Comparison of SABER non-LTE Retrievals of Kinetic Temperature with Ground-based measurements

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-σAcknowledgements

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 comparisonWe 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: maya@iaa.es

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 (1) 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(2) 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• t = 120 minutes

MAUNA LOA(20N, 156W)

20-93 kmJan-Dec 2002

I.S. McDermid

TABLE MOUNTAIN

(34N, 118W)20-93 km

Jan-Dec 2002

I.S. McDermid

SONDRE STROMFJORD

(67N,51W)30-85 km

Jan-Dec 2002

J. Thayer

MAUI(21N,156W)80-105 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