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

1. Comparison of SABER non-LTE Retrievals of Kinetic Temperature with Ground-based measurements 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. 5ARCON Corp., Waltham, MA, USA. 6AFRL, Hanscom AFB, MA, USAContact: maya@iaa.es • The kinetic temperature • SABER Tkneeded for retrieving all other SABER products and to studyenergy budget,response to solar forcing anddynamics of theMLT region • Tkprofiles retrieved from CO2 emission at 15 µmwhich is affected by non-LTEin the MLT region • Need to use a retrieval algorithm which accounts for non-LTE effects • The SABER instrument • Launched on board the TIMED satellite at the end of 2001 • 10 channel broadband radiometer covering from 1.27 µm to15 µmMeasurements of emission from 10 to 150 km with a very high signal to noise ratio and taken daily and near globally • It providesP-Tkdaytime & nighttime up to the lower thermosphere • Italso provides O3, H2O and CO2 vmr’s and OH, O2 (1D ) and NO ver’s • The retrieval • LTEretrieval  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 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. Convergence criteria: • 10ºx10º around lidar site • Dt = 120minutes SABER LTE Tk retrieval LIDAR Tk measurements SABER non-LTE Tk retrieval TABLE MOUNTAIN (34N, 118W) 20-93 km Jan-Dec 2002 I.S. McDermid MAUNA LOA (20N, 156W) 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 Note how SABER non-LTE Tk reproduces lidar structure Non-LTE Tk (red) similar to LTE Tk (green) below 80 km • 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 • SABERnon-LTE Tk similar to LTE Tk below 80 km • SABERnon-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 Effect of quenching of CO2 by atomic oxygen 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. 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.