Meteorology Commons^™

Adaptive Monte Carlo Sampling For Cloud And Microphysics Calculations, Thomas Franz-Peter Roessler

Theses and Dissertations

An important problem in large-scale modeling of the atmosphere is the parametrization of clouds and microphysics on subgrid scales. The framework Cloud Layers Unified By Binormals (CLUBB) was developed to improve the parametrization of subgrid variability. Monte Carlo sampling is used to couple the different physical processes, which improves the grid average of subgrid tendencies.

In this Thesis we develop an adaptive Monte Carlo sampling algorithm that re-uses sample points of the previous time step by re-weighting them according to the change of the underlying distribution. This process is called 'what-if sampling' and is an application of importance sampling. An …

Influence Of Ndbc Buoy Design On Sea Surface Temperature Trends In The Coastal United States, Alexander Keith Nickerson

Theses and Dissertations

The sea surface temperature (SST) record is the one of the oldest climate records, stretching back to 1662. Since that time, voluntary observing ships (VOSs) have been including these data in their ship‘s log. Due to the sparseness of VOS data, moored buoys were created to provide data at regular intervals in order to provide a more continuous record with data collection unaffected by human error. The SST sensor in National Data Buoy Center (NDBC) buoys is inside a hull and not in direct contact with the ocean. Thus, the design of the buoy may subject them to additional biases …

An Analysis Of The Moisture And Moist Static Energy Budgets In Amip Simulations, Kristine Adelaide Boykin

Theses and Dissertations

An analysis of the second phase of the Atmospheric Model Intercomparison Project (AMIP) simulations has been conducted to understand the physical processes that control precipitation in the tropics. This is achieved primarily through the analysis of the moisture and moist static energy budgets. Overall, there is broad agreement between the simulated and observed precipitation, although specific tropical regions such as the Maritime Continent poses challenges to these simulations. The models in general capture the latitudinal distribution of precipitation and key precipitating regions including the Inter-Tropical Convergence Zone (ITCZ) and the Asian Monsoon. The simulations portrayed the global patterns of evaporation …

Surface Cooling Due To Precipitation In The Tropics, Camila Gomes Martins Ramos

Theses and Dissertations

Precipitation is an important component of the global hydrological cycle. It affects the upper ocean salinity by adding freshwater to the ocean. In addition, precipitation plays a role in cooling the ocean and land surfaces, when the temperature of the raindrops is lower than the temperature of the surface. However, the surface cooling due to precipitation (QP) remains an overlooked feature and is not included in the Intergovernmental Panel on Climate Change (IPCC) models. One might expect that heavy precipitation events may lead to large QP, which can impact the surface temperature, surface energy balance, and local- to regional-scale circulations. …

Meeting The Dod’S Tactical Weather Needs Using Cubesats, Shayna K. Mckenney

Theses and Dissertations

This thesis investigates a CubeSat design that uses Commercial-Off-The-Shelf (COTS) components to capture, store, process, and downlink collected terrestrial weather data at resolutions near stat-of-the-art. The weather phenomena to be detected and transmitted in a timely manner are cloud formations, wind profiles, ocean currents, sea state, lightning, temperature profiles, and precipitation. It is hypothesized and shown that the proposed design will provide an improvement on the current U.S. tactical weather collection satellites because of the anticipated increased reliability and lowered cost to build and maintain the proposed CubeSat constellation. The methodology employed a multi-phase approach through the collective research of …

The Influence Of Assimilated Targeted Observations Upon Ensemble Forecasts Of Convection Initiation, Alexandra Marie Keclik

Theses and Dissertations

The influence of assimilating targeted meso-α- to synoptic-scale observations collected in the upstream, pre-convective environment upon subsequent short-range ensemble forecasts of convection initiation (CI) across the central United States for the fifteen aircraft missions conducted by the Mesoscale Predictability Experiment (MPEX) in May and June 2013 is evaluated in this study. Utilizing the ensemble Kalman filter implementation within the Data Assimilation Research Testbed software package as coupled to version 3.4.1 of the Advanced Research version of the Weather Research and Forecasting model, two nearly-identical thirty- member ensembles of short-range forecasts are conducted for each mission. Initial conditions for one ensemble …

