1. Comparison of SABER non-LTE Retrievals of Kinetic Temperature with Ground-based measurements
CONCLUSIONS
Good general agreement between SABER Tk (v1.01) and Lidar Tk:
- Mid-latitudes: High latitudes:
<±3K from 20 to 65 km • <-3K from 40 to 55 km
<-6K from 65 to 85 km • <-9K from 55 to 75 km
<-15K above 85 km • <±3K above 75 km
Both SABER and Lidars show similar inversion layers in the Tk profiles
However, SABER Tk generally 1-3K warmer below 35 km and ~3-5K colder above
SABER non-LTE Tk similar to LTE Tk below 80 km
SABER non-LTE retrieval reproduces structure in Tk profiles better than LTE above 80 km
Change of a factor of 2 in kco2-o keeps SABER and Lidar difference within their 1-σ
Acknowledgements
We would like to thank C.S. Gardner, J. Thayer and I.S. McDermid for providing the data from lidars at Maui, Sondre Stromfjord and Table Mountain & Mauna Loa respectively.
Effect of quenching of CO2 by atomic oxygen
The comparison
We present comparisons of non-LTE retrievals of Tk from SABER with ground-based measurements in the MLT region at several latitudes and dates. We show some typical examples extracted from a set of more than 200 pairs of coincidences found.
M. García-Comas1, M. López-Puertas1, C.J. Mertens2, M.G. Mlynczak2, J.M. Russell3, E.E. Remsberg2, L.L. Gordley4, P.P. Wintersteiner5, J.R. Winick6, and R.H. Picard6
1 Inst. de Astrofísica de Andalucía (CSIC), Granada, Spain. 2 NASA Langley Research Center, Hampton, VA, USA. 3 Hampton Univ., Hampton, VA, USA. 4 G&A Technical Software, Newport News, VA, USA. 5 ARCON Corp., Waltham, MA, USA. 6 AFRL, Hanscom AFB, MA, USAContact:
The SABER instrument
Launched on board the TIMED satellite at the end of 2001
10 channel broadband radiometer covering from 1.27 µm to 15 µm Measurements of emission from 10 to 150 km with a very high signal to noise ratio and taken daily and near globally
It provides P-Tk daytime & nighttime up to the lower thermosphere
It also provides O3, H2O and CO2 vmr’s and OH, O2 (1D ) and NO ver’s
The kinetic temperature
SABER Tk needed for retrieving all other SABER products and to study energy budget, response to solar forcing and dynamics of the MLT region
Tk profiles retrieved from CO2 emission at 15 µm which is affected by non-LTE in the MLT region
Need to use a retrieval algorithm which accounts for non-LTE effects
The retrieval
LTE retrieval  LTE Tk-P (v1.01)
Non-LTE retrieval:
SABER non-LTE retrieval code (C. Mertens et al., ST8-1TU30-006)
N2, O2, and O(3P) from TGCM
TOA at 140 km
CO2 vmr profiles from rocket measurements
kCO2-O = 6x10-12 cm3 s-1
We have studied the effect of reducing the collisional quenching rate of CO2(n2) by O(3P) by a factor of 2. It tends to increase SABER Tk above 90 km by up to 7K.
SABER non-LTE Tk retrieval
SABER LTE Tk retrieval
LIDAR Tk measurements
Convergence criteria:
• 10ºx10º around lidar site
• Dt = 120 minutes
MAUNA LOA
(20N, 156W)
20-93 km
Jan-Dec 2002
I.S. McDermid
TABLE MOUNTAIN
(34N, 118W)
SONDRE STROMFJORD
(67N,51W)
30-85 km
J. Thayer
MAUI
(21N,156W) km
Apr & Jul 2002
C.S. Gardner
Non-LTE Tk (red) similar to LTE Tk (green) below 80 km
Note how SABER non-LTE Tk reproduces lidar structure