Iterative selective spatial variance reduction of MYD11A2 LST data

The aim of this research effort is to develop a method that will allow to map and evaluate thermal anomalies in SW USA from the MYD11A2 night land surface temperature (LST) imagery being available for the year 2014, that present higher spatial (1 km) and temporal (46 images per year) resolution than the MYD11C3 LST data (12 images per year at 5.6 km spatial resolution). The fact that is MYD11A2 LST imagery is projected to a rectangular grid did not affect the X, Y and elevation (H) spatial decorrelation stretch. Principal component analysis and linear regression models isolated and removed the X, Y, H (spatial) dependent variance included in the data while metrics devised verified the selective spatial variance reduction. The reconstructed 46 LST images represent the amount the LST deviates from the X, Y and H predicted for the year 2014. The thematic information content of the reconstructed LST images is verified by cluster analysis and mapped the spatial extend and the temporal variability of thermal anomalies within the study area. The positive thermal anomaly clusters are spatially arranged mainly west of Sierra Nevada in Great Basin Section where extensional tectonics create a series of titled elongated mountain blocks along the N to S direction in between basins bounded by normal faults, while the negative thermal anomaly clusters are spatially arranged along the coastal region, further north and in the western region far from the tilted mountain tectonic blocks of the Great Basin Section. The spatial maps that define regions with (positive or negative) thermal anomalies and distinct mean land response could assist landcover studies and support urban and rural planning in the context of emerging climatic change.     

Sedimentary evolution of a late Pleistocene wetland indicating extreme coastal uplift in southern Tanzania

Facies analyses of Pleistocene deposits from southern coastal Tanzania (Lindi District) document that sediments formed in a wetland evolving on a coastal terrace in the Lindi Fracture Zone foreland. The exposed succession shows a marked sedimentary change from tidal to terrestrial facies. ¹⁴C analyses on gastropod shells indicate the emergence of the Lindi coast at ∼ 44 ¹⁴C ka BP. Emergence and subsequent elevation of terraces to 21 m above present-day sea level was linked to the falling eustatic sea level prior to the last glacial maximum, and to a periodic elevation due to extensional tectonic episodes in the eastern branch of the East African Rift System (EARS). Since ∼ 44 ¹⁴C ka BP tectonic uplift at the coast was 80-110 m, comparable to that in the extreme uplift areas of the EARS.     

Retrieving of Land Surface Temperature Using Thermal Remote Sensing and GIS Techniques in Kandaihimmat Watershed,Hoshangabad, Madhya Pradesh

Remotely sensed thermal infrared (TIR) data have been widely used to retrieve land surface temperature (LST). LST is an important parameter in the studies of urban thermal environment and dynamics. In the study, an attempt has been made using LANDSAT 8 thermal imagery to compute LST and the associated land cover parameters viz; land surface emissivity (LSE), normalized difference vegetation index (NDVI), normalized difference built-up index (NDBI) and normalized difference water index (NDWI). Landsat 8 TIRS band 10 & 11 (thermal bands) during 21 Oct. 2016, 22 Nov.2016, 24 Dec. 2016 and 09 Jan. 2017 were processed for LST analysis. However, band 5 & band 4 of the imagery was processed for NDVI, band 6 & band 5 for NDBI and band 2 & band 5 for NDWI analysis. LST has been derived from both the bands 10 &11 and validated by in-situ observations on the date and time of satellite overpass from the study area. Band 10 derived LST have shown much temperature difference while comparing with the in-situ observations. However, LST derived from band 11 found similar & close to the in-situ measurements. Relationship between band 11 results and in-situ observed measurements were developed, which has showing a strong correlation with (r² = 0.991). Land surface emissivity were also evaluated which shows variation in different land cover surfaces like vegetation, settlement, forest cover and water body. The study has proven that land surface temperature derived from satellite band 11 is the actual surface temperature of the study area.     

