ID: 58128
Title: Representing major soil varaibility at regional scale by constrained Latin hypercube sampling of remote sensing data
Author: V L Mulder, S de Bruin, M E Schaepman
Editor: F van der Meer
Year: 2013
Publisher: Elsevier, Vol 21, April 2013
Source: Centre for Ecological Sciences
Reference: None
Subject: International Journal of Applied Earth Observation and Geoinformation
Keywords: Sampling design, soil survey, Variogram analysis, ASTER
Abstract: This apper presents a sparse, remote sensing-based sampling approach making use of conditional Latin Hypercube Sampling (cLHS) to assess variability in soil properties at regional scale. The method optimizes the sampling scheme for a defined spatial population based on selected covariates, which are assumed to represent the variability of the target variables. The optimization also accounts for specifc constraints and cpsts expressing the field sampling effort. The approach is demonstrated using a case study in Morocco, where a small but representative sample record had to be collected over a 15,000 km2 area within 2 weeks. The covariate space of the Latin Hypercube consisted of the first three principal components of ASTER imagery as well as elevation. Comparison of soil properties taken from the topsoil with the existing soil map, a geological map and lithological data showed that the sampling approach was successful in representing major soil variability. The cLHS sample failed to express spatial correlation; constraining the LHS by a distance criterion favoured large spatial variability within a short distances resulting in an overestimationof the variograms nugget and short distance varaibility. However, the exhaustive covariate data appeared to be spatially correlated which supports our premise that once the relation between spatially explicit remote sensing data and soil properties has been modelled, the latter can be spatially predicted based on the densely samled remotely sensed data. Therefore, the LHS approach is considered as time and cost efficient for regional scale surveys that rely on remote sensing-based prediction of soil properties.
Location: TE12, New Biological Sciences, IISc
Literature cited 1: None
Literature cited 2: None
ID: 58127
Title: View-illumination effects on hyperspectral vegetation indices in the Amazonian tropical forest
Author: Lenio Soares Galvao, Fabio Marcelo Breunig, Joao Roberto dos Santos, Yhasmin Mendes de Moura
Editor: F van der Meer
Year: 2013
Publisher: Elsevier, Vol 21, April 2013
Source: Centre for Ecological Sciences
Reference: None
Subject: International Journal of Applied Earth Observation and Geoinformation
Keywords: Hyperspectral remote sensing, Hyperion, vegetation indices, PROSAIL, Tropical forst, view angle, directional effects, dry season
Abstract: Because of the pointing capability of the Hyperion/Earth Observing -One (EO-1) to improve the revisit time of the scene, temporal series of narrowband vegetation indices (VIs) can be generated to study the phenology of the Amazonian tropical forests. In this study, 10 selected narrowband VIs calculated from yperion nadir and off-nadir data and from different view directions (forward scattering and backscattering) were anlayzed for their sensitivity to view-illumination effects along the dry season on the Seasonal Semi-deciduous Forest. Data analysis was also supported by PROSAIL modeling to simualte the spectral response of this forest type in both directions. Hyperion and PROSAIL results showed that the Enhanced Vegetation Index (EVI) and Photochemical Reflectance Index (PRI) were the two more anisotropic VIs, whereas the Normalized Difference Vegetation Index (NDVI), Structure Insensitive Pigment Index (SIPI) and the Vogelmann Red Edge Index (VOG) were comparatively less sensitive to view-illumination effects. When compared to the other VIs and because of the greater dependence on the near-infrared (NIR) reflectance, EVI showed a different spectral behavior. EVI increased from forward scattering to backscattering and with decreasing solar zenith angle (SZA) towards the end of the local dry season, due to reduction in shading and enhancement of the illumination effects. On the other hand, PRI was higher with increasing shading in the forward scattering direction, as deduced from the PROSAIL simulation. Results emphasized the importance of taking itno account bidirectional effects when analyzing temporal series of VIs collected over tropical forests by imaging spectrometers with pointing capability or even by multispectral sensors with large field -of-view (FOV).