The Reliability And Skill Of Air Force Weather’S Ensemble Prediction Suites, Derek A. Burns

Theses and Dissertations

The Ensemble Prediction Suites (EPS) used at the 557th Weather Wing (557 WW) provide probability based forecasts for thousands of worldwide locations. Point Ensemble Probability (PEP) bulletins are tailored specifically to the United States military and its criteria for operationally significant weather. This study assesses the performance of PEPs from each EPS at 17 Continental United States (CONUS) locations. Results from April to October of 2015 show that each EPS is underforecasting ceilings and visibility for most forecast hours at several locations. The underforecasting of ceilings is most severe at Vandenberg AFB, an area prone to frequent marine layer fog …

Forecasting Sea Breeze Enhanced Thunderstorms At Eglin Air Force Base: A Comparison Between Empirical Methods And The High Resolution Rapid Refresh Model, Matthew P. King

Theses and Dissertations

Summer thunderstorms pose the greatest forecast challenge for the United States Air Force's 96th Weather Flight (96WF) which provides weather support for Eglin Air Force Base (AFB). Located on Florida's panhandle, Eglin AFB encompasses the Department of Defense's largest range complex which covers 134,000 sq mi (347,000 sq km) of water and 724 sq mi (1875 sq km) of land. Due to the base's coastal location and unique coastline geometry, sea breeze is a dominant forecast consideration for thunderstorms. The 96 WF currently utilizes an empirical method, called WINNDEX, developed by former staff meteorologist Roger Winn to aid in thunderstorm …

Operational Exploitation Of Satellite-Based Sounding Data And Numerical Weather Prediction Models For Directed Energy Applications, David C. Meier

Theses and Dissertations

The wealth of available scientific data collected by the modern constellation of meteorological satellites can be exploited in new and innovative ways, with direct benefit to directed energy applications. The Atmospheric Infrared Sounder (AIRS) provides accurate, geolocated temperature data, which are used as the starting point for the derivation of atmospheric parameters critical to prediction of sensor or directed energy system performance. Twenty-four hour data coverage is achieved by extending the atmospheric characterization between satellite observations using Numerical Weather Prediction (NWP) models. A technique is developed to derive wind profiles using AIRS temperature data and the accuracy of these winds …

Predictability Of Sea Ice Near Bifurcations, Dawn Marie Kopacz

Theses and Dissertations

There is evidence in Earth’s history of relatively stable climate regimes abruptly transitioning to alternative states. It has been argued that the greatest potential for such abrupt transitions in Earth’s system in the near future is located in the Arctic. Here we analyze the Arctic sea ice evolution of two current generation climate models that exhibit critical transitions. We demonstrate the detectability of two early warning signals: increased variance and increased autocorrelation. We introduce another metric that forewarns of abrupt changes in sea ice; a decrease in predictability before the threshold points. Observations of Arctic sea ice extent are searched …

Seasonal Influences Upon And Long-Term Trends In The Length Of The Atlantic Hurricane Season, Juliana Marie Karloski

Theses and Dissertations

Atlantic tropical cyclone (TC) seasons vary yearly in length with some seasons significantly shorter or longer than normal. Kossin (2008) suggested that from 1980 to 2007, the Atlantic TC season increased in length; however, their study only considered a subset of the Atlantic basin south of 30°N and east of 75°W. It is uncertain whether this trend holds over the entire Atlantic basin or continues into the present. It is also unclear as to whether meaningful sub-seasonal variability in the environmental factors necessary for TC formation exists between early- and late-starting and -ending seasons.

Quantile regression is used to evaluate …

Using A Semiprognostic Test To Elucidate Key Model Errors Of Warm Rain Processes Within A Unified Parameterization Of Clouds And Turbulence, Justin Kyle Weber

Theses and Dissertations

The representation of clouds and turbulence remains one of the foremost challenges in modeling earth's climate system and continues to remain one of the greatest sources of uncertainty in future climate projections. Increased attention has been given to unifying cloud and turbulence parameterizations in order to avoid the artificial categorization of cloud and turbulence regimes. One such unified parameterization is known as the Cloud Layers Unified by Binormals (CLUBB). CLUBB is a single column model of clouds and turbulence that assumes subgrid scale variability can be represented by a joint probability density function (PDF) of temperature, moisture, momentum, and hydrometeors. …

