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风廓线雷达在重污染天气与逆温层关系研究中的应用 总被引：1，自引：0，他引：1
本文利用气象要素地面观测和环境空气质量监测数据,结合对流层风廓线雷达探测资料,深入研究了2013—2019年发生在青岛地区的65个重污染天气的逆温层变化特征及其与重污染天气的关系。结果表明:(1)青岛地区的重污染天气主要发生在12月至次年1月,重污染发生当日的空气质量指数(Air quality iudex AQI)有“双峰”结构的日变化特征;(2)逆温层早于重污染天气出现,当逆温层高度降低且强度增强,或逆温层高度维持较低、强度维持较强而厚度增厚时,重污染持续或加强;当逆温层高度升高、强度减弱或厚度变薄时,重污染减弱或消散;(3)根据热成风原理,利用风廓线雷达资料可以提前3~7 h预测当地重污染天气的发生,从根本上弥补了常规探空资料低时间分辨率的不足。本文首次将风廓线雷达资料用于分析逆温层变化,而不是平流输送作用,这不仅增加了一个判断影响AQI变化气象条件的新手段,也为今后进一步研究逆温层与重污染天气之间的关系增加了一个有效的新途径,对精准预判某地重污染天气发生的具体时间节点有重要的参考意义和业务应用价值。 相似文献
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The accurate detection of heavy metal-induced stress on crop growth is important for food security and agricultural, ecological and environmental protection. Spectral sensing offers an efficient and undamaged observation tool to monitor soil and vegetation contamination. This study proposed a methodology for dynamically estimating the total cadmium (Cd) accumulation in rice tissues by assimilating spectral information into WOFOST (World Food Study) model. Based on the differences among ground hyperspectral data of rice in three experiments fields under different Cd concentration levels, the spectral indices MCARI1, NREP and RH were selected to reflect the rice stress condition and dry matter production of rice. With assimilating these sensitive spectral indices into the WOFOST + PROSPECT + SAIL model to optimize the Cd pollution stress factor fwi, the dynamic dry matter production processes of rice were adjusted. Based on the relation between dry matter production and Cd accumulation, we dynamically simulating the Cd accumulation in rice tissues. The results showed that the method performed well in dynamically estimating the total amount of Cd accumulation in rice tissues with R2 over 85%. This study suggests that the proposed method of integrating the spectral information and the crop growth model could successfully dynamically simulate the Cd accumulation in rice tissues. 相似文献
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Winter precipitation over Central Asia and the western Tibetan Plateau (CAWTP) is mainly a result of the interaction between the westerly circulation and the high mountains around the plateau. Empirical Orthogonal Functions (EOFs), Singular Value Decomposition (SVD), linear regression and composite analysis were used to analyze winter daily precipitation and other meteorological elements in this region from 1979 to 2013, in order to understand how interactions between the regional circulation and topography affect the intraseasonal variability in precipitation. The SVD analysis shows that the winter daily precipitation variability distribution is characterized by a dipole pattern with opposite signs over the northern Pamir Plateau and over the Karakoram Himalaya, similar to the second mode of EOF analysis. This dipole pattern of precipitation anomaly is associated with local anomalies in both the 700 hPa moisture transport and the 500 hPa geopotential height and is probably caused by oscillations in the regional and large-scale circulations, which can influence the westerly disturbance tracks and water vapor transport. The linear regression shows that the anomalous mid-tropospheric circulation over CAWTP corresponds to an anti-phase variation of the 500 hPa geopotential height anomalies over the southern and northern North Atlantic 10 days earlier (at 95% significance level), that bears a similarity to the North Atlantic Oscillation (NAO). The composite analysis reveals that the NAO impacts the downstream regions including CAWTP by controlling south-north two branches of the middle latitude westerly circulation around the Eurasian border. During the positive phases of the NAO, the northern branch of the westerly circulation goes around the northwest Tibetan Plateau, whereas the southern branch encounters the southwest Tibetan Plateau, which leads to reduced precipitation over the northern Pamir Plateau and increased precipitation over the Karakoram Himalaya, and vice versa. 相似文献
