Research

Recent Activities

Studying Global Cloud Cover Changes
Wylie and Menzel have been monitoring seasonal changes in global cloud cover with multi-spectral observations from the eleven polar orbiting HIRS (High resolution Infrared Radiation Sounder) since December 1978. The HIRS longwave infrared data have a higher sensitivity to semi-transparent cirrus clouds than visible and infrared window techniques. Clouds are found in 71% of all HIRS observations from 65 S to 65 N; high clouds are observed in 33% of the observations. Closer investigation of the tropics indicates that there has been little overall change in the global total cloud cover. There is the possibility of a small increase in high cloud cover from the first decade to the second (about 2%) however orbit drift of some sensors and instrument differences may be part of this. Significant weather events such as El Nino Southern Oscillation or volcanic eruptions may also be influencing the trends. Since 2000, the Moderate resolution Imaging Spectro-radiometer (MODIS) is starting to generate another cloud data set that must be understood and connected with the HIRS cloud data; early indications are promising that MODIS will be a more than worthy successor to the venerable HIRS.

The monthly average frequency of clouds and high clouds (above 6 km) from 70 south to 70 north latitude from 1979 to 2002; Wylie et al. 2005.
click for larger version

Combining Radiometric and Geometric Sounding
Borbas, Menzel and Weisz, have studied the use of Global Positioning System Radio Occultation (GPS/RO) measurements from the CHAMP (CHAllenging Mini-satellite Payload) and SAC-C (Satellite de Aplicaciones Cientificas-C, Argentinean Satellite) satellites to improve tropospheric profile retrievals derived from high spectral resolution infrared measurements under clear sky conditions. Broadband radiometric ATOVS (Advance TIROS Operational Vertical Sounder instrument on NOAA polar orbiting satellites) cobined with CHAMP data were found to produce improved temperature profile determinations, especially in the vicinity of the tropopause.. More recently high spectral resolution Atmospheric Infrared Sounder (AIRS) and the Advanced Microwave Sounding Unit (AMSU) measurements were combined with GPS data for regression based profile retrievals. AIRS/AMSU temperature retrievals show the largest improvement from the inclusion of GPS in the tropopause region – about 0.5 K between 100 and 280 hPa. When GPS data between 1 and 26 km layer are included in the combination, AIRS/AMSU moisture retrievals also show improvement of about 0.2 g/kg between 750 to 400 hPa. GPS/RO data are found to provide valuable upper tropospheric information that improves the profile retrieval from AIRS and AMSU

Validation of the UW AIRS/AMSU temperature (left two panels) and moisture (mixing ratio in g/kg, right two panels) retrievals without (solid) and with (dashed) GPS/RO data with the best estimate profiles at the SGP and NSA ARM sites. The second and fourth panels show difference of the two RMS profiles as the impact of using GPS/RO data in the retrievals. Positive values mean improvements. GPS/RO data between 6 and 26 km layer were used in this study.
Click for larger version

Investigating cloud properties with high spectral resolution data
Plokhenko and Menzel are studying opportunities for 3-dimensional cloud property characterization using the combination of vertical cloud structure determined by AIRS high spectral resolution infrared measurements and MODIS high horizontal resolution measurements when semi-transparent high clouds cover lower clouds. Using a cloud radiative transfer model wherein cloud amount and cloud top pressure are adjusted in each of 25 levels (spaced to provide uniform vertical resolution as much as possible) to match calculated with measured radiances for the AIRS spectral bands, cloud amount profiles are estimated.

A case study has been processed for an AIRS granule over the Mediterranean Sea on 16 November 2002 at 00 UTC. The AIRS found cloud amount of 10 to 20% in each level between 5 to 10 km. Initial validation over lidar sites (e.g. Barrow Alaska) have produced encouraging comparisons of cloud profiles.

AIRS cloud amount profile retrieval fields (line versus element) at 100, 200, 300, and 500 hPa for a granule over the Mediterranean on 16 Nov 2002 at 00 UTC; cloud amount for each level is given as a percentage.
Click for larger version

Cloud amount profiles up to 15100 meters (on the y-axis) shown as a transect along element 20 (on the x-axis) of the figure above shows good continuity from one AIRS field of view to the next.
Click for larger version.

