Wednesdays at 12:45 p.m. – 1:45 p.m. —
UNLESS OTHERWISE NOTED.
In complex urban environments with diverse urban canyon structures and building materials, mixed with human-modified green space, there is a particularly strong influence on the directional anisotropy. However, this anisotropic effect at a satellite pixel scale (e.g. 1 km) is hard to quantify with current techniques through airborne observations and modeling. Moreover, it is still unknown how this anisotropy of LST influences estimates of the surface urban heat island (SUHI). In this talk, I will introduce our novel technique by using long-term MODIS LST products to quantify the LST anisotropy for different levels of urban land use intensities. Taking Chicago and New York as two examples, the results show strong diurnal and spatial differences in anisotropy. The daytime maximum effective anisotropic effects can be up to 9 K for the most urbanized areas associated with two types of anisotropic “hot-spots”, while the nighttime anisotropic effects are weaker but still discernible. Some unique features specific to each city highlight the impact of diverse urban surface properties and geographic settings on anisotropy. Moreover, I will discuss the influence of directional anisotropy on satellite-retrieved SUHI measurements. At the end, I will talk about an ongoing project about developing a Sun-Urban-Sensor viewing model to potentially adjust the anisotropic effect on MODIS LST and the challenges that we are facing.
Atmospheric mercury is a toxic pollutant that is harmful to humans, especially during gestational development and childhood. Humans are exposed to mercury through the consumption of fish and rice that grow in marine and aquatic ecosystems that are mercury contaminated through atmospheric wet deposition. Many lakes, rivers and coastal waters throughout the United States contain mercury at levels that harm wildlife and people who consume fish from these waters. Highest mercury wet deposition in the Continental United States is found along the Gulf Coast region. In contrast to other water-soluble anthropogenic pollutants, including sulfate and nitrate, the region of high mercury wet deposition does not overlap the peak emission region, which is much farther north. Highest mercury deposition in all of US regions is found in Puerto Rico, far removed from major emission sources.
It is hypothesized that this anomalous behavior of mercury wet deposition is tied to global cycle of mercury and geographic variability of precipitation system morphologies. Due to long atmospheric residence time, insoluble gaseous elemental mercury is subject to long range transport and is oxidized in the stratospheric air mass to soluble forms. Idealized numerical model simulations indeed show that convective systems are most effective at tapping this upper atmospheric reservoir of soluble mercury and thus have higher mercury wet deposition. These findings were further tested through statistical analysis of observations from the Mercury Deposition Network. Even after accounting for differences in rainfall amounts, there are significant differences in mercury wet deposition as a function of precipitation system type. Our studies show that geographic variability of precipitation system morphology could explain the anomalous patterns of mercury wet deposition.
August 31st — An Overview of Earth and Atmospheric Science Research at the Universities Space Research Association, Scott Miller, USRA
The Universities Space Research Association (USRA) is a non-profit corporation founded in 1969 by the National Academy of Sciences at NASA’s request, and is uniquely structured to form and maintain relationships with universities and other organizations across the country. USRA has provided support to NASA Marshall Space Flight Center (MSFC) since 1971, and to the National Space Science and Technology Center (NSSTC) since its inception in 2000. In January 2012, USRA’s Huntsville Program was elevated to an Institute with the formation of the Science and Technology Institute (STI), with core support in science, technology, and education.
USRA has a broad research portfolio in the Earth and Atmospheric Sciences, not only at NASA MSFC, but also in conjunction with NASA GSFC, and recently, NASA ARC. This presentation will begin with a brief introduction to USRA and the local STI organizations, followed by a series of highlights spanning the USRA Earth Science portfolio, both at the NSSTC, and our other research locations. This overview will also include discussion on a number of USRA operated programs that may be of interest to current and recent graduate students, such as our internship programs, and the NASA Postdoctoral Program. This overview will also include discussion on a number of USRA operated programs that may be of interest to current and recent graduate students, such as our internship programs, and the NASA Postdoctoral Program.
Vortex Rossby Waves (VRWs) have been hypothesized to exist in tropical cyclones (TCs), acting as an axisymmetrizing mechanism to the inner core flow and restored by the radial gradient of storm vorticity. In addition, they have been identified as a possible mechanism for inner core spiral rainband formation and a mechanism by which the symmetric flow may be enhanced. The majority of VRW knowledge comes from theoretical and numerical studies. Only two observational studies performed at coarse temporal and spatial resolutions have been previously published.
