Seminars for Scientists

Fall 2010 Schedule:

9/9/2010 – Solar Wind Interaction With the Giant Magnetospheres

Speaker:   Peter Delamere
Date & Time:   September 9, 2010 ,  4:00pm Location: LSTB-299

Abstract:
 

Jupiter’s and Saturn’s immense magnetospheres differ considerably from Earth’s. These magnetospheres are generated in part by a strong planetary dynamo and by rapid rotation (~10 hour period). However, key differences lie in the internal sources of plasma (100s kg/s) provided by Io and Enceladus. Centrifugal stresses acting on the corotating, low-beta plasma in the inner… Read more »

9/16/2010 – Title: TBD

Speaker:   Kalevi Mursula
Date & Time:   September 16, 2010 ,  4:00pm Location: LSTB-299

Abstract:
 

The heliospheric magnetic field (HMF) is hemispherically asymmetric so that the field dominant in the northern hemisphere is weaker but has a larger area than in the south. As a consequence, the heliospheric current sheet (HCS) is shifted southwards. This asymmetry, also called the bashful ballerina, typically persists during three-year intervals in the late declining… Read more »

9/23/2010 – Formation of the Ganymede/Callisto Dichotomy and Titan’s Interior State from Impacts During the Late Heavy Bombardment

Speaker:   Amy Barr
Date & Time:   September 23, 2010 ,  4:00pm Location: Duane D-142

Abstract:
 

Despite their similar sizes and compositions, Ganymede and Callisto have followed different evolutionary pathways. Ganymede has experienced extensive geological activity and has a large rock core. Callisto’s surface is ancient. Core formation in Callisto has apparently been incomplete; its interior has layers of mixed ice and rock. The Ganymede/Callisto dichotomy could have arisen during an… Read more »

9/30/2010 – First Results from SDO Extreme Ultraviolet Variability Experiment (EVE)

Speaker:   Tom Woods, Rachel Hock, Frank Eparvier, and Andrew Jones
Date & Time:   September 30, 2010 ,  4:00pm Location: LSTB-299

Abstract:
 

The Extreme ultraviolet Variability Experiment (EVE) aboard the NASA Solar Dynamics Observatory (SDO) was launched on 11 February 2010. The EVE instruments measure the solar extreme ultraviolet (EUV) irradiance from 0.1 to 105 nm with unprecedented spectral resolution (0.1 nm), temporal cadence (10 sec minimum), and accuracy (20% or better). This seminar will discuss some… Read more »

10/8/2010 – Reconstructing Pre-Historic Temperatures from Natural Proxies: Statistical Methods in Paleoclimate Research

Speaker:   Martin Tingley (ATOC/LASP)
Date & Time:   October 8, 2010 ,  4:00pm Location: Duane, Gamow tower

Abstract:
 

The instrumental temperature record covers at most 150 years. Because a longer record is needed to characterize the natural variability of the climate system, it is necessary to call upon climate proxy data, which are noisy and sparsely distributed in space. Information about pre-historic temperatures can be derived from elements of the natural world sensitive… Read more »

10/21/2010 – Oort Cloud Formation – The Role of the Sun’s Birth Cluster

Speaker:   Hal Levison (SwRI)
Date & Time:   October 21, 2010 ,  4:00pm Location: Duane D-142

Abstract:
 

Oort cloud comets are currently believed to have formed in the Sun’s proto-planetary disk, and to have been ejected to large heliocentric orbits by the giant planets. I will review the evolution of our understanding of Oort cloud formation. I will present the currently best models and show that they fail to reproduce all of… Read more »

10/29/2010 – Exploring the Antarctic Ozone Hole using Long-Duration Balloons

Speaker:   Linnea Avallone (LASP/ATOC)
Date & Time:   October 29, 2010 ,  4:00pm Location: Duane, Gamow tower

Abstract:
 

The Antarctic “Ozone Hole” was first reported in the literature 25 years ago by Farman et al. [1985]. Despite intense research in the ensuing years into the chemical, microphysical and dynamical processes that create this phenomenon, there remain sufficient gaps in our knowledge that we cannot say with certainty when in the future the “ozone… Read more »

