Preparing Geographers for Interdisciplinary Research: Graduate Training at the Interface of the Natural and Social Sciences

Recent debates about the state of geography raise valuable questions about how the discipline can and should change in response to shifting institutional realities. Focusing on the breadth and interdisciplinarity of geography, these discussions often overlook the role of pedagogy—particularly graduate training—in adapting the discipline to new institutional landscapes. Drawing on experiences as current and recent geography doctoral students, we identify institutional seedlings of opportunity that can be cultivated toward a spectrum of alternative doctoral training models. These alternatives offer significant opportunities to better prepare early-career geographers for success and to solidify geography's position as a leader in interdisciplinary research.     

Simultaneous mapping of SO2, SO, NaCl in Io’s atmosphere with the Submillimeter Array

Many of the key properties of Io’s atmosphere, such as its spatial distribution, temperature, column density and composition, are still not fully assessed despite decades of extensive observations. The contribution of the possible gas sources to the atmospheric replenishment are then still unclear.This paper presents disk-resolved observations performed with the Submillimeter Array (SMA) at 345 GHz of atmospheric rotational lines of the main atmospheric species SO₂, and, for the first time, of the minor species SO and NaCl. All these species appear concentrated on the anti-jovian hemisphere, but do not share the same spatial distribution. The obtained maps and line-averaged fluxes are compared to realistic models simulating gas sources including volcanic plume outgassing, SO₂ frost sublimation and photolysis. Arguments in favor of each sources are examined and compared to observations, putting constraints on their relative roles for each species.While sublimation clearly appears as the favored major source for SO₂, SO₂ photolysis may account for most of the production of SO. Using constraints on the volcanic plumes distribution from Galileo results, we find that direct volcanic input can only contribute for a minor fraction of atmospheric SO₂, but represent a more significant source for SO atmosphere, and is likely to be the only source for NaCl. Temperature and column densities findings are also presented for SO₂, and compare well to previously published observations and atmospheric models.     

Flooding duration and volume more important than peak discharge in explaining 18 years of gravel–cobble river change

Floods play a critical role in geomorphic change, but whether peak magnitude, duration, volume, or frequency determines the resulting magnitude of erosion and deposition is a question often proposed in geomorphic effectiveness studies. This study investigated that question using digital elevation model differencing to compare and contrast three hydrologically distinct epochs of topographic change spanning 18 years in the 37-km gravel–cobble lower Yuba River in northern California, USA. Scour and fill were analysed by volume at segment and geomorphic reach scales. Each epoch's hydrology was characterized using 15-min and daily averaged flow to obtain distinct peak and recurrence, duration, and volume metrics. Epochs 1 (1999–2008) and 3 (2014–2017) were wetter than average with large floods reaching 3206 and 2466 m³/s, respectively, though of different flood durations. Epoch 2 (2008–2014) was a drought period with only four brief moderate floods (peak of 1245 m³/s). Total volumetric changes showed that major geomorphic response occurred primarily during large flood events; however, total scour and net export of sediment varied greatly, with 20 times more export in epoch 3 compared to epoch 1. The key finding was that greater peak discharge was not correlated with greater net and total erosion; differences were better explained by duration and volume above floodway-filling stage. This finding highlights the importance of considering flood duration and volume, along with peak, to assess flood magnitude in the context of flood management, frequency analysis, and resulting geomorphic changes.     

Monitoring Venus’ mesospheric winds in support of Venus Express: IRAM 30-m and APEX observations

