95 research outputs found
Moving Composition: Writing in a Mobile World
We live in an increasingly mobile society on many levels. Mobile devices, including the smartphone, tablet, and wearables, allow for composing and communicating from anywhere and in new ways, a phenomenon that is especially deserving of attention by composition studies scholars and teachers. Mobile composition processes are impacted by the symmetry of humans and technology as each equally shapes one another. This interplay of mobile devices (including wearables) and humans impacts composition ecologies, processes, and definitions of writing. The role of analog mobile writers also informs our current practices and approaches to a mobile composition as many writers have sought to write on the move. Educational researchers identify mobile learning as unique with attributes not afforded in analog or tethered learning environments. Mobile composition is poised to take advantage of the authentic, collaborative, and new opportunities for making meaning that exist in this form of teaching and learning. Mobile composition also transcends the literature from established composition studies and mobile learning frameworks by residing and inventing the burgeoning digital apparatus, electracy, that follows and extends the practices of oral and literate civilizations. Electracy\u27s teaching and learning corollary, post(e)-pedagogy, offers ways to make use of mobile devices in this new framework. Finally, this dissertation project includes a mobile composition course prototype that models a post(e)-pedagogical approach and encourages further critical exploration and invention of communication practices with mobile devices, especially by composition faculty and students but in higher education overall
Mesospheric Temperature Climatology and Comparisons Above the Rocky Mountains
A Rayleigh-scatter lidar has been operated by the Center for Atmospheric and Space Sciences (CASS) at Utah State University (USU) since 1993. The lidar measures atmospheric temperatures between 45 and 90 km which are important for understanding the physics and chemistry of the middle atmosphere. The temperature profiles were used to create a multi-year temperature climatology. This climatology was used for comparisons with the temperature climatology from the Purple Crow Lidar at the University of Western Ontario, and nightly temperature profiles from the SABER instrument on board the TIMED satellite
Rayleigh-Scatter Lidar Observations at USU\u27s Atmospheric Lidar Observatory (Logan,UT) - Temperature Climatology, Temperature Comparisons with MSIS, and Noctilucent Clouds
The Earth\u27s atmosphere is typically characterized by its temperature structure, which naturally divides the atmosphere into several discrete regions. They are in order of increasing altitude the troposphere, stratosphere, mesosphere, and thermosphere. The first layer and a large portion of the second layer of the Earth\u27s atmosphere are routinely measured via weather balloons that are launched twice daily around the globe. Satellites and their development have motivated the study of the thermosphere. It is the middle region of the Earth atmosphere, which is mainly composed of the mesosphere that lacks routine in situ measurements. Routine observations are therefore carried out via remote sensing. Ground-based instruments typically provide high resolution measurements of the atmosphere over a single point on the globe and space-based instrument capture a global picture at lower resolution.
A Rayleigh-scatter lidar has been in operation at Utah State University ( 41 . 7°N III .8°N) starting in September 1993. Observations have continued from that point until the present when funding and observing conditions have permitted. Under normal observational conditions the backscattered photons are proportional to the atmospheric density. These relative density profiles can be used to derive absolute temperature profiles over much of the middle atmosphere. The resulting II years of temperature profiles have been combined into a single composite year which contains - 900 nights and - 5000 hours of observations. This climatology was compared to the mid-latitude climatology from the French lidar group at Haute Provence and relatively good agreement was obtained. It was also compared to the NRL MSIS empirical model to explore the model\u27s validity at mid-latitudes. Some significant differences were found.
The coldest atmospheric temperatures are found at the mesopause near the summer solstice. Small ice crystals formed in this region and can grow to form noctilucent clouds (NLC) which are the highest naturally occurring clouds in the atmosphere. Previously, NLC observations have been limited to the region poleward of so• but NLCs have been observed with the ALO lidar on two occasions. Their formation has been attributed to atmospheric dynamics, a large amplitude wave, rather than a general cooling of the atmosphere
MESOSPHERIC TEMPERATURE CLIMATOLOGY ABOVE UTAH STATE UNIVERSITY
A Rayleigh-scatter lidar has been in operation at Utah State University (41.7o N, 111.8 ° W) starting in September 1993 until the present (October 2003). The return profiles from the atmosphere have been analyzed to provide temperature measurements of the middle atmosphere from 45 to 90 km. Various methods of averaging were used to construct a temperature climatology of the region based on these observations. The data analysis algorithm has been critically analyzed to find possible sources of error, and has been compared to an independently derived technique. The resulting temperatures have been compared to other mid-latitude lidars with good agreement. Comparisons were made with temperatures from other ground-based instruments at Bear Lake Observatory. Additional comparisons were carried out with two satellite-based instruments, WINDII and SABER. The comparison of individual nights with the SABER instrument produced surprisingly good agreement considering the difference in the two methds. With the basic analysis of the temperature climatology completed in this work, an outline is given for future research and upgrades to the facility
