 《气象与减灾研究》2019,42(1):46-53

在人工遮雨的条件下,采用盆栽的种植方式探究"皖麦68"营养生长期(返青期—开花期)及生殖生长期(开花期—成熟期)轻度干旱胁迫(土壤相对含水量为55%±5%)及复水(土壤相对含水量为70%±5%)对其光合生理特性及产量结构的影响。结果表明:返青期至成熟期充分供水(CK)的小麦旗叶光合参数和产量最高。开花至成熟期复水(DN)的小麦叶片在复水后光合能力迅速恢复,表现出了超补偿效应:光合速率(16.43μmol/(m~2·s))甚至超过了CK(15.01μmol/(m~2·s));采用非直角双曲线模型拟合小麦旗叶的光响应曲线,其中DN的曲角θ最大;DN产量较CK略有降低但千粒重为34.51 g,高于CK(34.44 g)。开花至成熟期轻度干旱(ND)及全生育期轻度干旱(DD)的小麦光合特征参数与产量均显著降低。DD产量最低、品质最差,但其收获指数I_H高于CK、仅次于DN。在小麦返青期—开花期进行水分管理适量减少灌溉,开花期—成熟期复水能够提升籽粒的干物质积累量,获得较高的产量及品质。  相似文献   

Improved reliability of ENSO hindcasts with multi-ocean analyses ensemble initialization     

Jieshun Zhu  Bohua Huang  Magdalena A. Balmaseda  James L. Kinter III  Peitao Peng  Zeng-Zhen Hu  Lawrence Marx 《Climate Dynamics》2013,41(9-10):2785-2795

Currently, ensemble seasonal forecasts using a single model with multiple perturbed initial conditions generally suffer from an “overconfidence” problem, i.e., the ensemble evolves such that the spread among members is small, compared to the magnitude of the mean error. This has motivated the use of a multi-model ensemble (MME), a technique that aims at sampling the structural uncertainty in the forecasting system. Here we investigate how the structural uncertainty in the ocean initial conditions impacts the reliability in seasonal forecasts, by using a new ensemble generation method to be referred to as the multiple-ocean analysis ensemble (MAE) initialization. In the MAE method, multiple ocean analyses are used to build an ensemble of ocean initial states, thus sampling structural uncertainties in oceanic initial conditions (OIC) originating from errors in the ocean model, the forcing flux, and the measurements, especially in areas and times of insufficient observations, as well as from the dependence on data assimilation methods. The merit of MAE initialization is demonstrated by the improved El Niño and the Southern Oscillation (ENSO) forecasting reliability. In particular, compared with the atmospheric perturbation or lagged ensemble approaches, the MAE initialization more effectively enhances ensemble dispersion in ENSO forecasting. A quantitative probabilistic measure of reliability also indicates that the MAE method performs better in forecasting all three (warm, neutral and cold) categories of ENSO events. In addition to improving seasonal forecasts, the MAE strategy may be used to identify the characteristics of the current structural uncertainty and as guidance for improving the observational network and assimilation strategy. Moreover, although the MAE method is not expected to totally correct the overconfidence of seasonal forecasts, our results demonstrate that OIC uncertainty is one of the major sources of forecast overconfidence, and suggest that the MAE is an essential component of an MME system.  相似文献   

黑龙江省封冻前土壤底墒趋势变化分析     

朱海霞  纪仰慧  宫丽娟  吕佳佳  曲辉辉  李百超 《气象科技》2013,41(1):196-201

利用黑龙江省1981-2010年的土壤湿度数据,以富锦县、龙江县、双城县、黑河市、海伦县为代表点,分析了黑龙江省东、西、南、北、中各区域封冻前(11月8日)0～30 cm土层土壤湿度的趋势变化和干湿变化,采用线性趋势、5年滑动平均和Mann-Kendall法检验变化趋势,利用Mann-Kendall和Yamamoto法对土壤湿度变化趋势进行突变点检验.结果表明:封冻前0～30 cm土层各地土壤湿度在30年间均有不同程度下降,西部龙江县下降剧烈,中部海伦县较剧烈,北部黑河市和南部双城县次之,上述代表点20 cm土层土壤湿度下降均达到了P＜0.05以内的显著水平,东部富锦县下降趋势最弱;经Mann-Kendall法检验,0～30 cm土层龙江县、海伦县土壤湿度出现了下降的突变区域,其余代表点的土壤湿度变化趋势在近几年中逐渐接近或已经超越了显著线;1994年是龙江县10 cm、20 cm土壤湿度下降的突变时期;黑龙江省各地土壤湿度的下降与封冻前一段时期内气温和降水变化密切相关,还与土壤物理性质的恶化等因素有关.  相似文献   

