Wednesdays at 12:45 p.m. – 1:45 p.m. —
UNLESS OTHERWISE NOTED.
Wednesday, January 6th – TBD – ATS780/ATS781 Introduction
Wednesday, January 13th – No Seminar – AMS Meeting
For at least 3 decades, oceanic lightning flashes are known to be more energetic, via proxy observations of return stroke peak current or flash radiances. Surprisingly, this fact has been gently swept under the rug, in the context that up-to-date, not a single initiative has delved into this outstanding problem. Our recent study over the US reveals that the responsible physical mechanism is far from a “detection artifact” or other oversimplified arguments such as e.g. “lower flash rate hence higher peak current”. In contrast, the results strongly suggest that the physical mechanism responsible lives inside the thundercloud and might pertain to both chemistry and microphysics.
Since 2012, periodic collections of 1-min resolution super rapid scan operations for GOES-R (SRSOR) observations from the GOES-14 satellite were recorded for significant weather events over the U.S., to mimic the expected 30-sec data collections from GOES-R beginning in 2017. Data were collected in visible and infrared channels at 1 and 4 km resolution, respectively. Provided past research on convective storm initiation, and given tools that derive cloud motion winds from these data, insights into convective cloud develop and convective storm morphology can be made when 1-min SRSOR observations are analyzed, when compared to more traditional 15-min resolution GOES imagery.
SRSOR cloud-top temperature analysis map the heights of cloud tops, and hence infer aspects of the cloud’s main updraft as it deepens over time, while use of 3.9 µm reflectance imagery provides information on when a cloud’s top glaciates. Similarly, so-called “mesoscale atmospheric motion vectors” (mAMV) help identify cloud-scale wind flows at cloud top. Use of all datasets has allowed us to see, for the first time in geostationary satellite imagery, short-term changes in updraft magnitudes likely related to components of buoyancy (latent heat release, the shape of the buoyancy profile, hydrometeor loading), while hinting at aspects of entrainment influences on cumulus cloud updraft behavior. Specifically, the timing of cloud top glaciation appears correlated to an invigoration of convective cloud updrafts ~3 km above the 0° C isotherm. With respect to mAMV-derived flows, use of 1-min resolution data allows for the development of objectively derived cloud top divergence (CTD) and vorticity (CTV) flow fields. Results show that storm-relative CTD and CTV fields over both ordinary and more organized convective storms are coherent over time, and CTD modulates relative to the intensity of the main updraft, and therefore helps quantify storm organization. Ordinary convection CTD signals tend to be much weaker and shorter lived than supercell cases. Results also suggest that a CTV “couplet” signature often exists over tornadic supercell storms, while all supercell cases in 2014 and 2015 exhibited strong, maintained CTD maxima values located near their respective overshooting top locations. Idealized supercell storms simulated by the WRF-ARW model develop similar CTV “couplet” signature, which when analyzed with the vorticity tendency equation, suggests that vortex tilting is the primary mechanism creating the CTV signatures as observed in SRSOR data.
Wednesday, February 3rd – Ethnographic observations on uncertainty among operational forecasters (or why all uncertainties are not equal) – Jack Friedman (Center for Applied Social Research, University of Oklahoma)
“Why doesn’t the public respond to tornado warnings the way that they should?” “Should we continue to use the words ‘watches’ and ‘warnings,’ or would changing the language of our communication improve the public’s response?” “How can we reduce false alarms so that the public believes us and takes appropriate action?”
Questions like these have haunted the weather enterprise for many years, but there has been little consensus on how to solve these problems or whether these are even the right questions to be asking. Indeed, much of the current focus on PHI – Probabilistic Hazard Information – has been prompted by the perception that greater transparency and scientifically-grounded understandings of the uncertainties in forecasting can save more lives and protect property better than the current state of warnings. However, the challenge remains that, for many meteorologists, this would mean accepting that they need to convey probabilistic uncertainties to publics who they may or may not believe can understand probabilistic information.
Taking a “person-centered,” ethnographic approach to the study of meteorologists in the National Weather Service, Dr. Friedman will discuss research that explores how meteorologists describe everyday uncertainties in their work. This talk will consider how different perceptions of uncertainty – including 1) professional/career uncertainties; 2) uncertainties regarding forecasting models, sensing technologies, and different forms of communication; and 3) uncertainties associated with their perceptions of various “publics” and consumers/users of weather information – shape the different possibilities open to operational meteorologists seeking to protect life and property in their work as forecasters for the NWS. This talk will conclude with a brief overview of upcoming social science research with forecasters in the Huntsville area connected to the 2016 VORTEX-SE experiments.
