Michael S. Ramsey

Monitoring urban land cover change: An expert system approach to land cover classification of semiarid to arid urban centers

Abstract The spatial and temporal distribution of land cover is a fundamental dataset for urban ecological research. An expert (or hypothesis testing) system has been used with Landsat Thematic Mapper (TM) data to derive a land cover classification for the semiarid Phoenix metropolitan portion of the Central Arizona-Phoenix Long Term Ecological Research (CAP LTER) site. Expert systems allow for the integration of remotely sensed data with other sources of georeferenced information such as land use data, spatial texture, and digital elevation models (DEMs) to obtain greater classification accuracy. Logical decision rules are used with the various datasets to assign class values to each pixel. TM reflectance data acquired in 1998 [visible to shortwave infrared (VSWIR) bands plus a vegetation index] were initially classified for land cover using a maximum likelihood decision rule. In addition, spatial texture of the TM data was calculated. An expert system was constructed to perform postclassification sorting of the initial land cover classification using additional spatial datasets such as texture, land use, water rights, city boundaries, and Native American reservation boundaries. Pixels were reclassified using logical decision rules into 12 classes. The overall accuracy of this technique was 85%. Individual class users accuracy ranged from 73% to 99%, with the exception of the commercial/industrial materials class. This class performed poorly (users accuracy of 49%) due to the similarity of subpixel components with other classes. The results presented here indicate that the expert system approach will be useful both for ongoing CAP LTER research, as well as the planned global Urban Environmental Monitoring (UEM) program of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument.

Determining soil moisture and sediment availability at White Sands Dune Field, New Mexico, from apparent thermal inertia data

[1] Determinations of soil moisture and sediment availability in arid regions are important indicators of local climate variability and the potential for future dust storm events. Data from the Advanced Spaceborne Thermal Emission and Reflection (ASTER) radiometer were used to derive the relationships among potential soil erosion, soil moisture, and thermal inertia (TI) at the spatial scale of aeolian landforms for the White Sands Dune Field between May 2000 and March 2008. Land surface apparent thermal inertia (ATI) data were used to derive an approximation of actual TI in order to estimate the wind threshold velocity ratio (WTR). The WTR is a ratio of the wind velocity thresholds at which soil erosion occurs for wet soil versus dry soil. The ASTER‐derived soil moisture retrievals and the changes through time at White Sands were interpreted to be driven primarily by precipitation, but the presence of a perched groundwater table may also influence certain areas. The sediment availability of dunes, active playa surfaces and the margin of the alluvial fans to the west were determined to be consistently higher than the surrounding area. The sediment availability can be primarily explained by precipitation events and the number of dry days prior to the data acquisition. Other factors such as vegetation and the amount of surface crusting may also influence soil mobility, but these were not measured in the field. This approach showed the highest modeled sediment availability values just days prior to the largest dust emission event at White Sands in decades. Such an approach could be extended to a global monitoring technique for arid land systems that are prone to dust storms and for other regional land surface studies in the Sahara.

The protracted development of focused magmatic intrusion during continental rifting

The transition from mechanical thinning toward focused magmatic intrusion during continental rifting is poorly constrained; the tectonically active Main Ethiopian Rift (MER) provides an ideal study locale to address this issue. The presence of linear magmatic-tectonic belts in the relatively immature central MER may indicate that the transition from mechanical to magmatic rifting is more spatially distributed and temporally protracted than has previously been assumed. Here we examine lava geochemistry and vent distribution of a Pliocene-Quaternary linear magmatic chain along the western margin of the central MER—the Akaki Magmatic Zone. Our results show limited variability in parental magma that evolve in a complex polybaric fractionation system that has not changed significantly over the past 3 Ma. Our results suggest the following: (1) channeling of plume material and the localization of shear- or topography-induced porosity modulates melt intrusion into the continental lithosphere. (2) Pre-existing lithospheric structures may act as catalysts for intrusion of magmas into the lithospheric mantle. (3) The midcrustal to upper crustal strain regime dictates the surface orientation of volcanic vents. Therefore, although linear magmatic belts like those in the central MER may young progressively toward the rift axis and superficially resemble oceanic style magmatism, they actually represent prebreakup magmatism on continental crust. The oldest linear magmatic belts observed seismically and magnetically at the edge of the ocean basins thus may not, as is often assumed, actually mark the onset of seafloor spreading.

Eolian dynamics and sediment mixing in the Gran Desierto, Mexico, determined from thermal infrared spectroscopy and remote-sensing data

The Gran Desierto dune field is only partially composed of quartz-rich sands from the ancestral Colorado River. Local sources have been previously underestimated as a major source of sand because previous remote-sensing studies were limited in their capability to detect silicate minerals. Compositions of sands were evaluated in this study using a combination of laboratory thermal emission spectroscopy and thermal remote-sensing data acquired from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument. The spatial interpolation of sample compositions allowed visualization of the sand transport pathways from feldspar-rich local sources by revealing gradients of composition between the dune field and surrounding local sources. The laboratory data were comparable to the remote-sensing retrievals of quartz and feldspar abundance. The mineralogical maturity of the Desierto dunes could be determined by the quartz/feldspar ratio, therefore providing a context for understanding the provenance of the Gran Desierto in relation to other Mojave and Sonoran dune fields. The composition of a previously undescribed group of dunes east of the Pinacate, the Sonoyta dunes, was measured as higher in potassium feldspar relative to the rest of the dune field. The composition of Sonoyta dunes is characteristic of other Mojave dune fields, which are more isolated near local feldspar-rich sources. South of the Pinacate, quartz-rich sand from the west admixes with feldspar-rich sand from the Sonoyta dunes to the east. The northern margin of the Gran Desierto is similarly enriched in feldspar from alluvial fans, and the coastal sand is influenced by carbonate sand that does not appear to survive transport to the inland dunes.

