Remote sensing of aeolian processes

This review focuses on recent advances that have taken place in the use of remote sensing to observe aeolian processes, and to highlight recent approaches that have enabled and been employed to observe and quantify aeolian processes at a range of scales. As remote technologies continue to develop, the review emphasizes the significance that, in their different forms, these data are applicable across all scales at which aeolian processes operate. To address this, the review examines a range of space-borne, airborne and near-surface technologies

Understanding dust sources through remote sensing: making a case for CubeSats

Dust sources have been revealed through remote sensing, first regionally by ~1° resolution sensors (TOMS), then at sub-basin scale by moderate-resolution sensors (MODIS). Sensors with higher spatial resolution until recently were poorly temporally-resolved, precluding their use for systematic investigations of sources. Now, “CubeSat” constellations with high-temporal-and-spatial-resolution sensors such as PlanetScope offer ~3 m resolution and daily (to sub-daily) temporal resolution. We illustrate the spatio-temporal dust plume observation capabilities of CubeSat data through a dust event case study, Bolson de los Muertos playa, Chihuahuan Desert, Mexico. For the event, PlanetScope showed numerous discrete point sources, revealing variability of surface erodibility and emission over ~8% of a focus area at time of capture. The unprecedented detail of PlanetScope imagery revealed plume development where outer-playa sands and fluvial-deltaic inputs contact lacustrine silts/clays, consistent with field-studies. PlanetScope’s high fidelity improves spatial quantification and temporal constraint of source activity, and we assess the spatio-temporal capabilities of CubeSat in context with other dust observation remote sensing systems. Compared to previous satellite technologies, CubeSats bring better potential to link remote sensing to field observations of emission. This leap forward in the remote sensing of dust sources calls for the systematic analysis of CubeSat imagery in source area

Effect of ZnSO₄ on Sucrose Concentration–response Function.

<p>Each concentration of sucrose plus ZnSO₄ was dispensed in 3 wells, and of sucrose alone in 2 wells, per plate; controls were dispensed in 4-6 wells each per plate (See Figure S7 for plate configuration corresponding to the experiment illustrated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072391#pone-0072391-g009" target="_blank">Figure 9</a>). Upper panel shows sweet taste quality plotted as percent of responses made on the sucrose lever. Lower panel shows concentration–response function for palatability plotted as mean licks per trial. Data are plotted as mean of responses averaged across 4 rats. Error bars are SEM. SUC = sucrose, CIT = citrate, QUI = quinine. Data are representative of 3 equivalent experiments.</p

Effect of Alloxan on Sucrose Concentration–response Function.

<p>Each concentration of sucrose plus alloxan was dispensed in 3 wells, and of sucrose alone in 2 wells, per plate; controls were dispensed in 4-6 wells each per plate (See Figure S7 for plate configurations corresponding to the experiment illustrated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072391#pone-0072391-g008" target="_blank">Figure 8</a>). Upper panel shows sweet taste quality plotted as percent of responses made on the sucrose lever. Lower panel shows concentration–response function for palatability plotted as mean licks per trial. Data are plotted as mean of responses averaged across 4 rats. Error bars are SEM. SUC = sucrose, ALOX = alloxan, CIT = citrate, QUI = quinine. Data are representative of 3 equivalent experiments.</p

Concentration–response Functions for 8 Different Sweeteners in a Single Test Session.

<p>Eight sweeteners (SUC = sucrose, REB A = rebaudioside A, ACE K = acesulfame potassium, SCR = sucralose, SAC = saccharine, STEV = stevioside, GLY = L-glycine, and SC45647) were tested for both taste quality and palatability across a range of concentration. Positive control: 100 mM SUC = sucrose; Negative controls: 10 mM CIT = citrate, 1 mM QUI = quinine, water and 100 mM NaCl. Upper panels shows graphs of sweet taste quality plotted as percent of responses made on the sucrose lever. Lower panel shows concentration–response functions for palatability, plotted as mean licks/trial, obtained in the same experiment. Each concentration of test article was dispensed into a single well of a 96-well plate. Data are plotted as mean of responses to contents from a single well per concentration of test article and 6-7 wells for controls per rat, averaged across 4 rats. Error bars are SEM. Data are representative of 3 equivalent experiments. See Figure S5 for plate configuration corresponding to the experiment illustrated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072391#pone-0072391-g006" target="_blank">Figure 6</a>.</p

Relationship Between Lick Rates and Trial Number for Water, Sucrose, and NaCl.