Mesospheric Temperature Climatology at the USU/CASS Atmospheric Lidar Observatory (ALO)
The Center for Atmospheric and Space Sciences (CASS) at Utah State University (USU) operates the ALO for the study of the middle atmosphere. Mesospheric observations between 45 and 90 km have been carried out on an observe when possible philosophy at night from 1993 to present. The location of ALO is unique as its mid-latitude location places it well within the Rocky Mountains which are a major orographic source for gravity waves. The lidar facility is located on the Utah State University campus, where it is very accessible to students. The relative observations from the lidar are reduced to provide absolute temperature profiles, which are important for understanding the physics and chemistry of the middle atmosphere. The temperature profiles were used to create a multi-year temperature climatology to examine secular, annual, seasonal variations, to compare with other temperature observations, and with modeled temperatures
An Earlier Lidar Observation of a Noctilucent Cloud above Logan, Utah (41.7Âş N, 111.8Âş W)
A Rayleigh-scatter lidar has been operated at the Atmospheric Lidar Observatory (ALO) on the Utah State University (USU) campus (41.7º N, 111.8º W) for the last 11 years. During the morning of 22 June 1995 a noctilucent cloud (NLC) was observed with the lidar, for approximately one hour, well away from the twilight periods when NLCs are visible. This sighting of an NLC at this latitude shows that the first sighting in 1999 [Wickwar et al., 2002] was not a unique occurrence. This 1995 observation differs from the 1999 one in that temperatures could be deduced. The hourly profiles are at least 20 K cooler than the 11-year June climatology for ALO near the NLC altitude. However, the cool temperatures arose because of a major temperature oscillation or wave, not because the whole profile was cooler. These lidar observations were supplemented by OH rotational observations from approximately 87 km, which also showed unusually cold temperatures on this night. While these NLC observations equatorward of 50° may be significant harbingers of global change, the mechanism is more complicated than a simple overall cooling or increase in water vapor
Atmospheric Lidar Observatory (ALO) Ten-Year Mesospheric Temperature Climatology
The Rayleigh-scatter lidar at the Atmospheric Lidar Observatory (ALO) on the Utah State University (USU) (41.7°N, 111.8°W) campus has been in operation since 1993. The temperature database now contains over ten years of Rayleigh-scatter temperatures. A multi-year temperature climatology has been calculated from these observations along with the RMS and interannual variability. These temperatures and the climatology are currently being used in a number of mesospheric studies, including mesospheric inversion layers, tides, planetary waves, cyclical variations, trends, longitudinal comparisons, and validation studies
Mid-Latitude Climatologies of Mesospheric Temperature and Geophysical Temperature Variability Determined with the Rayleigh-Scatter Lidar at ALO-USU
From 1993-2004, 839 nights were observed with the Rayleigh-scatter lidar at Utah State University’s Atmospheric Lidar Observatory. They were reduced to obtain nighttime mesospheric temperatures between 45 and ~90 km, which were then combined to derive composite annual climatologies of mid-latitude temperatures and geophysical temperature variability. At 45 km, near the stratopause, there is a ~250 K temperature minimum in mid-winter and a 273 K maximum in mid-May. The variability behaves oppositely, being 7-10 K in winter and 2.5 K in summer. At 85 km, there is a 215 K temperature maximum at the end of December and a 170 K mesopause minimum in early June. In contrast, the variability is roughly constant at ~20 K. At both low and high altitudes, the temperatures change much more rapidly in spring than in fall. The transition between these opposite temperature behaviors is 65 km. Distinctive temperature structures occur in all regions. In mid-winter, between 45 and 50 km, a 6 K warm region appears, most likely from occasional sudden stratospheric warmings. Above that, a “cold valley” extends to 70 km, which may be related to the bottom side of intermittent inversion layers. Both regions have increased variability. Near 85 km, there is a very rapid heating event of 25 K/month in August with high variability. In October, a temperature minimum, a “cold island”, occurs from 78–86 km with low variability, indicating a regular feature. These USU results are compared extensively to those from other mid-latitude lidars in Canada and France
Middle Atmosphere Temperature Results from a New, High-powered, Large-Aperture Rayleigh Lidar
In June–July 2012, observations were carried out using the recently upgraded, large-aperture, Rayleigh-scatter lidar system located at the Atmospheric Lidar Observatory (ALO) on the campus of Utah State University, in Logan, UT (41.7 N, 111.8 W). This time period was significant because it enabled us to observe the annual temperature minimum in the upper mesosphere-lower thermosphere region. The data collected during the campaign were analyzed for temperatures between ~70–109 km. The results above ~95 km are the first obtained with a Rayleigh-scatter lidar, extending the technique well into the lower thermosphere. A great deal of variability from night-to-night is evident in these temperature profiles and in the mesopause altitude. The profiles also show considerable wave activity from large amplitude waves. The temperatures are compared to those from the MSISe90 model and from the 11-year ALO temperature climatology. This new capability for the ALO Rayleigh lidar, like any new observational capability, opens the potential for new discoveries in this hard-to-observe region
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