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Snowfall and the subsequent evolution of the snowpack have a large effect on the surface energy balance and water cycle of the Tibetan Plateau (TP). The effects of snow cover can be represented by the WRF coupled with a land surface... more
Snowfall and the subsequent evolution of the snowpack have a large effect on the surface energy balance and water cycle of the Tibetan Plateau (TP). The effects of snow cover can be represented by the WRF coupled with a land surface scheme. The widely used Noah scheme is computationally efficient, but its poor representation of albedo needs considerable improvement. In this study, an improved albedo scheme is developed using a satellite-retrieved albedo that takes snow depth and age into account. Numerical experiments were then conducted to simulate a severe snow event in March 2017. The performance of the coupled WRF/Noah model, which implemented the improved albedo scheme, is compared against the model’s performance using the default Noah albedo scheme and against the coupled WRF/CLM that applied CLM albedo scheme. When the improved albedo scheme is implemented, the albedo overestimation in the southeastern TP is reduced, reducing the RMSE of the air temperature by 0.7°C. The improved albedo scheme also attains the highest correlation between the satellite-derived and the model-estimated albedo, which provides for a realistic representation of both the snow water equivalent (SWE) spatial distribution in the heavy snowbelt (SWE > 6 mm) and the maximum SWE in the eastern TP. The underestimated albedo in the coupled WRF/CLM leads to underestimating the regional maximum SWE and a consequent failure to estimate SWE in the heavy snowbelt accurately. Our study demonstrates the feasibility of improving the Noah albedo scheme and provides a theoretical reference for researchers aiming to improve albedo schemes further.
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Presents an operational algorithm for retrieving foliage and soil temperatures over mixed land surface pixels on the basis of the analysis of dual-angle and multichannel observations made by ATSR-2. First a physical model to retrieve... more
Presents an operational algorithm for retrieving foliage and soil temperatures over mixed land surface pixels on the basis of the analysis of dual-angle and multichannel observations made by ATSR-2. First a physical model to retrieve separately foliage and soil temperatures from two-angle measurements using the six channels of ATSR-2 is recalled briefly. Four visible, near-infrared and short wave infrared channels are used to determine the fraction cover of vegetation within a pixel, while the two thermal infrared channels are used to determine with the split window method the ground surface brightness temperatures at two view angles. Then an implementation of this method is given and several case studies are undertaken with ATSR-2 data, showing encouraging results of the two-component temperature retrieval
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The energy and water cycle over the Tibetan Plateau play an important role in the Asian Monsoon system, which in turn is a major component of both the energy and water cycles of the global climate system. The intensive observation and... more
The energy and water cycle over the Tibetan Plateau play an important role in the Asian Monsoon system, which in turn is a major component of both the energy and water cycles of the global climate system. The intensive observation and long term observation of the GEWEX (Global Energy and Water cycle Experiment) Asian Mon- soon Experiment on the Tibetan
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Mountain glaciers are one of the major fresh water resources. Glacier mass balance on the Tibetan Plateau (TP) can directly reflect local climate change and plays a crucial role in the terrestrial water cycle and food security of local... more
Mountain glaciers are one of the major fresh water resources. Glacier mass balance on the Tibetan Plateau (TP) can directly reflect local climate change and plays a crucial role in the terrestrial water cycle and food security of local people. In this study, we improved the procedure to analyze Three-Line-Array (TLA) stereo images to estimate the glaciers mass balance in Kangri Karpo mountains using Zi Yuan-3 (ZY-3) TLA data and C-band Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) in two periods, i.e. 2000–2013 and 2013–2017. The results showed that the mean mass balance of glaciers between 2000 and 2017 was −0.91 ± 0.02 m w.e. a−1. The glaciers presented accelerated mass loss in recent years (2013–2017, −2.84 ±0.05 m w.e. a−1), compared with the first decade in 21st (2000–2013, −1.59 ± 0.03 m w.e. a−1), while the melt rate in debris-covered glaciers was larger than in clean-ice glaciers.
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Various factors contribute to forest fire hazard, and among them vegetation moisture is the one that dictates susceptibility to fire ignition and propagation. The scientific community has developed a number of spectral indices based on... more
Various factors contribute to forest fire hazard, and among them vegetation moisture is the one that dictates susceptibility to fire ignition and propagation. The scientific community has developed a number of spectral indices based on remote sensing measurements in the optical domain for the assessment of vegetation equivalent water thickness (EWT), which is defined as the mass of liquid water per unit of leaf surface. However, fire models rely on the live fuel moisture content (LFMC) as a measure of vegetation moisture. LFMC is defined as the ratio of the mass of the liquid water in a fresh leaf over the mass of oven dry leaf, and spectral indices proposed so far fail in capturing LFMC variability. Recently, the perpendicular moisture index (PMI), based on MODIS, was pro-posed to overcome this limitation and provide a direct measure of LFMC. The aim of this research was to understand the potential and limitations of the PMI in predicting fire hazard, towards its ap-plication in a practical context. To this purpose, a data set of more than 7,700 fires recorded in Campania (13,595 km2), Italy, between 2000 and 2008 was compared with PMI derived from MODIS images. Results show that there is no relationship between PMI and fire size, whereas a linear correlation was found between the spectral index and fire rate of spread.