Study of regional monsoonal effects on landslide hazard zonation in Cameron Highlands, Malaysia

In general, landslides in Malaysia mostly occurred during northeast and southwest periods, two monsoonal systems that bring heavy rain. As the consequence, most landslide occurrences were induced by rainfall. This paper reports the effect of monsoonal-related geospatial data in landslide hazard modeling in Cameron Highlands, Malaysia, using Geographic Information System (GIS). Land surface temperature (LST) data was selected as the monsoonal rainfall footprints on the land surface. Four LST maps were derived from Landsat 7 thermal band acquired at peaks of dry and rainy seasons in 2001. The landslide factors chosen from topography map were slope, slope aspect, curvature, elevation, land use, proximity to road, and river/lake; while from geology map were lithology and proximity to lineament. Landslide characteristics were extracted by crossing between the landslide sites of Cameron Highlands and landslide factors. Using which, the weighting system was derived. Each landslide factors were divided into five subcategories. The highest weight values were assigned to those having the highest number of landslide occurrences. Weighted overlay was used as GIS operator to generate landslide hazard maps. GIS analysis was performed in two modes: (1) static mode, using all factors except LST data; (2) dynamic mode, using all factors including multi-temporal LST data. The effect of addition of LST maps was evaluated. The final landslide hazard maps were divided into five categories: very high risk, high risk, moderate, low risk, and very low risk. From verification process using landslide map, the landslide model can predict back about 13–16% very high risk sites and 70–93% of very high risk and high risk combined together. It was observed however that inclusion of LST maps does not necessarily increase the accuracy of the landslide model to predict landslide sites.     

Analysing transition of land surface temperature and derived indices with respect to elevation values in Kohima Saddar

Human activities have affected the urban environment resulting in a drastic change in the surface temperature. The impact of urban heat islands is noticeable in urban areas than in rural areas. The thermal band of Landsat 8 data is used to retrieve the spatial distribution of land surface temperature (LST) over Kohima Sadar for the years 2009, 2015 and 2020 with the Mono-window algorithm. Urban Thermal Field Variance Index (UTFVI) is used to assess the ecological condition in the area impacted by LST. Cartosat-1 Digital Elevation Model (Carto DEM) is used to understand the variations of LST and indices values with reference to the elevation profile located at different random points. The variations in the land cover are categorized as per the values of normalized difference vegetation index (NDVI) and built-up density index (BUI). This work estimates the influence of elevation over LST, vegetation, and the built-up area. Results implies a negative correlation between LST and NDVI whereas a positive correlation between LST and BUI. Likewise, NDVI and BUI show a strong negative correlation. It is observed that LST is independent of elevation profile but the variation of LST depends on the impact of change in topography urbanization, deforestation, and afforestation. There is no significant relationship of elevation with the variations in NDVI and BUI values. It is observed that the impact of emissivity influences the estimation of LST values. For the locations having the highest and lowest LST, NDVI, and BUI values, 50 random points are generated for the entire region, and validation is executed with the google earth historical image.

     

集成多时相ETM+影像的证据推理湿地遥感分类

选择黑龙江省扎龙湿地自然保护区作为研究区,开展了基于Dempster-Shafer理论的证据推理方法(ER)湿地遥感空间分类研究,提出了一种针对ETM+多波段遥感影像的计算证据支持度的新算法,利用证据推理方法集成研究区5个时相的ETM+影像。研究表明,证据推理方法能有效集成多时相ETM+影像实现湿地空间分类,其总体分类精度比基于任一单时相影像的最大似然法(MLC)分类精度都高,提高幅度约为2%~12%。     

The offshore east African rift system: new insights from the Sakalaves seamounts (Davie Ridge,SW Indian Ocean)

The offshore branch of the East African Rift System (EARS) has developed during Late Cenozoic time along the eastern Africa continental margin. While Neogene–Pleistocene extensional tectonic deformation has been evidenced along the northern segment of the Davie Ridge, the spatial extent of deformation further south remains poorly documented. Based on recent and various oceanographic datasets (bathymetric surveys, dredge samples and seismic profiles), our study highlights active normal faulting, modern east–west extensional tectonic deformation and Late Cenozoic alkaline volcanism at the Sakalaves Seamounts (18°S, Davie Ridge) that seem tightly linked to the offshore EARS development. In parallel, rift‐related tectonic subsidence appears responsible for the drowning of the Sakalaves Miocene shallow‐water carbonate platform. Our findings bring new insights regarding the development of the EARS offshore branch and support recent kinematic models proposing the existence of a plate boundary across the Mozambique Channel.     