Location: TE12, New Biological Sciences, IISc
Literature cited 1: None
Literature cited 2: None
ID: 58126
Title: Estimating salinity stress in sugarcane fields with spaceborne hyperspectral vegetation indices
Author: S Hamzeh, A A Naseri, S K AlaviPanah, B Mojaradi, H M Bartholomeus, J G P W Clevers, M Behzad
Editor: F van der Meer
Year: 2013
Publisher: Elsevier, Vol 21, April 2013
Source: Centre for Ecological Sciences
Reference: None
Subject: International Journal of Applied Earth Observation and Geoinformation
Keywords: Salinity stress, vegetation indices, hyperion, hyperspectal, sugarcane
Abstract: The presence of salt in the soil profile negatively affects the growth and development of vegetation. As a result, the spectral reflectance of vegetation canopies varied for different salinity levels. This research was conducted to (1) investigate the capability of satellite-based hyperspectral vegetation indices (VIs) for estimating soil salinity in agricultural fields, (2) evaluate the performance of 21 existing VIs and (3) develo new VIs based on a combination of wavelengths sensitive for multipel stresses and find the best one for estimating soil salinity. For this prupose a Hyperion image of September 2, 2010, and data on soil salinity at 108 locations in sugarcan (Saccharum officina L) fields were used. Results show that soil salinity could well be estimated by some of these VIs. Indices related to chlorophyll absorption bands or based on a combination of chlorophyll and water absorption bands had the highest correlation with soil salinity. In contrast, indices that are only based on water absorption bands had low to medium correlations, while indices that use only visible bands did not perform well. From the investigated indices the optimized soil-adjusted vegetation index (OSAVI) had the strongest relationship (R2 = 0.69) with soil salinity for the training data, but it did not perform well in the validation phase. The validation procedure showed that the new salinity and water stress indices (SWSI) implemented in this study (SWSI-1, SWSI-2, SWSI-3) and the Vogelmann red edge index yielded the best results for estimating soil salinity for independent fields with root mean square errors of 1.14, 1.15, 1.17 and 1.15 dS/m, respectively. Our results show that soil salinity could be estimated by satellite-based hyperspectral VIs, but validation of obtained models for independent data is essential for selecting the best model.
Location: TE12, New Biological Sciences, IISc
Literature cited 1: None
Literature cited 2: None
ID: 58125
Title: Estimation of discharges at river mouth with MODIS image
Author: Kohei Hashimoto, Kazuo Oki
Editor: F van der Meer
Year: 2013
Publisher: Elsevier, Vol 21, April 2013
Source: Centre for Ecological Sciences
Reference: None
Subject: International Journal of Applied Earth Observation and Geoinformation
Keywords: Remote sensing, suspended sediment concentration, coastal area
Abstract: The transport of the sediment, carried in suspension by water, is central to hydrology and the ecological functioning of river floodplains and deltas. River dishcarge estimation is useful for demonstrating this information. In this study, we extracted MODIS reflectance values from a pixel near the river mouth after carrying out the simple atmospheric correction method, then applied single regression analysis to reflectance values and the in situ discharge of Naka River in Tokushima prefecture and Monobe River in Kochi prefecture, Japan. MODIS images and in situ data were taken from January through December , 2004. As a result, both in Naka River and Monobe River, robustly positive relationships between the discharges observed in situ and remotely sensed MODIS refectance data in the region of river mouth were found throughout the year. In addition, we estimated monthly and annual average discharge from the MODIS reflectance with the regression formula. As a result, in situ average discharge was well estimated.