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Within the Dutch national remote sensing programme, a remote sensing algorithm (SEBAL) was developed to map heat fluxes for heterogeneous land surfaces for the Earth Observation System - Climate Hydrology project. A set of tools has been... more
Within the Dutch national remote sensing programme, a remote sensing algorithm (SEBAL) was developed to map heat fluxes for heterogeneous land surfaces for the Earth Observation System - Climate Hydrology project. A set of tools has been created for processing currently ...
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Research Interests: Environmental Science, Geology, Multidisciplinary, Seasonality, Case Study, and 12 moreHeat Flux, Seasonal variation, IS success, Tibetan Plateau, Soil Heat Flux, Thematic mapper, Geophysical, Sensible Heat Flux, Normalized Difference Vegetation Index, surface temperature, Latent Heat, and Latent Heat Flux
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Drought hazards induced by continuous water shortage may damage crop growth and cause severe grain loss. With one of the most intensive irrigation systems, the Indus basin has supported agriculture for millennia and feeds up more than 300... more
Drought hazards induced by continuous water shortage may damage crop growth and cause severe grain loss. With one of the most intensive irrigation systems, the Indus basin has supported agriculture for millennia and feeds up more than 300 million people. The water supply for the basin scale irrigation is dominated by melting of glaciers and snowpack in the Himalaya and Karakoram mountain ranges, ground water as well as the Asian monsoon rainfall. To understand how ecosystems over the Indus basin with such complex water supply mechanism response to meteorological drought (rainfall shortage) is critical for future drought monitoring and evaluation applications. This study evaluated the spatiotemporal response pattern using correlation analysis of rainfall anomalies (3-month scale) and vegetation anomalies (1-month scale) with long-term satellite observations. The result found that the vegetation over northern Indus valley significantly coupled to rainfall variation during both summer (Kharif) and winter (Rabi) monsoon season. While significant response during Kharif season also was identified over the southern part, especially over the Punjab, where was well equipped with irrigation system. We concluded that special attention should be paid to drought assessment in terms of rainfall and vegetation anomaly over the Indus basin.
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A method for separating bare soil and foliage component temperatures in a pixel is presented which exploits the ATSR-2 multispectral and dual angle view capability. In this study, we develop first a method using visible and near infrared... more
A method for separating bare soil and foliage component temperatures in a pixel is presented which exploits the ATSR-2 multispectral and dual angle view capability. In this study, we develop first a method using visible and near infrared channel data at two-angle views to perform atmospheric corrections in these channels allowing simultaneous retrieval of aerosol opacity and land surface bidirectional reflectance. Then, on the basis of the radiative transfer theory in a canopy, we develop a model to retrieve separately soil and vegetation temperatures from two-angle measurements using all channels of ATSR-2. The visible and near-infrared channels are used to determine the fraction cover of vegetation within a pixel. While the two thermal infrared channel data are employed to determine with split window technique the ground surface brightness temperatures at two view angles. Several case studies are undertaken with ATSR-2 data, the results indicate that both vegetation and soil temperatures can be retrieved with acceptable uncertainty from multi-directional brightness temperatures if the description of the nature and content of the pixel is appropriate.
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The monthly nighttime light data observed by the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor onboard the National Polar-orbiting Partnership (NPP) satellite are useful to assess human activities. However, noise in the VIIRS... more
The monthly nighttime light data observed by the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor onboard the National Polar-orbiting Partnership (NPP) satellite are useful to assess human activities. However, noise in the VIIRS data and unstable power supply in many areas often limit its application in detecting anthropic activities. This study aims to develop a new method (i.e., Patches Denoising Method, PDM) to remove noise in the VIIRS monthly nighttime light data towards better information on anthropic activities. The new synthesized data were examined in the Sahel region where the intensity of nighttime light is often affected by unstable power supply. The results showed that the new data could capture more settlements correctly compared with the annual data released by the National Centers for Environmental Information (NCEI) of the National Oceanic and Atmospheric Administration (NOAA). This suggests that the Patches De-noising Method is a useful way to remove noise in the NPP-VIIRS monthly nighttime light data.