Landsat data to evaluate urban expansion and determine land use/land cover changes in Penang Island,Malaysia

Land surface temperature (LST) plays an important role in local, regional and global climate studies. LST controls the distribution of the budget for radiation heat between the atmosphere and the earth’s surface. Therefore, it is important to evaluate abrupt changes in land use/land cover (LULC). Penang Island, Malaysia has been experiencing a rapid and drastic change in urban expansion over the past two decades due to growth in industrial and residential areas. The aim of this study was to investigate and evaluate the impact of LST with respect to land use changes in Penang Island, Malaysia. Three supervised classification techniques known as maximum likelihood, minimum distance-to-mean and parallelepiped were applied to the images to extract thematic information from the acquired scene by using PCI Geomatica 10.1 image processing software. These remote sensing classification techniques help to examine land-use changes in Penang Island using multi-temporal Landsat data for the period of 1999–2007. Training sites were selected within each scene and seven land cover classes were assigned to each classifier. The relative performance of each technique was evaluated. The accuracy of each classification map was assessed using a reference data set consisting of a large number of samples collected per category. Two Landsat satellite images captured in 1999 and 2007 were chosen to classify the LULC types using the maximum likelihood classification method, determined from visible and near-infrared bands. The study revealed that the maximum likelihood classifier produced superior results and achieved a high degree of accuracy. The LST and normalised difference vegetation index (NDVI) were computed based on changes in LULC. The results showed that the urban (highly built-up) area increased dramatically, and grassland area increased moderately. Inversely, barren land decreased obviously, and forest area decreased moderately. While urban (minimally built-up) area decreased slightly. These changes in LULC caused at significant difference in LST between urban and rural areas. Strong correlation values were observed between LST and NDVI for all LULC classes. The remote sensing technique used in this study was found to be efficient; it reduced the time for the analysis of the urban expansion, and it was found to be a useful tool to evaluate the impact of urbanisation with LST.     

Sediment geochemistry and tectonic setting: Application of discrimination diagrams to early stages of intracontinental rift evolution,with examples from the Okavango and Southern Tanganyika rift basins

In this article, we have applied discriminant diagrams and bivariate plots for tectonic setting to Quaternary sediments from the East African Rift System (EARS). Sediment samples used in this study represent two different phases in early stage intracontinental rift evolution: the alluvial fan of the nascent Okavango system and a lacustrine basin within the relatively more mature Tanganyika system. The diagrams for tectonic setting for major elements place the majority of these EARS sediments within the passive margin (PM) setting. Passive margin sandstones are generally enriched in SiO₂ and depleted in Na₂O, CaO and TiO₂ reflecting their highly recycled nature. Based on major element discriminant diagrams, we propose two new fields for early stage intracontinental rift evolution (alluvial fan and lacustrine basin), within the previously defined passive margin field. The rare earth element (REE) patterns from both Okavango and Tanganyika sediments exhibit patterns similar to PAAS, with ash layers from the Rungwe volcanics in the Tanganyika samples exhibiting an enrichment in REE relative to the bulk sediment.     

The relationship between land surface temperature and land use/land cover in Guangzhou,China

The integration of remote sensing, geographic information system, landscape ecology and statistical analysis methods was applied to study the urban thermal environment in Guangzhou. Normalized Difference Vegetation Index (NDVI), Normalized Difference Build-up Index (NDBI), Normalized Difference Barren Index (NDBaI) and Modified Normalized Difference Water Index (MNDWI) were used to analyze the relationships between land surface temperature (LST) and land use/land cover (LULC) qualitatively. The result revealed that, most urban built-up lands were located in the middle part, and high LST areas mostly and were in the middle and southern parts. Therefore, the urbanization and thermal environment in the middle and southern parts need to be determined. Land surface temperature increased with the density of urban built-up and barren land, but decreased with vegetation cover. The relationship between MNDWI and LST was found to be negative, which implied that pure water would decrease the surface temperature and the polluted water would increase the surface temperature. A multiple regression between LST and each indices as well as the elevation was created to elevate the urban thermal environment, which showed that NDVI, NDBI, NDBaI, MNDWI were effective indicators for quantifying LULC impacts on LST.     