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The assimilation of Earth observation (EO) data into crop models has proven to be an efficient way to improve yield prediction at a regional scale by estimating key unknown crop management practices. However, the efficiency of prediction depends on the uncertainty associated with the data provided to crop models, particularly climatic data and soil physical properties. In this study, the performance of the STICS (Simulateur mulTIdisciplinaire pour les Cultures Standard) crop model for predicting corn yield after assimilation of leaf area index derived from EO data was evaluated under different scenarios. The scenarios were designed to examine the impact of using fine-resolution soil physical properties, as well as the impact of using climatic data from either one or four weather stations across the region of interest. The results indicate that when only one weather station was used, the average annual yield by producer was predicted well (absolute error <5%), but the spatial variability lacked accuracy (root mean square error = 1.3 t ha−1). The model root mean square error for yield prediction was highly correlated with the distance between the weather stations and the fields, for distances smaller than 10 km, and reached 0.5 t ha−1 for a 5-km distance when fine-resolution soil properties were used. When four weather stations were used, no significant improvement in model performance was observed. This was because of a marginal decrease (30%) in the average distance between fields and weather stations (from 10 to 7 km). However, the yield predictions were improved by approximately 15% with fine-resolution soil properties regardless of the number of weather stations used. The impact of the uncertainty associated with the EO-derived soil textures and the impact of alterations in rainfall distribution were also evaluated. A variation of about 10% in any of the soil physical textures resulted in a change in dry yield of 0.4 t ha−1. Changes in rainfall distribution between two abundant rainfalls during the growing season led to a significant change in yield (0.5 t ha−1 on average). Our results highlight the importance of using fine-resolution gridded daily precipitation data to capture spatial variations of rainfall as well as using fine-resolution soil properties instead of coarse-resolution soil properties from the Canadian soil dataset, especially for regions with high pedodiversity. 相似文献
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利用自动气象站观测资料、青岛雷达产品以及“天衍”雷达拼图产品和ERA5再分析资料,对台风“巴威”外围致山东半岛西部强降水过程的中尺度特征及环境条件进行分析。结果表明：1）“巴威”在黄海北上期间,其外围暖湿气流与冷空气在山东半岛西部到鲁东南交汇,对流层中低层形成东北—西南向深厚的切变线,高层处于高空急流入口区右侧,低层辐合、高层辐散有利于产生强降水,强降水位于850 hPa切变线及其右侧偏东风一侧。2）前期降水回波先后表现为两条有组织的线形回波带,其形成、发展和移动与850 hPa切变线密切相关;后期切变线右侧偏东风气流中γ中尺度辐合不断触发单体新生,青岛即墨境内组合反射率因子CR、差分反射率因子ZDR、差分相移率KDP均显著增大,导致即墨南泉连续两个小时雨强大于100 mm•h-1。3）切变线附近垂直上升运动深厚,850 hPa以下水汽通量辐合较强,为中尺度系统提供了触发条件和水汽条件;850 hPa,θse暖舌位置与切变线一致,暖舌中心达352 K,为中尺度系统发生、发展提供了能量条件;对流层中高层弱冷空气对触发强对流天气起到一定作用。4）850 hPa以下水汽通量辐合量值≤-8×10-7 g•cm-2•hPa-1•s-1的区域与暴雨区基本吻合,水汽通量辐合中心及垂直上升运动中心越低越有利于出现强降水。 相似文献
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《Deep Sea Research Part II: Topical Studies in Oceanography》1999,46(3-4):677-699