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ABSTRACT The objective of this project is to develop a quantitative and operational system for nationwide drought monitoring and drought impact assessment for application in agriculture, water resources and environmental management in... more
ABSTRACT The objective of this project is to develop a quantitative and operational system for nationwide drought monitoring and drought impact assessment for application in agriculture, water resources and environmental management in China using ESA, Chinese and other relevant satellite data as major data source in combination with other data source (e.g. meteorological and drought statistics, etc.). An extension to drought prediction and adaptation to climate change will be made compared to the Dragon I drought monitoring project. In detail the project aims to generate: (1) a real time drought monitoring and prediction system, (2) improved understanding of land surface processes and land-atmosphere interactions over different terrains (e.g. agriculture land, forest, Gobi desert, high plateau, polar environment), (3) improved algorithms for estimation of land surface parameters and heat fluxes, (4) assessment of economic loss caused by drought and adaptation measures under climatic change, (5) training of young scientists in the area of water, climate and environment. In this contribution, progresses in retrievals of soil moisture using data from different methods are addressed, including in-situ observations, direct retrievals using data from satellite sensors and numerical modeling. The used sensors include ASAR, ASCAT, and AMSR-E. The accuracy of available soil moisture products are assessed using in-situ data collected by the Tibetan Plateau soil moisture monitoring network developed for this and other projects.
There is a wide set of digital images, where the problem of detecting specific structures is filtering between multiple and complex lines and secondary elements. The real problem is extracting relevant information from images, discarding... more
There is a wide set of digital images, where the problem of detecting specific structures is filtering between multiple and complex lines and secondary elements. The real problem is extracting relevant information from images, discarding uninteresting information previously, during and after the segmentation process. In this work, we resume the advantages and disadvantages of each approach, concluding a basic preference of filtering as soon as possible. In this sense, we present a method of filtering during segmentation, which mixes the mobile windows and the seeded regions approaches. Main steps are: 1) The whole image is divided in windows with a size related with the searched structures; 2) Previous knowledge about the location of the searched elements is applied to reduce the number of windows; 3) The number of windows is reduced using distribution and compacity conditions; 4) The population of each work windows is analyzed to fix one threshold; 5) Filtered work pairs are segmented using simple two populations criteria; 6) Analyzing the detected segments, the list of work window-threshold pairs is extended to include new windows. Most relevant result is the definition of a new border based segmentation approach, which gives good results searching specific objects in complex images.
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Research Interests: Environmental Engineering, Civil Engineering, Environmental Science, Geology, Water resources, and 13 moreLiDAR, Applied Economics, Standard Deviation, Evapotranspiration, Watershed, High Resolution, Wavelength, Scale Effect, Penetration Depth, Instruments and Techniques, Surface Finish, Altimeter, and roughness length
In order to detect coherent structures on satellite images, the authors used an extended set of segmentation algorithms. Applying this set to a group of test images, a collection of segmented images was obtained, where different methods... more
In order to detect coherent structures on satellite images, the authors used an extended set of segmentation algorithms. Applying this set to a group of test images, a collection of segmented images was obtained, where different methods highlighted different structures. Due to the diversity of valid solutions, it was necessary to evaluate the adequacy of the different options for specific
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The rainfall-runoff process consists of an excess rainfall process and a runoff concentration process. A transient one-dimen-sional finite difference model describing the partitioning of precipitation between surface runoff, soil moisture... more
The rainfall-runoff process consists of an excess rainfall process and a runoff concentration process. A transient one-dimen-sional finite difference model describing the partitioning of precipitation between surface runoff, soil moisture storage and deep percolation, through the coupling ...
Research Interests: Environmental Engineering, Civil Engineering, Environmental Science, Soil moisture, Outflow, and 15 moreArid Zone, Arid Region, Precipitation, Thematic mapper, Finite Difference, Arid, Runoff Curve Number, Vegetation Cover, Rainfall Runoff Modelling, HYDROGRAPH, Geographic Information System, Hydrological Processes, Unsaturated Zone, Hydrological, and Surface Runoff
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The arid zones of Argentina and India have been compared. In both regions run-off is often generated by the Hortonian infiltration surplus overland flow, and run-off response to precipitation input tends to be rapid. The sediment... more
The arid zones of Argentina and India have been compared. In both regions run-off is often generated by the Hortonian infiltration surplus overland flow, and run-off response to precipitation input tends to be rapid. The sediment transport is governedby the transport capacity of run-off rather than by the availability of erodible material. The magnitude of hydrological processes is different in response to the different rainfall regimes.