基于遥感专题解译的白洋淀湿地底部DEM构建

基于多时相Landsat遥感影像,利用适合白洋淀湿地信息提取的综合提取方法提取湿地范围。将湿地范围视为水体淹没区,淹没区的边界线视为对应地表水位高程的等高线,并根据遥感影像、高程控制点等对淀区内受人为影响的局部区域进行校正,插值生成白洋淀湿地底部的数字高程模型(DEM)。选用遥感影像和地面高程控制点对构建的数字高程模型进行验证,遥感影像验证精度在80%以上,地面控制点验证误差在±0.5 m以内的点达到80%。这种由一系列遥感影像提取等高线生成数字高程模型的方法可以弥补白洋淀湿地内数字高程信息不足的缺陷,对于提高白洋淀湿地的水均衡计算和构建湖泊与地下水耦合模型的精度有着重要意义。     

ERA-Interim地表温度数据集在青藏高原冻土分布制图应用的适用性评估

地表温度综合反映了大气、植被和土壤等因素的能量交换状况, 是冻土分布模型和一些寒区陆面过程模式的上边界条件, 对多年冻土分布制图和活动层厚度估算有重要意义. 为了评估ERA-Interim 地表温度产品在青藏高原地区的适用性, 综合比较了青藏高原69个海拔2 000 m以上气象站1981-2013年地面实际观测值与ERA-Interim之间的差异及其分布状况. 结果表明, 两种资料的变化趋势一致, 但是ERA-Interim地表温度在数值上与实际观测值差别显著, 平均偏低7.4℃. 原因之一可能是由ERA-Interim再分析资料格点的海拔高度与气象站实际海拔高度差异引起的. 根据两种温度产品之间海拔的差异, 对ERA-Interim地表温度重新进行模拟, 经过模拟后的ERA-Interim地表温度与实际观测值的差值在大部分气象站变小, 平均偏高0.4℃. 因此, 经过重新模拟的ERA-Interim地表温度基本能够反映青藏高原地表温度的真实情况. 以模拟后的ERA-Interim地表温度作为地面冻结数模型的输入参数模拟了青藏高原冻土分布, 结果表明青藏高原多年冻土区面积为1.14×10⁶ km², 季节冻土区面积为1.43×10⁶km².     

城市不透水面与地表温度定量关系的遥感分析

作为城市下垫面的最主要组成部分,城市不透水面是引发城市热岛效应的主要因素,但目前不透水面与地表温度之间的定量关系仍不明确,不同研究的结论也不尽相同。选取了上海、广州、北京、长沙、兰州、福州等6个代表我国不同区域的城市作为研究区来进一步研究城市不透水面与城市热环境的定量关系。采用Landsat ETM+影像和线性光谱混合分析法提取出各个研究区的不透水面,利用热红外波段反演出各研究区的地表温度,采用多种回归模型和大样本量对二者之间的相关关系进行定量分析;在此基础上讨论了不透水面对城市热环境的影响机制。结果表明：不透水面与地表温度呈明显的正相关关系,并且以指数函数为最佳拟合模型,回归方程的相关系数均为0.750以上,最高可达0.954 1;高不透水面盖度地区的升温幅度更大,比低不透水面盖度地区高出0.600~1.700 ℃,其原因主要是高不透水面盖度地区的植被覆盖率低,蒸腾蒸发作用小。     