Location: TE12, New Biological Sciences, IISc
Literature cited 1: None
Literature cited 2: None
ID: 58124
Title: Integration of logistic regression, Markov chain and cellular automata models to simulate urban expansion
Author: jamal Jokar Arsanjani, Marco Helbich, Wolfgang Kainz, Ali Darvishi Boloorani
Editor: F van der Meer
Year: 2013
Publisher: Elsevier, Vol 21, April 2013
Source: Centre for Ecological Sciences
Reference: None
Subject: International Journal of Applied Earth Observation and Geoinformation
Keywords: Land use change, Logistic regression, Markov chain, cellular automata, Tehran
Abstract: This research analyses the suburban expansion in the metropolitan area of Tehran, Iran. A hybrid model consisting of logistic regression model, Markov chain (MC), and cellular automata (CA) was designed to improve the peformance of the standard logistic regression model. Environmental and socio-economic variables dealing with urban sprawl were operationalised to create a probability surface of sptiotemporal states of built-up land use for the years 2006, 2016, and 2016. For validation, the model was evaluated by means of relative operating characteristic values for different sets of varibles. The approach was calibrated for 2006 by cross comparing of actual and simulated land use maps. The achieved outcomes represent a much of 89% between simulated adn actual mpas of 2006, which was satisfactory to approve the calibration process. Thereafter, the calibrated hybrid approach was implemented for forthcoming years. Finally, future land use maps for 2016 and 2026 were predicted by means of this hybrid approach. The simulated maps illustrate a new wave of suburban development in the vicinity of Tehran at the western border of the metropolits during the next decades.
Location: TE12, New Biological Sciences, IISc
Literature cited 1: None
Literature cited 2: None
ID: 58123
Title: Using advanced InSAR time series techniques to monitor landslide movements in Badong of the three Gorges region,China
Author: Peng Liu, Zhenhong Li, Trevor Hoey, Cem Kincal, Jingfa Zhang, Qiming Zeng, Jan-Peter Muller
Editor: F van der Meer
Year: 2013
Publisher: Elsevier, Vol 21, April 2013
Source: Centre for Ecological Sciences
Reference: None
Subject: International Journal of Applied Earth Observation and Geoinformation
Keywords: landslide, three Gorges, InSAR, Small baseline InSAR, time series
Abstract: The Three Gorges occupy 193 km of the middle reaches of teh Yangtze River between Fengjie in Chongqing and Yichang in Hubei Province, China. Due to steep valley-side slopes and long-term river incision, landslides are a major hazard in the Three Gorges region. In this study, we employ the SBAS InSAR technique to process Envisat SAR images collected between 2003 and 2010. Our time series results enable identification of two distinct landslides with deformation rates of up to 10-15 mm/yr in Badong Country, and field evidence is used to verify the positions of these failures. With both descending and ascending observations, two-dimensional velocity fields in north and up directions are recovered to better understand the landslide movements. Obvious correlation between seasonal landslide movements and water level changes is observed, which not only provides strong support of our InSAR time series results, but also indicates the impacts of water level changes to landslide activities.
Location: TE12, New Biological Sciences, IISc
Literature cited 1: None
Literature cited 2: None
ID: 58122
Title: Comparative analysis of land use/cover change trajectories and their driving forces in two small watersheds in the western Loess plateau of China
Author: Dongchuan Wang, Jianhua Gong, Liding Chen, Lihui Zhang, Yiquan Song, Yujuan Yue
Editor: F van der Meer
Year: 2013
Publisher: Elsevier, Vol 21, April 2013
Source: Centre for Ecological Sciences
Reference: None
Subject: International Journal of Applied Earth Observation and Geoinformation
Keywords: Change trajectories, landuse/cover change, landscape metrics, relative land use suitability indes, comparative analysis
Abstract: To prevent soil loss and achieve better ecological environments, soil conservation measures have been taken during the past decades in the western Loess Plateau of China. In this paper, a case study was taken in Luoyu valley and Lver valley, two sub-watersheds of Xihe watershed adn comparison was carried out between them. The main object of this study is to monitor land use/cover changes in the two similar small watersheds utilizing SPOT5 imageries by object-oriented human-computer interactive classification method, further develop the method of spatio-temporal analysis of land use/cover change by using pattern metrics of change trajectories nad relative land use suitability index (R) in smaller watersheds, and make compaisons between the two similar small watersheds, taking water and soil conservation measures into consideration. Results show that combining GIS and RS, this method can be perfectly applied to make comparisons between different small watersheds with simialr geographical backgrounds. And land use/cover spatiotemporal dynamic change characteristics can be preferably expressed by pattern metrics of change trajectories and R values based on topographical data. Different emphases have been laid according to their own geological backgrounds in the two watersheds and human activities have different effects on the landscapes of the two watersheds. The main change pattern is from slope farmland to terrace (322, the largest in Luoyu valley) or to economic fruit forest (344, the largest in Lver valley). R value of every slope grade in both of the two watersheds drops with the rising of slope degree on the whole and it shows that there is still much to do for people in the two watersheds in consideration that all the R values aer still lower than 0.7.