Utilizing Four Dimensional Lightning And Dual-Polarization Radar To Develop Lightning Initiation Forecast Guidance, Andrew J. Travis

Theses and Dissertations

Lightning initiation is a major forecast challenge faced by Air Force's 45th Weather Squadron (45 WS), which provides weather support to Cape Canaveral Air Force Station and Kennedy Space Center (KSC). Prior studies by Thurmond (2014) and Woodard (2011) have shown that dual-polarization (DP) radar can be used to identify the presence of hydrometeors indicative of cloud charging, leading to improved lightning initiation forecasts. The 45 WS currently employs empirical lightning initiation forecast rules which state that in-cloud lightning is likely when radar reflectivity meets or exceeds 37.0 dBZ above the -10°C height. This study examined 249 convective cells from …

Evaluating The Surface Layer Wind Profile In The Wrf, Robert Stephen James

Theses and Dissertations

The purpose of this thesis is to investigate how the surface vertical wind profile responds to different planetary boundary layer schemes in computer models. Local surface roughness is one of the elements represented in these schemes, and is used when interpolating winds down from the lowest model level to the surface, so this needs to be accurately represented in the model. Computer models rely on one bulk estimate of surface roughness for a given grid point, despite the complexity of surrounding terrain. Data for this research was gathered from local surface observations and computer simulations, which looked at two different …

A Preliminary Evaluation Of Advanced Dvorak Technique-Derived Intensity Estimate Errors And Biases During The Extratropical Transition Of Tropical Cyclones Using Synthetic Satellite Imagery, Alex Manion

Theses and Dissertations

Real-time and historical tropical cyclone (TC) intensity estimates during extratropical transition (ET) are derived mainly from satellite-based methods such as the Dvorak Technique (DT) and Advanced Dvorak Technique (ADT). However, the empirical relationships developed between cloud organization patterns and cyclone intensity that underlie the DT and ADT are primarily tropical in nature and thus become less reliable during ET. Preliminary analyses suggest that ADT-derived intensity estimates are weak-biased during ET; however, due to the lack of direct observations of cyclone intensity during ET, the extent to which this is true is unknown. Herein, an attempt to quantify errors during this …

Multi-Periodic Climate Dynamics: Spectral Analysis Of Instrumental, Short- And Long-Length Proxy Temperature Records, Michael David Madsen

Theses and Dissertations

Analyzing 26 short-length (less than 3000 years) instrumental and proxy temperature records and five long-length (greater than 3000 years) proxy temperature records using Discrete Fourier Transform has shown that as the length of significant periods increase in the time domain then so does the power at which the period is observed. A t-test verifies that a positive correlation exist between the length of the significant periods and the power with a confidence level of ∝ >0.05. Significant frequencies with period greater than 30 years are confirmed using Monte Carlo simulations, which were created using a nonlinear approach known as fractional …

Re-Examining An Air Mass-Based Approach To Detecting Structural Climate Change, 1948-2011, Joseph James Larsen

Theses and Dissertations

Air mass-based approaches to observing changes in climate can have considerable value beyond simple trends of temperature and moisture, providing more thorough understanding of structural climate patterns. Few methodologies have adequately characterized recent air mass modification, however. This research seeks to update and improve upon the methods of a prior study, providing new data from 1948-2011, as well as more rigorous statistical analyses. Air mass types were created, and monthly averages of temperature, dewpoint, and relative frequency were calculated for each of the air masses in all four seasons; then the time series were submitted to regression analysis. The results …

Validation Of The Air Force Weather Agency Ensemble Prediction Systems, William B. Clements

Theses and Dissertations

Air Force Weather Agency's (AFWA) Ensemble Prediction Systems (EPS), Global Ensemble Prediction System (GEPS), 20km Mesoscale Ensemble Prediction System (MEPS20) and 4km Mesoscale Prediction System (MEPS4), were evaluated from April to October 2013 for 10 locations around the world to determine how accurately forecast probabilities for wind and precipitation thresholds and lightning occurrence match observed frequencies using Aerodrome Routine Meteorological Reports (METARs) and Aerodrome Special Meteorological Reports (SPECIs). Reliability diagrams were created for each forecast hour detailing the Brier skill score (BSS) to depict EPS performance compared to climatology for each site and score composition through reliability, resolution and uncertainty. …

