University of Colorado at Boulder University of Colorado CU Home Search A to Z Index Map

Seminars (for Scientists) 2009

Below is the schedule of LASP Science Seminars for the Spring 2009 semester. Most dates and speakers will be finalized within one week of the seminar, so check this site often for the most current information. All LASP seminars are open to the public EXCEPT those labeled “internal”.

LASP science seminars are generally on Thursdays from 4:00-5:00 p.m., with refreshments served at 3:45 p.m. Seminars at LSTB (in the East Campus Research Park) are in the main auditorium, room 299, while the seminars at the on-campus Duane building are in room D-142 unless otherwise noted.

For more information or if you have questions contact:

Sebastian Schmid
Phone: 303-492-6401
email: firstname.lastname@lasp.colorado.edu


Spring 2009

DATE Speaker/comment Title/abstract Location
Jan 8

4:00-5:00pm

K. Sebastian Schmidt, Johannes-Gutenberg-Universität Mainz Germany, LASP Spectral resolution and spatial structure: Why are they necessary for
accurate climate-relevant observations?

ABSTRACT:

Both spectral and spatial resolution of space- and airborne radiometers have increased tremendously over the last two decades. At the same time, climate, cloud, and radiative transfer models became considerably more accurate due to growing computing capabilities. The question arises: How much resolution and accuracy is needed for which application? In this context, “prioritization” of error sources is a keyword in current climate-related discussions. Some errors in our present understanding of the climate system are well-characterized and documented (for example in ICCP reports). Others may be underrated in their importance, partly because of lacking observations. I will present some of the reasons why we should care about resolution when tackling current issues in climate observations. I will then illustrate this with two specific examples from my own research. The first example introduces a hybrid model-measurement approach for quantifying the spectral radiative forcing of the so-called cloud-aerosol continuum (a much-discussed new concept), combining data from a NOAA field experiment and radiative transfer modeling at the LASP parallel computing facilities. The second shows how spectrally and spatially resolved field measurements from a current NASA experiment help unravel a 10-year old question: that of enhanced measured cloud absorption, unaccounted for by model calculations. In sum, I will explain why spectral and structural information is vital for improving our understanding of the climate system in future research and missions.

LSTB
Monday,   Feb. 2

3:00 PM

Dr. James A. Slavin,

Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, Maryland

MESSENGER Observations of Magnetic Reconnection in Mercury’s Magnetosphere

ABSTRACT:

During MESSENGER’s second flyby of Mercury on October 6, 2008, very intense reconnection was observed between the planet’s magnetic field and a steady southward interplanetary magnetic field (IMF). The dawn magnetopause was threaded by a strong magnetic field normal to its surface, ~ 14 nT, that implies a rate of reconnection ~10 times the typical rate at Earth and a cross-magnetospheric electric potential drop of ~ 30 kV. The highest magnetic field observed during this second flyby, ~160 nT, was found at the core of a large dayside flux transfer event (FTE). This FTE is estimated to contain magnetic flux equal to ~5% that of Mercury’s magnetic tail or approximately one order of magnitude higher fraction of the tail flux than is typically found for FTEs at Earth. Plasmoid and traveling compression region (TCR) signatures were observed throughout MESSENGER’s traversal of Mercury’s magnetotail with a repetition rate comparable to the Dungey cycle time of ~ 2 min. The TCR signatures changed from south-north, indicating tailward motion, to north-south, indicating sunward motion, at a distance ~ 2.6 RM (where RM is Mercury’s radius) behind the terminator indicating that the near-Mercury magnetotail neutral line was crossed at that point. Overall, these new MESSENGER observations suggest that magnetic reconnection at the dayside magnetopause is very intense relative to what is found at Earth and other planets, while reconnection in Mercury’s tail is similar to that in other planetary magnetospheres, but with a very short Dungey cycle time.

LSTB A200
Thursday, Feb. 12 Steve Miller

University College, London

The role of H3+ in planetary atmospheres

ABSTRACT:

The simple molecular ion H3+ has been known in the laboratory since 1911, when it was discovered by JJ Thomson while carrying out experiments on “rays of positive electricity”. It is stable, but highly reactive, making it an initiator chemical changes in mixed gases such as planetary atmospheres and the interstellar medium.

The enormous anharmonicity of its vibrational modes means that has strong infrared emission bands throughout the near-infrared. This enables it to play the role of a “thermostat” even when temperatures reach >2500K. As a charge carrier, a provider of conductivity, H3+ also plays a pivotal role in energy generation in planetary atmospheres.