Location: TE12, New Biological Sciences, IISc
Literature cited 1: None
Literature cited 2: None
ID: 58121
Title: Inter-comparison of satellite rainfall products for representing rainfall diurnal cycle over the Nile basin
Author: Alemseged Tamiru Haile, Emad Habib, Mohamed Elsaadani, Tom Rientjes
Editor: F van der Meer
Year: 2013
Publisher: Elsevier, Vol 21, April 2013
Source: Centre for Ecological Sciences
Reference: None
Subject: International Journal of Applied Earth Observation and Geoinformation
Keywords: CMORPH, TRMM-3B42, Satellite-rainfall validation, Rainfall diurnal cycle, Rainfall occurrence, Lake Victoria, Lake Tana, Nile
Abstract: In this study, the authors inter-compared the performance of three satellite-rainfall products in representing the diurnal cycle of rain occurrence and rain rate over the Nile basin in eastern Africa. These products are the real time (RT) and post-real-time (PRT) (bias adjusted) versions of Tropical Rainfall Measuring Mission (TRMM) and other sources product known as TRMM-3B42 and the National Oceanopgraphic and Atmospheric Administration climate Prediction Center (NOAA-CPC) product which is based on the CPC morphing technique (CMORPH). The rainfall diurnal cycles are re-produced using these products with specific focus on assessing effects of geographic location and topgraphic features. The perfromance of the satellite products in representing rainfall diurnal cycle shows large variation over the Nile basin. The products overestimate rain occurrence over the lakes, islands, and shores adn underestimate occurrence over mountain tops. Overall, CMORPH performs better than TRMM-3B42 RT and TRMM-3B42 PRT in capturing the diurnal cycle of rain rate in Lkae Tana basin. However, the difference between the two products is very small for Lake Victoria basin, where both products perform more favorably. Over most of the Nile basin areas, the use of fine versus coarse temporal and spatial resolution of the CMORPH product shwoed large differences for diurnal cycle of rain occurrence than that of rain rate. Results also show that the bias adjustment of TRMM-3B42 product does not necessaily bring imporvements probably since the adjustments are not performed based on local rain gauge data.
Location: TE12, New Biological Sciences, IISc
Literature cited 1: None
Literature cited 2: None
ID: 58120
Title: Assessing floristic composition with multispectral sensors-A compaison based on monotemporal and multiseasonal field spectra
Author: Hannes Feilhauer, Frank Thonfeld, Ulrike Faude, Kate S He, Duccio Rocchini, Sebastian Schmidtlein
Editor: F van der Meer
Year: 2013
Publisher: Elsevier, Vol 21, April 2013
Source: Centre for Ecological Sciences
Reference: None
Subject: International Journal of Applied Earth Observation and Geoinformation
Keywords: Conservation, Isometric Feature Mapping, Optical remote sensing, Partial Least Squares regression, Subclass information, vegetation
Abstract: Assessing and mapping patterns of (semi-) natural vegetation types at a large spatial scale is a difficult task. The challenge increases if the floristic variation within vegetation types (i.e., subtype variation of species composition) is the target. A desirable way to deal with this task may be to address such vegetation patterns with remote-sensing approaches. In particular data from multispectral sensors are easy to obtain, globally accessible, and often provide a high temporal resolution. They hence offer a comprehensive basis for vegetation mapping. The potential of such sensors for vegetation mapping has, however, never been thoroughly investigated. In particular, a systematic test regarding the spectral capabilities of these data for an assessment of detailed floristic variation has not been implemented to data. We thus addressed in this study the question how the ability of optical sensors to map floristic variation is affected by their respective spectral coverage and number of bands. To answer this question, we simulated monotemporal and multiseasonal data of eleven multispectral sensors. These data were used to model gradual transitions in species composition (i.e., floristic gradients) within three types of spontaneous vegetation typical for Central Europe using Partial Least Squares regression. Comparison of the model fits (raning up to R2 = 0.76 in cross-validation) illustrated the potential of multispectral data for detailed vegetation mapping. The results show that spectral coverage of the entire solar-reflective domain is the most important sensor characteristic for a successful assessment of floristic variation. Model and sensor performances as well as limitations are thoroughly discussed, and recommendations for sensor development are made based on the final conclusions of this study.