A Crowdsourced Hail Dataset: Potential, Biases, And Inaccuracies, Joseph Robert Pehoski

Theses and Dissertations

Hail is a substantial severe weather hazard in the USA, with significant damage to property and

crops occurring annually. Traditional methods of forecasting hail size have limited accuracy, and despite

improvements in remote sensing of precipitation, the fall characteristics of hail make quantification of

hail imprecise. Research into hail is ongoing, but traditional hail datasets have known biases and low

spatiotemporal resolution. The increased usage of smartphones creates the opportunity to use a

crowdsourced dataset provided by the Precipitation Identification Near the Ground (PING) program, a

program developed by the National Severe Storms Laboratory. PING data is compared to approximate …

Assessing The Predictability Of Convection Initiation Using An Object-Based Approach, Brock James Burghardt

Theses and Dissertations

Improvements in numerical forecasts of deep, moist convection have been notable in recent years and are in large part due to increased computational power allowing for the explicit numerical representation of convection. Accurately forecasting the timing and location of convection initiation (CI), however, remains a substantial forecast challenge. This is attributed to the inherently limited intrinsic predictability of CI due to its dependence on highly non-linear moist physics and fine-scale atmospheric processes that are poorly represented in observations. Because CI is the starting point of deep, moist convection that grows upscale, even small errors in initial convective development can rapidly …

Turbulence Measurement In The Atmospheric Boundary Layer Using Cellular Telephone Signals, Lee R. Burchett

Theses and Dissertations

This thesis investigated a new method for measuring the intensity of turbulence in the planetary boundary layer that shows a high correlation with measurements from weather radar. The method takes measurements of cell phone signal strength and uses scintillation in the signal to estimate the strength of local turbulence. Using cell phone signals provides unique measurement advantages: it is a passive measurement method, it is not strongly affected by precipitation, and one device can potentially measure several paths at once. The measurements were taken using an Android® cell phone running a custom built application. The strength of turbulence was quantified …

Operations-Focused Optimized Theater Weather Sensing Strategies Using Preemptive Binary Integer Programming, Andrew J. Geyer

Theses and Dissertations

This thesis describes a method that optimally deploys weather sensors of all types in a battlefield environment. Gridded climatology models are used to determine an estimate for the weighted frequency of occurrence of operationally significant inclement weather events. That data is used to formulate a series of preemptive Binary Integer Linear Programs that maximize detection of expected operationally significant inclement weather occurrences within the constraints of feasibility of sensor deployment, sensor operational lifespan and the sensor’s ability to detect the operationally significant inclement weather elements. The preemptive Binary Integer Linear Programs are combined into a single objective function that maintains …

Assessment Of Weather Sensitivities And Air Force Weather (Afw) Support To Tactical Lasers In The Lower Troposphere, Francesco J. Echeverria

Theses and Dissertations

ATL scientists need to develop a full understanding of the interaction effects between a high-energy laser beam and the atmosphere through which it propagates. Achieving this understanding is important for many reasons. In particular, the high cost of DE weapons systems makes each propagation event expensive. Having an understanding of the atmosphere in which a high-energy laser propagates will increase efficiency and effectiveness of the ATL weapon system, which in turn will decrease cost of operation. A tool that allows for the ATL war-fighter to determine the atmospheric effects on laser propagation currently does not exist. This study creates a …

Development Of A Defense Meteorological Satellite Program (Dmsp) F-15 Disturbance Storm-Time (Dst) Index, James M. Bono

Theses and Dissertations

As the DoD's use of space and space assets increases, so does its need for timely and accurate predictions of space weather conditions. A good understanding of the data from satellites together with data from ground stations can help model and determine variations in the space environment. An accurate, real-time Disturbance storm-time (Dst) index would be a primary input into current and future space weather models The Dst index is a measure of geomagnetic activity used to assess the severity of magnetic storms. The index is based on the average value of the horizontal component of the Earth's magnetic field …