Remote Sensing Lectures
A series of lectures on remote sensing have been offered in Bertinoro, Italy 23 August – 4 September 2004, Krakow, Poland 8-12 May 2006, and Ostuni, Italy 8-16 June 2006 by Drs Paul Menzel and Paolo Antonelli. The World Meteorological Organization Technical Document “Applications with Meteorological Satellites” authored by Dr. Menzel was used as a text during these lectures. The courses included materials on (a) radiation and the radiative transfer equation, (b) remote sensing of the Earth surface and its atmosphere, (c) instrument considerations, (d) algorithms for detecting and estimating moisture, precipitation, and clouds properties, and (e)ccurrent and future capabilities of the global observing system Fifty hours of classroom work was split between lectures and laboratory exercises that emphasized investigation of high spatial resolution visible and infrared data (from the Moderate resolution Imaging Spectroradiometer, MODIS, and Meteosat Second Generation, MSG) and high spectral resolution infrared data (from Advanced Infrared Sounder, AIRS). Homework assignments and classroom tests verified that good progress was made in learning and mastering the materials presented.

Research Fields

Satellite Meteorology
Possibilities for remote sensing of the atmosphere from a geosynchronous and polar orbiting spacecraft are being explored. Specifications for vertical temperature and moisture sounders are being established. Techniques are being developed to exploit the new opportunities offered by GOES-8/9/10 to describe the time variations in the structure and behavior of the atmosphere on the synoptic and mesoscale (e.g., hurricanes and tornadoes). Improved determination of cloud properties (height and emissivity) from indirect infrared sensing over decades initially with HIRS on POES and recently with MODIS and AIRS on Terra and Aqua is another research project.

Theoretical Solid State Physics
This work probed the electronic energy band structure of crystals. The method of linear combinations of atomic orbitals was applied to perfect crystals for Hartree-Fock self-consistent-field calculations of band structures and associated properties such as electronic wave functions of atoms in crystals, electron charge distributions in crystals under various potentials, and transition probabilities of electron excitations. A first principles calculation of the optical properties of crytals (density of states, imaginary part of the dielectric function) was completed. Electronic energy levels and wave functions of complex atom clusters were also determined. Post doctoral work was focused on the electronic states of point defects in crystals (e.g., deep defect levels in semiconductors).



