High-Resolution Active Optical Remote Sensing of Atmospheric Processes II Posters

Atmospheric Science [A]

A33A
CC:Hall E Wednesday 1400h

Presiding: S Ismail, NASA Langley Research Center; G S Peng, The Aerospace Corporation; Y Hu, NASA Langley Research Center; D M Tratt, The Aerospace Corporation

A33A-01

Dust in the Planetary Boundary Layers of Mars and Earth

* Dickinson, C S (cameron.dickinson@gmail.com), York University, Petrie Science Bldg, 4700 Keele St., Toronto, ON M3J1P3, Canada
Whiteway, J (whiteway@yorku.ca), York University, Petrie Science Bldg, 4700 Keele St., Toronto, ON M3J1P3, Canada
Popovici, V (vladp@yorku.ca), York University, Petrie Science Bldg, 4700 Keele St., Toronto, ON M3J1P3, Canada
Komguem, L (komguem@yorku.ca), York University, Petrie Science Bldg, 4700 Keele St., Toronto, ON M3J1P3, Canada
Cook, C (clivec@yorku.ca), York University, Petrie Science Bldg, 4700 Keele St., Toronto, ON M3J1P3, Canada
Seabrook, J (jseab@yorku.ca), York University, Petrie Science Bldg, 4700 Keele St., Toronto, ON M3J1P3, Canada
Carswell, A (allanc@optech.ca), Optech Inc., 300 Interchange Way, Vaughan, ON L4K 5Z8, Canada
Daly, M (Mike.Daly@mdacorporation.com), MacDonald, Dettwiler and Associates, 9445 Airport Road, Brampton, ON L6S 4J3, Canada
Phoenix Science Team, (psmith@lpl.arizona.edu) AB: The LIDAR on the Phoenix spacecraft has provided observations of the distribution of dust and clouds in the Martian atmosphere, while Phoenix's Surface Stereoscopic Imager provided estimates of total column dust opacity. Initial analysis indicates that the fine dust is well mixed within the Planetary Boundary Layer up to heights of 4 to 6 km. Observations with an equivalent lidar system were obtained in November of 2007 in the Australian desert. Simultaneous measurements of the Australian dust were also obtained, and include in situ measurements obtained by over flying aircraft, sampling humidity as well as particle size and number with height, as well as a ground-based instrument measuring the total optical depth. Test cases of Terrestrial and Martian lidar signals are presented, and properties of the Martian dust are inferred based on the in situ measurements made in Australia.

A33A-02

Mesospheric Atmospheric Gravity Wave Properties Derived From Rayleigh-Scatter Lidar Observations Above Logan, Utah

* Kafle, D N (d.n.kafle@aggiemail.usu.edu), Utah State University, Center for Atmospheric and Space Sciences, 4405 Old Main Hill, Logan, UT 84322-4405, United States
Wickwar, V B (Vincent.Wickwar@usu.edu), Utah State University, Center for Atmospheric and Space Sciences, 4405 Old Main Hill, Logan, UT 84322-4405, United States

Approximately 900 nights of observations with a Rayleigh-scatter lidar at Utah State University's Atmospheric Lidar Observatory (41.7°N, 111.8°W), spanning the 11-year period from late 1993 through 2004, have been reduced to derive nighttime temperature and relative density profiles between 45 and 90 km, i.e., over the entire mesosphere. Of these, 150 profiles that extend to 90 km or above were used in this work, which is based mainly on relative density data with 3-km altitude resolution and 1-hour temporal resolution. This is, we believe, the first comprehensive study of monochromatic gravity waves using Rayleigh-scatter lidar observations extending through the entire mesosphere at mid-latitudes. The variations of relative density perturbations were used to identify the presence of monochromatic gravity waves. These waves have a clear downward phase progression (i.e. upward energy propagation) with the most prevalent vertical phase velocity (c_z) of 0.6 ms^-1 (2.2 km/hr). The most dominant vertical wavelength (λ_z) is 12 km. The values of the Brunt-Väisälä frequency, N(rad/sec), the maximum gravity wave frequency, were calculated by using seasonally averaged nightly temperature and temperature derivative profiles. Using the gravity wave dispersion relations and the values of c_z, λ_z, and N, other gravity wave parameters such as wave period (τ), horizontal wavelength (λ_x), horizontal phase velocity (c_x), and horizontal distance to the source region (X) were calculated. The most prevalent values of τ, λ_x, c_x and are 6 hours, 550 km, and 35 ms^-1 (125 km/hr), respectively. The most dominant values of X for 45-km and 90-km altitudes are 2500 km and 5000 km, respectively, which suggest that these large-scale gravity waves are generated from a very distant and very extended source region. There appears to be a seasonal dependence in c_z, τ, λ_x, and X but not in λ_x and c_x. The vertical phase velocities maximized in summer whereas the apparent periods, horizontal wavelengths, and horizontal distance to the source region maximized in winter. The magnitude of the relative density perturbations on average grew with altitude with an e- folding distance of 20 km, which is larger than the 2H = 14 km expected for undisturbed gravity wave propagation, where H is the scale height. This means that the amplitude of the observed fluctuations increases less rapidly with altitude than for the undisturbed situation, which also implies that significant gravity- wave energy dissipation occurs in this region.