利用光学卫星遥感数据监测抚顺地区煤矿开采引起的地貌变化

抚顺市是中国重要的采煤城市之一,100多年的煤矿开采已经使抚顺地区的地貌特征发生了重大变化。由于长期的露天开采,抚顺西露天矿形成了一个海拔约为-300m的深坑;煤矿的地下开采造成了大面积的地表沉陷;与此同时,煤矸石的露天堆积形成了3个排土场。本研究利用多时相的美国Landsat MSS（Multispectral Scanner）,TM（Thematic Mapper）,ETM⁺（Enhanced Thematic Mapper Plus）,以及日本ASTER（Advanced Spaceborne Thermal Emission and Reflection Radiometer）卫星遥感数据分析过去近30年来抚顺地区煤矿开采所引起的地貌变化。多时相卫星遥感图像的对比分析显示,由于地面沉陷引起的地表积水面积在近5年（2001～2006年）内出现明显增大的趋势,增加了1.73km。同期的ASTER DEM数据对比分析还发现,西露天矿的开采深度在不断增加,最大增加量为55m,与此同时出现的新增排土场造成地面高程增加量最大为25m。这一研究表明利用遥感技术可以定量监测人类矿产开发活动所引起的地貌特征变化及其过程。     

http://www.sciencedirect.com/science/article/pii/S1674987115001280

The East African Rift system(EARS)provides a unique system with the juxtaposition of two contrasting yet simultaneously formed rift branches,the eastern,magma-rich,and the western,magma-poor,on either sides of the old thick Tanzanian craton embedded in a younger lithosphere.Data on the pre-rift,syn-rift and post-rift far-field volcanic and tectonic activity show that the EARS formed in the context of the interaction between a deep mantle plume and a horizontally and vertically heterogeneous lithosphere under far-field tectonic extension.We bring quantitative insights into this evolution by implementing high-resolution 3D thermo-mechanical numerical deformation models of a lithosphere of realistic rheology.The models focus on the central part of the EARS.We explore scenarios of plumelithosphere interaction with plumes of various size and initial position rising beneath a tectonically pre-stretched lithosphere.We test the impact of the inherited rheological discontinuities(suture zones)along the craton borders,of the rheological structure,of lithosphere plate thickness variations,and of physical and mechanical contrasts between the craton and the embedding lithosphere.Our experiments indicate that the ascending plume material is deflected by the cratonic keel and preferentially channeled along one of its sides,leading to the formation of a large rift zone along the eastern side of the craton,with significant magmatic activity and substantial melt amount derived from the mantle plume material.We show that the observed asymmetry of the central EARS,with coeval amagmatic(western)and magmatic(eastern)branches,can be explained by the splitting of warm material rising from a broad plume head whose initial position is slightly shifted to the eastern side of the craton.In that case,neither a mechanical weakness of the contact between the craton and the embedding lithosphere nor the presence of second plume are required to produce simulations that match observations.This result reconciles the passive and active rift models and demonstrates the possibility of development of both magmatic and amagmatic rifts in identical geotectonic environments.     

基于被动微波的寒旱区地表温度反演

以各频段水平极化和垂直极化发射率问的相关关系为条件,利用被动微波数据反演地表温度.算法既解决了地表温度反演过程中发射率难以确定的问题,又克服了热红外遥感受大气影响较大的缺点,其物理意义清晰,计算简便.算法以MODIS温度产品为评价标准,对36.5GHz和89 GHz反演结果进行分析.结果表明:89 GHz亮温数据反演精度高于36.5 GHz;与耕地和草场反演精度相比,裸土和山地反演精度较高.其原因在于高频数据穿透能力较低,能更好地表达地表温度.同时,低频数据相对高频更容易受到地表土壤水分变化的影响,发射率相对不够稳定,对反演结果有一定影响.     

A new approach of combining aerial photography with satellite imagery for landslide detection

Subsequent rainfall after a strong earthquake can easily trigger landslides. Aerial photography is always available after a strong earthquake but not always available in a timely manner after a subsequent rainfall following the earthquake. Sometimes, only panchromatic imagery is available because of its relatively low cost and large cover capacity. To detect multi-temporal landslides induced by earthquake and its post long-term effect, in company of other factors such as subsequent rainfall, traditionally, it needs to carry out image classification multi-times to calculate the variance information. Therefore, the accuracy will be affected by accumulated errors from multi-classification, and the process is very time-consuming. In this paper, a new semi-automatic approach combing aerial photograph with satellite imagery was proposed for rapid mapping of multi-temporal landslides. The approach can enhance the change information of each landslide event in one detection process. In addition, slope units were introduced to separate the detected conjoint landslides. Chenjiaba area, which located in the highest seismic intensity zone of Wenchuan earthquake in Beichuan, China, and had a strong rainfall 4 months later, was selected as a case study to demonstrate the usefulness of this methodology. Accuracy assessment was carried out by comparing those extracted ones with a manually prepared landslide inventory map. Correctly detected were 90.1 and 94.2 % for earthquake-induced landslides and new landslides, respectively. Results show that this approach is capable of mapping different temporal landslides efficiently and quickly.     

