Visible–near infrared spectral indices for mapping mineralogy and chemistry with OSIRIS‐REx

The primary objective of the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS‐REx) mission is to return to Earth a pristine sample of carbonaceous material from the primitive asteroid (101955) Bennu. To support compositional mapping of Bennu as part of sample site selection and characterization, we tested 95 spectral indices on visible to near infrared laboratory reflectance data from minerals and carbonaceous meteorites. Our aim was to determine which indices reliably identify spectral features of interest. Most spectral indices had high positive detection rates when applied to spectra of pure, single‐component materials. The meteorite spectra have fewer and weaker absorption features and, as a result, fewer detections with the spectral indices. Indices targeting absorptions at 0.7 and 2.7–3 μm, which are attributable to hydrated minerals, were most successful for the meteorites. Based on these results, we identified a set of 17 indices that are most likely to be useful at Bennu. These indices detect olivines, pyroxenes, carbonates, water/OH‐bearing minerals, serpentines, ferric minerals, and organics. Particle size and albedo are known to affect band depth but had a negligible impact on interpretive success with spectral indices. Preliminary analysis of the disk‐integrated Bennu spectrum with these indices is consistent with expectations given the observed absorption near 3 μm. Our study prioritizes spectral indices to be used for OSIRIS‐REx spectral analysis and mapping and informs the reliability of all index‐derived data products, including a science value map for sample site selection.     

Chemical coagulation of humic substances: A comparison of natural aquatic versus soil-extracted materials

Aquatic humic substances can be removed by chemical coagulation during water treatment. Hydrolyzing metals such as Al(III) and Fe(III), as well as commercially available cationic polyelectrolytes, can effectively remove humic substances prior to chlorination, thus reducing the formation of trihalomethanes. Synthetic waters, produced by adding soil-extracted fulvic acids to distilled water containing a clay source and various salts, have some merit in approximating the behavior of aquatic humic substances during chemical coagulation; however, caution must be exercised in the interpretation and applicability of the results.     

Wildfire evacuation experiences of band members of Whitefish Lake First Nation 459, Alberta,Canada

This paper presents results of a study which examined how a mandatory wildfire evacuation affected members of Whitefish Lake First Nation 459, in Alberta, Canada. A qualitative case study approach was used, and semi-structured interviews were completed with 45 band members to learn about their evacuation experiences during the wildfire evacuation in May 2011 and explore the factors that complicated the evacuation process and put further strain on the evacuees and First Nation. This evacuation caused considerable distress for evacuees and had negative effects for the First Nation. Factors that affected evacuation experiences included: (1) transportation issues compounded by cultural land-use activities, (2) fear of home loss compounded by existing housing shortages, (3) information and lack of media interest, (4) language, (5) poverty, (6) large multi-generational families, (7) health concerns, and (8) reimbursement of evacuation-related expenses to the community. An overarching factor that affected the entire evacuation was jurisdiction. Based on these findings, recommendations are provided for emergency managers on improving wildfire evacuation experiences for Indigenous peoples.

     

Diagnosing Climate Feedbacks in Coupled Ocean–Atmosphere Models

We review the methodologies used to quantify climate feedbacks in coupled models. The method of radiative kernels is outlined and used to illustrate the dependence of lapse rate, water vapor, surface albedo, and cloud feedbacks on (1) the length of the time average used to define two projected climate states and (2) the time separation between the two climate states. Except for the shortwave component of water vapor feedback, all feedback processes exhibit significant high-frequency variations and intermodel variability of feedback strengths for sub-decadal time averages. It is also found that the uncertainty of lapse rate, water vapor, and cloud feedback decreases with the increase in the time separation. The results suggest that one can substantially reduce the uncertainty of cloud and other feedbacks with the accumulation of accurate, long-term records of satellite observations; however, several decades may be required.     

