Matching Items (15)
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Description
Dust devils have proven to be commonplace on Mars, although their occurrence is unevenly distributed across the surface. They were imaged or inferred by all six successful landed spacecraft: the Viking 1 and 2 Landers (VL-1 and VL-2), Mars Pathfinder Lander, the Mars Exploration Rovers Spirit and Opportunity, and the

Dust devils have proven to be commonplace on Mars, although their occurrence is unevenly distributed across the surface. They were imaged or inferred by all six successful landed spacecraft: the Viking 1 and 2 Landers (VL-1 and VL-2), Mars Pathfinder Lander, the Mars Exploration Rovers Spirit and Opportunity, and the Phoenix Mars Lander. Comparisons of dust devil parameters were based on results from optical and meteorological (MET) detection campaigns. Spatial variations were determined based on comparisons of their frequency, morphology, and behavior. The Spirit data spanning three consecutive martian years is used as the basis of comparison because it is the most extensive on this topic. Average diameters were between 8 and 115 m for all observed or detected dust devils. The average horizontal speed for all of the studies was roughly 5 m/s. At each site dust devil densities peaked between 09:00 and 17:00 LTST during the spring and summer seasons supporting insolation-driven convection as the primary formation mechanism. Seasonal number frequency averaged ~1 dust devils/ km2/sol and spanned a total of three orders of magnitude. Extrapolated number frequencies determined for optical campaigns at the Pathfinder and Spirit sites accounted for temporal and spatial inconsistencies and averaged ~19 dust devils/km2/sol. Dust fluxes calculated from Pathfinder data (5x10-4 kg/m2/s and 7x10-5 kg/m2/s) were well with in the ranges calculated from Spirit data (4.0x10-9 to 4.6x10-4 kg/m2/s for Season One, 5.2x10-7 to 6.2x10-5 kg/m2/s during Season Two, and 1.5x10-7 to 1.6x10-4 kg/m2/s during Season Three). Based on the results a campaign is written for improvements in dust devil detection at the Mars Science Laboratory's (MSL) site. Of the four remaining candidate MSL sites, the dusty plains of Gale crater may potentially be the site with the highest probability of dust devil activity.
ContributorsWaller, Devin (Author) / Greeley, Ronald (Thesis advisor) / Christensen, Philip R. (Philip Russel) (Committee member) / Cerveny, Randall (Committee member) / Arizona State University (Publisher)
Created2011
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Description
Large, violent storms come through the Phoenix area during monsoon season, and currently, the best ways to predict them are not very accurate. The primary goal of this investigation is to see if a mechanism can be developed for the prediction of these storms in Phoenix during monsoon season. In

Large, violent storms come through the Phoenix area during monsoon season, and currently, the best ways to predict them are not very accurate. The primary goal of this investigation is to see if a mechanism can be developed for the prediction of these storms in Phoenix during monsoon season. In order to answer this question, two data sets (a remote sensing satellite imagery and a ground-based weather information set) will be used and their measurements will be compared against one another using a corresponding time as the related variable. The goal is to try and identify some type of correlation or explanation of correlation. Events known as moisture surges (from the gulf surge \u2014 which comes from the California Gulf) will be identified and then compared in some detail. These chutes of moisture surge through Arizona, primarily up through Yuma in a northeasterly direction. The point of the investigation is to prove or disprove that satellite imagery can be used as an analog for dew point measurements in areas where ground measurements are not available. If this can be demonstrated, then, because of the high temporal resolution of the remote sensing data, satellite imagery could be used as an identifier of oncoming storms.
ContributorsCarter, Shaylina Rae (Author) / Christensen, Phil (Thesis director) / Cerveny, Randall (Committee member) / Hagee, Warren (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / School of Earth and Space Exploration (Contributor)
Created2013-05
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Description
The Great Plains region of the central United States and southern Canada is a promising location for wind energy resource development. Wind energy site assessments and forecasts can benefit from better understanding the variability that may result from several teleconnections affecting North America. This thesis investigates how the El Niño/Southern

The Great Plains region of the central United States and southern Canada is a promising location for wind energy resource development. Wind energy site assessments and forecasts can benefit from better understanding the variability that may result from several teleconnections affecting North America. This thesis investigates how the El Niño/Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO), and the Pacific/North American Pattern (PNA) impact mean monthly wind speeds at 850 hPa over the Great Plains. Using wind speeds from the NCAR/NCEP Reanalysis 1, correlations were computed between the mean monthly wind speeds and average monthly teleconnection index values. A difference of means test was used to compute the change in wind speeds between the positive and negative phases of each index. ENSO was not found to have a significant impact on wind speeds, while the NAO and PNA patterns weakly affected wind speeds. The NAO index was positively (negatively) correlated with wind speeds over the northern (southern) plains, while the PNA index was negatively correlated with wind speeds over most of the plains. Even a small change in wind speed can have a large effect on the potential power output, so the effects of these teleconnections should be considered in wind resource assessments and climatologies.
ContributorsOrdonez, Ana Cristina (Author) / Cerveny, Randall (Thesis director) / Svoma, Bohumil (Committee member) / Balling, Robert (Committee member) / Barrett, The Honors College (Contributor) / School of Geographical Sciences and Urban Planning (Contributor)
Created2013-05
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Description
The Mid-South region, which consists of west Tennessee, northeast Arkansas, north Mississippi, and the Missouri bootheel, is one of many areas in the United States that frequently faces the threats to life and property posed by tornadoes. Forecasting the occurrence of tornadoes is arguably the biggest challenge for meteorologists responsible

