SOFIE multi-wavelength infrared extinctions are being used to retrieve the temperature of mesospheric ice particles, simultaneously with particle shape. The ice temperatures (iceT) are up to 20K colder than V1.022 SOFIE temperatures retrieved from CO2 transmission measurements. The figure below compares SOFIE ice temperatures to the mesopause CO2 temperature from SOFIE, and from the falling sphere (FS) climatology of Lubken [1999]. The mesopause frost point temperature (Tice) is also shown.

SOFIE meteoric smoke extinction versus time and height for the Southern Hemisphere. Black dots indicate NLCs, and the black bar represents missing data. Time ranges from June 2007 through June 2009 and the abscissa is labeled by the first letter of each month. The results are monthly zonal averages and white regions represent extinction below 5e-9 1/km.

Credit: Space Dynamics Laboratory

PMC Frequency NH 2007-2010

Ice Layer as seen with AIM instrument sensitivity.

Northern Hemisphere 06 May 2008: Time versus altitude cross sections of SOFIE temperature, water vapor, ice (PMC) occurrence frequency, ozone, and methane. The plots show the cold summer mesopause region in both hemispheres which is accompanied by increasing water vapor and the sudden appearance of ice.
Credit: SOFIE instrument team at GATS, Inc.

Southern Hemisphere 06 May 2008: Time versus altitude cross sections of SOFIE temperature, water vapor, ice (PMC) occurrence frequency, ozone, and methane. The plots show the cold summer mesopause region in both hemispheres which is accompanied by increasing water vapor and the sudden appearance of ice.
Credit: SOFIE instrument team at GATS, Inc.

SOFIE PMC measurement results for the 2007 northern polar summer as time-height cross sections of a) ice detection frequency, b) ice mass density, c) particle shape (axial ratio of an oblate spheroid), and d) effective radius. Three-day average ice layer top, peak, and bottom altitudes are overlain in all panels (solid lines), and average mesopause heights are shown in a). White regions indicate the absence of data.

PMC measurement showing a PMC near 86-87km.
The figure shows the SOFIE signals for the first detected PMC of the 2008 Northern Hemisphere season. The signals (formulated as extinctions) are for the 3 micron PMC channel. Band 9 is shown in green, band 10 in red and the DV signal in blue. The signals have been smoothed slightly to help illustrate the PMC signature.
Credit: SOFIE instrument team at GATS, Inc.

SOFIE measurements are being used to examine hemispheric differences in PMCs and their environment. The figure shows SOFIE results for the northernsummer of 2007, and the southern sumer of 2007/08. Ice is more frequent and appears about 10 days earlier in the north compared to the south. The altitude of peak extinction (Zmax) for southern PMCs is about 3 km higher, consistent with the southern mesopause being about 3 km higher than in the north. Northern PMCs have greater ice mass densities, and are characterized by slightly more aspherical particles, than in the south. Water vapor measurements at Zmax are similar in the north and south.

Mean SABER and SOFIE H2O profiles and comparison statistics for 33 events.

SOFIE temperatures near a latitude of 65°N on June 21 (top) and Dec 21 (bottom).

SOFIE and HALOE H2O profiles.

Hemispheric temperature difference expressed as NH-SH. See Figure 2.6.3-1 for the altitude of the mesopause.

Southern altitudes and occurrence frequencies for 2007 from AIM

Time - height cross section of SOFIE H2O and O3 observations for the 2007 northern polar summer. Mesopause altitude (solid line) and the altitude of peak extinction (dashed line) are also indicated.

Average ice mass density (Mice) and axial ratio (AR) profiles based on SOFIE observations during July 2007. Average profiles were constructed by vertically aligning individual profiles so that the extinction peak altitudes (Zmax) were located at the July average value (83.2 km). Horizontal dot-dash lines show the average ice layer top (86.5 km), peak, and bottom (80.0 km) altitudes. The July average mesopause height was 86.8 km.

Probability distributions of the Gaussian size distribution a) concentration, b) median radius, and c) width, retrieved from SOFIE measurements at Zmax in the northern hemisphere during 2007 (black lines) are compared to the distribution of results obtained at Zmax from lidar measurements over ALOMAR in 2007. Average SOFIE values are indicated by vertical dotted lines. The range of model size distribution parameters from Rapp et al. [2007], and concentration from lidar results reported by von Cossart et al. [1999] are indicated. These independent results are arbitrarily located on the ordinate.

Credit: Space Dynamics Laboratory