Dr. Thomas J. Greenwald Profile

Dr. Thomas J. Greenwald

at Univ of Wisconsin Madison

SPIE Involvement:

Author

Publications (5)

Proceedings Article | 18 September 2018 Presentation + Paper

Overview of the NASA TROPICS CubeSat constellation mission

W. Blackwell, S. Braun, B. Zavodsky, C. Velden, T. Greenwald, D. Herndon, R. Bennartz, M. DeMaria, G. Chirokova, R. Atlas, J. Dunion, F. Marks, R. Rogers, H. Christophersen, B. Annane

Proceedings Volume 10769, 1076908 (2018) https://doi.org/10.1117/12.2320333

KEYWORDS: Satellites, Microwave radiation, Radiometry, Spatial resolution, Spectrometers, Temporal resolution, Antennas, Data modeling

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Recent technology advances in miniature microwave radiometers that can be hosted on very small satellites has made possible a new class of affordable constellation missions that provide very high revisit rates of tropical cyclones and other severe weather. The Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission was selected by NASA as part of the Earth Venture–Instrument (EVI-3) program and is now in development with planned launch readiness in late 2019. The overarching goal for TROPICS is to provide nearly all-weather observations of 3-D temperature and humidity, as well as cloud ice and precipitation horizontal structure, at high temporal resolution to conduct high-value science investigations of tropical cyclones (TCs). TROPICS will provide rapid-refresh microwave measurements (median refresh rate better than 60 minutes for the baseline mission) over the tropics that can be used to observe the thermodynamics of the troposphere and precipitation structure for storm systems at the mesoscale and synoptic scale over the entire storm lifecycle. TROPICS will comprise a constellation of at least six CubeSats in three low-Earth orbital planes. Each CubeSat will host a high performance radiometer to provide temperature profiles using seven channels near the 118.75 GHz oxygen absorption line, water vapor profiles using three channels near the 183 GHz water vapor absorption line, imagery in a single channel near 90 GHz for precipitation measurements (when combined with higher resolution water vapor channels), and a single channel at 205 GHz that is more sensitive to precipitation-sized ice particles and low-level moisture. This observing system offers an unprecedented combination of horizontal and temporal resolution in the microwave spectrum to measure environmental and inner-core conditions for TCs on a nearly global scale and is a major leap forward in the temporal resolution of several key parameters needed for assimilation into advanced data assimilation systems capable of utilizing rapid-update radiance or retrieval data. Here, we provide an overview of the mission and an update on current status, with a focus on unique characteristics of the Cubesat system, recent performance simulations on a range of observables to be provided by the constellation, and a summary of science applications.

SPIE Journal Paper | 1 September 2010

Global distribution of instantaneous daytime radiative effects of high thin clouds observed by the cloud profiling radar

Yong-Keun Lee, Thomas Greenwald, Ping Yang, Steven Ackerman, Hung-Lung Huang

JARS, Vol. 4, Issue 01, 043543, (September 2010) https://doi.org/10.1117/12.10.1117/1.3491858

KEYWORDS: Clouds, Chromium, Shortwaves, Radar, Profiling, Reflectivity, Ocean optics, Convection, Atmospheric optics, Satellites

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Proceedings Article | 29 August 2005 Paper

Rapid forward and adjoint calculations of thermal hyperspectral radiances in cloudy atmospheres

Thomas Greenwald, Ralf Bennartz, Hung-Lung Huang, Chris O'Dell, Andrew Heidinger

Proceedings Volume 5890, 58901A (2005) https://doi.org/10.1117/12.620056

KEYWORDS: Clouds, Particles, Scattering, Radiative transfer, Multiple scattering, Principal component analysis, Atmospheric modeling, Fast radiative transfer, Thermal modeling, Water

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Proceedings Article | 22 December 2004 Paper

Fast passive microwave radiative transfer in precipitating clouds: toward direct radiance assimilation

Ralf Bennartz, Chris O'Dell, Thomas Greenwald, Andrew Heidinger

Proceedings Volume 5654, (2004) https://doi.org/10.1117/12.578801

KEYWORDS: Data modeling, Radiative transfer, Scattering, Clouds, Microwave radiation, Satellites, Liquids, Atmospheric modeling, Systems modeling, Sensors

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Proceedings Article | 19 August 1998 Paper

Ice cloud scattering signatures observed by the SSM/T-2

Thomas Greenwald, Sundar Christopher

Proceedings Volume 3503, (1998) https://doi.org/10.1117/12.319488

KEYWORDS: Clouds, Particles, Scattering, Microwave radiation, Satellites, Imaging systems, Sensors, Optical spheres, Temperature metrology, Environmental sensing

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