Thermal infrared data analyses of Meteor Crater, Arizona: Implications for Mars spaceborne data from the Thermal Emission Imaging System

Thermal infrared (TIR) data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument are used to identify the lithologic distribution of the Meteor Crater ejecta blanket and nearby (within ~3 km) region. This has many applications to the analysis of data from the Thermal Emission Imaging System (THEMIS) instrument that is currently in orbit at Mars. ASTER and THEMIS, whereas orbiting different planets, have similar spatial and spectral resolutions. THEMIS represents the highest spatial resolution (100 m) to date of the Martian surface, thereby allowing small (~ 1km) impact craters to be studied in detail for the first time. Meteor Crater serves as an analog for the many similar-sized impact sites on the surface of Mars. These sites are future research targets with THEMIS, and ASTER data of Meteor Crater provides ideal data and geologic landscape in preparation for future THEMIS investigations. Fieldwork at Meteor Crater yielded sample collection of the primary lithologies and an opportunity to validate previously-collected high-resolution (3.2 m), airborne Thermal Imaging Multispectral Scanner (TIMS) data. Laboratory thermal emission spectra were obtained for the samples collected. Deconvolution of ASTER TIR emissivity data were performed with image end-members and sample end-members. Comparisons of the spaceborne data to high-resolution airborne TIMS data were used to assess the validity of the ASTER end-member analyses. The ASTER image end-member analysis agreed well with the earlier TIMS end-member analysis where the effects of resolution degradation were accounted for. Laboratory spectra and mineral spectral libraries provided poor fits of deconvolution of multispectral TIR data. Lithologies with similar spectral signatures or with low areal abundances were difficult to identify.Using the same methodology as that applied to the ASTER TIR data of Meteor Crater, THEMIS TIR data of a small (~ 1 km) impact crater in Syrtis Major were analyzed. The craters rim and ejecta blanket was found to contain larger particle sizes than the surrounding (ejecta-free) plain, indicating a young (fresh) impact age and little or no accumulation of dust. The composition of the rim, ejecta, and surrounding plain was determined to be basaltic. It is hoped that the work performed here will complement future investigations of fresh impact sites with THEMIS data that may be used to solve geologic questions such as 1.) the composition of ejecta blocks that represent pre-impact, underlying stratigraphy in high-albedo, dust-covered regions of Mars, 2.) the approximate age of impact, and 3.) regolith/dust thickness, which appears to be a factor of #2.

Identification of Fugitive Dust Generation, Transport, and Deposition Areas Using Remote Sensing

Fugitive (or airborne) dust is a primary cause of decreased air quality, as well as being a potential health hazard. Urban and agricultural areas are of particular interest as fugitive dust sources because of their potential for releases during soil disturbance, ongoing industrial and commercial processes, and agricultural activities. Typical strategies for assessing and monitoring fugitive dust source areas include numerical modeling of atmospheric circulation patterns, field assessments, and collection of dust samples using various methods. Analysis of remotely sensed multi-spectral data provides another alternative for identifying fugitive dust source, transport, and sink areas. Multi-spectral (visible to shortwave infrared) data acquired by the Enhanced Thematic Mapper Plus (ETM+) instrument on board the Landsat 7 satellite is used to perform land-cover classifications for the Nogales, AZ, region. Data acquired during the winter of 2000 and the summer of 2001 are used to assess seasonal variations and detect land-cover changes of significance to dust-transport processes. An expert system approach using spectral, textural, and vegetation abundance data is used to classify the ETM+ data into land-cover types important to dust-transport models. The determined overall accuracy of the land-cover classifications is 74 percent. These results can be used to identify (and calculate areal percentages of) fugitive dust source, transport, and sink regions. This spatially explicit, digital data product is useful both as an input into dust-transport models and as a check on the results of such models.

Long-Term Volcanic Activity at Shiveluch Volcano: Nine Years of ASTER Spaceborne Thermal Infrared Observations

Shiveluch (Kamchatka, Russia) is the most active andesitic volcano of the Kuril-Kamchatka arc, typically exhibiting near-continual high-temperature fumarolic activity and periods of exogenous lava dome emplacement punctuated by discrete large explosive eruptions. These eruptions can produce large pyroclastic flow (PF) deposits, which are common on the southern flank of the volcano. Since 2000, six explosive eruptions have occurred that generated ash fall and PF deposits. Over this same time period, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument has been acquiring image-based visible/near infrared (VNIR), short wave infrared (SWIR) and thermal infrared (TIR) data globally, with a particular emphasis on active volcanoes. Shiveluch was selected as an ASTER target of interest early in the mission because of its frequent activity and potential impact to northern Pacific air transportation. The north Pacific ASTER archive was queried for Shiveluch data and we present results from 2000 to 2009 that documents three large PF deposits emplaced on 19 May 2001, 9 May 2004, and 28 February 2005. The long-term archive of infrared data provides an excellent record on the changing activity and eruption state of the volcano.

