MODIS

MODIS
  • 文章类型: Journal Article
    孕妇极易受到环境压力的影响,例如环境颗粒物(PM)。特别是在他们的第三个三个月,他们的身体经历显著的氧化应激。为进一步把这一对话落到实处,当前的研究评估了来自高污染城市亚兹德的健康孕妇(n=150名家庭主妇;18-40岁;妊娠年龄>36周),伊朗,2021年9月至11月。采用中分辨率成像光谱辐射计(MODIS)获取的气溶胶光学深度(AOD)数据作为影响变量,并使用现场收集的PM10数据进行验证(r=0.62,p值<0.01)。血小板计数之间的联系,酶(SGOT,SGPT,LDH,胆红素),使用广义加性模型评估代谢产物(尿素和酸性尿酸)和AOD数据的不同组合.结果表明,AOD的时间变异性很高(0.94±0.51),但具有空间稳定的分布模式。妊娠晚期的平均AOD,其次是三个月的高峰,被确定为最重要的非线性预测因子,而妊娠早期和整个妊娠期间的平均AOD与任何生物标志物均无显著关联。考虑到AOD变量与母体氧化应激之间的关联,需要紧急规划来改善敏感亚人群的城市空气质量。
    Pregnant women are highly vulnerable to environmental stressors such as ambient particulate matter (PM). Particularly during their 3rd trimester, their bodies undergo significant oxidative stresses. To further consolidate this dialogue into practice, the current study evaluated healthy pregnant women (n = 150 housewives; 18-40 years old; gestation age >36 weeks) from the highly polluted city of Yazd, Iran, from September to November 2021. The aerosol optical depth (AOD) data retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS) were employed as influencing variables and validated using field-collected PM10 data (r = 0.62, p-value <0.01). The links between blood platelet count, enzymes (SGOT, SGPT, LDH, bilirubin), metabolic products (urea and acid uric) and different combinations of AOD data were assessed using the Generalized Additive Model. The results showed a high temporal variability in AOD (0.94 ± 0.51) but a spatially stable distribution pattern. The mean AOD during the 3rd trimester, followed by that of the three-month peak, were identified as the most significant non-linear predictors, while the mean AOD during the 1st trimester and throughout the entire pregnancy showed no significant associations with any of the biomarkers. Considering the associations found between AOD variables and maternal oxidative stresses, urgent planning is required to improve the urban air quality for sensitive subpopulations.
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  • 文章类型: Journal Article
    植被健康指数(VHI)是用于评估植被健康和状况的指标,基于卫星衍生数据。它提供了压力或活力的综合指标,常用于农业,生态学,和环境监测,以预测植被健康变化。尽管有其优势,很少有关于预测VHI作为未来预测的研究,特别是使用最新有效的机器学习方法。因此,本研究的主要目的是利用遥感图像预测VHI值。为了实现这一目标,该研究提出采用组合的卷积神经网络(CNN)和一种称为长短期记忆(LSTM)的特定类型的循环神经网络(RNN),被称为ConvLSTM。VHI时间序列图像是根据从Terra和Aqua卫星上的中分辨率成像光谱仪(MODIS)获得的归一化植被指数(NDVI)和地表温度(LST)数据计算的。除了传统的基于图像的计算,该研究建议使用NDVI和LST时间序列的全球最小值和全球最大值(全球范围)来计算VHI。研究结果表明,具有1层结构的ConvLSTM通常比2层和3层结构提供更好的预测。1步的平均均方根误差(RMSE)值,2步,和提前3步的VHI预测分别为0.025、0.026和0.026,每个步骤代表一个8天的预测范围。此外,所提出的使用应用的ConvLSTM结构的全局比例模型优于传统的VHI计算方法。
    The Vegetation Health Index (VHI) is a metric used to assess the health and condition of vegetation, based on satellite-derived data. It offers a comprehensive indicator of stress or vigor, commonly used in agriculture, ecology, and environmental monitoring for forecasting changes in vegetation health. Despite its advantages, there are few studies on forecasting VHI as a future projection, particularly using up-to-date and effective machine learning methods. Hence, the primary objective of this study is to forecast VHI values by utilizing remotely sensed images. To achieve this objective, the study proposes employing a combined Convolutional Neural Network (CNN) and a specific type of Recurrent Neural Network (RNN) called Long Short-Term Memory (LSTM), known as ConvLSTM. The VHI time series images are calculated based on the Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) data obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra and Aqua satellites. In addition to the traditional image-based calculation, the study suggests using global minimum and global maximum values (global scale) of NDVI and LST time series for calculating the VHI. The results of the study showed that the ConvLSTM with a 1-layer structure generally provided better forecasts than 2-layer and 3-layer structures. The average Root Mean Square Error (RMSE) values for the 1-step, 2-step, and 3-step ahead VHI forecasts were 0.025, 0.026, and 0.026, respectively, with each step representing an 8-day forecast horizon. Moreover, the proposed global scale model using the applied ConvLSTM structures outperformed the traditional VHI calculation method.