Variations in the distribution of chemotaxonomic pigments were monitored in the Arabian Sea and the Gulf of Oman at the end of the SW monsoon in September 1994 and during the inter-monsoon period in November/December 1994 to determine the seasonal changes in phytoplankton composition. The Gulf of Oman was characterized by sub-surface chlorophyll maxima at 20-40 m during both seasons, and low levels of divinyl chlorophyll a indicated that prochlorophytes did not contribute significantly to the total chlorophyll a. Prymnesiophytes (19′-hexanoyloxyfucoxanthin), diatoms (fucoxanthin) and chlorophyll b containing organisms accounted for most of the phytoplankton biomass in September, while prymnesiophytes dominated in November/December. In the Arabian Sea in September, high total chlorophyll a concentrations up to 1742 ng l-1 were measured in the coastal upwelling region and a progressive decline was monitored along the 1670 km offshore transect to oligotrophic waters at 8°N. Divinyl chlorophyll a was not detected along this transect except at the two most southerly stations where prochlorophytes were estimated to contribute 25–30% to the total chlorophyll a. Inshore, the dominance of fucoxanthin and/or hexanoyloxyfucoxanthin indicated that diatoms and prymnesiophytes generally dominated the patchy phytoplankton community, with zeaxanthin-containing Synechococcus also being important, especially in surface waters. At the southern oligotrophic localities, Synechococcus and prochlorophytes dominated the upper 40 m and prymnesiophytes were the most prominent at the deep chlorophyll maximum. During the inter-monsoon season, total chlorophyll a concentrations were generally half those measured in September and highest levels were found on the shelf (1170 ng l-1). Divinyl chlorophyll a was detected at all stations along the Arabian Sea transect, and we estimated that prochlorophytes contributed between 3 and 28% to the total chlorophyll a, while at the two oligotrophic stations this proportion increased to 51–52%. While procaryotes were more important in November/December than September, eucaryotes still accounted for >50% of the total chlorophyll a. Pigment/total chlorophyll a ratios indicated that 19′-hexanoyloxyfucoxanthin-containing prymnesiophytes were the dominant group, although procaryotes accounted for 65% at the two southerly oligotrophic stations. 相似文献
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利用自动气象站观测资料、青岛雷达产品以及“天衍”雷达拼图产品和ERA5再分析资料,对台风“巴威”外围致山东半岛西部强降水过程的中尺度特征及环境条件进行分析。结果表明：1）“巴威”在黄海北上期间,其外围暖湿气流与冷空气在山东半岛西部到鲁东南交汇,对流层中低层形成东北—西南向深厚的切变线,高层处于高空急流入口区右侧,低层辐合、高层辐散有利于产生强降水,强降水位于850 hPa切变线及其右侧偏东风一侧。2）前期降水回波先后表现为两条有组织的线形回波带,其形成、发展和移动与850 hPa切变线密切相关;后期切变线右侧偏东风气流中γ中尺度辐合不断触发单体新生,青岛即墨境内组合反射率因子CR、差分反射率因子ZDR、差分相移率KDP均显著增大,导致即墨南泉连续两个小时雨强大于100 mm?h-1。3）切变线附近垂直上升运动深厚,850 hPa以下水汽通量辐合较强,为中尺度系统提供了触发条件和水汽条件;850 hPa,θse暖舌位置与切变线一致,暖舌中心达352 K,为中尺度系统发生、发展提供了能量条件;对流层中高层弱冷空气对触发强对流天气起到一定作用。4）850 hPa以下水汽通量辐合量值≤-8×10-7 g?cm-2?hPa-1?s-1的区域与暴雨区基本吻合,水汽通量辐合中心及垂直上升运动中心越低越有利于出现强降水。 相似文献
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利用导航卫星反射信号(GNSS-R)进行海风海浪探测为海洋气象提供了一种新的观测手段,数据分析及有效性检定是确定系统探测能力的重要过程.在描述北斗GEO卫星进行海风探测机理的基础上,利用北斗反射信号的相关时间进行了海风的反演.同时针对国家北斗应用项目"基于北斗导航卫星的大气海洋和空间监测预警应用示范工程"在山东进行试验和试运行期间产生的风速观测数据进行分析,并通过与标准数据的对比,确定了该方法的有效性. 相似文献
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利用多普勒天气雷达资料和常规观测资料,分析了2017年8月6日山东东部地区一次罕见的极大风速达到12～13级的雷暴大风事件。此次过程发生在高空西北气流影响下,中低层强垂直风切变和较大的温度直减率为雷暴大风的出现提供了有利环境条件。中尺度边界辐合线不断触发新的对流单体,最终形成飑线结构。此次过程10级以上雷暴大风在雷达图上的主要特征包括：近地层显著的径向辐散（速度差≥35 m·s-1）或者大的径向速度（速度绝对值≥29 m·s-1）;较显著的中层径向辐合（MARC）特征（速度差≥30 m·s-1）或者强中反气旋结构（速度差≥31 m·s-1）;中气旋底部高度扩展至2 km以下等特征。 相似文献