CMA-MESO三维变分同化系统2m相对湿度资料同化研究     

徐枝芳  吴洋  龚建东  蔡怡 《气象学报》2021,79(6):943-955

为了提高CMA-MESO （China Meteorological Administration Mesoscale model）（原GRAPES）三维变分同化系统中2 m相对湿度资料的应用效果,改善模式中相对湿度的分析和降水预报效果,分析了2015年6—8月T639（T639L60全球中期数值预报系统,0.28125°×0.28125°）分析场低层相对湿度和2 m相对湿度之差与表征稳定度的理查森数（Ri）的关系,发现二者有很好的相关,Ri＜0时,模式低层相对湿度与2 m相对湿度的差异较小,基本在同化观测误差范围内。依据该统计结果,对CMA-MESO同化系统中2 m相对湿度同化方案进行优化,Ri＜0时,将观测站地形低于模式地形的2 m相对湿度观测由观测站高度改为模式最低层高度进行同化,形成新的2 m相对湿度同化方案,旨在解决2 m相对湿度资料同化时模式地形高度与观测站高度不同的影响。2018年7月CMA-MESO三维变分同化系统（3DVar）个例和连续试验结果显示:新的2 m相对湿度同化方案同化分析资料数量明显增加,且08时多于20时（北京时）,新增观测点新息向量（背景减观测）与周围原有观测新息向量保持基本一致,分析残差偏差和均方根误差减小,降水预报效果明显改善。新2 m相对湿度同化方案通过提高观测站低于模式地形高度的观测资料合理应用,从而改善了3 km模式系统同化分析和预报效果。   相似文献   

宁波北仑港区一次航道海雾地基多源信息观测特征分析     

胡利军  杨豪  高爱臻  郑铮 《气象科技》2021,49(2):192-199

结合天气形势、高空风场、370 m高塔、地面要素、激光云高仪、毫米波雷达等资料,对宁波北仑港区航道2018年2月15日海雾过程进行分析.结果 表明,这是一次以锋前雾为主的海雾过程,在上暖下冷的锋面背景下,地面水汽充沛、风力温和,近地层逆温结构,都为海雾的形成和维持提供了有利条件.上下大气风向不一致,不利于垂直方向空气交...  相似文献   

ECMWF细网格2 m温度预报产品在南疆西部温度预报中的释用          下载免费PDF全文

玛依热.艾海提  希热娜依.铁力瓦尔地  王鹏飞 《沙漠与绿洲气象(新疆气象)》2021,15(5):1-7

利用2016年1月1日—2018年12月31日ECMWF细网格模式2 m温度预报产品，使用三次多项式差值方法内插到站点，并用中短期天气预报检验方法，对南疆西部12个国家站与15个区域自动站共27个站的最高、最低气温未来24 h预报效果进行检验分析。结果表明：ECMWF细网格模式2 m温度预报产品对南疆西部非山区站未来24 h最高、最低气温的预报能力较好，对山区站未来24 h预报效果差；对南疆西部最高、最低气温的预报效果随季节变化，夏季预报准确率高于冬季，秋季预报准确率最低；模式最高气温预报准确率在降雪、高温天气时较高，最低气温预报准确率在降雨时较高，在高温过程中较低；模式对于降雨、降雪、大风/沙尘等天气最高气温预报偏低，高温事件中最高气温预报偏高。最低气温预报在降雨、高温天气中偏高，降雪时偏低，大风/沙尘天气最低气温预报偏东地区偏高、偏北地区偏低。降雪、高温天气预报相对降雨、大风/沙尘天气预报效果更稳定。  相似文献   

Petrology of nepheline syenite gneiss from Amazonian Brazil     

G. R. Lowell  R. Netuno Villas 《Geological Journal》1983,18(1):53-75

Nepheline syenite gneiss is exposed in three localities near the village of Boca Nova (47·04′W, 1°51′S) in northeastern Pará, Brazil. Isotopic and chemical evidence for an igneous premetamorphic history include: (1) bulk compositions which plot in the Q–Ne–Ks system on a peralkaline fractionation curve; (2) bulk compositions which fall on the Hviddal igneous trend in the SiO₂–Al₂O₃–Na₂O + K₂O molecular diagram; (3) an average K/Rb ratio identical to the average for nepheline syenites of the Khibina massif; (4) K/Rb ratios which lie on the ideal igneous fractionation curve; (5) Nb(Ta) contents far in excess of average crustal abundance; and (6) a low Sr₈₇/Sr⁸⁶ value (0·7034) characteristic of mantle derivation. Post-kinematic lit-par-lit injections, discordant veins, and concordant pods of leucocratic nepheline–alkali feldspar pegmatite partially replaced the metamorphic assemblage and destroyed any microscopic equilibrium texture that may have been present. The final disequilibrium assemblage consists of Fe-rich biotite and two generations each of sodic plagioclase, microcline, and nepheline. Some minor metasomatic chemical effects may be present in the rocks but a case for nephelinization of crustal rocks cannot be documented. Field, petrographic, and chemical constraints indicate that the Boca Nova gneiss is an early-stage migmatite formed by anatexis of metamorphosed igneous nepheline syenite or its volcanic equivalent. Regional metamorphism and partial melting opened the Rb-Sr system so that the whole-rock Rb/Sr isochron age of 724 m.y. has no unambiguous interpretation. A K/Ar age of 580 ± 10 m.y. from biotite denning the metamorphic foliation is regarded as a minimum date for the regional metamorphism and anatexis. No other alkaline rocks of comparable age are known in the Sao Luis Craton.  相似文献   