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  • 文章类型: Journal Article
    浮游植物生物量空间分布的准确预测,由叶绿素a(CHL-a)浓度表示,对于评估海洋环境中的生态条件很重要。这项研究开发了基于超参数优化决策树的机器学习(ML)模型,以预测孟加拉湾海洋浮游植物CHL-a的地理分布。为了在很大的空间范围内预测CHL-a,卫星衍生的海洋颜色特征遥感数据(CHL-a,有色溶解的有机物,光合有效辐射,颗粒有机碳)和气候因素(夜间海面温度,表面吸收长波辐射,2003年至2022年的海平面压力)用于训练和测试模型。从这项研究中获得的结果表明,CHL-a的最高浓度发生在海湾的沿海带和河口附近。分析表明,除了光合有效辐射,有机组分与CHL-a表现出比气候特征更强的正相关关系,它们是负相关的。结果表明,所选择的决策树方法都具有较高的R2和较低的均方根误差(RMSE)误差。此外,XGBoost在预测CHL-a的地理分布方面优于所有其他模型。为了在季节性基础上评估模型的有效性,在孟加拉湾地区验证了性能最佳的XGBoost模型,该模型在预测Chl-a的空间分布以及夏季的像素值方面表现出良好的性能,冬季和季风季节。这项研究为研究人员预测孟加拉湾的CHL-a提供了最佳的ML模型。此外,它还有助于提高我们对CHL-a空间动力学的了解,并协助监测孟加拉湾的海洋资源。值得注意的是,印度洋的水质在性质上是非常动态的,因此,需要额外的努力来测试该研究模型在不同季节和空间梯度下的有效性.
    An accurate prediction of the spatial distribution of phytoplankton biomass, as represented by Chlorophyll-a (CHL-a) concentrations, is important for assessing ecological conditions in the marine environment. This study developed a hyperparameter-optimized decision tree-based machine learning (ML) models to predict the geographical distribution of marine phytoplankton CHL-a in the Bay of Bengal. To predict CHL-a over a large spatial extent, satellite-derived remotely sensed data of ocean color features (CHL-a, colored dissolved organic matter, photosynthetically active radiation, particulate organic carbon) and climatic factors (nighttime sea surface temperature, surface absorbed longwave radiation, sea level pressure) from 2003 to 2022 are used to train and test the models. Results obtained from this study have shown the highest concentrations of CHL-a occurred near the Bay\'s coastal belts and river estuaries. Analysis revealed that aside from photosynthetically active radiation, organic components exhibited a stronger positive relationship with CHL-a than climatic features, which are correlated negatively. Results showed the chosen decision tree methods to all possess higher R2 and lower root mean square error (RMSE) errors. Furthermore, XGBoost outperforms all other models in predicting the geographic distribution of CHL-a. To assess the model efficacy on seasonal basis, a best performing XGBoost model was validated in the Bay of Bengal region which has shown a good performance in predicting the spatial distribution of Chl-a as well as the pixel values during the summer, winter and monsoon seasons. This study provides the best ML model to researchers for predicting CHL-a in the Bay of Bengal. Further it helps to improve our knowledge of CHL-a spatial dynamics and assist in monitoring marine resources in the Bay of Bengal. It worth noting that the water quality in the Indian Ocean is very dynamic in nature, therefore, additional efforts are needed to test the efficacy of this study model over different seasons and spatial gradients.