The Mid-South region, which consists of west Tennessee, northeast Arkansas, north Mississippi, and the Missouri bootheel, is one of many areas in the United States that frequently faces the threats to life and property posed by tornadoes. Forecasting the occurrence of tornadoes is arguably the biggest challenge for meteorologists responsible for the region. This study analyzes synoptic scale weather conditions associated with tornadoes in the Mid-South with the hopes of identifying patterns conducive to tornadic activity and that these patterns can be used to better forecast potential tornado days. It is hypothesized that patterns associated with tornado formation can be identified and that certain patterns may be more favorable to stronger tornadoes or tornado outbreaks than others.
To find these patterns, I analyzed surface and upper air features were analyzed on days where multiple tornadoes occurred from January 1999 to March 2018. Specifically, the surface low pressure, 500hPa trough, and 850 and 300hPa jets were analyzed. Using a floating nine point grid system, I identified the location of the Mid-South in relation to the feature. In the end, eight patterns of similar grid locations were identified to be related to tornado days. For example, the Mid-South was frequently to the southeast of the surface low. However, no correlation appears to exist between the patterns and the number or intensity of tornadoes. It is recommended that in the future these patterns be tested as a forecast method and/or compared to non-tornado days to verify that they are valid tools.
ContributorsWanless, Anna Cecilia (Author) / Cerveny, Randall (Thesis director) / Svoma, Bohumil (Committee member) / School of Geographical Sciences and Urban Planning (Contributor, Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
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Description

Arizona is a unique state in that rain is not a normal occurrence throughout most of the year (NWS). Arizona averages from less than three months to half a month of measurable precipitation days per year (WRCC). With that, it is important to know the public’s understanding as well as

Arizona is a unique state in that rain is not a normal occurrence throughout most of the year (NWS). Arizona averages from less than three months to half a month of measurable precipitation days per year (WRCC). With that, it is important to know the public’s understanding as well as their general trend of likeness towards the weather forecasts they receive. A questionnaire was distributed to 426 people in the state of Arizona to review what they understand from the forecasts and what they would like to see on social media and television.

ContributorsHermansen, Alexis Nicole (Author) / Alvarez, Melanie (Thesis director) / Cerveny, Randall (Committee member) / Hondula, David M. (Committee member) / Walter Cronkite School of Journalism & Mass Comm (Contributor) / School of Geographical Sciences and Urban Planning (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
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Description
The El Niño Southern Oscillation (ENSO) consists of a linkage between changes in sea-surface temperatures and atmospheric pressure across the Tropical Pacific. ENSO encompasses three phases: neutral events, warm/El Niño events in which sea-surface temperatures are warmer-than-normal and the pressure gradient decreases across the Equatorial Pacific, and cold/La Niña events

The El Niño Southern Oscillation (ENSO) consists of a linkage between changes in sea-surface temperatures and atmospheric pressure across the Tropical Pacific. ENSO encompasses three phases: neutral events, warm/El Niño events in which sea-surface temperatures are warmer-than-normal and the pressure gradient decreases across the Equatorial Pacific, and cold/La Niña events in which Tropical Pacific sea-surface temperatures are cooler-than-normal and the pressure gradient increases. Previous studies have determined a connection between variations in ENSO phase and weather patterns across the globe, focusing particularly on surface temperature and precipitation patterns in the United States. However, little research exists that attempts to link changes in ENSO phase with severe weather in Arizona. Therefore, in this study, I analyzed how variations in ENSO phase affect the frequency, intensity, and spatial distribution of four types of severe weather from 1959 to 2016 in Arizona, including a) tornado events, b) severe thunderstorm wind events, c) hail events, and d) heavy rain and flash flood events. I collected data on the Oceanic Niño Index (ONI), a measure of ENSO, as well as storm reports for each severe weather phenomenon dating back to 1959. Then, I analyzed the frequency of each Arizona severe weather event type within each of the twelve annual months and over the entire study period. I also analyzed mean intensity values (Fujita/Enhanced Fujita Scale rating, path width, and path length for tornadoes; hail diameter in millimeters for hail; and wind gust speed for severe thunderstorm wind events) for each severe weather phenomenon, excluding the heavy rain and flash flood events. Finally, I used the Mean Center and Directional Distribution tools in ArcGIS to determine variations in the spatial distribution and mean centers between each ENSO phase for each severe weather event type. I found that ENSO phase, particularly La Niña, does impact the frequency and intensity of tornadoes, hail, thunderstorm wind, and heavy rain/flash flood events in Arizona. However, it appears that ENSO does not affect the spatial distribution of these Arizona severe weather phenomena. These findings attempt to fill in the gap in the literature and could help meteorologists better forecast changes in Arizona severe weather, in turn allowing Arizonans to better prepare for and mitigate the effects of severe weather across the state.
ContributorsGreenwood, Trey Austin (Author) / Cerveny, Randall (Thesis director) / Balling, Robert (Committee member) / School of Geographical Sciences and Urban Planning (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
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Description