Isothermal compression of an eclogite from the Western Gneiss Region (Norway)     

Martin Simon  Pavel Pitra  Philippe Yamato  Marc Poujol 《Journal of Metamorphic Geology》2023,41(1):181-203

In the Western Gneiss Region in Norway, mafic eclogites form lenses within granitoid orthogneiss and contain the best record of the pressure and temperature evolution of this ultrahigh-pressure (UHP) terrane. Their exhumation from the UHP conditions has been extensively studied, but their prograde evolution has been rarely quantified although it represents a key constraint for the tectonic history of this area. This study focused on a well-preserved phengite-bearing eclogite sample from the Nordfjord region. The sample was investigated using phase-equilibrium modelling, trace-element analyses of garnet, trace- and major-element thermobarometry and quartz-in-garnet barometry by Raman spectroscopy. Inclusions in garnet core point to crystallization conditions in the amphibolite facies at 510–600°C and 11–16 kbar, whereas chemical zoning in garnet suggests growth during isothermal compression up to the peak pressure of 28 kbar at 600°C, followed by near-isobaric heating to 660–680°C. Near-isothermal decompression to 10–14 kbar is recorded in fine-grained clinopyroxene–amphibole–plagioclase symplectites. The absence of a temperature increase during compression seems incompatible with the classic view of crystallization along a geothermal gradient in a subduction zone and may question the tectonic significance of eclogite facies metamorphism. Two end-member tectonic scenarios are proposed to explain such an isothermal compression: Either (1) the mafic rocks were originally at depth within the lower crust and were consecutively buried along the isothermal portion of the subducting slab or (2) the mafic rocks recorded up to 14 kbar of tectonic overpressure at constant depth and temperature during the collisional stage of the orogeny.  相似文献   

沈阳区域气象中心中尺度数值预报业务系统的改进与拓展   总被引：4，自引：2，他引：4       下载免费PDF全文

周小珊杨森  陈力强 《气象科技》2003,31(5):262-267

介绍了改进后的沈阳区域气象中心中尺度数值预报业务系统的产品和运行情况。沈阳区域气象中心中尺度数值预报业务系统于1997年投入业务运行，目前已从最初的仅提供降水预报产品，发展到能提供降水预报、热带气旋路径预报、空气污染气象条件预报、人工增雨服务指导产品和城市环境气象业务预报所需的基本气象要素预报等多种业务所需的预报产品。业务系统每日两次自动运行，预报产品直接进入MICAPS、Vis5d、Grads绘图系统，进行图形显示，并直接进入区域气象中心局域网上的中尺度数值预报网页。目前，本系统的预报产品已经成为预报员每日必看的参考工具，经沈阳中心气象台评定，2002年汛期对辽宁省降水预报准确率已超过日本东亚模式。  相似文献   

大陆动力学数值模拟:问题、进展与展望     

李忠海  崔起华  钟辛易  刘明启  王杨  皇甫鹏鹏 《地质学报》2021,95(1):238-258

大陆动力学是地球动力学的基本组成部分,是板块构造理论的重要拓展,是固体地球科学的核心命题之一.在系统的地质、地球物理和地球化学观测的基础上,数值模拟是探讨大陆动力学过程和机制的有效手段.本文主要基于大陆动力学数值模拟,围绕大陆形成和演化过程的四个关键科学问题进行总结和探讨.①大陆起源与早期地球动力学演化.现今观测到的最...  相似文献   

2000-2015年华北地区8月极端干旱的异常环流型及其波活动特征          下载免费PDF全文

徐玮平  孟祥新  伯忠凯  邢雅敏 《海洋气象学报》2021,41(1):92-99

利用1961-2015年华北地区54个国家级气象观测站夏季8月逐日降水资料和2000-2015年欧洲中期天气预报中心(ECMWF)再分析数据,研究了华北地区8月极端干旱的异常环流型及原因.结果 表明:华北地区极端干旱事件以年际变化为主,2000-2015年华北地区极端干旱年在中高纬500 hPa高度距平场上存在“-、+...  相似文献   

Exposure to extreme climate decreases self-rated health score: Large-scale survey evidence from China     

《Global Environmental Change》2022

High temperature is a growing threat and impacts public health through different exposure mechanisms. Our study constructs a comprehensive exposure measurement based on temperature variability, duration, and effective influence range. We investigate human responses to high temperatures through self-rated health scores based on individual-level data from China Labor-force Dynamic Survey (CLDS). Results show that higher temperature and temperature variability significantly decrease self-rated health scores. Subjective health risk is most significantly related to the cumulative temperature in the previous two weeks. We also find that the exposure effects at night and on weekdays are more severe. Workers who experience greater exposure from commuting and work environments are negatively impacted by high temperatures. In addition, men, the elderly, middle and low education groups, rural residents are more likely to be impacted by high temperatures.  相似文献