Thunderstorms can produce a variety of hazards such as hail, damaging winds, tornadoes, heavy rain, lightning, aircraft icing, and turbulence, each of which represent a significant threat to life and property. Many hazardous storms have updrafts of sufficient intensity to penetrate through the tropopause and into the lower stratosphere, transporting tropospheric aerosols, chemical species, water vapor, and ice which have a significant impact on the Earth’s climate system. Analysis of GOES 1-minute resolution “super-rapid scan” satellite imagery indicates that hazardous storms develop quite rapidly, from small cumulus to a tornadic supercell in as little as one hour. The presence of tropopause-penetrating (i.e. “overshooting”) cloud tops and associated ice cloud detrainment in the lower stratosphere, and rapid changes in 1) cloud-top temperature during storm initiation, 2) mature storm updraft intensity, and 3) cloud-top divergence and vorticity near the updraft region are indicators of hazardous storms that can be detected by automated satellite imager-based algorithms up to 1 hour in advance of hazardous weather.
This presentation will describe recent advances in automated satellite-based detection of hazardous storm updrafts via their overshooting top (OT) signature and weather and climate analyses using OT detection product output along with other ground- and space-based datasets. The detection algorithm, developed using support from the GOES-R program, identifies OT regions at the individual geostationary or polar-orbiting satellite pixel scale (~1-4 km) using visible (during daytime only) and infrared channel imagery combined with numerical weather analysis data. The algorithm can operate with data from almost any satellite imager and has been used to analyze hazardous storms at variety of temporal scales such as those depicted by GOES at 1-minute frequency up to the full 35+ year AVHRR data record. Several long-term regional and global OT databases will be shown that highlight interesting climatological distributions of hazardous storms at high spatial (up to 0.2°) resolution.
Wildland fires impact the atmospheric environment by releasing sensible and latent heat fluxes that modify the flow near the fire front. In addition, the injection of smoke aerosols into the boundary layer and mid troposphere shades the earth’s surface inducing circulations that can flow opposite to the ambient wind. These processes can affect fire behavior at a range of scales and therefore, a better understanding of fire-atmosphere interactions will improve fire behavior modeling and eventually lead to increased firefighter and community safety. This presentation will discuss new observations of wildfire micrometeorology made during both planned, small-scale field experiments and opportunistic wildfire observational campaigns.
A number of field experiments have been conducted in order quantify the microscale nature of turbulence and fire-induced winds around free burning head fires on both flat terrain and on slopes. The FireFlux II experiment conducted in 2013 in tall grass fuels, moderate winds, and on flat terrain, measured the near-surface wind structure as the fire passed the instrumentation array. Results show that fire-induced winds accelerate through the fire front and in alignment with the ambient flow. Observational evidence suggests that this acceleration is associated with a region of surface low pressure that develops at the fire front in response to plume heating and is to simulations that indicate the low pressure feature develops downstream of the fire front.
At the larger scale, plume observations from active wildfires in California were made during the 2014 Rapid Deployments to Wildfires (RaDFire) field campaign using a truck mounted Doppler lidar profiling system. Observations from 8 major wildfires highlight poorly understood aspects of pyro-convection including (1) rotating updrafts, (2) penetrative convection, (3) turbulent entrainment, and (4) smoke-induced density currents. Density currents of this sort constitute a previously unobserved mechanism for smoke transport and are unlikely to be well resolved by operational forecast models. Our analyses show that the density current results from differential heating between smoke-free and smoke-filled portions of the atmospheric boundary layer. The leading edge of the thermally direct circulation forms a meso-front, which exhibits clear density current characteristics including an elevated head and Kelvin-Helmholtz waves. Using thermodynamic and kinematic observations, there is good agreement between the frontal structure and density current theory. This result, combined with scaling arguments, conclusively demonstrates the observed circulation is due to thermal contrasts and that smoke particulate loading is not important in this case. These findings indicate broader implications fire-atmosphere interactions have on communities that may be impacted by smoke inundation from large wildfires.
