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Ramsey E.,U.S. Geological Survey | Rangoonwala A.,Five Rivers Services LLC
OCEANS 2012 MTS/IEEE: Harnessing the Power of the Ocean | Year: 2012

Our research focused on the effectiveness of high spatial resolution and fully polarimetric L-band SAR (NASA Uninhabited Aerial Vehicle SAR [UAVSAR]) for mapping oil in wetlands, specifically during the Macondo-1 oil spill and its impacts within Barataria Bay in eastern coastal Louisiana. Oil detection relied on PolSAR decomposition and subsequent classifications of the pre-spill (2009) and post-spill (2010) single look complex (SLC) scenes and numerous site observations. Results found that observed shoreline marsh structural damage accompanied by oil occurrence were evident as anomalous features on post-spill but not on the pre-spill SLC flight line data and that these nearshore features were reflected as a change in dominant scatter in Freeman-Durden (FD) and Cloude-Pottier (CP) decompositions and Wishart classifications seeded with the FD and CP classes. Pre- and post-spill SLC data and all decompositions and classifications also revealed a class of interior marshes within the central core of the study region that was associated with a transform of dominant scatter mechanism. The change of dominant scatter is associated with a preponderance of evidence that supports the penetration of oil-polluted waters into interior marshes. Contrary to documented nearshore impacts, however, the lack of contemporaneous observational data and possible shallow flooding in the pre-spill marsh prevent absolute determination of whether UAVSAR detected oil occurrences in the interior marshes. © 2012 IEEE. Source


Ramsey E.,U.S. Geological Survey | Rangoonwala A.,Five Rivers Services LLC | Bannister T.,Five Rivers Services LLC
Journal of the American Water Resources Association | Year: 2013

Satellite Synthetic Aperture Radar (SAR) was evaluated as a method to operationally monitor the occurrence and distribution of storm- and tidal-related flooding of spatially extensive coastal marshes within the north-central Gulf of Mexico. Maps representing the occurrence of marsh surface inundation were created from available Advanced Land Observation Satellite (ALOS) Phased Array type L-Band SAR (PALSAR) (L-band) (21 scenes with HH polarizations in Wide Beam [100 m]) data and Environmental Satellite (ENVISAT) Advanced SAR (ASAR) (C-band) data (24 scenes with VV and HH polarizations in Wide Swath [150 m]) during 2006-2009 covering 500 km of the Louisiana coastal zone. Mapping was primarily based on a decrease in backscatter between reference and target scenes, and as an extension of previous studies, the flood inundation mapping performance was assessed by the degree of correspondence between inundation mapping and inland water levels. Both PALSAR- and ASAR-based mapping at times were based on suboptimal reference scenes; however, ASAR performance seemed more sensitive to reference-scene quality and other types of scene variability. Related to water depth, PALSAR and ASAR mapping accuracies tended to be lower when water depths were shallow and increased as water levels decreased below or increased above the ground surface, but this pattern was more pronounced with ASAR. Overall, PALSAR-based inundation accuracies averaged 84% (n = 160), while ASAR-based mapping accuracies averaged 62% (n = 245). © 2013 American Water Resources Association. This article is a U.S. Government work and is in the public domain in the USA. Source


Ramsey E.,U.S. Geological Survey | Spruce J.,Computer Sciences Corp. | Rangoonwala A.,Five Rivers Services LLC | Rangoonwala A.,IAP World Services Inc. | And 6 more authors.
Photogrammetric Engineering and Remote Sensing | Year: 2011

We studied the use of daily satellite data from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors to assess wetland forest damage and recovery from Hurricane Katrina (29 August 2005 landfall). Processed MODIS daily vegetation index (VI) trends were consistent with previously determined impact and recovery patterns provided by the "snapshot" 25 m Landsat Thematic Mapper optical and RADARSAT-1 synthetic aperture radar satellite data. Phenological trends showed high 2004 and 2005 pre-hurricane temporal correspondence within bottomland hardwood forest communities, except during spring green-up, and temporal dissimilarity between these hardwoods and nearby cypresstupelo swamp forests (Taxodium distichum [baldcypress] and Nyssa aquatica [water tupelo]). MODIS VI trend analyses established that one year after impact, cypress-tupelo and lightly impacted hardwood forests had recovered to near prehurricane conditions. In contrast, canopy recovery lagged in the moderately and severely damaged hardwood forests, possibly reflecting regeneration of pre-hurricane species and stand-level replacement by invasive trees. © 2011 American Society for Photogrammetry and Remote Sensing. Source


