A5010002637- Meteorological Phenomena and Simulations
- Precipitation Measurement and Analysis
- Atmospheric Ozone and Climate
- Spectroscopy and Laser Applications
- Atmospheric aerosols and clouds
- Climate variability and models
- Soil Moisture and Remote Sensing
- Atmospheric chemistry and aerosols
- Ocean Waves and Remote Sensing
- Calibration and Measurement Techniques
- Superconducting Materials and Applications
- Tropical and Extratropical Cyclones Research
- Atmospheric and Environmental Gas Dynamics
- Ionosphere and magnetosphere dynamics
- Electromagnetic Launch and Propulsion Technology
- Cryospheric studies and observations
- Gyrotron and Vacuum Electronics Research
- Atomic and Subatomic Physics Research
- Scientific Measurement and Uncertainty Evaluation
- Intermetallics and Advanced Alloy Properties
- Spacecraft Design and Technology
- Metallic Glasses and Amorphous Alloys
- Advanced Materials Characterization Techniques
- Arctic and Antarctic ice dynamics
- Advanced Sensor Technologies Research
Massachusetts Institute of Technology
2010-2024
Chestnut Hill College
2014
Federal Office of Metrology and Surveying
2006-2011
Universities Austria
2000-2002
University of Vienna
1997-2002
TU Wien
2002
General Electric (Austria)
2001
Institute for Telecommunication Sciences
1992
IIT@MIT
1982
California Institute of Technology
1973
The Atmospheric Infrared Sounder (AIRS), the Advanced Microwave Sounding Unit (AMSU), and Humidity for Brazil (HSB) form an integrated cross-track scanning temperature humidity sounding system on Aqua satellite of Earth Observing System (EOS). AIRS is infrared spectrometer/radiometer that covers 3.7-15.4-/spl mu/m spectral range with 2378 channels. AMSU a 15-channel microwave radiometer operating between 23 89 GHz. HSB four-channel makes measurements 150 190 In addition to supporting...
The Atmospheric Infrared Sounder (AIRS) and its two companion microwave sounders, AMSU HSB were launched into polar orbit onboard the NASA Aqua Satellite in May 2002. required sounding system to provide high-quality research data for climate studies meet NOAA's requirements improving operational weather forecasting. NOAA requirement translated global retrieval of temperature humidity profiles with accuracies approaching those radiosondes. AIRS also provides new measurements several...
Measurements, made in different laboratories, of absorption by water vapor microwave windows are compared with models for the continuum. A reanalysis some these measurements leads to conclusion that laboratory data best represented a combination Liebe's [1987] millimeter‐wave propagation model (MPM) foreign‐broadened component continuum and 1993 version MPM self‐broadened component. This combined is validated comparison atmospheric emission.
The problem of absorption microwaves by molecular oxygen in the atmosphere is treated means a first-order approximation to impact theory overlapping spectral lines. By including only coupling between adjacent rotational states collisions, we have devised simple approximate method for computing interference lines from measurements on resolved need an empirically determined function describing linewidth/ pressure ratio eliminated. Comparisons with at atmospheric pressures show that accounts...
Abstract. Atmospheric radiative transfer models are extensively used in Earth observation to simulate processes occurring the atmosphere and provide both upwelling downwelling synthetic brightness temperatures for ground-based, airborne, satellite radiometric sensors. For a meaningful comparison between simulated observed radiances, it is crucial characterise uncertainty of such models. The purpose this work quantify due associated spectroscopic parameters, compute temperature uncertainties...
The NOAA-15 weather satellite carries the Advanced Microwave Sounding Units-A and -B (AMSU-A, AMSU-B) which measure thermal emission from an atmospheric oxygen band, two water lines, several window frequencies. An iterated minimum-variance algorithm retrieves profiles of temperature humidity in atmosphere this data. Relative is converted into absolute with use retrieved profile. Two important issues retrieval problem are modeling surface clouds. a priori emissivity computed on basis...
Absorption of electromagnetic waves by rotational transitions molecules is formulated for the case in which wave frequency displaced from resonance an amount large compared to reciprocal duration a typical binary collision, and also differences between frequencies strong resonances gas. In this far-wing limit, Fano’s relaxation operator reduced scalar parameter depends on displacement. This not symmetric with respect reflection about resonance, but becomes when multiplied factor exp(ℏωd/2kT)...