Wednesday, February 24th – Improvements n regional forest type mapping via correction of LandSat bi-directional effects: Implications for REDD+ related forest carbon monitoring – Emil Cherrington (CATHALAC)
Wednesday, March 2nd – Natural gas and corn ethanol: How U.S. energy choices affect air quality and climate – Joost de Gouw (NOAA Earth System Research Lab, CIRES)
Since 2000, energy production and use in the United States have seen several large shifts. The domestic production of natural gas and crude oil increased strongly due to the widespread use of horizontal drilling and hydraulic fracturing, which made the extraction of oil and gas from shale and tight sand formations economically feasible. In 2015, the domestic production of natural gas was at an all-time high, and the production of crude oil was very near the all-time high. Increasingly, electric power plants use natural gas instead of coal for fuel. Finally, 10% of gasoline now consists of ethanol made from corn. All of these changes have affected the emissions of greenhouse gases and reactive trace gases to the atmosphere, as well as the formation of secondary products like ozone and particulate matter from these precursors. In this talk, we will look at some of these changes and the implications for climate, air quality and air toxics. Results were obtained during multiple NOAA-led field studies during 2011-2015 in Colorado, Utah and using the NOAA WP-3D aircraft operated over the Southeastern U.S. in 2013 and from North Dakota to Texas in 2015.
Wednesday, March 9th – Elevated convective systems and extreme rainfall – Russ Shumacher (Department of Atmospheric Science, Colorado State University)
Mesoscale convective systems (MCSs) are responsible for a large fraction of warm-season extreme rainfall events over the continental United States, as well as other midlatitude regions globally. The rainfall production in these MCSs is determined by numerous factors, including the large-scale forcing for ascent, the organization of the convection, cloud microphysical processes, and the surrounding thermodynamic and kinematic environment. Furthermore, heavy-rain-producing MCSs are most common at night, which means that well-studied mechanisms for MCS maintenance and organization such as cold pools (gravity currents) are not always at work. In this study, we use numerical model simulations and recent field observations to investigate the sensitivity of low-level MCS structures, and their influences on rainfall, to the details of the thermodynamic environment. In particular, small alterations to the initial conditions in idealized and semi-idealized simulations result in comparatively large precipitation changes, both in terms of the intensity and the spatial distribution. The uncertainties in the thermodynamic environments in the model simulations will be compared with high-resolution observations from the Plains Elevated Convection At Night (PECAN) field experiment in 2015. Furthermore, hypotheses addressing why stable low-level environments, and especially those supporting low-level vortices (such as supercells embedded within MCSs), are particularly favorable for extreme rainfall will be presented and evaluated. The results of these studies have implications for the paradigms of “surface-based” versus “elevated” convection, as well as for the predictability of warm-season convective rainfall.
Wednesday, March 16th – Phased array radar weather applications – Pam Heinselman (NOAA/OAR National Severe Storms Lab, University of Oklahoma)
Wednesday, March 23rd – SPRING BREAK
Wednesday, March 30th – Intense convection in subtropical South America: Perspectives on processes, improving prediction, and mitigating social impacts – Steve Nesbitt (University of Illinois)
Wednesday, April 6th – Aerosols under natural conditions in the Amazon basin and the impact from anthropogenic emissions – Jian Wang (Atmospheric Science Division Brookhaven National Laboratory)
Atmospheric aerosols strongly influence the climate system by scattering and absorbing sunlight, and by serving as nuclei of cloud droplet and ice crystals. Currently the effects of aerosol on climate remain one the largest uncertainties in the climate change since pre-industrial era. A large portion of the uncertainties in simulated climate change is due to the uncertainties of natural aerosol processes and properties represented in models. Amazon rainforest represents more than half of the planet’s remaining rainforests, and is is one of the few continental regions where aerosol particles and their precursors can be studied under near-natural conditions.
The Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) experiment took place around the urban region of Manaus in the central Amazon from January 2014 to December 2015. GoAmazon2014/5, a cooperative project of Brazil, Germany, and the USA, employed an unparalleled suite of measurements at nine ground sites and onboard two aircraft to investigate the flow of background air into Manaus, the emissions into the air over the city, and the advection of the pollution downwind of the city. Here I present aerosol properties, including aerosol size distribution and CCN spectrum observed at the T0a background site (Amazon Tall Tower Observatory, 150 km upwind of Manaus) and the T3 site (70 km downwind of Manaus). Also shown are aerosols observed onboard the DOE Gulfstream-1 research aircraft both under background condition and inside the Manaus plume. The sources and sinks of the boundary layer aerosol particles under the natural conditions are examined. The evolution of Manaus pollution plume and its impact on aerosol population, cloud condensation nuclei (CCN) activity, cloud properties and rainfall will be discussed. The observations of the GoAmazon2014/5 experiment show the aerosol lifecycle and its controlling processes under natural conditions, and how they may be affected by present-day as well as future economic development and pollution over the Amazonian tropical forest.
Wednesday, April 13th – ATS781 Course Presenters (first presentations) – (ATS Department)
A Comparison of the VLF Waveform and Optical Emissions Using Ground-Based and Satellite-Based Lightning Detection Methods
Faculty Advisor: Dr. Phillip Bitzer
With the launch of The Geostationary Lightning Mapper (GLM), investigation into how to best use this data is imperative. This research takes a first look at the use of group level lightning data detected by the Lightning
Imaging Sensor (LIS) in conjunction with a ground based lightning detection
network. Using a logistic regression model, certain characteristics of the
VLF waveform were found to be significant in the prediction of LIS group
Identifying Dual-Polarization Radar Signatures to Increase the Lead Times of Convective Wind Warnings at Cape Canaveral Air Force Station and NASA Kennedy Space Center
Faculty Advisor: Dr. Lawrence Carey
The United States Air Force¹s 45th Weather Squadron utilizes C-band
dual-polarization radar data when issuing warnings for convective wind
events at Cape Canaveral Air Force Station and NASA Kennedy Space Center.
Currently, these convective wind warnings do not provide as much lead-time
as desired by the 45th Weather Squadron. This study aims to identify various
C-band radar signatures that are commonly observed within storms that
ultimately produce a convective wind event at the Cape Canaveral Air Force
Station and NASA Kennedy Space Center complex to help improve lead times for
Application of a Recursive Filter Analysis for Derivation of GOES Super
Rapid Scan Deep Convective Cloud Top Derived Flow Fields
Faculty Advisor: Dr. John Mecikalski
Geostationary Satellite Super Rapid Scan deep convective cloud flow field shave been calculated for the past two years and have shown promise in identifying features unique to supercell thunderstorms at the cloud top. The
original approach for flow field derivation involved use of a Barnes (1973)
objective analysis to derive divergence and vorticity on a grid, which does
not work well with non-spatially uniform observations of atmospheric motion
vectors (AMVs). Results will be presented from a new recursive filter
approach which allows for the incorporation of numerical weather prediction
background upper tropospheric flow data into the gridded fields, and reduces
the Barnes (1973) problems caused by non-uniformity of typical AMVs.
Irrigation Impacts on Cloud Cover over the Great Plains
Faculty Advisor: Dr. Udaysankar Nair
A 2km grid spacing Weather Research and Forecasting (WRF) model was used to simulate irrigation impacts on cloud cover in the Great Plains. This study adds to the well-documented role of irrigation impacts on precipitation patterns in the Great Plains. This research is proof of concept for a
potential field campaign to study these affects.
An Analysis of the Relationship between Fire and Landslides in Nepal using Remotely-Sensed Datasets
Faculty Advisor: Dr. Tom Sever
Fires can have a devastating impact on local culture. Often, fires can strip community forests of virtually all vegetation, leaving swaths of land bare and susceptible to other potential disasters, such as landslides. I am
interested in determining a potential relationship between fires and
landslide susceptibility for events triggered by excessive precipitation and
by strong earthquakes. Such a relationship has been well established in
other geographic regions of the world that are susceptible to both fires and
landslides, such as the Western United States.
Investigation into the effects of climate variability and land cover change on the hydrologic system of the Lower Mekong Basin
Faculty Advisor: Dr. Robert Griffin
This research investigates how climate variability, specifically variations in the precipitation regime, as well as land cover change will affect the hydrologic budget both spatially and temporally within the Lower Mekong
Basin with a focus on water availability, i.e. floods and droughts. This
goal is achieved by (1) modeling land cover change for a baseline scenario
as well as changes in land cover with specific increases for land cover
classes and (2) using projected climate variables and modeled land cover as
input into the VIC hydrologic model. The resulting modeled water budget and
streamflow for the Lower Mekong system are analyzed against historic values
to understand if the hydrologic system changes due to climate variability or
land cover change, where these changes occur, and to what degree these
changes affect the water budget.
