Conveners:
Elsayed Talaat (APL, Elsayed.Talaat@jhuapl.edu)
Larry Paxton (APL, Larry.Paxton@jhuapl.edu)
Sam Yee (APL, jeng-hwa_yee@jhuapl.edu)
Jim Russell (Hampton U, james.russell@hamptonu.edu)
Tom Woods (LASP, tom.woods@lasp.colorado.edu)
Qian Wu (NCAR/HAO, qwu@ucar.edu)
2004 Friday 02 July 0800-1000 AM
The TIMED/CEDAR Workshop was organized into four mini-sessions covering:
Team Representatives:
GUVI - Larry Paxton
SABER - Jim Russell
SEE - Tom Woods
TIDI - Rick Niciejewski
Instrument representatives briefed the audience on a self-assessment of data quality, issues, and availability. In summary, the TIMED data has made good progress in ensuring the quality of the data and in making it available to the public. For more information on the TIMED mission and data products, go to http://www.timed.jhuapl.edu.
After the instrument question and answer sessions, Joe She discussed a collaborative effort to improve the temperature and indirectly validate CO2 retrievals from SABER ("CSU Lidar-SABER Cooperation", C. Mertens and J. She). Nighttime comparisons of SABER and CSU lidar temperature in the mesosphere and lower thermosphere are improved by 5-6 K by using the SABER-mean retrieved CO2 profile in the nighttime SABER non-LTE temperature retrieval algorithm versus using a modeled CO2 profile. The improved SABER/CSU comparisons suggest that the SABER CO2 profiles represent an improvement in our knowledge of the vertical distribution of CO2 in the mesosphere and lower thermosphere. In other words, CSU lidar temperatures are being used indirectly "validate" SABER CO2 vmr and at the same time improve the SABER nighttime tempertures.
Jeremy Winick then presented a study of the inversion layers seen in both SABER and the CSU lidar ("SABER Temperature and OH retrievals and Ground-based Lidar and Imaging of Mesospheric Bores and Similar Events", J. Winick et al.). Temperature profiles from SABER and CSU lidar are consistent and show the same inversion structure in early October, 2002. SABER was able to provide the geographical extent of the inversion layer in altitude and the north-south direction. Work is in progress to use extensive SABER data to study the frequency of inversions - relationship to tides and other geophysical parameters.
Jeff Forbes provided an overview of his IDS team's ongoing projects to analyze the mean and waves from SABER and TIDI data ("Tides, Planetary Waves and Eddy Forcing of the Zonal Mean Circulation," J. Forbes et al.). These efforts include delineating tides and planetary waves in TIMED data, combining space-borne and groundbased data for wave analysis, separating the zonal mean from the migrating tides. These analyses will provide direction to model simulations that address the role of tide and planetary dissipation on the zonal mean wind and temperature structure of the MLT region.
Qian Wu presented analysis of the diurnal and semidiurnal tides in TIDI data and comparisons to modeled tides ("TIDI Observations of Diurnal and Semi-diurnal tides", Q. Wu et al.). The TIDI meridional neutral wind data show clear signs of the diurnal and semi-diurnal tides where the diurnal tide at low latitudes was gradually replaced by the semi-diurnal tide at mid-latitudes. The diurnal tide has a vertical wavelength close to 20 km and peaks at about 97 km. The Global Scale Wave Model diurnal tide is comparably smaller in amplitude and longer in vertical wavelength (~ 25 km) and peaks above 100 m.
The GSWM diurnal tide peaks above 100 km. Both TIDI and GSWM show stronger semi-diurnal tides in the southern hemisphere. In general, the amplitudes of GSWM model and TIDI observation are not inconsistent.