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  • 文章类型: Journal Article
    随着城市发展对环境的影响越来越大,空气质量问题引起了全国和全球的广泛关注。研究城市化对空气质量的影响对城市的合理发展具有重要意义。MODIS-MAIAC(中分辨率成像光谱仪-大气校正的多角度实施)气溶胶光学深度(AOD)产品,利用DMSP/OLS(国防气象卫星计划/运营线路扫描系统)和NPP/VIIRS(Suomi国家极地轨道合作伙伴/可见光红外成像辐射计套件)夜光,探讨了2009-2018年济南市环境治理政策颁布前后AOD与城市化发展的时空变化和相关性。结果表明:(1)济南市AOD的空间分布具有北高南低的特点,西高东低,中部地区的一些地区较低;时间上有明显的季节性变化,夏季AOD最高,冬季最低。2009-2013年,AOD的年平均变异量增加了20.6%,2014-2018年下降35.3%;(2)济南市夜灯分布逐步扩大,反映了这座城市的持续发展。与城市周边地区相比,城市地区气溶胶的空间分布相对较低。(3)2009-2013年AOD与夜光的时空分布呈显著正相关。然而,从2014年到2018年,随着环境治理政策的实施,这种关系转变为AOD和夜光的时空分布之间的显着负相关。通过分析济南市近十年来城市发展与气溶胶深度的相关性,可以得出结论,城市发展并不必然导致AOD水平升高。值得注意的是,济南政府在控制大气环境方面取得了显著成效,近年来的进步证明了这一点。
    With the insidiously growing impact of urban development on the environment, the issue of air quality has attracted extensive attention nationally and globally. It is of great significance to study the influence of urbanization on air quality for the rational development of cities. MODIS-MAIAC (Moderate Resolution Imaging Spectroradiometer-Multi-Angle Implementation of Atmospheric Correction) Aerosol optical depth (AOD) product, DMSP/OLS (Defense Meteorological Satellite Program/Operational Linescan System) and NPP/VIIRS (Suomi National Polar-orbiting Partnership/Visible Infrared Imaging Radiometer Suite) night-light were used to explore the spatiotemporal variation and correlation between AOD and urbanization development before and after the promulgation of environmental governance policies in Jinan City from 2009 to 2018. Results show that (1) the spatial distribution of AOD in Jinan had the characteristics of high in the north and low in the south, high in the west and low in the east, and low in some parts of the central region; there was a significant seasonal variation in time, with the highest AOD in summer and the lowest in winter. During 2009-2013, the annual average variation of AOD increased by 20.6%, while during 2014-2018, it decreased by 35.3%; (2) The distribution of night-light in Jinan City has progressively expanded, mirroring the city\'s ongoing development. The spatial distribution of aerosols in urban areas was relatively low compared to the surrounding areas of the city. (3) From 2009 to 2013, there existed a significant positive correlation between the spatial and temporal distribution of AOD and night-light. However, from 2014 to 2018, with the implementation of environmental governance policies, this relationship shifted to a significant negative correlation between the spatial and temporal distribution of AOD and night-light. Through an analysis of the correlation between urban development and aerosol depth in Jinan City over the past decade, it can be concluded that urban development does not inevitably result in elevated AOD levels. Notably, the Jinan government has achieved remarkable results in controlling the atmospheric environment, as evidenced by recent years\' improvements.