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Research Interests: Environmental Science, Remote Sensing, Research evaluation, Surface Roughness, Flow, and 15 moreEcosystems, Drag, Remote, Geomatic Engineering, New Mexico, Agricultural Research, High Resolution, Roughness, Numerical Model, Complex terrain, Boundary Layer, Parameters, Fluxes, Surface Finish, and Altimeter
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We applied a measure of foliar phenology to interpolate climate statistics and produce a bioclimate classification for a vast plain in Argentina, with sparse weather observations. As a measure of foliar phenology, we used parameters... more
We applied a measure of foliar phenology to interpolate climate statistics and produce a bioclimate classification for a vast plain in Argentina, with sparse weather observations. As a measure of foliar phenology, we used parameters obtained by modelling NDVI time series with a Fast Fourier Transform (FFT) applied to a 9-year time series of NOAA-AVHRR NDVI GAC images. FFT decomposes the series into an average signal and two sinusoidal components. Selected FFT parameters were mean NDVI, amplitude and phase for a 1-year period. Climate data were annual rainfall (P) and mean temperature (T) expressed as Potential Evapotranspiration (PET) estimated by an empirical equation (PET= 68.64 T). P/PET ratio was related to FFT parameters by fitting a multiple linear regression model with P/PET as predicted variable and FFT parameters as predictive variables. The regression model, that explained 92% of the P/PET variation, was then applied to the entire selected images (parameters) to obtain a m...
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This cooperation between the Italian Space Agency (ASI) and the Canadian Space Agency (CSA), in the field of Earth Observation resulted a program for the Joint Definition Phase (JDP) of a Joint Hyperspectral Mission. The aim of this... more
This cooperation between the Italian Space Agency (ASI) and the Canadian Space Agency (CSA), in the field of Earth Observation resulted a program for the Joint Definition Phase (JDP) of a Joint Hyperspectral Mission. The aim of this phase, which started in September 2006, is to share the Italian and Canadian hyperspectral missions heritage (HERO, HypSEO, MITHRIS and THEMA) to define the implementation of a Joint Mission providing VNIR/SWIR/MIR/TIR data for Earth observation applications. The conceptual design of the mission is based on the science and application mission objectives and on the high-level mission requirements. The result is a small satellite mission operating in low earth orbit for 5 years and carrying Hyperspectral, Panchromatic, Medium Infrared (MIR) and Thermal Infrared (TIR) payloads. This agile satellite will primarily operate in a targeting mode with a <7 days re-look period. The mission is to provide access to all of the Canadian territory and to an equivale...
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In order to detect coherent structures on satellite images, the authors used an extended set of segmentation algorithms. Applying this set to a group of test images, a collection of segmented images was obtained, where different methods... more
In order to detect coherent structures on satellite images, the authors used an extended set of segmentation algorithms. Applying this set to a group of test images, a collection of segmented images was obtained, where different methods highlighted different structures. Due to the diversity of valid solutions, it was necessary to evaluate the adequacy of the different options for specific
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Research Interests: Geography and Evaporation
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About 3% of the province consists of irrigated areas. The major crops are: vineyard 53%, fruit farming 17%, vegetables 11 %, fodder 8%, forest 6%, olives 3%, and others 2% (Estadisticas Agropecuarias de Mendoza 1988). The province has... more
About 3% of the province consists of irrigated areas. The major crops are: vineyard 53%, fruit farming 17%, vegetables 11 %, fodder 8%, forest 6%, olives 3%, and others 2% (Estadisticas Agropecuarias de Mendoza 1988). The province has about 9 O00 km of irrigation canals. Of these, 500 km of primary and secondary canals are concrete-lined; the others are earth-lined.
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La factibilidad de obtener productos agrícolas de calidad, irrigados con agua salina, hace necesario evaluar áreas periféricas al oasis irrigado para determinar su aptitud para el cultivo. El objetivo es articular diversas metodologías... more
La factibilidad de obtener productos agrícolas de calidad, irrigados con agua salina, hace necesario evaluar áreas periféricas al oasis irrigado para determinar su aptitud para el cultivo. El objetivo es articular diversas metodologías para cartografiar y evaluar unidades ecológicamente homogéneas en tierras marginales de Mendoza utilizando las comunidades vegetales como indicador. Se relevó un área piloto mediante procesamiento de imagen LANDSAT/TM y se analizó la vegetación, suelo y freática. Las unidades evaluadas y sus respectivos rangos de salinidad, en dS m-1, hasta 50 cm fueron: estepa de Heterostachys ritteriana, 91-83; matorral de Allenrolfea vaginata con H. ritteriana, 83-48; matorral abierto de A.vaginata con Prosopis strombulifera, 62-55; estepa abierta de Suaeda divaricata con Atriplex argentina, 52-83; matorral de S. divaricata con Lycium tenuispinosum, 40-43; bosquecillo abierto de Prosopis flexuosa, 37-26; matorral denso de Prosopis alpataco, 7-6. La concentración de...