Ramsey III E.,U.S. Geological Survey | Rangoonwala A.,Five Rivers Services LLC | Chi Z.,University of Louisiana at Lafayette | Jones C.E.,Jet Propulsion Laboratory | Bannister T.,University of Louisiana at Lafayette
Remote Sensing of Environment | Year: 2014

Landsat Thematic Mapper and Satellite Pour l'Observation de la Terre (SPOT) satellite based optical sensors, NASA Uninhabited Aerial Vehicle synthetic aperture radar (UAVSAR) polarimetric SAR (PolSAR), and field data captured the occurrence and the recovery of an undetected dieback that occurred between the summers of 2010, 2011, and 2012 in the Spartina alterniflora marshes of coastal Louisiana. Field measurements recorded the dramatic biomass decrease from 2010 to 2011 and a biomass recovery in 2012 dominated by a decrease of live biomass, and the loss of marsh as part of the dieback event. Based on an established relationship, the near-infrared/red vegetation index (VI) and site-specific measurements delineated a contiguous expanse of marsh dieback encompassing 6649.9. ha of 18,292.3. ha of S. alterniflora marshes within the study region. PolSAR data were transformed to variables used in biophysical mapping, and of this variable suite, the cross-polarization HV (horizontal send and vertical receive) backscatter was the best single indicator of marsh dieback and recovery. HV backscatter exhibited substantial and significant changes over the dieback and recovery period, tracked measured biomass changes, and significantly correlated with the live/dead biomass ratio. Within the context of regional trends, both HV and VI indicators started higher in pre-dieback marshes and exhibited substantially and statistically higher variability from year to year than that exhibited in the non-dieback marshes. That distinct difference allowed the capturing of the S. alterniflora marsh dieback and recovery; however, these changes were incorporated in a regional trend exhibiting similar but more subtle biomass composition changes. © 2014 Elsevier Inc. Source


Glorioso B.M.,U.S. Geological Survey | Hardin Waddle J.,U.S. Geological Survey | Hefner J.,Five Rivers Services LLC
Herpetology Notes | Year: 2015

Reproductive aspects of Ambystoma salamanders were investigated at sites in Louisiana (2010–12) and Mississippi (2013). Three species occurred at the Louisiana site, Spotted Salamander (A. maculatum), Marbled Salamander (A. opacum), and Mole Salamander (A. talpoideum), whereas only Spotted Salamanders were studied at the Mississippi site. A total of 162 and 71 egg masses of Spotted Salamanders were examined at the Louisiana and Mississippi sites, respectively. Significantly more Spotted Salamander eggs per egg mass were observed at the Mississippi site (x̄ = 78.2) than the Louisiana site (x̄ = 53.8; P < 0.001). The mean snout–vent length of female Spotted Salamanders at the Mississippi site (82.9 mm) was significantly larger than the Louisiana site (76.1 mm; P < 0.001). Opaque Spotted Salamander egg masses were not found at the Mississippi site, but accounted for 11% of examined egg masses at the Louisiana site. The mean number of eggs per egg mass at the Louisiana site did not differ between opaque (47.3) and clear (54.6) egg masses (P = 0.21). A total of 47 egg masses of the Mole Salamander were examined, with a mean number of 6.7 embryos per mass. Twenty-three individual nests of the Marbled Salamander were found either under or in decaying logs in the dry pond basins. There was no difference between the mean numbers of eggs per mass of attended nests (93.0) versus those that were discovered unattended (86.6; P = 0.67). Females tended to place their nests at intermediate heights within the pond basin. © 2015, Societas Europaea Herpetologica. All right resurved. Source

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