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  • 文章类型: Journal Article
    每年都会发生洪水,由于严重的气候变化,世界范围内的财产和人类生命受到巨大损害。冬季,积雪占山区的主导地位。因此,春季河流流量明显增加,当雪逐渐融化并伴随着这个季节的降雨。这项研究旨在评估雪参数,如积雪,月平均积雪量,通过使用Terra卫星,从2020年初冬到夏末融雪,MODIS传感器,和FLDAS模型来估算德黑兰省Kan盆地的GoogleEarthEngine系统中相当于融雪的水量。在本研究中,水文模型HEC-HMS用于评估积雪参数对Kan河排放量的影响。在这项研究中,使用Sentinel-2卫星的图像提取了土地利用图,以获得更高的精度。最后,Sentinel-1雷达图像用于评估洪水对该地区的影响并监测变化。
    Floods occur yearly, with great property and human life damage worldwide due to severe climate changes. Snow cover dominates the mountainous areas in winter. Therefore, the river discharge increases significantly in spring, when the snow melts gradually and is accompanied by rain this season. This study aims to evaluate the snow parameters such as snow cover, monthly average snow cover, and snowmelt from early winter to late summer 2020 by using the Terra satellite, MODIS sensor, and the FLDAS model to estimate the amount of water equivalent to snowmelt in the Google Earth Engine system for Kan basin in Tehran province. The hydrological model HEC-HMS was used for assessing the effect of snow parameters on the amount of Kan River discharge in this study. The land use map was extracted by using the image of the Sentinel-2 satellite to acquire more accuracy in this study. Finally, Sentinel-1 radar images were used to evaluate the effect of flood on the area and monitor the changes.
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  • 文章类型: Journal Article
    城市化,特别是在城市周边地区,通常会导致严重改变区域土地利用和土地覆盖(LULC)。城市周边地区的建筑增加影响了城市群居民对必要便利设施的区域可及性,并严重影响了区域环境,正如在印度喜马拉雅山山麓的查mu地区所观察到的那样。本研究旨在评估过去二十年来查谟地区城市扩张的增长,以及城市化如何根据定性参数影响与城市增长相对应的便利设施数量的滞后。Further,制定了参数化方案来评估设施质量。与印多尔进行了比较,规划中的智慧城市,基于舒适性指数评估城市化和住宅质量的现状。该研究还调查了查mu区城市和郊区环境中某些气候变量中观察到的无差别。调查是通过多环缓冲区分析方法进行的,该方法利用了基于2002年,2013年和2021年Landsat8/7卫星图像的土地利用土地覆盖(LULC)产品。使用MODIS气溶胶光学深度(AOD)和地表温度(LST)产品分析了设置中的差异。分析导致确定关键城市参数,包括城市区域,密度,和增长率,揭示了距市中心25-27公里的显着城市化。在城市和城市以下地区观察到显着的差异,表明LST和AOD的上升较高,特别是在最近十年。这些调查为城市和气候解决方案当局的规划和管理提供了关键信息,特别是在极度濒危的地区。
    Urbanization, particularly in peri-urban areas, often results in critically transforming the regional land use and land cover (LULC). The increased built-up in peri-urban areas affects the regional accessibility of residents of urban clusters to requisite amenities and severely affects the regional environment, as observed in the case of Jammu district situated in the foothills of the Indian Himalayas. The present study is aimed at assessing the rise of urban sprawls in Jammu district over the past two decades and how the urbanization has affected the lag in the number of amenities corresponding to the urban growth based on qualitative parameters. Further, a parameterization scheme is developed to assess the amenities quality. A comparison is made with Indore, a planned smart city, to assess the status of urbanization and residential quality based on an amenity index. The study also investigates the indifferences observed in some of the climate variables in the urban and sub-urban settings of the Jammu district. The investigation is conducted through a multi-ring buffer analysis approach utilizing the land use land cover (LULC) products based on Landsat 8/7 satellite imagery of 2002, 2013, and 2021. The indifferences in the settings are analyzed using MODIS aerosol optical depth (AOD) and land surface temperature (LST) products. The analysis leads to determination of critical urban parameters including the urban area, density, and growth rate, revealing significant urbanization at 25-27 km from the city center. Significant indifferences are observed in urban and sub-urban areas indicating higher rise in LST and AOD, particularly in the recent decade. These investigations provide critical information to urban and climate solution authorities for planning and management, particularly in critically endangered areas.