James Russell presented an overview of the radiative balance in the middle atmosphere ("The Radiative Budget of the MLT System: Outstanding Issues", M. Mlynczak et al.). Additionally, he also showed four case studies of issues in radiative balance that are being addressed by SABER measurements. In the first case study, he highlighted how the uncertainties in the CO2-O quenching rate (a factor of 4 difference between lab and inferred values) can induce significant uncertainties in radiative cooling and retrieved temperature from SABER. This situation may be remedied by new results combined with TIMED data. The second case study is that the larger NO-O rate coefficient impacts modeling of the thermospheric heat budget and interpretation of remote sensing measurements of the NO cooling rate. A combination of NO, CO2 emission measurements from TIMED may resolve the situation of the effects of the CO2 quenching rate on the atmospheric cooling and temperature retrievals. Thirdly, the range of values reported for the O2(1)+O reaction yields a large uncertainty in retrieved H2O. There is a need to determine the temperature dependence of the newly reported rate and to test it using H2O retrievals against correlative measurements. In the fourth case study, the OH(v)+O rates that are critical to interpretation of SABER data need measurement verification, and determination of the reactive vs. quenching channels.
Dan Marsh presented comparisons between SABER data and simulations from the Hamburg Model of the Neutral and Ionized Atmosphere ("Preliminary SABER/HAMMONIA comparisons", D. Marsh and H. Schmidt). Good agreement was seen in ozone and temperature between 100 and 1e-4 hPa. An observed enhancement in the ozone secondary maximum mixing ratio was successfully reproduced by the model and is related to changes in photochemistry brought about by the cool summer mesopause.
Geoff Crowley presented a quick introduction to thermospheric energetics, describing the important heating and cooling term distributions with altitude and latitude.
Larisal Goncharenko presented investigations on the variations in the thermosphere and ionosphere using multi-instrument observations during the April 2002 period, with focus on periods with small geomagnetic disturbances ("Variability in the thermosphere and ionosphere during minor geomagnetic disturbances in April 2002 and its association with IMF By orientation," L. Goncharenko, et al.). Large (30-50%) and long-lasting reductions in the daytime electron density were observed at midlatitudes by the array of incoherent scatter radars, ionosondes and GPS receivers. The GUVI data revealed a reduction in the daytime O/N2 ratio in the coincident area. She suggested that these ionospheric and thermospheric disturbances result from high-latitude energy input and efficient transport of regions with reduced O/N2 to lower latitudes and emphasized the importance of a strong positive By component of the interplanetary magnetic field in the transport of regions with reduced O/N2.
Hyosub Kil presented an overview of studies that can be performed with low-latitude GUVI data ("New science using GUVI data", H. Kil). For instance, using GUVI 135.6 nm high-resolution global maps, one can construct a climatology of plasma bubble characteristics and global distribution (latitudinal extent, thickness, and tilt). One can also put together an F-region plasma climatology. With GUVI measurements of the location and strength of the ionization anomaly, one is also able investigate the effects of electric field and neutral winds on the global ionospheric morphology during quiet and disturbed periods. Finally, GUVI limb measurements allow the investigation of the growth conditions for equatorial plasma bubbles.
Yongliang Zhang presented highlights of coordinated studies of GUVI and other satellite data ("GUVI New Results", Y. Zhang). Double dayside detached auroras were seen in GUVI and Geotail. Nightside detached auroras were present in GUVI and DMSP, as were undulations in diffuse proton auroras and observations of thin cusp. He also presented comparisons between retrieved O/N2 from GUVI and IMAGE/FUV, and derived Qeuv from GUVI and SOHO_SEM.
In the last presentation of the session, Pallamraju Duggirala presented groundbased observations from Boston using the HIRISE spectrograph that revealed a large enhancement in OI 630.0nm emissions during 1400-1900 LT on October 30, 2003, ("HIRISE Observations of Daytime Aurora Over Boston in response to the Magnetic Disturbance of October 30, 2003", D. Pallamraju). These enhancements were a factor of 2 to 6 larger than the dayglow emissions of around 4-6 KR observed before 1400 LT on the same day. Sometimes these intense enhancements in the brightness were also visible in the unprocessed (raw) spectral images. The solar zenith angles during these times were as small as 70 degrees, making this one of the first daytime auroral observations from Boston.