<p>Data points are licks per trial plotted according to their corresponding trial number. All data in the plots were generated by 4 rats across four training sessions in which water, 100 mM sucrose, and 100 mM NaCl each were presented in 32 trials per session (thus, 4 rats x 32 trials x 4 sessions = 512 data points for each tastant.) The lines within the plots represent the results of the linear regression.</p

Concentration–response Functions are Stable Across Tests Following Completion of Discrimination Training.

<p>Upper graphs in each panel show sweet taste quality plotted as percent of responses made on the sucrose lever. Lower panels show concentration–response functions for palatability plotted as mean licks per trial. Data are plotted as mean of responses to contents from 4 wells for sucrose concentration range and 12-14 wells for controls per rat, averaged across 4 rats. Error bars are SEM. Open symbols represent values obtained for control tastants: ○ = 100 mM sucrose; ▽ = water; □ = 100 mM NaCl; △ = 10 mM citric acid; ◇ = 1 mM quinine. Closed symbols = test article: ● = sucrose. Results in each panel are of single experiments performed in sequential weekly intervals. See Figure S4 for plate configuration corresponding to the experiment illustrated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072391#pone-0072391-g003" target="_blank">Figure 3</a>.</p

Schematic of the Apparatus.

<p>Two retractable levers in the front panel operate a food pellet dispenser. The front half of the floor swings upward to expose a sub-chamber beneath. A standard 96-well plate is placed on an x-y motion table in the sub-chamber. When the floor is closed, the contents of a single well can be accessed by licking through an aperture in the floor. Insertion of a rat’s tongue disrupts the path of a laser beam projected across the top of the well, activating a switch that produces the levers. Above each lever is a stimulus light. The chamber also contains a house-light in the ceiling and a tone generator on the rear wall (not pictured).</p

Test of the Potential for an In Vivo Primary Screen for Sweet Taste Properties.

<p>A panel of 15 sweeteners and polycose was tested by a cohort of 4 rats for detection of sweet taste quality (plotted as percent sucrose-appropriate lever presses, upper panel) and palatability (licks/trial, lower panel). Data for each sweetener (both taste quality and palatability) appear directly above and directly below their corresponding labels. Luo Han = Luo han guo, GLZ = glycyrrhizic acid, Reb A = rebaudioside A). Dashed blue and red lines respectively mark the mean responses to water (negative control) and to 100 mM sucrose (positive control). A single low (light gray bars) and single high concentration (dark gray bars) of each test sweetener was dispensed in two wells, and controls in 6-7 wells each, per plate. Concentration pairs were 0.01 and 0.1 mM (SC45647, stevioside, rebaudioside A), 0.1 and 1 mM (saccharin, Ace-K, sucralose), 1 and 10 mM (aspartame, cyclamate, glycyrrhizic acid) and 10 and 100 mM (L-glycine, glucose, maltose, fructose, trehalose). Luo han guo was tested at 1 and 10 mg/ml and polycose at 1% and 10% solutions. Results were averaged across 4 rats and the data shown in the figure are representative of two equivalent experiments. See Figure S6 for plate configuration corresponding to the experiment illustrated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072391#pone-0072391-g007" target="_blank">Figure 7</a>.</p

Concentration–response Functions for Salt and Umami Tastes.

<p>Upper graphs in each panel show taste quality plotted as percent of responses made on the standard-appropriate lever. Lower panels show concentration–response functions for palatability plotted as mean licks per trial. Data are plotted as mean of responses to contents from 4 wells per concentration of test article and 10-14 wells for controls per rat, averaged across 4 rats. Error bars are SEM. <b>A</b>: Rats were trained to discriminate the taste of 100 mM NaCl (○) from water (▽), 100 mM sucrose (□), 10 mM citric acid (△), and 1 mM quinine (◇). Test article: ● = NaCl. <b>B</b>: Rats were trained to discriminate the taste of 100 mM MSG+100 µM amiloride (○) from water (▽), 100 mM sucrose (*), 100 mM NaCl (□), 10 mM citric acid (△) and 1 mM quinine (◇). Test article: ● = MSG + amiloride. See Figure S8 for plate configurations corresponding to the experiment illustrated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072391#pone-0072391-g010" target="_blank">Figure 10A</a>; Figure S9 corresponds to the experiment of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072391#pone-0072391-g010" target="_blank">Figure 10B</a>.</p