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  • 文章类型: Journal Article
    在印度北部,燃烧残茬是一个新兴的环境问题,这对该地区的空气质量有严重影响。虽然一年内发生两次燃茬,第一次在4月至5月期间,再次在10月至11月由于稻谷燃烧,这种影响在10月至11月期间是严重的。气象参数的作用和大气中反转条件的存在加剧了这一点。大气质量的恶化可以归因于燃烧残茬的排放,这可以从观察到的土地利用土地覆盖(LULC)模式的变化中看出。火灾事件,以及气溶胶和气态污染物的来源。此外,风速和风向也在改变指定区域内污染物和颗粒物的浓度方面发挥作用。本研究是针对旁遮普邦进行的,哈里亚纳邦,德里,和北方邦西部研究了燃茬对印度恒河平原(IGP)该地区气溶胶负荷的影响。在这项研究中,气溶胶水平,烟羽的特点,污染物的远距离迁移,2016年至2020年10月至11月期间,受影响地区在印度恒河平原(印度北部)地区进行了卫星观测。通过MODIS-FIRMS(中分辨率成像光谱辐射计-用于资源管理系统的火灾信息)观测,据透露,燃茬事件有所增加,2016年期间观察到的事件数量最多,然后从2017年到2020年,随后几年的事件数量有所减少。MODIS观测显示,从西向东有很强的AOD梯度。在10月至11月的燃烧高峰期,盛行的西北风有助于烟羽在印度北部蔓延。这项研究的结果可用于扩展季风后季节印度北部的大气过程。污染物,烟羽的特点,该地区生物质燃烧气溶胶的影响区域对天气和气候研究至关重要,特别是考虑到过去二十年来农业燃烧的上升趋势。
    Stubble burning is an emerging environmental issue in Northern India, which has severe implications for the air quality of the region. Although stubble burning occurs twice during a year, first during April-May and again in October-November due to paddy burning, the effects are severe during October-November months. This is exacerbated by the role of meteorological parameters and presence of inversion conditions in the atmosphere. The deterioration in the atmospheric quality can be attributed to the emissions from stubble burning which can be perceived from the changes observed in land use land cover (LULC) pattern, fire events, and sources of aerosol and gaseous pollutants. In addition, wind speed and wind direction also play a role in changing the concentration of pollutants and particulate matter over a specified area. The present study has been carried out for the states of Punjab, Haryana, Delhi, and western Uttar Pradesh to study the influence of stubble burning on the aerosol load of this region of Indo-Gangetic Plains (IGP). In this study, the aerosol level, smoke plume characteristics, long-range transport of pollutants, and affected areas during October-November from year 2016 to 2020 were examined over the Indo-Gangetic Plains (Northern India) region by the satellite observations. By MODIS-FIRMS (Moderate Resolution Imaging Spectroradiometer-Fire Information for Resource Management System) observations, it was revealed that there was an increase in stubble burning events with the highest number of events being observed during the year 2016 and then a decrease in the number of events in subsequent years from 2017 to 2020. MODIS observations revealed a strong AOD gradient from west to east. The prevailing north-westerly winds assist the spread of smoke plumes over Northern India during the peak burning season of October to November. The findings of this study might be used to expand on the atmospheric processes that occur over northern India during the post-monsoon season. The pollutant, smoke plume features, and impacted regions of biomass-burning aerosols in this region are critical for weather and climate research, especially given the rising trend in agricultural burning over the previous two decades.