1995—2010年静止卫星云量数据检验和评价     

席琳  师春香  赵笔峰  朱晨  黄晓龙 《气象科技》2013,41(1):8-14

对利用FY2和GMS静止气象卫星建立的东亚地区气候数据集(EAGSCDR FY2 and GMS Geostationary Satellite Climate Data Record over East Asia)进行了检验和评估,使用的检验源数据包括中国地面气候资料与国际卫星云气候计划ISCCP D2月平均云量数据集.对由上述3种不同观测手段得到的多年平均总云量的空间分布特征分析结果表明:3种资料的总云量分布形势有较好的一致性,但是在40°N以北地区,ISCCP和EAGSCDR得到的总云量在量值上高于地面观测值.用地面观测资料检验华南及长江流域EAGSCDR的云检测产品的结果表明,总的准确率为82.10％,总漏判率6.85％,总误判率为11.05％,秋冬季节准确率偏低.EAGSCDR与ISCCP云量都是由卫星资料处理得到的,二者差异主要来自算法的不同,检验结果表明,EAGSCDR中的云量产品精度优于ISCCP云量,并且其时间分辨率可达到1 h,空间分辨率达到5 km,由此可见,EAGSCDR的云产品比ISCCP云产品更有优势.  相似文献   

探空气球施放筒设计     

文永仁  赵毅勇  陈士英  王继凤  祝景先  戴玉芝 《气象科技》2013,41(4):635-638

探空气球的充灌和施放是高空气象观测工作的重要组成部分.目前高空观测中雷达跟踪探空仪、探空信号接收和数据处理都已经实现自动化,只有探空气球的充灌和施放是人工操作,气球充灌氢气有一定危险性,且至少需要一个观测员来完成施放气球工作.该文在分析探空气球充灌和施放各环节工作的基础上,介绍了一种探空气球施放筒的设计方案,以及在业务试验中存在的问题和改进方法,为高空气象观测系统的全程自动化创造条件.  相似文献   

温室黄瓜低温气象灾害指标   总被引：4，自引：0，他引：4  

彭晓丹  杨再强  柳笛  张婷华  周志龙  朱凯  赵翔 《气象科技》2013,41(2):394-400

以黄瓜品种津优35号(Jingyou 35)为试材,于2011年设计不同低温（5、7、9、11 ℃,以25 ℃为对照）处理的人工环境控制试验,系统研究不同低温胁迫对黄瓜叶片光合作用特性及抗氧化酶活性的影响。结果表明：黄瓜叶片最大光合速率随低温胁迫程度的增加依次降低;在不同低温胁迫下,随胁迫时间的延长,黄瓜叶片光补偿点不断升高,光饱和点不断降低;在5 ℃、7 ℃和9 ℃低温处理下,随胁迫时间的延长,光系统Ⅱ最大光化学效率呈下降趋势,光化学淬灭不断降低,非光化学淬灭的变化趋势相反;黄瓜叶片中的超氧化物歧化酶活性随着处理温度的降低先升高后下降;过氧化物酶活性在9 ℃处理24 h后达到最高;过氧化氢酶活性随着处理温度的降低而升高;丙二醛含量大于对照,随胁迫程度的增加先升高,后略有下降。通过研究建立了温室黄瓜低温气象灾害指标,划分为4个等级,分别为轻度、中度、重度和极重,可为设施农业气象服务提供科学依据。  相似文献   

The amino acid composition of the Sutter's Mill CM2 carbonaceous chondrite     

Aaron S. Burton  Daniel P. Glavin  Jamie E. Elsila  Jason P. Dworkin  Peter Jenniskens  Qing‐Zhu Yin 《Meteoritics & planetary science》2014,49(11):2074-2086