And finally – and not altogether tongue-in-cheek – it may turn out to have been the saviour of the Solar System as we know it. Not bad for such a little molecule!

Duane D-142
Thursday, Feb. 19 John Wahr

Department of Physics and CIRES, University of Colorado

Some applications of the GRACE satellite mission, including monitoring changes in the polar ice sheets.

Abstract:

NASA and the German Space Agency launched the GRACE satellite gravity mission in 2002. The mission is projected to last through 2013. GRACE provides highly accurate solutions for the Earth’s global gravity field every month. Differences between fields for different months provide information about time-variability in the gravity field, and so about month-to-month fluctuations in the Earth’s mass distribution, at scales of a few hundred km and greater. The results can be used to study a wide range of geophysical signals, from changes in the water and snow stored on land and in the ground, ice mass loss in the polar ice sheets, changes in ocean bottom pressure and ocean mass variability, and processes in the solid Earth (e.g post-glacial-rebound; very large earthquakes).

In this talk I will describe the GRACE mission, putting it in the context of earlier time-variable gravity measurements from satellites. I will focus on cyrospheric and hydrological applications: those that involve changes in the distribution of snow and ice in the Greenland and Antarctic ice sheets and of water and snow on continents.

LSTB 299
Thursday, Feb. 26 Dan Baker

LASP

“Taking AIM at the space environment–When bad space weather is good”

Abstract:

The AIM (Aeronomy of Ice in the Mesosphere) spacecraft was launched on 25 April 2007. AIM is currently producing all planned observations. Some days after launch, however, AIM began to exhibit a problem in which it would not always achieve proper receiver uplink communications lock. During several periods from May 2007 to present there have been days without any successful uplinks from the ground operators to AIM. In this context, we examined solar conditions and geomagnetic activity. We formed the tentative hypothesis that higher solar wind speeds would lead to greater geomagnetic activity and this, in turn, seemed to lead to improved AIM operations. In this paper we present analysis of AIM bitlock to show when relative improvements or diminutions in spacecraft operations have occurred. We conclude that the spacecraft bitlock problem clearly is related, in part, to space environment conditions (along with a gradual secular trend toward lower performance). The best predicator of ‘good lock’ state seems to be a shift from low (or quiet) geomagnetic and solar wind conditions toward more disturbed conditions. We do not fully understand the mechanism(s) by which disturbed space weather improves AIM performance. However, we note that use of space weather forecast tools has been an important, supportive adjunct to this key new space flight program.

LSTB 299
Thursday, Mar 12 Jeff Thayer “Discovery of a New Upper Atmosphere Breathing Mode “

Abstract:

Recent satellite measurements have enabled discovery of a recurrent ‘breathing’, or expansion and contraction, of the Earth’s upper atmosphere at periods of several days. Evidence of this ‘breathing’ is found in upper atmospheric density, composition, and in gases responsible for cooling the upper atmosphere. The discovery of multi-day periodicities in the upper atmosphere is shown to be well correlated with solar wind high speed disturbances that originate at the sun. This new solar-terrestrial connection opens the possibility of improving predictions of satellite drag and predictions of the ionospheric behavior.

LSTB
Monday, Mar 16

2:00-3:00

Rob Wilson “Calculation Challenges from Cassini CAPS: Thermal Ion Flow Velocities in Saturn’s Magnetosphere Moments”

Abstract:

The motion of thermal ions is surprisingly unresolved at Saturn. Due to Saturn’s strong magnetic field it is expected that plasma close to planet will co-rotate with the magnetic field, but where does this break down? The two Voyager fly-bys suggest this happens around 6 Saturn radii from the planet, although the passes were non- equatorial. One exciting result from the Cassini orbiter was the discovery that Enceladus (at 4 Saturn radii) is a primary source of magnetospheric plasma, but does the subsequent mass loading of field lines by the fresh plasma inhibit rigid co-rotation?

Cassini’s Plasma Spectrometer (CAPS) ion counting data provides the ability to calculate thermal ion moments, such as ion density, temperature, flow speed and composition, however due to various features this is not a simple matter. Two techniques are described that allow moments values to be calculated, allowing an equatorial velocity profile to be calculated from in-situ measurements on Saturn’s day-side for the first time.

Duane D142
Thursday, Mar 19 Daniel Scheeres “The life-cycles of small asteroids”

Abstract:

The recent verification that small asteroids are rubble piles and are subject the YORP effect (i.e, that solar radiation pressure makes asteroid spin rates change over relatively short time spans) has wide-ranging consequences for the life cycles of these bodies. As the spin rate of an asteroid changes, its minimum energy configuration can change and lead to profound shifts in how its mass is distributed. If the spin rate continues to increase it becomes possible for an asteroid to fission into multiple pieces, forming a binary asteroid. These proto-binary asteroids can follow several fundamentally different paths as a function of their initial morphology, including mutual escape, re-impact, and transition into a stable binary system. Recent in situ and remote observations of asteroids support this picture, and imply that the smallest members of the asteroid family lead an active and interesting life.