Wednesday, April 20th – ATS781 Course Presenters (remaining presentations) – (ATS Department)
Developing an automated tool to monitor weekly Alabama forest health using multispectral data
Faculty Advisor: Dr. Robert Griffin
Alabama contains over 23 million acres of timberland, accounting for 69% of the state’s total land area. Of this timberland acreage, 31% is comprised of private pine plantations. My research aims to develop an automated tool incorporating remote sensing data that can give near real-time warning of threats to forest health, including pest infestations, drought, and fires.
A Case Study of the Ozone Enhancement in the Lower Troposphere from Biomass
Faculty Advisor: Dr. Michael Newchurch
An ozone enhancement in the lower troposphere over Huntsville was observed by the Rocket-city O3 Quality Evaluation in the Troposphere (RO3QET) lidar on September 18, 2015. This case study combines in situ and remotely sensed data with air quality and trajectory model to provide the linkage between the enhanced ozone with the biomass burning in Mississippi Valley. These integrated analyses and preliminary findings provide insights into the ozone source attribution and quantification work in the future.
Analysis and Characterization of QLCS Tornadic Debris Signatures for Utilization in Operational Settings
Faculty Advisor: Dr. Larry Carey
Much research has been conducted to further understand and characterize tornadic debris signatures (TDS’s). For this study, the primary objective is to characterize TDS’s that are associated with weaker tornadoes (EF-0, EF-1, and some low end EF-2’s) that form in a Quasi-Linear Convective System (QLCS) environment to improve their operational utility. Data from the Advanced Radar for Meteorological and Operational Research, ARMOR (C-band), and several National Weather Service Weather Surveillance Radars – 1988 Doppler, WSR-88D’s (S-band), were collected and utilized for this study. Numerous polarimetric variables were recorded for each TDS which include: ZHH, VR, ρHV, and ZDR. The maximum and minimum values for each variable are recorded to investigate potential refinements to the TDS thresholds for operational forecasters to utilize in QLCS situations. Preliminary results show that the TDS’s associated with QLCS tornadoes generally last no more than two to three volume scans, and rarely are higher than a few thousand feet.
Can Environmental Factors indicate the Health of Green Sea Turtles (Chelonia mydas)?
Faculty Advisor: Dr. Thomas Sever
The first know sighting of Fibropapillomatosis in Chelonia mydas (Green Sea Turtle) expressed in tumors (FP tumors) was in 1938. Since the 1980s, the number of turtles seen with FP tumors has reached a level that is alarming. Many factors have been hypothesized to be the cause. Some research has suggested water runoff pollution, coastal sewage, antibiotics, hypoxia, and water qualities such as temperature, salinity, or chlorophyll-a concentration. For this study, Sea Surface Temperature and Ocean Color, chlorophyll-a concentration, is compared to FP tumor occurrence in green sea turtles in five areas of interest: St. Lucie Power Plant, Indian River Lagoon, Big Bend / Crystal River region, Key West National Wildlife Refuge,
and Lake Worth Lagoon.
Evaluating the Effects of Meteorological and Physiographic Factors in Frost Occurrence and Crop Damage Thresholds in the Kenyan Highlands
Faculty Advisor: Dr. Robert Griffin
Due to inadequacy of information on frost risk and inefficiency of early warning systems to cushion farmers, hefty losses amounting to millions of dollars have been incurred in the past following freeze damage to crops. The goal of the current research is to determine the statistical relationship between local physiographic and meteorological attributes and LST consistent with radiative frost in order to facilitate effective delineation of frost occurrence zones and damage thresholds. Based on MODIS LST, past records of
frost events, local topography and weather patterns, the research will test a logistic regression for predicting probability of frost occurrence.
An Assessment of Predicted Flood Risk Using Social Media
Faculty Advisor: Dr. Robert Griffin
Social media, such as Twitter, is a growing medium for the public to share storm reports. This research aims to develop a tool using GIS that can be used to predict areas at risk for flooding. I plan on testing the ability of social media as a means to validate the predicted flood risk areas.
Wednesday, April 27th – April 27th – 5 Years Later – Kevin Knupp, et al. – (ATS Department)