用于地表温度场与断裂构造关系分析的分段均值法——以江山 绍兴断裂金衢段为例

提出了一种用于地表温度场与断裂构造关系分析的分段均值法。方法以已知断裂带中心线为准,向两侧一定范围作等间距划分,统计各等分带内的平均地表温度和平均距离,通过绘制平均地表温度与平均距离之间的相关性曲线来描述地表温度场与断裂构造之间的关系。在江山绍兴断裂金衢段的实际应用中,方法以Landsat 7 ETM+热红外遥感影像为数据源,描述了研究区地表温度场与深大断裂带之间的关系。认为地表温度场与北东走向的江山绍兴断裂带、常山漓渚断裂带和球川萧山断裂带的相关性明显,区域特征稳定。在各断裂带影响范围内,距离断裂带越近,地表温度越高;北西走向的淳安温州断裂带和东西走向的衢州天台断裂带均处于地表温度梯度变化带,断裂带两侧可能分属不同的地表温度场。     

The East African Rift System and the impact of orographic changes on regional climate and the resulting aridification

Several proxy data indicate an aridification of the East African climate during the Neogene, which might be influenced by the orographic changes of the East African Rift System (EARS) induced by tectonic forcing during the last 20 million years. To investigate the impact of the orography and especially of the rifts, the regional climate model CCLM is used, covering the EARS with Lake Victoria in the centre of the model domain. CCLM is driven by the ERA-Interim reanalysis and applied with a double-nesting method resulting in a very high spatial resolution of 7 km. The resolution clearly shows the shoulders and rifts of the western and eastern branch of the EARS and the Rwenzoris within the western branch. To analyse the orographic influence on climate, a new technique of modifying the orography is used in this sensitivity study. The shoulders of the branches are lowered and the rifts are elevated, resulting in a smoothed orography structure with less altitude difference between the shoulders and rifts. The changes in 2 m-temperature are very local and associated with the changes in the orography. The vertically integrated moisture transport is characterised by less vortices, and its zonal component is increased over the branches. The resulting amount of precipitation is mainly decreased west of the western branch and increased in the rift of the western branch. In the eastern branch, however, the changes in the amount of precipitation are not significant. The changes in the precipitation and temperature patterns lead to a shift of biomes towards a vegetation coverage characterised by more humid conditions in the northern part of the model domain and more arid conditions in the South. Thus, the aridification found in the proxy data can be attributed to the orographic changes of the rifts only in the northern model domain.     

MODIS地表温度产品在青藏高原连续多年冻土区的适用性分析

利用自动气象站观测的长波辐射计算得到的地表温度对MODIS地表温度(LST)产品在青藏高原中部连续多年冻土区的精度进行验证, 并利用具有较高空间分辨率的Landsat 5 TM和Landsat 7 ETM+反演的地表温度与MODIS LST产品进行了对比分析. 结果表明: 白天MODIS LST产品的平均绝对误差(MAE)和均方根误差(RMSE)分别约为3.42~4.41 ℃和4.41~5.29 ℃, 夜晚MODIS产品MAE和RMSE分别为2.15~2.90 ℃和3.05~3.78 ℃, 精度高于白天; MODIS LST与TM、ETM+反演的地表温度一致性较好, 相关系数分别达到0.85和0.95. 说明MODIS LST产品在连续多年冻土区的适用性较高, 是研究多年冻土地表热状况的一个非常好的数据源. 而且, 不同空间尺度的遥感数据之间一致性较好, 可考虑将多源遥感数据应用于多年冻土热状况监测研究.