Channel‐planform evolution in four rivers of Olympic National Park,Washington, USA: the roles of physical drivers and trophic cascades

Identifying the relative contributions of physical and ecological processes to channel evolution remains a substantial challenge in fluvial geomorphology. We use a 74‐year aerial photographic record of the Hoh, Queets, Quinault, and Elwha Rivers, Olympic National Park, Washington, USA, to investigate whether physical or trophic‐cascade‐driven ecological factors – excessive elk impacts after wolves were extirpated a century ago – are the dominant drivers of channel planform in these gravel‐bed rivers. We find that channel width and braiding show strong relationships with recent flood history. All four rivers widened significantly after having been relatively narrow in the 1970s, consistent with increased flood activity since then. Channel planform also reflects sediment‐supply changes, evident from landslide response on the Elwha River. We surmise that the Hoh River, which shows a multi‐decadal trend toward greater braiding, is adjusting to increased sediment supply associated with rapid glacial retreat. These rivers demonstrate transmission of climatic signals through relatively short sediment‐routing systems that lack substantial buffering by sediment storage. Legacy effects of anthropogenic modification likely also affect the Quinault River planform. We infer no correspondence between channel evolution and elk abundance, suggesting that trophic‐cascade effects in this setting are subsidiary to physical controls on channel morphology. Our findings differ from previous interpretations of Olympic National Park fluvial dynamics and contrast with the classic example of Yellowstone National Park, where legacy effects of elk overuse are apparent in channel morphology; we attribute these differences to hydrologic regime and large‐wood availability. Published 2016. This article is a U.S. Government work and is in the public domain in the USA     

Exploring the anatomy of Geographic Information Systems and Technology (GIS&T) textbooks

Choosing a textbook is among the most important decisions instructors make in preparation for an academic term. Geographic Information Systems and Technology (GIS&T) textbook development has been influenced by a unique set of circumstances, mainly the rapid development of the discipline within an interdisciplinary environment, which has resulted in a continuous state of evolution. We examine the anatomy of GIS&T textbooks through a comparison of their organization, content, and depth of coverage. Specifically, utilizing the Geographic Information Science and Technology Body of Knowledge (BoK) as a comprehensive reference, we categorize the content of 26 of the most widely used introductory GIS textbooks. Our results show that there has been consistent coverage of topics over time, with analytical methods and geospatial data being the most prominent topics covered in texts. However, individual textbooks place varying emphasis on the BoK knowledge areas, which is potentially useful to instructors seeking books that emphasize particular knowledge areas. Additionally, long‐term trends indicate a shift toward an emphasis on new forms of geospatial data (e.g., social media). Ongoing efforts to expand and revise the BoK reflect how the discipline continues to manage its own evolution as new geographic research linked to GIS and GIScience emerges.     

Does fire alter soil water repellency in subtropical coastal sandy environments?

Irregular wetting, water repellency, and preferential flow are well‐documented properties of coastal sandy podzols, though little is known about the effect of fire on unsaturated zone processes in this environment. This study investigates water repellency at and below the soil surface in two coastal sandy podzols following bushfire. Water drop penetration time tests were applied to burned and unburned soils at a high dune field site in South East Queensland, Australia. It was found that the mean water drop penetration time of the burned soil was four times that of the unburned soil, but both soils were largely non‐repellent. Post‐fire repellency peaked below the surface in a patchy layer, in contrast to the laterally extensive layer reported in other studies, and high organic matter content in the soil did not appear to significantly influence repellency post‐burn. Non‐parametric statistics were used to quantify the high spatial variability in water repellency, which was ultimately insufficiently captured by atypically large (n = 1000 drop) datasets. This study confirms the presence of naturally occurring repellency and patchy infiltration in sandy soils while demonstrating that conclusively describing the influence of fire is challenging in a soil with heterogeneous infiltration characteristics. With respect to this uncertainty, it appears that fire does not increase soil water repellency such that infiltration and runoff processes due to fire‐induced water repellency would differ post‐burn.