11/4/2010 – The Lunar Atmosphere: Some Ado About Almost Nothing

Speaker:   Richard Hodges
Date & Time:   November 4, 2010 ,  4:00pm Location: LSTB-299

Abstract:
 

Prior to the Apollo era the lunar atmosphere was thought to be a collision-less, ballistic conduit for thermal evaporation that balances the inflow of solar wind ions with their loss as neutrals. However, the first atmospheric species to be identified on the moon was radiogenic argon-40, and its identification was the indirect result of a… Read more »

11/11/2010 – The nature of Turbulence in Circumstellar disks: Magnetorotational and Baroclinic Instability

Speaker:   Hubert Klahr (Max-Planck Institute for Astronomy, Heidelberg)
Date & Time:   November 11, 2010 ,  4:00pm Location: Duane D-142

Abstract:
 

Turbulence in circumstellar disks diffuses small solid material, leads to collisions among larger objects, concentrates boulders promoting planetesimal formation via gravity and also has an impact on planet migration. Despite the importance of turbulence, its nature is not completely understood so far. In certain regions of the disk the gas is sufficiently ionized for magneto-hydrodynamics… Read more »

11/12/2010 – Stratospheric circulation changes and their relation to species distributions

Speaker:   Karen Rosenlof (ATOC/LASP)
Date & Time:   November 12, 2010 ,  4:00pm Location: Duane, Gamow Tower

Abstract:
 

Results from two recent papers discussing changes in stratospheric constituents driven by changes in the circulation and some associated impacts on climate will be presented. In the first paper (Solomon et al., 2010), we show that a significant decrease in stratospheric water vapor a consequence of an increase in the mass flux into the tropical… Read more »

11/18/2010 – Saturn’s rings under a microscope: Cassini UVIS results

Speaker:   Miodrag Sremcevic
Date & Time:   November 18, 2010 ,  4:00pm Location: Duane D-142

Abstract:
 

After 6 years of Cassini mission the Ultraviolet Imaging Spectrograph (UVIS) instrument recorded more than hundred stellar occultations by Saturn’s rings. Most of the observed occultations have excellent resolution on the order of ten meters or even better. In this talk we give overview of UVIS results on the rings small scale structure. The high… Read more »

11/18/2010 – Saturn’s rings under a microscope: Cassini UVIS results

Speaker:   Miodrag Sremcevic
Date & Time:   November 18, 2010 ,  4:00pm Location: Duane D-142

Abstract:
 

After 6 years of Cassini mission the Ultraviolet Imaging Spectrograph (UVIS) instrument recorded more than hundred stellar occultations by Saturn’s rings. Most of the observed occultations have excellent resolution on the order of ten meters or even better. In this talk we give overview of UVIS results on the rings small scale structure. The high… Read more »

12/3/2010 – Saturn’s rings under a microscope: Cassini UVIS results

Speaker:   Brian Toon (ATOC/LASP)
Date & Time:   December 3, 2010 ,  4:00pm Location: Duane, Gamow Tower

Abstract:
 

The talk will describe some of the scientific issues that are driving research in this area, results from recent studies, and plans for future field missions.

12/9/2010 – Development of the approach for comprehensive retrieval of aerosol properties from enhanced satellite observations

Speaker:   Oleg Dubovik (Laboratoire d’Optique Atmosphérique, Université de Lille 1, France)
Date & Time:   December 9, 2010 ,  4:00pm Location: LSTB-A200

Abstract:
 

We propose to enhance aerosol retrievals by emphasizing statistical optimization in inversion of advanced satellite observations. The concept improves retrieval accuracy relying on pronounced data redundancy (excess of the measurements number over number of unknowns). The concept has been successfully adopted and refined in the operational AERONET algorithm retrieving the detailed aerosol properties from ground-based… Read more »

12/10/2010 – The retrievals of detailed aerosol from AERONET sun/sky-radiometers: Overview of inversion principles, products and advances.