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  • 文章类型: Journal Article
    草原区牧草产量的估算对于确定放牧能力和维持生态平衡具有重要的理论和现实意义。由于采样数据和遥感数据之间的空间不一致,提高基于遥感的鲜草产量(FGY)估算精度是一个难点。利用不同空间尺度的植被覆盖度,本文提出了一种基于空间尺度变换(SST)的FGY估计模型,采用归一化差异植被指数(NDVI)作为其估计因子,利用锡林郭勒盟的草原,内蒙古,作为研究领域。结果表明,基于SST的FGY估计模型能够大大提高估计精度;使用截距为零的线性(线性-0)和幂函数构建的估计模型的相对估计误差(REE)分别为18.16%和18.35%。分别。利用线性-0和幂函数构建的估算模型对锡林郭勒盟草地的草产量进行了估算,估计的总FGYs为8.777×1010千克和8.583×1010千克,分别。这两个模型得到了大致相同的估计,但它们在单位FGY的空间分布上存在显著差异。以净初级生产力(NPP)为例,进一步验证了其他遥感数据作为估算因子的有效性,结果表明,基于SST的FGY估算还有效地提高了草产量的估算精度。
    Estimating the grass yield of a grassland area is of vital theoretical and practical significance for determining grazing capacity and maintaining ecological balance. Due to the spatial inconsistency between sampling and remote sensing data, improving the accuracy of fresh grass yield (FGY) estimation based on remote sensing is difficult. Using vegetation coverage at different spatial scales, this paper proposes a spatial scale transformation (SST)-based estimation model for FGY adopting normalized difference vegetation index (NDVI) as its estimation factor, using the grassland in Xilingol League, Inner Mongolia, as the study area. Results showed that the SST-based FGY estimation model was able to greatly improve estimation precision; the relative estimation error (REE) of the estimation models constructed using linear with intercept zero (linear-0) and power functions were 18.16% and 18.35%, respectively. The estimation models constructed using linear-0 and power functions were employed to estimate the grass yield of the grassland in Xilingol League, and the total FGYs estimated were 8.777 × 1010 kg and 8.583 × 1010 kg, respectively. The two models obtained roughly the same estimates, but there were significant differences between them in the spatial distributions of FGY per unit. Taking net primary productivity (NPP) as an example, the effectiveness of other remote sensing data as estimation factors was further verified, and the results showed that SST-based estimation for FGY also effectively improved the estimation accuracy of grass yield.
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  • 文章类型: Journal Article
    美国国家航空航天局(NASA)的中分辨率成像光谱仪(MODIS)提供了大量地球数据集的陆地产品。另一方面,研究人员发现很难在特定地点检索这些数据。地表温度(LST)的提取和分析方法,土地利用和土地覆盖(LULC),和高程在这项研究中提出。所提供的R命令使提取特定位置的数据的耗时过程更易于访问。因此,以巴厘岛LST的统计研究为例。在巴厘岛的15个地区,二次多项式确定了五种可能的变暖模式,而逻辑回归模型评估了变暖的可能性。调查结果表明,在过去的二十年中,巴厘岛有25.2%的人口变暖,城市和建成区以及落叶林的温度最高,与海拔成反比。全球变暖引发了许多学术兴趣,并已成为一个严重的气候问题。这项工作中提出的技术简化了LST的提取,LULC,和来自MODIS卫星的高程数据。这些方法也可以用于具有相同拓扑的其他数据集,如归一化植被指数(NDVI),气溶胶光学深度(AOD),和夜光数据。
    The Moderate Resolution Imaging Spectroradiometer (MODIS) of the National Aeronautics and Space Administration (NASA) offers numerous land products of the Earth\'s datasets. On the other hand, researchers find it difficult to retrieve this data for specific places. The methods for extracting and analyzing land surface temperature (LST), land use and land cover (LULC), and elevation are presented in this study. The R commands provided make the time-consuming process of extracting data for specific places much more accessible. As a result, a statistical study of LST over Bali is shown as an example. Over the 15 regions of Bali, a quadratic polynomial identified five possible warming patterns, while a logistic regression model assessed the probability of warming. The findings suggest that 25.2% of Bali has warmed during the last two decades, with temperatures being highest in urban and built-up areas and deciduous forests and inversely associated with elevation. Global warming has sparked a lot of academic interest and has become a serious climate problem. The techniques proposed in this work simplify the extraction of LST, LULC, and elevation data from MODIS satellites. These approaches can also be used on other datasets with identical topologies, such as the normalized difference vegetation index (NDVI), aerosol optical depth (AOD), and night light data.