Comparison Of A Conceptual Model And Objective Indicators Of Extratropical Transition In The Western North Pacific, Gregory D. Fox

Theses and Dissertations

The primary purpose of this research is to provide guidance to forecasters from the Joint (Air Force/Navy) Typhoon Warning Center (JTWC) in Pearl Harbor to use in differentiating between the stages of extratropical transition (ET) of tropical cyclones (TCs). Not only is ET relevant to the Department of Defense, since JTWC stops providing TC warnings once they have undergone ET, but it is also applicable to the meteorological community since there currently "is no commonly accepted definition of ET" (Jones et al 2003). This research compares the results of a conceptual model of ET using subjective satellite analysis with the …

Forecasting Advective Sea Fog With The Use Of Classification And Regression Tree Analyses For Kunsan Air Base, Danielle M. Lewis

Theses and Dissertations

Advective sea fog frequently plagues Kunsan Air Base (AB), Republic of Korea, in the spring and summer seasons. It is responsible for a variety of impacts on military operations, the greatest being to aviation. To date, there are no suitable methods developed for forecasting advective sea fog at Kunsan, primarily due to a lack of understanding of sea fog formation under various synoptic situations over the Yellow Sea. This work explored the feasibility of predicting sea fog development with a 24-hour forecast lead time. Before exploratory data analysis was performed, a geographical introduction to the region was provided along with …

Verification Of Meteorological Data Reports From The Rq-4a Global Hawk Unmanned Aerial Vehicle, Steven M. Callis

Theses and Dissertations

Unmanned aerial vehicles (UAVs) have onboard sensors that continuously record weather data during their missions. This information is extremely valuable to both the meteorological and UAV communities with numerous potential benefits, which include improved weather forecast products and additional weather intelligence for military planners. The value of any dataset is directly related to its accuracy and this research determined the accuracy of weather data obtained from a particular UAV, the RQ-4A Global Hawk. This was accomplished through statistical analysis and comparisons with upper-air data and Atmospheric Slant Path Analysis Model (ASPAM) profiles of the atmosphere. Recommendations are provided for the …

Dust Storm Forecasting For Al Udeid Ab, Qatar: An Empirical Analysis, Kevin S. Bartlett

Theses and Dissertations

Dust storms are extreme weather events that have strong winds laden with visibility reducing and operations limiting dust, The Central Command Air Forces (CENTAF) 28th Operational Weather Squadron (OWS) is ultimately responsible for forecasting weather in the vast, data denied region of Southwest Asia in support of daily military and humanitarian operations. As a result, the 28th OWS requests a simplified forecasting tool to help predict mesoscale dust events that affect coalition operations at Al Udeid AB, Qatar. This research satisfies the 28th OWS request through an extensive statistical analysis of observational data depicting seasonal dust events over the past …

Feasibility Of Using Classification Analyses To Determine Tropical Cyclone Rapid Intensification, Jonathan W. Leffler

Theses and Dissertations

Tropical cyclone intensity techniques developed by Dvorak have thus far been regarded by tropical meteorologists as the best identification and forecast schemes available using satellite imagery. However, in recent years, several ideologies have arisen which discuss alternative means of determining typhoon rapid intensification or weakening in the Pacific. These theories include examining channel outflow patterns, potential vorticity superposition and anomalies, tropical upper tropospheric trough interactions, environmental influences, and upper tropospheric flow transitions. It is now possible to data mine these atmospheric parameters thought partly responsible for typhoon rapid intensification and weakening to validate their usefulness in the forecast process. Using …

A Statistically-Based Method For Predicting Fog And Stratus Dissipation, Louis L. Lussier Iii

Theses and Dissertations

The method is a success in producing forecasts for ceiling and visibility criteria that had never previously been examined. It is suggested that the 15 OWS incorporate this methodology into their operational forecasting routine. Ceiling forecasts at Dover AFB and McGuire AFB show improvements over conditional climatology ranging from 1-51% with an average improvement of 19.2% when verified against an independent data set. McGuire AFB visibility forecasts show an average improvement over conditional climatology of 3%. These findings are of particular importance to the Air Force in general and specifically to the 15th Operational Weather Squadron (15 OWS) who produces …