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The North American Monsoon System (NAMS) contributes ~55% of the annual rainfall in the Chihuahuan Desert during the summer months. Relatively frequent, intense storms during the NAMS increase soil moisture, reduce surface temperature and lead to runoff in ephemeral channels. Quantifying these processes, however, is difficult due to the sparse nature of coordinated observations. In this study, I present results from a field network of rain gauges (n = 5), soil probes (n = 48), channel flumes (n = 4), and meteorological equipment in a small desert shrubland watershed (~0.05 km2) in the Jornada Experimental. Using this high-resolution network, I characterize the temporal and spatial variability of rainfall, soil conditions and channel runoff within the watershed from June 2010 to September 2011, covering two NAMS periods. In addition, CO2, water and energy measurements at an eddy covariance tower quantify seasonal, monthly and event-scale changes in land-atmosphere states and fluxes. Results from this study indicate a strong seasonality in water and energy fluxes, with a reduction in Bowen ratio (B, the ratio of sensible to latent heat fluxes) from winter (B = 14) to summer (B = 3.3). This reduction is tied to shallow soil moisture availability during the summer (s = 0.040 m3/m3) as compared to the winter (s = 0.004 m3/m3). During the NAMS, I analyzed four consecutive rainfall-runoff events to quantify the soil moisture and channel flow responses and how water availability impacted the land-atmosphere fluxes. Spatial hydrologic variations during events occur over distances as short as ~15 m. The field network also allowed comparisons of several approaches to estimate evapotranspiration (ET). I found a more accurate ET estimate (a reduction of mean absolute error by 38%) when using distributed soil moisture data, as compared to a standard water balance approach based on the tower site. In addition, use of spatially-varied soil moisture data yielded a more reasonable relationship between ET and soil moisture, an important parameterization in many hydrologic models. The analyses illustrates the value of high-resolution sampling for quantifying seasonal fluxes in desert shrublands and their improvements in closing the water balance in small watersheds.
ContributorsTempleton, Ryan (Author) / Vivoni, Enrique R (Thesis advisor) / Mays, Larry (Committee member) / Fox, Peter (Committee member) / Arizona State University (Publisher)
Created2011
Description
I believe the human mind is not an accurate reproducer of objects and events, but a tool that constructs their qualities. Philosophers Bowman Clarke, James John, and Amy Kind have argued for and against similar points, while Daniel Hoffman and Jay Dowling have debated cases from a psychological perspective. My understanding of their discourse surfaces in Cognize Normal-Like Pleez, a video installation designed to capture the enigmatic connection between perceivers and the things they perceive. The composition encapsulates this theme through a series of five videos that disseminate confusing imagery paired with mangled sounds. The miniatures operate in sequence on computer monitors set inside a haphazardously ornamented tower. Though the original sources for each video communicate clear, familiar subjects, the final product deliberately obscures them. Sometimes sounds and images flicker for only brief moments, perhaps too fast for the human mind to fully process. Though some information comes through, important data supplied by the surrounding context is absent.
I invite the audience to rationalize this complexing conglomerate and reflect on how their established biases inform their opinion of the work. Each person likely draws from his or her experiences, cultural conditioning, knowledge, and other personal factors in order to create an individual conceptualization of the installation. Their subjective conclusions reflect my belief concerning a neurological basis for the origin of qualities. One’s connection to Cognize’s images and sounds, to me, is not derived solely from characteristics inherent to it, but also endowed by one’s mind, which not only constructs the attributes one normally associates with the images and sounds (as opposed to the physics and biology that lead to their construction), but also seamlessly incorporates the aforementioned biases. I realize my ideas by focusing the topics of the videos and their setting around the transmission of information and its obfuscation. Just as one cannot see or hear past the perceptual barriers in Cognize, I believe one cannot escape his or her mind to “sense” qualities in an objective, disembodied manner, because the mind is necessary for perception.
I invite the audience to rationalize this complexing conglomerate and reflect on how their established biases inform their opinion of the work. Each person likely draws from his or her experiences, cultural conditioning, knowledge, and other personal factors in order to create an individual conceptualization of the installation. Their subjective conclusions reflect my belief concerning a neurological basis for the origin of qualities. One’s connection to Cognize’s images and sounds, to me, is not derived solely from characteristics inherent to it, but also endowed by one’s mind, which not only constructs the attributes one normally associates with the images and sounds (as opposed to the physics and biology that lead to their construction), but also seamlessly incorporates the aforementioned biases. I realize my ideas by focusing the topics of the videos and their setting around the transmission of information and its obfuscation. Just as one cannot see or hear past the perceptual barriers in Cognize, I believe one cannot escape his or her mind to “sense” qualities in an objective, disembodied manner, because the mind is necessary for perception.
ContributorsLempke, John Paul (Author) / Suzuki, Kotoka (Thesis advisor) / Knowles, Kristina (Committee member) / Stover, Chris (Committee member) / Arizona State University (Publisher)
Created2018