Speaker:   Oleg Dubovik (Laboratoire d’Optique Atmosphérique, Université de Lille 1, France)
Date & Time:   December 10, 2010 ,  4:00pm Location: Duane D-142

Abstract:
 

The AERONET operational retrievals rely on the algorithm by Dubovik and King [2000]. This algorithm is based on the principles of optimized statistical estimations and derives detailed size distribution and spectral complex refractive index by fitting measurements of both direct and diffuse radiation. It also provides such radiative characteristics as aerosol spectral single scattering albedo… Read more »

9/9/2010 – Solar Wind Interaction With the Giant Magnetospheres

Speaker:   Peter Delamere
Date & Time:   September 9, 2010 ,  4:00 PM Location: LSTB-299

Abstract:
 

Jupiter’s and Saturn’s immense magnetospheres differ considerably from Earth’s. These magnetospheres are generated in part by a strong planetary dynamo and by rapid rotation (~10 hour period). However, key differences lie in the internal sources of plasma (100s kg/s) provided by Io and Enceladus. Centrifugal stresses acting on the corotating, low-beta plasma in the inner… Read more »

9/23/2010 – Formation of the Ganymede/Callisto Dichotomy and Titan’s Interior State from Impacts During the Late Heavy Bombardment

Speaker:   Amy Barr
Date & Time:   September 23, 2010 ,  4:00 PM Location: Duane D-142

Abstract:
 

Despite their similar sizes and compositions, Ganymede and Callisto have followed different evolutionary pathways. Ganymede has experienced extensive geological activity and has a large rock core. Callisto’s surface is ancient. Core formation in Callisto has apparently been incomplete; its interior has layers of mixed ice and rock. The Ganymede/Callisto dichotomy could have arisen during an… Read more »

9/30/2010 – First Results from SDO Extreme Ultraviolet Variability Experiment (EVE)

Speaker:   Tom Woods, Rachel Hock, Frank Eparvier, and Andrew Jones
Date & Time:   September 30, 2010 ,  4:00 PM Location: LSTB-299

Abstract:
 

The Extreme ultraviolet Variability Experiment (EVE) aboard the NASA Solar Dynamics Observatory (SDO) was launched on 11 February 2010. The EVE instruments measure the solar extreme ultraviolet (EUV) irradiance from 0.1 to 105 nm with unprecedented spectral resolution (0.1 nm), temporal cadence (10 sec minimum), and accuracy (20% or better). This seminar will discuss some… Read more »

10/8/2010 – Reconstructing Pre-Historic Temperatures from Natural Proxies: Statistical Methods in Paleoclimate Research

Speaker:   Martin Tingley (ATOC/LASP)
Date & Time:   October 8, 2010 ,  4:00 PM Location: Duane, Gamow tower

Abstract:
 

The instrumental temperature record covers at most 150 years. Because a longer record is needed to characterize the natural variability of the climate system, it is necessary to call upon climate proxy data, which are noisy and sparsely distributed in space. Information about pre-historic temperatures can be derived from elements of the natural world sensitive… Read more »

10/21/2010 – Oort Cloud Formation – The Role of the Sun’s Birth Cluster

Speaker:   Hal Levison (SwRI)
Date & Time:   October 21, 2010 ,  4:00 PM Location: Duane D-142

Abstract:
 

Oort cloud comets are currently believed to have formed in the Sun’s proto-planetary disk, and to have been ejected to large heliocentric orbits by the giant planets. I will review the evolution of our understanding of Oort cloud formation. I will present the currently best models and show that they fail to reproduce all of… Read more »

10/29/2010 – Exploring the Antarctic Ozone Hole using Long-Duration Balloons

Speaker:   Linnea Avallone (LASP/ATOC)
Date & Time:   October 29, 2010 ,  4:00 PM Location: Duane, Gamow tower

Abstract:
 

The Antarctic “Ozone Hole” was first reported in the literature 25 years ago by Farman et al. [1985]. Despite intense research in the ensuing years into the chemical, microphysical and dynamical processes that create this phenomenon, there remain sufficient gaps in our knowledge that we cannot say with certainty when in the future the “ozone… Read more »