Location: TE12, New Biological Sciences, IISc
Literature cited 1: None
Literature cited 2: None
ID: 58119
Title: Evaluation of vertical accuracy of open source Digital Elevation Model (DEM)
Author: Sandip Mukherjee, P K Joshi, Samadrita Mukherjee, Aniruddha Ghosh, R D Garg, Anirban Mukhopadhyay
Editor: F van der Meer
Year: 2013
Publisher: Elsevier, Vol 21, April 2013
Source: Centre for Ecological Sciences
Reference: None
Subject: International Journal of Applied Earth Observation and Geoinformation
Keywords: DEM accuracy, Cartosat, SRTM, ASTER, Terrain morphology
Abstract: Digital Elevation Model (DEM) is a quantitative representation of terrain and is important for Earth Science and hydrological applications. DEM can be generated using photogrammetry, interferometry, ground and laser surveying and other techniques. Some of the DEMs such as ASTER, SRTM, and GTOPO 30 are freely available open source products. Each DEM contains intrinsic errors due to primary data acquisition technology and processing methodology in relation with a particular terrain and land cover type. The accuracy of these datasets is often unknown and is non-uniform within each dataset. In this study we evaluate open source DEMs (ASTER and SRTM) and their derived attributes using high postings Cartosat DEM and Survey of India (SOI) height information. It was found that representation of terrain characteristics is affected in the coarse postings DEM. The overall vertical accuracy shows RMS error of 12.62 m and 17.76 m for ASTER and SRTM DEM respectively, when compared with Cartosat DEM. The slope and drainage network delineation are also violated. The terrain morphology strongly influences the DEM accuracy. These results can be highly useful for researchers using such products in various modeling exercises.
Location: TE12, New Biological Sciences, IISc
Literature cited 1: None
Literature cited 2: None
ID: 58118
Title: Introducting sensor spectral response into the classification process
Author: Francisco Javier Mesas-Carrascosa, Isabel Luisa Castillejo-Gonzalez, Manuel Sanchez de la Orden, Alfonso Garcia-Ferrer Porras
Editor: F van der Meer
Year: 2013
Publisher: Elsevier, Vol 21, April 2013
Source: Centre for Ecological Sciences
Reference: None
Subject: International Journal of Applied Earth Observation and Geoinformation
Keywords: Overlapped spectral bands, ISODATA, minimum distance, spectral response function
Abstract: Many sensors have their bands overlapped and therefore do not set a normal space. If a spectral distance is measured, as in first-order statistical classifiers, the direct consequence is that the result will not be the most accurate. Image classification processes are independent of the spectral response function of the sensor, so this overlap is usually ignored during image processing. This paper presents a methodology that introduces teh spectral response function of sensors into the classification process to increase its accuracy. This process takes place in two steps: first, incident energy values of the sensors are reconstructed; second, the energy of the bands is set in an orthonormal space using a matrix singular value decomposition. Sensors with and withouit overlapping spectral bands were simulated to evaluate the reconstruction of energy values. The whole process was implemented on the types of images with medium, high and very high spatial resolution obtained with the sensors ASTER, IKONOS and DMC camera, respectively. These images were classified by ISODATA and minimum distance algorithms. The ISODATA classifier showed well-defined features in the processed images, while the results were less clear in the original images. At the same time, the minimum distance classifier showed that overall accuracy of the processed images increased as the maximum tolerance distance decreased compared to the original images.