High levels of surface ozone pollution have been shown to have adverse effects on human health and our environment. For at least the past decade, ozone concentrations in Phoenix, Arizona have been above the federal health standard, set in place by the Environmental Protection Agency. It is crucial that all

High levels of surface ozone pollution have been shown to have adverse effects on human health and our environment. For at least the past decade, ozone concentrations in Phoenix, Arizona have been above the federal health standard, set in place by the Environmental Protection Agency. It is crucial that all factors contributing to rising tropospheric ozone levels within the Phoenix metropolitan area are analyzed to better understand this risk for future mitigation efforts. Consequently, the primary objective of this study is specifically to examine meteorological factors' influence on Phoenix’s ground level ozone by comparing days of ozone exceedances with ozone non-exceedances days over the course of 2010-2020. To carry out this research, various weather conditions for both exceedance and non-exceedance ozone days were studied using unpaired Student’s t-tests and Pearson product-moment correlation tests. The results of this study suggest that the most significant factors that are associated with the occurrence of surface ozone exceedances in Phoenix are wind speed and temperature, whereas the least significant variables are wind direction and sky conditions. This indicates that more stable synoptic conditions in which skies are clearer, allowing for higher temperatures and more stagnant air movement, are ideal for ozone production leading to an ozone exceedance. The results from this honors thesis will be useful as it will aid in greater understanding of the relationship between Phoenix’s surface ozone and weather, aiding future ozone forecasting.

ContributorsLeffel, Jessica (Author) / Cerveny, Randall (Thesis director) / Pace, Matthew (Committee member) / Krahenbuhl, Dan (Committee member) / Barrett, The Honors College (Contributor) / School of International Letters and Cultures (Contributor) / Hugh Downs School of Human Communication (Contributor) / School of Geographical Sciences and Urban Planning (Contributor)
Created2022-05
Description
This study examines the linkage between surface level ozone and planetary boundary layer meteorological variables in the Phoenix Metropolitan region during the summer North American Monsoon period for years 2010 through 2020. Data used in this study was obtained and derived from both 1200 UTC radiosonde observations launched from the

This study examines the linkage between surface level ozone and planetary boundary layer meteorological variables in the Phoenix Metropolitan region during the summer North American Monsoon period for years 2010 through 2020. Data used in this study was obtained and derived from both 1200 UTC radiosonde observations launched from the Phoenix National Weather Service office, and 8-hour average ozone concentration measurements from Maricopa County monitoring stations. Specific boundary layer meteorological variables examined in this study included inversion temperature, mixing level pressure, mixing level height, and the surface level variables of temperature, dew point temperature, pressure, wind speed, and meridional and zonal wind directions. The daily maximum, 8-hour average ozone concentrations among all Maricopa County monitoring stations were used in this study. To determine ozone’s linkage to meteorological variables, normality tests, determination of Pearson product moment correlation coefficient and/or the Spearman rank correlation coefficient, and the discriminative Student’s two-sided t-test statistic between ozone exceedance and non-exceedance days were used. Statistically significant coefficients indicate weak negative correlations between surface level ozone and surface level pressure, and mixing level pressure, and weak positive correlations between surface level ozone and surface level temperature, surface level zonal wind direction, mixing level height, and inversion temperature. These correlations were linear for surface level pressure, surface level temperature, and inversion temperature. The two-sided Student’s t-test statistic indicates a significant difference in the mean on ozone exceedance and non-exceedance days for surface level temperature, and the upper-air variables of mixing level height, mixing level pressure, and inversion temperature. Both correlations and differences in the mean of upper-air variables showed statistically significant results. These findings suggest that further research should be completed to determine the forecasting ability of morning sounding analyses on surface level ozone in locations exhibiting similar emissions and geographic features as the Phoenix Valley.
ContributorsLopez, David (Author) / Cerveny, Randall (Thesis director) / Balling, Robert (Committee member) / Barrett, The Honors College (Contributor) / School of Music, Dance and Theatre (Contributor) / Department of Physics (Contributor) / School of Geographical Sciences and Urban Planning (Contributor)
Created2023-05