We determined the abundances and enantiomeric compositions of amino acids in Sutter's Mill fragment #2 (designated SM2) recovered prior to heavy rains that fell April 25–26, 2012, and two other meteorite fragments, SM12 and SM51, that were recovered postrain. We also determined the abundance, enantiomeric, and isotopic compositions of amino acids in soil from the recovery site of fragment SM51. The three meteorite stones experienced terrestrial amino acid contamination, as evidenced by the low d/l ratios of several proteinogenic amino acids. The d/l ratios were higher in SM2 than in SM12 and SM51, consistent with rain introducing additional l‐ amino acid contaminants to SM12 and SM51. Higher percentages of glycine, β‐alanine, and γ‐amino‐n‐butyric acid were observed in free form in SM2 and SM51 compared with the soil, suggesting that these free amino acids may be indigenous. Trace levels of d +l‐ β‐aminoisobutyric acid (β‐AIB) observed in all three meteorites are not easily explained as terrestrial contamination, as β‐AIB is rare on Earth and was not detected in the soil. Bulk carbon and nitrogen and isotopic ratios of the SM samples and the soil also indicate terrestrial contamination, as does compound‐specific isotopic analysis of the amino acids in the soil. The amino acid abundances in SM2, the most pristine SM meteorite analyzed here, are approximately 20‐fold lower than in the Murchison CM2 carbonaceous chondrite. This may be due to thermal metamorphism in the Sutter's Mill parent body at temperatures greater than observed for other aqueously altered CM2 meteorites.  相似文献   

Presolar grains in the CM2 chondrite Sutter's Mill     

Xuchao Zhao  Yangting Lin  Qing‐Zhu Yin  Jianchao Zhang  Jialong Hao  Michael Zolensky  Peter Jenniskens 《Meteoritics & planetary science》2014,49(11):2038-2046

The Sutter's Mill (SM) carbonaceous chondrite is a regolith breccia, composed predominantly of CM2 clasts with varying degrees of aqueous alteration and thermal metamorphism. An investigation of presolar grains in four Sutter's Mill sections, SM43, SM51, SM2‐4, and SM18, was carried out using NanoSIMS ion mapping technique. A total of 37 C‐anomalous grains and one O‐anomalous grain have been identified, indicating an abundance of 63 ppm for presolar C‐anomalous grains and 2 ppm for presolar oxides. Thirty‐one silicon carbide (SiC), five carbonaceous grains, and one Al‐oxide (Al₂O₃) were confirmed based on their elemental compositions determined by C‐N‐Si and O‐Si‐Mg‐Al isotopic measurements. The overall abundance of SiC grains in Sutter's Mill (55 ppm) is consistent with those in other CM chondrites. The absence of presolar silicates in Sutter's Mill suggests that they were destroyed by aqueous alteration on the parent asteroid. Furthermore, SM2‐4 shows heterogeneous distributions of presolar SiC grains (12–54 ppm) in different matrix areas, indicating that the fine‐grained matrix clasts come from different sources, with various thermal histories, in the solar nebula.  相似文献   

Records of the Moon‐forming impact and the 470 Ma disruption of the L chondrite parent body in the asteroid belt from U‐Pb apatite ages of Novato (L6)     

Qing‐Zhu Yin  Qin Zhou  Qiu‐Li Li  Xian‐Hua Li  Yu Liu  Guo‐Qiang Tang  Alexander N. Krot  Peter Jenniskens 《Meteoritics & planetary science》2014,49(8):1426-1439

Novato, a newly observed fall in the San Francisco Bay area, is a shocked and brecciated L6 ordinary chondrite containing dark and light lithologies. We have investigated the U‐Pb isotope systematics of coarse Cl‐apatite grains of metamorphic origin in Novato with a large geometry ion microprobe. The U‐Pb systematics of Novato apatite reveals an upper intercept age of 4472 ± 31 Ma and lower intercept age of 473 ± 38 Ma. The upper intercept age is within error identical to the U‐Pb apatite age of 4452 ± 21 Ma measured in the Chelyabinsk LL5 chondrite. This age is interpreted to reflect a massive collisional resetting event due to a large impact associated with the peak arrival time at the primordial asteroid belt of ejecta debris from the Moon‐forming giant impact on Earth. The lower intercept age is consistent with the most precisely dated Ar‐Ar ages of 470 ± 6 Ma of shocked L chondrites, and the fossil meteorites and extraterrestrial chromite relicts found in Ordovician limestones with an age of 467.3 ± 1.6 Ma in Sweden and China. The lower intercept age reflects a major disturbance related to the catastrophic disruption of the L chondrite parent body most likely associated with the Gefion asteroid family, which produced an initially intense meteorite bombardment of the Earth in Ordovician period and reset and degassed at least approximately 35% of the L chondrite falls today. We predict that the 470 Ma impact event is likely to be found on the Moon and Mars, if not Mercury.  相似文献