Location: TE12, New Biological Sciences, IISc
Literature cited 1: None
Literature cited 2: None
ID: 58117
Title: Analysis of ASTER data for mapping bauxite rich pockets within high altitude lateritic bauxite, Jharkhand, India
Author: Arindam Guha, Vivek Kr Singh, Reshma Parveen, K Vinod Kumar, A T Jeyaseelan, E N Dhanamjaya Rao
Editor: F van der Meer
Year: 2013
Publisher: Elsevier, Vol 21, April 2013
Source: Centre for Ecological Sciences
Reference: None
Subject: International Journal of Applied Earth Observation and Geoinformation
Keywords: ASTER, Bauxite, Lateritic bauxite, Index based principal component, topography
Abstract: Bauxite deposits of Jharkhand in India are resulted from the lateritization process and therefore are often associated with the laterites. In the present study, ASTER (Advanced Space borne Thermal Emission and Reflection Radiometer) image is processed to delineate bauxite rich pockets within the laterites. In this regard, spectral signatures of lateritic bauxite samples are analyzed laboratory with reference to the spectral features of gibbsite (main mineral constituent of bauxite) and goethite (main mineral constituent of laterite ) in VNIR-SWIR (visible-near infrared and short wave infrared) electromagnetic domain. The analysis of spectral signature of lateritic bauxite samples helps in understanding the differences in the spectral features of bauxites and laterites. Based on these differences; ASTER data based relative band depth and simple ratio images are derived for spatial mapping of the bauxites developed within the lateritic province. In order to integrate the complementary information of different index image, an index based principal component (IPC) image is derived to incorporate the correlative information of these indices to delineate bauxite rich pockets. The occurrence of bauxite rich pockets derived from the major bauxite occurrences of the area are controlle by slope and altitude. In addition to above, IPC image is draped over the digital elevation model (DEM) to illustrate how bauxite rich pockets are distributed with reference to the topographic variability of the terrain. Bauxite rich pockets delineated in the IPC image are also validated based on the known mine occurrences and existing geological map of the bauxite. It is also conceptually validated based on the spectral similarity of the bauxite pixels delineated in the IPC image with the ASTER convolved laboratory spectral of bauxite samples.
Location: TE12, New Biological Sciences, IISc
Literature cited 1: None
Literature cited 2: None
ID: 58116
Title: Mapping small wetlands of Kenya and Tanzania using remote sensing techniques
Author: E Mwita, G Menz, S Misana, M Becker, D Kisanga, B Boehme
Editor: F van der Meer
Year: 2013
Publisher: Elsevier, Vol 21, April 2013
Source: Centre for Ecological Sciences
Reference: None
Subject: International Journal of Applied Earth Observation and Geoinformation
Keywords: Aerial photography, Floodplain, Inland valleys, Laikipia, Pangani
Abstract: Although wetlands in Tanzania and Kenya have great potentials for agricultural production and a multitude of uses, many of them are not even documented on official maps. Lack of official recognition has done little in preventing there over utilization. As the wetlands continue to play remarkable roles in the movement of people and terrestrial species in the region. It is important that they are monitored and properly managed. This study was undertaken in Usambara highlands and the Pangani floodplain in Tanzania, the Mount Kenya highlands and Laikipia floodplain in Kenya to map the different types of wetlands in terms of their size, density, spatial distribution and use patterns. Remote sensing techniques and field surveys were adopted, and 51 wetlands were identified in flood plains within the semi-arid and sub-humid lowlands, and inland valleys in the region. The detailed maps generated showed the intensity of wetland use, inland valleys being the most intensively used, and are useful in monitoring changes in wetlands for their effective management. The use of multispectral resolution imagery, combined with field survey and GIS produced satisfactory results for the delineation and mapping of small wetlands and their uses.