A statistical theory, with a simple model for intermolecular potentials, is used to calculate the absorption of infrared waves by far wings water vapor rotational transitions. The similar ones that have been explain second virial coefficient. effectiveness self-broadening relative broadening nitrogen found increase frequency displacement from center band and decrease temperature, in agreement observed characteristics vapor.
Measurements of the complex dielectric constant, or relative permittivity, spectrum liquid water are modeled for frequencies up to 1 THz and temperatures 60 °C by a combination two components: Debye function, which characterizes reorientation molecules under influence an electric field, distributed-resonance is associated with vibrations intermolecular hydrogen bonds. This model provides good representation cloud measurements below 200 GHz at as low -25 °C.
Abstract. This paper presents a general approach to quantify absorption model uncertainty due in the underlying spectroscopic parameters. The is applied widely used microwave (Rosenkranz, 2017) and radiative transfer calculations 20–60 GHz range, which are commonly exploited for atmospheric sounding by radiometer (MWR). approach, however, not limited any frequency observing geometry, or particular instrument. In considered relevant uncertainties come from water vapor oxygen of following...
The Nimbus 5 microwave spectrometer has been used to measure thermal radiation in five frequency bands between 22.235 and 58.8 gigahertz, yielded both the temperature profile and, over ocean, vapor liquid water content of terrestrial atmosphere, even overcast conditions. Information also obtained on geophysical parameters that affect surface emissivity, such as ice type, sea roughness, snow cover. experiment demonstrates considerable potential passive sensing meteorological parameters.
Emissivities at a normal look angle have been computed for two models of ocean foam: porous dielectric and series thin water films. The give nearly the same results low foam densities. They show an emissivity spectrum that is roughly constant from 20 to 60 GHz tends decrease lower frequencies, depending on thickness density foam. A whitecap model (with graded density) shows less change with frequency. Radiometric measurements are described increased rough seas due white frequencies 10.7,...
Abstract. Atmospheric radiative transfer models are extensively used in Earth observation to simulate processes occurring the atmosphere and provide both upwelling downwelling synthetic brightness temperatures for ground-based, airborne, satellite radiometric sensors. For a meaningful comparison between simulated observed radiances, it is crucial characterize uncertainty such models. The purpose of this work quantify due associated spectroscopic parameters compute temperature uncertainties...
The thermally emitted microwave spectrum of the terrestrial atmosphere, viewed from above, is calculated for frequencies in vicinity a Zeeman‐split oxygen line. Previously omitted phase terms are included; their effect on brightness temperature can be as large 1.5 K linearly polarized measurements. For purpose using lines probe atmospheric profile, circular polarization radiometer would yield better vertical resolution. A double‐sideband measuring two include polarizer that reverses...
Simultaneous measurements of microwave emission from the earth, in oxygen band near 60 GHz and water vapor line 183 GHz, permit inference atmospheric temperature as a function two variables: pressure burden (integrated content above any level). Combination these profiles yields profile versus pressure. Occasional singularities retrievals can readily be identified excluded. Numerical simulations have been made, using subtropical midlatitude radiosonde stations, assuming surface reflectivities...
Line shapes are influenced by the dependence of collision cross sections on molecular speeds, with resulting effect absorption up to a few percents. Speed-dependence effects water line at 22.23 GHz and oxygen 118.75 calculated for atmospheric conditions common in midlatitudes. The vapor profiles retrieved ground-based microwave radiometer shows an impact (in simulations) comparable magnitude those measurement errors uncertainties spectroscopic parameters.
The atmospheric transmittance model for the Advanced Microwave Sounding Unit-A (AMSU-A) and Humidity Sounder Brazil (HSB) channels on Aqua spacecraft uses a polynomial approximation to temperature dependence of oxygen-band opacity within layers. It lookup tables calculate local water-vapor line intensity pressure-broadening parameters as well contributions absorption from continuum, distant lines, cloud liquid water. algorithm includes water-line self-broadening magnetic-field effect AMSU-A...