LSTB
Thursday, Mar 26

Seminar Cancelled due to inclement weather

Martina Kraemer In situ observations in Arctic, mid-latitude and tropical cirrus clouds

Abstract:

In situ measurements of total and gas phase water as well as ice crystals have been obtained during several airborne field experiments in the Arctic, at midlatitudes and in the tropics.

From the data set obtained in these experiments, the ice water content (IWC) in cirrus clouds is derived as a function of temperature for the range 183–250 K, thus extending previous climatologies to much lower temperatures and lower detectable IWC. For each temperature, IWC covers a broad band, decreasing with temperature over the whole temperature range. In the tropics, several events of enhanced ice water content are observed which are related to recent impact of convection.

The relative humidity with respect to ice (RHi) in clear air and in ice clouds is also investigated. RHi above water saturation are not detected in the entire data set, but, super- or subsaturations are frequently observed inside of cirrus at temperatures <205K. From a combined analysis of supersaturations and ice crystal numbers, we show that the in-cloud high, persistent supersaturations can possibly be explained by unexpected, frequent very low ice crystal numbers that could scarcely be caused by homogeneous ice nucleation.

LSTB 299

4-5pm

Thursday, April 2 Peter Pilewskie/Gregg Kopp The Shortwave Component of the CLARREO Mission

Monitoring perturbations in the long-term balance between Earth’s absorption of radiative energy from the Sun and its emission of infrared radiation to space is one of the primary objectives behind the Decadal Survey Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission. Through on-orbit traceability of measurements to SI standards, CLARREO will initiate benchmark climate data records that can be linked to future measurements and potentially be used to cross-calibrate other on-orbit instruments. We present results of studies that will aid in defining the requirements of an Earth-viewing spectrometer over the solar spectral domain for CLARREO, and an instrument concept for meeting those requirements.

To achieve the required level of accuracy in the shortwave requires an improvement on the order of a factor of ten over current state-of-the-art measurements of the Earth-scattered solar radiation. We are developing an Earth-viewing shortwave hyperspectral imager that will trace its calibration on-orbit to solar spectral irradiance, to be obtained by NOAA’s contribution to CLARREO as recommended in the Decadal Survey. Solar irradiance is known to better radiometric accuracy than any other calibration source available on-orbit. By cross-calibrating a hyperspectral imager with solar spectral irradiance, using techniques similar to those proven on the UARS and SORCE SOLSTICE instruments, the Earth-viewing imager will be calibrated, validated, and tracked on-orbit to the required accuracy and traceability levels.

A hyperspectral imager capable of cross-calibrating via direct solar irradiance measurements is currently being prototyped. Three precision attenuation methods allowing Sun and Earth-viewing are being developed and will be validated using a NIST-calibrated detector. This calibration technology will enable the creation of a climate data record that can be linked to future observations and thus establish a benchmark for detecting climate change.

LSTB

299

4:00-5:00

Thursday, April 9 Peter Delamere, LASP Is Jupiter’s magnetosphere fundamentally different than Earth’s?

Following the New Horizons’ encounter with Jupiter, there has been a flurry of debate in the literature regarding the fundamental nature of Jupiter’s magnetosphere. The observation of large plasmoids filling Jupiter’s magnetotail prompted the suggestion by McComas and Bagenal [2007] that Jupiter has “a fundamentally different interaction with the solar wind”. At Earth, there is abundant evidence of fundamental differences in magnetospheric configuration during periods of southward-directed and northward-directed interplanetary magnetic field (IMF). One of the dramatic signatures of solar wind energy input during southward IMF is the so-called auroral substorm. But a key difference at Jupiter is the addition of an internal plasma source from Io’s prodigious volcanic activity. The internal plasma source combined with the centrifugal stresses of this rapidly rotating (i.e. 10 hour period) gas giant leads to the generation of Jupiter’s internally-driven main auroral oval. The basic question, then, is what role does the solar wind play in the dynamics of the outer magnetosphere and the generation of Jupiter’s polar aurora? Much of the debate centers on the relative importance of Dungey-like convection vs. an Axford and Hines-like convection. We will compare Earth and Jupiter and show that one magnetosphere’s meat might be another magnetosphere’s poison.