We report on direct wind measurements in Venus’ mesosphere (90-115 km), performed in support of Venus Express, and based on CO millimeter observations. Most observations, sampling the CO(2-1) and CO(1-0) lines, were acquired with the IRAM 30-m telescope, over four distinct periods: (i) Summer 2006; (ii) May-June 2007, in association with the coordinated ground-based campaign; (iii) August 2007 inferior conjunction and (iv) September 2007. In the latter period, additional measurements (CO(3-2)) were obtained with the APEX 12-m telescope. Overall, the measurements indicate a large body of temporal variability of the Venus mesospheric field, but general features emerge: (i) winds strongly increase with altitude within the mesosphere, by a factor of 2-3 over a decade in pressure; (ii) many, but not all, of our observations can be viewed as the superposition of zonal retrograde and subsolar-to-antisolar (SSAS) flows of comparable speeds, typically 30-50 m/s near 0.1 mbar () and 90-120 m/s near 0.01 mbar () (iii) the wind field was very stable over three consecutive observing days in May-June 2007, but much more variable on a similar time base in August 2007 (iv) at a resolution, the nightside wind field appears very complex, with evidence that the SSAS flow does not reach high latitudes, and possible evidence for additional meridional winds. Our Summer 2006 observations, which sample Venus’ dayside, seem to suggest that a prograde zonal flow is superimposed to the SSAS circulation for this period. This surprising result, which implies a pre-midnight convergence of the wind field, requires confirmation, and fruitful comparisons may be obtained from the analysis of motions in the O₂ emission images, as observed by Venus Express.     

Considering Refugees Through 100 Years of Geographical Review

Given the role of the American Geographical Society and its flagship journal, Geographical Review, in the Paris Peace Conference and its prominence in the discipline of geography ever since, this paper considers how the journal takes account of refugees in its pages from 1916 to 2018 using a bibliometric approach. The term “refugee” was tracked in every Geographical Review article published during this time period, using content to generate data and analysis in QSR NVivo. First, we identify key trends in scholarship over time, then we note the rise and fall of important key terms, and finally, we examine both the countries analyzed and how these geographies change over time. The results of this bibliometric analysis of refugees in Geographical Review reflect both global geopolitical dynamics and refugee governance structures, and broader trends in epistemology in the discipline of geography. Observations made on these trends and variations indicate a need to further explore shifting paradigms and master narratives, both past and emerging, built around the “refugee” concept and its treatment within the discipline of geography.     

Physical studies of Centaurs and Trans-Neptunian Objects with the Atacama Large Millimeter Array

Once completed, the Atacama Large Millimeter Array (ALMA) will be the most powerful (sub)millimeter interferometer in terms of sensitivity, spatial resolution and imaging. This paper presents the capabilities of ALMA applied to the observation of Centaurs and Trans-Neptunian Objects, and their possible output in terms of physical properties. Realistic simulations were performed to explore the performances of the different frequency bands and array configurations, and several projects are detailed along with their feasibility, their limitations and their possible targets. Determination of diameters and albedos via the radiometric method appears to be possible on ∼500 objects, while sampling of the thermal lightcurve to derive the bodies’ ellipticity could be performed at least 30 bodies that display a significant optical lightcurve. On a limited number of objects, the spatial resolution allows for direct measurement of the size or even surface mapping with a resolution down to 13 milliarcsec. Finally, ALMA could separate members of multiple systems with a separation power comparable to that of the HST. The overall performance of ALMA will make it an invaluable instrument to explore the outer Solar System, complementary to space-based telescopes and spacecrafts.     

Distributed hydrologic and hydraulic modelling with radar rainfall input: Reconstruction of the 8–9 September 2002 catastrophic flood event in the Gard region,France

On 8–9 September 2002, an extreme rainfall event caused by a stationary mesoscale convective system (MCS) occurred in the Gard region, France. Distributed hydrologic and hydraulic modelling has been carried out to assess and compare the various sources of data collected operationally and during the post-event field surveys. Distributed hydrological modelling was performed with n-TOPMODELs and assessed for ungauged basins with the discharge estimates of the post-event surveys. A careful examination of the occurrence in time and space of the flash floods over the head watersheds indicates that flooding was controlled by the trajectory of the convective part of the MCS. Stationarity of the MCS over the Gardon watershed (1858 km² at Remoulins) for 28 h was responsible for the exceptional magnitude of the flood at this scale. The flood dynamics were characterized by an extensive inundation of the Gardonnenque plain upstream of the Gardon Gorges resulting in a significant peak flow reduction downstream. One-dimensional unsteady-flow hydraulic modelling was found to be required to reproduce these dynamics. Hydraulic modelling also proved to be potentially useful for the critical analysis and extrapolation of operational discharge rating curves.