11/4/2010 – The Lunar Atmosphere: Some Ado About Almost Nothing

Speaker:   Richard Hodges
Date & Time:   November 4, 2010 ,  4:00 PM Location: LSTB-299

Abstract:
 

Prior to the Apollo era the lunar atmosphere was thought to be a collision-less, ballistic conduit for thermal evaporation that balances the inflow of solar wind ions with their loss as neutrals. However, the first atmospheric species to be identified on the moon was radiogenic argon-40, and its identification was the indirect result of a… Read more »

11/11/2010 – The nature of Turbulence in Circumstellar disks: Magnetorotational and Baroclinic Instability

Speaker:   Hubert Klahr (Max-Planck Institute for Astronomy, Heidelberg)
Date & Time:   November 11, 2010 ,  4:00 PM Location: Duane D-142

Abstract:
 

Turbulence in circumstellar disks diffuses small solid material, leads to collisions among larger objects, concentrates boulders promoting planetesimal formation via gravity and also has an impact on planet migration. Despite the importance of turbulence, its nature is not completely understood so far. In certain regions of the disk the gas is sufficiently ionized for magneto-hydrodynamics… Read more »

11/12/2010 – Stratospheric circulation changes and their relation to species distributions

Speaker:   Karen Rosenlof (ATOC/LASP)
Date & Time:   November 12, 2010 ,  4:00 PM Location: Duane, Gamow tower

Abstract:
 

Results from two recent papers discussing changes in stratospheric constituents driven by changes in the circulation and some associated impacts on climate will be presented. In the first paper (Solomon et al., 2010), we show that a significant decrease in stratospheric water vapor a consequence of an increase in the mass flux into the tropical… Read more »

11/18/2010 – Saturn’s rings under a microscope: Cassini UVIS results

Speaker:   Miodrag Sremcevic
Date & Time:   November 18, 2010 ,  4:00 PM Location: Duane D-142

Abstract:
 

After 6 years of Cassini mission the Ultraviolet Imaging Spectrograph (UVIS) instrument recorded more than hundred stellar occultations by Saturn’s rings. Most of the observed occultations have excellent resolution on the order of ten meters or even better. In this talk we give overview of UVIS results on the rings small scale structure. The high… Read more »

12/3/2010 – Towards an improved understanding of the Tropical Tropopause Transition Layer, TC4, ATTREX and SEAC4RS

Speaker:   Brian Toon (ATOC/LASP)
Date & Time:   December 3, 2010 ,  4:00 PM Location: Duane, Gamow tower

Abstract:
 

The talk will describe some of the scientific issues that are driving research in this area, results from recent studies, and plans for future field missions.

12/9/2010 – Development of the approach for comprehensive retrieval of aerosol properties from enhanced satellite observations

Speaker:   Oleg Dubovik (Laboratoire d’Optique Atmosphérique, Université de Lille 1, France)
Date & Time:   December 9, 2010 ,  4:00 PM Location: LSTB-A200

Abstract:
 

We propose to enhance aerosol retrievals by emphasizing statistical optimization in inversion of advanced satellite observations. The concept improves retrieval accuracy relying on pronounced data redundancy (excess of the measurements number over number of unknowns). The concept has been successfully adopted and refined in the operational AERONET algorithm retrieving the detailed aerosol properties from ground-based… Read more »

12/10/2010 – The retrievals of detailed aerosol from AERONET sun/sky-radiometers: Overview of inversion principles, products and advances.

Speaker:   Oleg Dubovik (Laboratoire d’Optique Atmosphérique, Université de Lille 1, France)
Date & Time:   December 10, 2010 ,  4:00 PM Location: Duane D-142

Abstract:
 

The AERONET operational retrievals rely on the algorithm by Dubovik and King [2000]. This algorithm is based on the principles of optimized statistical estimations and derives detailed size distribution and spectral complex refractive index by fitting measurements of both direct and diffuse radiation. It also provides such radiative characteristics as aerosol spectral single scattering albedo… Read more »