Conclusion: recommendations and findings of the RED SEED working group

Abstract RED SEED stands for Risk Evaluation, Detection and Simulation during Effusive Eruption Disasters, and combines stakeholders from the remote sensing, modelling and response communities with experience in tracking volcanic effusive events. The group first met during a three day-long workshop held in Clermont Ferrand (France) between 28 and 30 May 2013. During each day, presentations were given reviewing the state of the art in terms of (a) volcano hot spot detection and parameterization, (b) operational satellite-based hot spot detection systems, (c) lava flow modelling and (d) response protocols during effusive crises. At the end of each presentation set, the four groups retreated to discuss and report on requirements for a truly integrated and operational response that satisfactorily combines remote sensors, modellers and responders during an effusive crisis. The results of collating the final reports, and follow-up discussions that have been on-going since the workshop, are given here. We can reduce our discussions to four main findings. (1) Hot spot detection tools are operational and capable of providing effusive eruption onset notice within 15 min. (2) Spectral radiance metrics can also be provided with high degrees of confidence. However, if we are to achieve a truly global system, more local receiving stations need to be installed with hot spot detection and data processing modules running on-site and in real time. (3) Models are operational, but need real-time input of reliable time-averaged discharge rate data and regular updates of digital elevation models if they are to be effective; the latter can be provided by the radar/photogrammetry community. (4) Information needs to be provided in an agreed and standard format following an ensemble approach and using models that have been validated and recognized as trustworthy by the responding authorities. All of this requires a sophisticated and centralized data collection, distribution and reporting hub that is based on a philosophy of joint ownership and mutual trust. While the next chapter carries out an exercise to explore the viability of the last point, the detailed recommendations behind these findings are detailed here.

Operational thermal remote sensing and lava flow monitoring at the Hawaiian Volcano Observatory

Abstract Hawaiian volcanoes are highly accessible and well monitored by ground instruments. Nevertheless, observational gaps remain and thermal satellite imagery has proven useful in Hawai‘i for providing synoptic views of activity during intervals between field visits. Here we describe the beginning of a thermal remote sensing programme at the US Geological Survey Hawaiian Volcano Observatory (HVO). Whereas expensive receiving stations have been traditionally required to achieve rapid downloading of satellite data, we exploit free, low-latency data sources on the internet for timely access to GOES, MODIS, ASTER and EO-1 ALI imagery. Automated scripts at the observatory download these data and provide a basic display of the images. Satellite data have been extremely useful for monitoring the ongoing lava flow activity on Kīlaueas East Rift Zone at Pu‘u ‘Ō‘ō over the past few years. A recent lava flow, named Kahauale‘a 2, was upslope from residential subdivisions for over a year. Satellite data helped track the slow advance of the flow and contributed to hazard assessments. Ongoing improvement to thermal remote sensing at HVO incorporates automated hotspot detection, effusion rate estimation and lava flow forecasting, as has been done in Italy. These improvements should be useful for monitoring future activity on Mauna Loa.

Surface textures and dynamics of the 2005 lava dome at Shiveluch volcano, Kamchatka

Shiveluch is one of the largest and most active andesitic volcanoes of the Kuril-Kamchatka arc. It commonly alternates between Vulcanian explosive eruptions and periods of dome growth and subsequent dome collapse–driven block-and-ash flows. The volcano was in an extended period of heightened activity for most of the period 2004–2010. We examined this activity in detail using thermal infrared (TIR) remote sensing as part of the urgent request protocol (URP) program of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument and confirmed the results with ground-based photography and airborne TIR camera data. High-spatial-resolution TIR images were collected during both daytime and nighttime satellite overpasses prior to and following the large explosive event/eruption of 27 February 2005 and the dome growth that followed. During a field campaign in August 2005, a helicopter overflight designed to acquire visible and TIR data of the active dome was performed. This was a nadir-looking, low-altitude overflight and the first ever of Shiveluch volcano involving non-Russian scientists. The image data revealed an active crease structure in the center of the dome with a distinctly different, crescent-shaped, high-temperature (>380 °C) zone roughly perpendicular to the crease. In order to provide a time context and estimate extrusion rates, the airborne data were compared to the spaceborne ASTER data and long-distance ground-based photography of the dome acquired by our Russian colleagues. The presence of a crease structure and the complex thermal pattern on the surface were both unexpected discoveries that reveal the way in which exogenous dome growth was occurring at the time. This highly active period at Shiveluch provides a unique example to better understand silicic lava dome growth using TIR data. The results also demonstrate a straightforward approach for fusing ground, air, and spaceborne image data, which could be applied to other active domes around the world.