The Shared Mobile Atmospheric Research and Teaching (SMART) radars have sampled multiple landfalling TCs in the United States including Hurricanes Isabel (2003), Frances (2004), and Irene (2011). The data collected over the inner core environments of these three TCs provided the opportunity to examine the inner core structure of TCs outside of the eyewall, including VRW-induced spiral rainbands. Three-dimensional radar wind retrievals indicate that the structure of spiral rainbands was similar to that of numerically simulated VRWs. In Hurricane Isabel, which was particularly well sampled, the measured azimuthal and radial phase speeds were compared to that of VRW theory and were found to be consistent with the theoretical phase speeds.
While other mechanisms may produce rainband-like features, the rainbands observed by the SMART radars in three TCs were induced by VRWs. Moreover, the VRW-induced vertical motions were key in producing a significant portion of rainfall within the inner core of TCs. Thus, the current stratiform conceptual model of the inner core does not adequately identify the roles of VRWs. A new conceptual model of the inner core and its associated rainbands is presented to reflect these new observations of the inner core.
Optical measurements of lightning have been used for several decades as a tool to understand the lightning discharge. Ground based, airborne, and spaced based optical observations have each provided unique information to enhance our understanding of lightning phenomenology. Despite its usefulness as a diagnostic tool, the conditions within the lightning channel that produce the optical radiation are coarsely understood, and basic physical properties such as the radiative efficiency or peak temperature and their spatial and temporal variation remain loosely constrained. This talk will review how ground based multi-band radiometric measurements of natural and rocket-triggered lightning have provided insight into the energy budget and thermodynamic evolution of the lightning discharge, and how similar measurements from aircraft will help to answer remaining questions.
Vegetation fires are an important source of air pollution in several regions of the world including Asia. Earth observation satellites have immense potential for fire detection, mapping and monitoring. Since the 1980s, remotely-sensed data acquired by sensors on several satellites, such as NOAA/AVHRR, LANDSAT/TM/ETM+, Terra/Aqua/MODIS, ENVISAT/AATSR, etc., have been utilized for detecting active fires and burned areas in several regions of the world. Parallel to improved sensor technologies and development, algorithms for active fire detection and burnt area mapping have improved significantly leading to development of operational fire products of known accuracy. In addition, several satellites such as TOMS, SCIAMACHY, GOME, MOPITT, MODIS, GOSAT, OCO and others are being used to monitor pollution from satellites. In such context, an important question with respect to satellite retrievals of air pollutants from fires is “how well do they capture temporal and spatial variations and how well do they relate to episodic events such as fires?” I will address this question using multi-satellite datasets with case study from Asia.
In the presentation, satellite remote sensing of fires will be highlighted for example, active fires, burnt area and fire radiative power products. The launch of Suomi-National Polar-orbiting Partnership (NPP) VIIRS during October 2011, further enhanced the fire monitoring capabilities due to its improved spatial resolution (than MODIS), and data aggregation scheme. Similarly, the successful launch of LANDSAT-8 during February 2013 has opened avenues for improved active fire detection and burnt area mapping at a higher resolution than MODIS or VIIRS; the latest updates from these satellites will be presented. In addition, case study examples from South/Southeast Asia on satellite remote sensing of fires and pollution will be showcased.
September 28th — Why Molecular Structure Matters in the Chemistry of Atmospheric Organic Aerosol Formation, Paul Ziemann/CU Boulder [V/C Shanhu Lee]
As part of our urban resiliency research, we develop scientific solutions that help different stakeholders fulfill their mission objectives. These solutions range from mapping suitable areas for siting renewable energy sources at a national scale to optimizing deicing rate during the winter season at a sub-county scale. In this talk, I will present applications of remote sensing data for energy and urban mobility.
November 2nd —Vulnerabilities of Irrigated Agriculture to Climate Change in the Columbia River Basin – Dr. Muhammad Barik (Visiting Scientist, USRA)
The Columbia River Basin is the fourth largest watershed in North America in terms of average annual flow. It is one of the most critical sources of water for regional hydropower generation, irrigation, flood control, ecosystem services, navigation, municipal and industrial use, tribal treaty commitments, and recreation. Impacts of anthropogenic climate change are already evident in this heavily managed river basin, threatening reliable access to water for present and future regional economic growth. This presentation will discuss the vulnerabilities of irrigated agriculture to climate change in the Columbia River Basin using an integrated biophysical and human decision-making modeling system.
November 9th — Chaotic Convection in CAM, Dave Randall/Colorado State University [V/C Dr. Nair]
November 16th — Recent Advanced in Meteorological Modeling in Support of Ecosystem and Human Health Research at the US. EPA, Kiran Alapaty/Associate Director-EPA [V/C Dr. Nair]
November 23rd — Assessing the Equity of Access to Greener Buildings: LEED-Certified Schools & Libraries, Their Surrounding Neighborhoods and who owns Them, Shuang Zhao/UAH ATS-Polical Science
November 30th — ATS/ESS 781 Student Seminars