Location: TE12, New Biological Sciences, IISc
Literature cited 1: None
Literature cited 2: None
ID: 58115
Title: Using remote sensing energy balance and evapotranspiration to characterize montane landscape vegetation with focus on grass and pasture lands
Author: Isabel Pocas, Mario Cunha, Luis S Pereira, Richard G Allen
Editor: F van der Meer
Year: 2013
Publisher: Elsevier, Vol 21, April 2013
Source: Centre for Ecological Sciences
Reference: None
Subject: International Journal of Applied Earth Observation and Geoinformation
Keywords: Landsat, METRICtm, Irrigated meadows, Lameiros, Deciduous and evergreen forests, PCA
Abstract: Water and energy balance interactions with vegetation in mountainous terrain are influenced by topographic effects, spatial variation in vegetation type and density, and water availability. This is the case for the mountainous areas of northern Portugal, where ancestral irrigated meadows (lamerios) are a main component of a complex vegetation mosaic. The widely used surface energy balance model METRIC was applied to four Landsat images to determine the spatial and temporal distribution of the energy balance terms in the identified land cover types (LCT). A discussion on the variability of evapotranspiration (ET) through the various vegetation types was supported by a comparison between the respective crop coefficients and those available in the literature corresponding to the LCT, which has shown the appropriateness of METRIC estimates of ET. METRIC products derived from images of May and June- NDVI, surface temeprature, net radiation, soil heat flux, sensible heat flux, and ET - were used to characterize the LCTs, through application of principal component analysis. Three principal components explained the variance of observed variables and their varimax rotated loadings allowed a good explanation of that behaviour of the explanatory variables in association with the LCTs. Information grained contributes to improve the characterization of the study area and may further support conservation and management of these mountain landscapes.
Location: TE12, New Biological Sciences, IISc
Literature cited 1: None
Literature cited 2: None
ID: 58114
Title: A simple method to directly retreive reference evapotranspiration from geostationary satellite images
Author: C Cammalleri, G Ciraolo
Editor: F van der Meer
Year: 2013
Publisher: Elsevier, Vol 21, April 2013
Source: Centre for Ecological Sciences
Reference: None
Subject: International Journal of Applied Earth Observation and Geoinformation
Keywords: Reference evapotranspiration, MSG geostationary satellite, Mediterranean enviornment
Abstract: Application of FAO-56 methodology for the assessment of reference evapotranspiration, ET0, is challenging in areas of the world with sparse meteorological network stations. For this reason alternative procedures using remotely observed data have been proposed in the literature. In this work, a simplified version of the Makkink approach [J.Inst. Wat. Eng.11: 277-288, 1957] was tested in a typical Mediterranean environment (Sicily, Italy). The implemented Makkink approach (MAK) uses remotely estimated solar radiation derived from Meteosat Second Generation (MSG) satelliet data and in situ observations of air temperature to assess ET0 at daily time scale. Alternatively, taking advantage of well-defined relationships that exist between seasonality, elevation and air temperatue, a deterministic procedure for estimating air temperature inputs used in the MAK approach (named RS) was also tested. This approach allows the assessment of daily ET0 without the need of auxillary air temperature ground observations. A comparison between the FAO-56 and MAK approaches was performed for 45 sites in Sicily over the period 2007-2010. Assuming FA0-56 as the benchmark, the average accuracy of the MAK methodology was 0.4 mm d-1, with a relative error of 12%. Similar to other applications of the same procedure, the MAk approach showed a slightly underestimation of ET0 high values; however, an average regression slope of 0.96 (and negligibleintercept) suggests a satisfactory agreement with the FA0-56 modeled values. Air temperature observations acquired during 2002-2006 were used to calibrate the deterministic relation between air temperature, seasonality ( as a function of the DOY) and orography (as a function of elevation). For the period 2007-2010, the RS approach performs similarly to MAK, with an average difference of less than 0.05 mm d-1. Analysis of monthly, seasonal and yearly ET0 maps shows a slight decrease in RS performance during June and July; nevertheless, the differences between MAK and RS approaches are negligible at all analyzed temporal scales.
Location: TE12, New Biological Sciences, IISc
Literature cited 1: None
Literature cited 2: None