LSTB 299
Thursday, April 16 Makenzie Lystrup Duane
Thursday, April 23 Scott Bailey, Jim Russell The Aeronomy of Ice in the Mesosphere Mission:  Science Results after four PMC seasons

Abstract: The Aeronomy of Ice in the Mesosphere (AIM) mission was launched from Vandenberg Air Force Base in California at 1:26:03 PDT on April 25, 2007 becoming the first satellite mission dedicated to the study of noctilucent clouds. A Pegasus XL rocket launched the satellite into a near perfect 600 km, noon – midnight, sun synchronous orbit. AIM carries three instruments – a nadir imager, a solar occultation instrument and an in-situ cosmic dust detector. This paper will provide a brief mission overview, instrument descriptions and scientific findings. Results from the first two years of AIM observations show that the NLC season turns on and off like a “geophysical light bulb” transitioning at the season start from no clouds to 100% occurrence frequency in days and vice versa at the season end. Data show that temperature change is a dominant factor in controlling season onset, variability during the season and season end.  Rising water vapor levels at the beginning and falling values at the end also play a key role in season initiation and cessation. Structures seen in the clouds look very much like complex features seen in tropospheric clouds including large regions of near circular ice voids. This paper will also describe the first satellite observations of cosmic smoke input to the atmosphere measured by the SOFIE instrument. AIM is approved to operate through September 30, 2012.

LSTB
Thursday May 14th Gregor Morfill,

Max-Planck Institut für extraterrestrische Physik

Germany

Self-organising plasmas – new fundamental physics and applications

Abstract:”Self-organising plasmas” – or “complex plasmas” consist of electrons, ions and charged microparticles. The charged microparticles can be visualised individually, allowing full kinetic access to the plasma distribution function for the first time. Complex plasmas can self-organise spontaneously to assume liquid and even crystalline states – these are new states of “soft matter”, which were discovered in 1994. New fundamental physics can be investigated with these systems, e.g. non-Hamiltonian thermodynamics, development of cooperative behaviour in strongly coupled systems, kinetic onset of turbulence in fluids, the particle distribution function at the critical point, the approach(es) to equilibrium, kinetic trigger(s) of instabilities and phase transitions, growth of crystallisation fronts etc..

The basic information on particle-plasma, particle-particle interactions and transport can be usefully employed in diverse fields, such as dust in fusion reactors, plasma processing and self-assembly, plasma-biophysics, plasma-medicine, astrophysics, solar system research, environmental topics and bio-hazards.

The talk aims to give an overview with experimental examples on some of these topics.

Thursday,

June 4th

Dr Grant Matthews,

ITT Space Systems Division

Observing cloud climate feedbacks in the Earth’s Radiation Budget with the help of blackbodies, the Sun & Moon and ice particles on the edge of space.

Abstract:It is essential to maintain global measurements of the Earth’s Radiation Budget (ERB) from space, which are the scattered solar and emitted thermal radiative fluxes leaving the planet. These are required for purposes of validating current climate model predictions of our planet’s future response to anthropogenic greenhouse gas forcing. The measurement accuracy and calibration stability required to resolve the magnitude of model suggested cloud climate feedbacks on the ERB has recently been estimated. The suggestion is for ERB data to strive for a calibration stability of ±0.3%/decade for scattered solar, ±0.5%/decade for emitted thermal and an overall absolute accuracy of 1Wm−2. The Clouds and the Earth’s Radiant Energy System (CERES) is currently the only satellite program to maintain global ERB measurements, beginning in January 1998. However the new climate calibration standards are beyond those originally specified by the NASA CERES program for its Edition 2 data release. Furthermore the CERES instrument optics have been discovered to undergo substantial in-flight degradation due to contaminant issues. This is not directly detectable using established calibration methods. Hence user applied revisions for Edition 2 SW data were derived to compensate for this effect, described as ‘spectral darkening’. Also an entirely new in-flight calibration protocol has been developed for CERES that uses Deep Convective Cloud albedo as a primary solar wavelength stability metric. This is then combined with a sophisticated contamination mobilization/polymerization model. The intention is to assign spectral coloration to any optical degradation occurring to the different CERES Earth observing telescopes. This work quantifies the stability of revised Edition 2 data. It also calculates stability which the new protocols could give CERES measurements if used. The conclusion is that the Edition 2 revisions restore the originally specified stability of CERES SW data. It is also determined that the climate calibration stability goals are reachable using the new in-flight methodologies presented. This will however require data sets of longer than approximately 10 years. It shall also require obtaining regular raster scans of the Moon by all operational CERES instruments.

LSTB
4-5 pm