	Research Recent Activities Studying Global Cloud Cover Changes Wylie and Menzel have been monitoring seasonal changes in global cloud cover with multi-spectral observations from the eleven polar orbiting HIRS (High resolution Infrared Radiation Sounder) since December 1978. The HIRS longwave infrared data have a higher sensitivity to semi-transparent cirrus clouds than visible and infrared window techniques. Clouds are found in 71% of all HIRS observations from 65 S to 65 N; high clouds are observed in 33% of the observations. Closer investigation of the tropics indicates that there has been little overall change in the global total cloud cover. There is the possibility of a small increase in high cloud cover from the first decade to the second (about 2%) however orbit drift of some sensors and instrument differences may be part of this. Significant weather events such as El Nino Southern Oscillation or volcanic eruptions may also be influencing the trends. Since 2000, the Moderate resolution Imaging Spectro-radiometer (MODIS) is starting to generate another cloud data set that must be understood and connected with the HIRS cloud data; early indications are promising that MODIS will be a more than worthy successor to the venerable HIRS. The monthly average frequency of clouds and high clouds (above 6 km) from 70 south to 70 north latitude from 1979 to 2002; Wylie et al. 2005. click for larger version Combining Radiometric and Geometric Sounding Borbas, Menzel and Weisz, have studied the use of Global Positioning System Radio Occultation (GPS/RO) measurements from the CHAMP (CHAllenging Mini-satellite Payload) and SAC-C (Satellite de Aplicaciones Cientificas-C, Argentinean Satellite) satellites to improve tropospheric profile retrievals derived from high spectral resolution infrared measurements under clear sky conditions. Broadband radiometric ATOVS (Advance TIROS Operational Vertical Sounder instrument on NOAA polar orbiting satellites) cobined with CHAMP data were found to produce improved temperature profile determinations, especially in the vicinity of the tropopause.. More recently high spectral resolution Atmospheric Infrared Sounder (AIRS) and the Advanced Microwave Sounding Unit (AMSU) measurements were combined with GPS data for regression based profile retrievals. AIRS/AMSU temperature retrievals show the largest improvement from the inclusion of GPS in the tropopause region – about 0.5 K between 100 and 280 hPa. When GPS data between 1 and 26 km layer are included in the combination, AIRS/AMSU moisture retrievals also show improvement of about 0.2 g/kg between 750 to 400 hPa. GPS/RO data are found to provide valuable upper tropospheric information that improves the profile retrieval from AIRS and AMSU Validation of the UW AIRS/AMSU temperature (left two panels) and moisture (mixing ratio in g/kg, right two panels) retrievals without (solid) and with (dashed) GPS/RO data with the best estimate profiles at the SGP and NSA ARM sites. The second and fourth panels show difference of the two RMS profiles as the impact of using GPS/RO data in the retrievals. Positive values mean improvements. GPS/RO data between 6 and 26 km layer were used in this study. Click for larger version *Investigating cloud properties with high spectral resolution data* Plokhenko and Menzel are studying opportunities for 3-dimensional cloud property characterization using the combination of vertical cloud structure determined by AIRS high spectral resolution infrared measurements and MODIS high horizontal resolution measurements when semi-transparent high clouds cover lower clouds. Using a cloud radiative transfer model wherein cloud amount and cloud top pressure are adjusted in each of 25 levels (spaced to provide uniform vertical resolution as much as possible) to match calculated with measured radiances for the AIRS spectral bands, cloud amount profiles are estimated. A case study has been processed for an AIRS granule over the Mediterranean Sea on 16 November 2002 at 00 UTC. The AIRS found cloud amount of 10 to 20% in each level between 5 to 10 km. Initial validation over lidar sites (e.g. Barrow Alaska) have produced encouraging comparisons of cloud profiles. AIRS cloud amount profile retrieval fields (line versus element) at 100, 200, 300, and 500 hPa for a granule over the Mediterranean on 16 Nov 2002 at 00 UTC; cloud amount for each level is given as a percentage. Click for larger version Cloud amount profiles up to 15100 meters (on the y-axis) shown as a transect along element 20 (on the x-axis) of the figure above shows good continuity from one AIRS field of view to the next. Click for larger version. Remote Sensing Lectures A series of lectures on remote sensing have been offered in Bertinoro, Italy 23 August – 4 September 2004, Krakow, Poland 8-12 May 2006, and Ostuni, Italy 8-16 June 2006 by Drs Paul Menzel and Paolo Antonelli. The World Meteorological Organization Technical Document “Applications with Meteorological Satellites” authored by Dr. Menzel was used as a text during these lectures. The courses included materials on (a) radiation and the radiative transfer equation, (b) remote sensing of the Earth surface and its atmosphere, (c) instrument considerations, (d) algorithms for detecting and estimating moisture, precipitation, and clouds properties, and (e)ccurrent and future capabilities of the global observing system Fifty hours of classroom work was split between lectures and laboratory exercises that emphasized investigation of high spatial resolution visible and infrared data (from the Moderate resolution Imaging Spectroradiometer, MODIS, and Meteosat Second Generation, MSG) and high spectral resolution infrared data (from Advanced Infrared Sounder, AIRS). Homework assignments and classroom tests verified that good progress was made in learning and mastering the materials presented. Research Fields *Satellite Meteorology* Possibilities for remote sensing of the atmosphere from a geosynchronous and polar orbiting spacecraft are being explored. Specifications for vertical temperature and moisture sounders are being established. Techniques are being developed to exploit the new opportunities offered by GOES-8/9/10 to describe the time variations in the structure and behavior of the atmosphere on the synoptic and mesoscale (e.g., hurricanes and tornadoes). Improved determination of cloud properties (height and emissivity) from indirect infrared sensing over decades initially with HIRS on POES and recently with MODIS and AIRS on Terra and Aqua is another research project. Theoretical Solid State Physics This work probed the electronic energy band structure of crystals. The method of linear combinations of atomic orbitals was applied to perfect crystals for Hartree-Fock self-consistent-field calculations of band structures and associated properties such as electronic wave functions of atoms in crystals, electron charge distributions in crystals under various potentials, and transition probabilities of electron excitations. A first principles calculation of the optical properties of crytals (density of states, imaginary part of the dielectric function) was completed. Electronic energy levels and wave functions of complex atom clusters were also determined. Post doctoral work was focused on the electronic states of point defects in crystals (e.g., deep defect levels in semiconductors).