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Notarnicola C.,EURAC Institute for Applied Remote Sensing
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2013

This paper presents an approach to improve the capability to retrieve soil moisture information from SAR data. More in details the proposed approach consider different inversion approaches and outlines a procedure how to combine the results derived from these regressors with the main aim to improve the accuracy in the estimation of the target variables. The approach was tested in the case of fully polarimetric AirSAR images acquired over agricultural fields covered with soybean and corn crops. The single regressors were an empirical and a Bayesian approach. The approaches were applied to C and L band images and also to a combination of both frequencies. The results indicate that when the retrieved information from the regressors are properly combined based on the select figures of merit such as R2 and RMSE the accuracy can improve up to around 30%. © 2013 IEEE. Source


Allen S.K.,University of Zurich | Allen S.K.,University of Geneva | Rastner P.,University of Zurich | Rastner P.,EURAC Institute for Applied Remote Sensing | And 4 more authors.
Landslides | Year: 2015

Heavy rainfall in June 2013 triggered flash flooding and landslides throughout the Indian Himalayan state of Uttarakhand, killing more than 6000 people. The vast majority of fatalities and destruction resulted directly from a lake outburst and debris flow disaster originating from above the village of Kedarnath on June 16 and 17. Here, we provide a systematic analysis of the contributing factors leading to the Kedarnath disaster, both in terms of hydrometeorological triggering and topographic predisposition. Topographic characteristics of the lake watershed above Kedarnath are compared with other glacial lakes across the north-western Himalayan states of Uttarakhand and Himachal Pradesh, and implications for glacier lake outburst hazard assessment in a changing climate are discussed. Our analysis suggests that the early onset of heavy monsoon rainfall (390 mm, June 10–17) immediately following a 4-week period of unusually rapid snow cover depletion and elevated streamflow was the crucial hydrometeorological factor, resulting in slope saturation and significant run-off into the small seasonal glacial lake. Between mid-May and mid-June 2013, snow-covered area above Kedarnath decreased by around 50 %. The unusual situation of the lake being dammed in a steep, unstable paraglacial environment but fed entirely from snowmelt and rainfall within a fluvial dominated watershed is important in the context of this disaster. A simple scheme enabling large-scale recognition of such an unfavourable topographic setting is introduced. In view of projected 21st century changes in monsoon timing and heavy precipitation in South Asia, more emphasis should be given to potential hydrometeorological triggering of lake outburst and debris flow disasters in the Himalaya. © 2015 Springer-Verlag Berlin Heidelberg Source


Santi E.,CNR Institute of Applied Physics Nello Carrara | Paloscia S.,CNR Institute of Applied Physics Nello Carrara | Pettinato S.,CNR Institute of Applied Physics Nello Carrara | Notarnicola C.,EURAC Institute for Applied Remote Sensing | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

Three algorithms for the retrieval of soil moisture content (SMC) from MetOp-ASCAT acquisitions have been developed and compared. This activity has been carried out in the framework of the ASCAT Round Robin exercise that was supported by ESA as a part of the Climate Change Initiative Phase 1 Soil Moisture Project. The algorithms have been developed and tested using the ASCAT Round Robin data package (ASCAT - RRDP) that was distributed among the partners of the project for developing and validating the algorithms and that was composed by a selection of 150 test sites derived from the International Soil Moisture Network (ISMN) was used. The locations of the in situ soil moisture measurements used for the Round Robin represent a wide range of climate conditions, covering a wide variety of vegetation types and vegetation density classes. © 2013 SPIE. Source


Nagler T.,ENVEO IT GmbH | Rott H.,ENVEO IT GmbH | Rott H.,University of Innsbruck | Hetzenecker M.,ENVEO IT GmbH | And 4 more authors.
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2012

Observations of the 3D ice velocity field are important for studies of glacier hydraulics and for modeling the dynamic response of glaciers to changing boundary conditions. A method for 3D ice velocity retrieval from repeat pass SAR data of crossing orbits applying offset tracking in amplitude images is presented. In contrast to the conventional technique for ice motion mapping which assumes surface-parallel flow, this method delivers the true velocity vector. The procedure is validated using in-situ GPS data on an outlet glacier of the Vatnajökull ice cap in Iceland. © 2012 IEEE. Source


Pasolli L.,University of Trento | Pasolli L.,EURAC Institute for Applied Remote Sensing | Notarnicola C.,EURAC Institute for Applied Remote Sensing | Bruzzone L.,University of Trento | And 6 more authors.
Canadian Journal of Remote Sensing | Year: 2011

In this work, the polarimetric capability of RADARSAT-2 images is exploited in the aim of soil moisture content retrieval in Alpine meadows and pastures. Three feature extraction methods are investigated: the simple polarimetric intensity and phase processing, the H/A/α polarimetric decomposition, and the Independent Component Analysis (ICA). The features extracted according to these strategies were assessed for their capability to improve the soil moisture estimation by considering both quantitative performance on a set of reference samples and qualitative analysis of the corresponding output soil moisture content maps. The method proposed for the soil moisture estimation was based on the Support Vector Regression technique combined with an innovative multi-objective model selection strategy. The results indicated that the use of polarimetric features such as HH and HV channels improved the estimation of soil moisture content in the investigated mountain area, especially because the HV channel was able to disentangle the vegetation effect on the radar signal. From the preliminary results presented in this paper, the use of the H/A/α polarimetric decomposition and the ICA technique seem to not determine a significant improvement in the soil moisture estimation. © 2012 CASI. Source

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