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  • 文章类型: Journal Article
    冬春干旱是我国云南省最突出的自然灾害之一。它们经常发生,持续时间长,伤害范围广,这对社会和经济发展产生了严重影响,以及农业生产和,因此,严重影响了该地区人民的生活。传统的干旱监测模型没有考虑地形,从而影响结果的比较性质,因为基线条件不相同。因此,本研究提出了一种考虑地形因素影响的干旱综合监测模型,以提高评价效果。首先,基于NASA的中分辨率成像光谱辐射计(MODIS)和热带降雨测量任务(TRMM3B43)数据,植被状况指数(VCI),温度条件指数(TCI),降水条件指数(TRCI),和三个地形因子地面高程(DEM),坡度(SLOPE),选择纵横比(ASPECT)作为模型参数。然后,利用多元线性回归模型构建了不考虑地形因素的干旱综合监测模型(模型A)和考虑地形因素的干旱综合监测模型(模型B)。最后,采用标准化降水蒸散指数(SPEI)对两种模式的效果进行评价,中国,采用模型B对研究区2008-2019年冬春干旱进行分析。结果表明:(1)模型B的相关系数在冬季和春季均高于模型A,模型B的标准误差低于模型A。(2)模型A和SPEI的等级一致率冬季为0.92,春季为0.33;模型B和SPEI的等级一致率冬季为0.83,春季为0.75。因此模型B的监测效果更加稳定。(3)研究期间存在周期性干旱,春季的干旱程度小于冬季。冬季出现中度和重度干旱。因此,这项研究的结论是,地形的影响对干旱的评估有重要的影响。考虑地形因素的干旱综合监测模型可以有效识别干旱的发生,因此,为云南西南部的防灾减灾政策提供了重要的投入。
    Droughts in winter and spring are one of the most prominent natural disasters in the Yunnan Province in China. They occur frequently, with long durations and have a wide range of damage, which has a serious impact on social and economic development, as well as agricultural production and, therefore, strongly impacts the lives of the people living in the region. The traditional drought monitoring model does not take terrain into consideration, thereby affecting the comparative nature of results, as baseline conditions are not the same. Therefore, this study proposed a comprehensive drought monitoring model considering the influence of terrain factors to improve the evaluation effect. Firstly, based on NASA\'s Moderate Resolution Imaging Spectroradiometer (MODIS) and Tropical Rainfall Measurement Mission (TRMM 3B43) data, vegetation condition index (VCI), temperature condition index (TCI), precipitation condition index (TRCI), and three terrain factors ground elevation (DEM), slope (SLOPE), aspect (ASPECT) were selected as model parameters. Then, a comprehensive drought monitoring model without considering terrain factors (Model A) and a comprehensive drought monitoring model of considering terrain factors (Model B) were constructed by using multiple linear regression models. Finally, the effects of the two models were evaluated by using standardized precipitation evapotranspiration index (SPEI) in southwest Yunnan Province, China, and model B was used to analyze the drought in winter and spring in the study area from 2008 to 2019. The results showed that (1) the correlation coefficient of model B was higher than that of model A in winter and spring and the standard error of model B was lower than that of model A. (2) The grade consistency rate of Model A and SPEI was 0.92 in winter and 0.33 in spring; the grade consistency between model B and SPEI was 0.83 in winter and 0.75 in spring, and therefore the monitoring effect of model B was more stable. (3) There were periodic droughts during the study period, and the degree of drought in spring was less than in winter. Medium and severe droughts were observed in winter. Thus, this study concluded that the effect of terrain has an important influence on the evaluation of droughts. The comprehensive drought monitoring model which considers topographic factors can effectively identify the occurrence of drought, and therefore provide significant input with regards to disaster prevention and mitigation policies in southwest Yunnan.
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