[1] The quality of the retrieved temperature-versus-pressure (or T(p)) profiles is described for the middle atmosphere for the publicly available Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) Version 1.07 (V1.07) data set. The primary sources of systematic error for the SABER results below about 70 km are (1) errors in the measured radiances, (2) biases in the forward model, and (3) uncertainties in the corrections for ozone and in the determination of the reference pressure for the retrieved profiles. Comparisons with other correlative data sets indicate that SABER T(p) is too high by 1-3 K in the lower stratosphere but then too low by 1 K near the stratopause and by 2 K in the middle mesosphere. There is little difference between the local thermodynamic equilibrium (LTE) algorithm results below about 70 km from V1.07 and V1.06, but there are substantial improvements/differences for the non-LTE results of V1.07 for the upper mesosphere and lower thermosphere (UMLT) region. In particular, the V1.07 algorithm uses monthly, diurnally averaged CO 2 profiles versus latitude from the Whole Atmosphere Community Climate Model. This change has improved the consistency of the character of the tides in its kinetic temperature (T k ). The T k profiles agree with UMLT values obtained from ground-based measurements of column-averaged OH and O 2 emissions and of the Na lidar returns, at least within their mutual uncertainties. SABER T k values obtained near the mesopause with its daytime algorithm also agree well with the falling sphere climatology at high northern latitudes in summer. It is concluded that the SABER data set can be the basis for improved, diurnal-to-interannual-scale temperatures for the middle atmosphere and especially for its UMLT region.Citation: Remsberg, E. E., et al. (2008), Assessment of the quality of the Version 1.07 temperature-versus-pressure profiles of the middle atmosphere from TIMED/SABER,
Abstract. Solar eruptions sometimes produce protons, which impact the Earth's atmosphere. These solar proton events (SPEs) generally last a few days and produce high energy particles that precipitate into the Earth's atmosphere. The protons cause ionization and dissociation processes that ultimately lead to an enhancement of odd-hydrogen and oddnitrogen in the polar cap regions (>60 • geomagnetic latitude). We have used the Whole Atmosphere Community Climate Model (WACCM3) to study the atmospheric impact of SPEs over the period . The very largest SPEs were found to be the most important and caused atmospheric effects that lasted several months after the events. We present the short-and medium-term (days to a few months) atmospheric influence of the four largest SPEs in the past 45 years (August 1972;October 1989; as computed by WACCM3 and observed by satellite instruments. Polar mesospheric NO x (NO+NO 2 ) increased by over 50 ppbv and mesospheric ozone decreased by over 30% during these very large SPEs. Changes in HNO 3 , N 2 O 5 , ClONO 2 , HOCl, and ClO were indirectly caused by the very large SPEs in October-November 2003, were simulated by WACCM3, and previously measured by Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). WACCM3 output was also represented by sampling with the MIPAS averaging kernel for a more valid comparison. Although qualitatively similar, there are discrepancies between the model and measurement with WACCM3 predicted HNO 3 and ClONO 2 enhancements being smaller than measured and N 2 O 5 enhancements being larger than measured. The HOCl enhancements were fairly Correspondence to: C. H. Jackman (charles.h.jackman@nasa.gov) similar in amounts and temporal variation in WACCM3 and MIPAS. WACCM3 simulated ClO decreases below 50 km, whereas MIPAS mainly observed increases, a very perplexing difference. Upper stratospheric and lower mesospheric NO x increased by over 10 ppbv and was transported during polar night down to the middle stratosphere in several weeks past the SPE. The WACCM3 simulations confirmed the SH HALOE observations of enhanced NO x in September 2000 as a result of the July 2000 SPE and the NH SAGE II observations of enhanced NO 2 in March 1990 as a result of the October 1989 SPEs.
The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) experiment on the Thermosphere‐Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite observed the infrared radiative response of the thermosphere to the solar storm events of April 2002. Large radiance enhancements were observed at 5.3 μm, which are due to emission from the vibration‐rotation bands of nitric oxide (NO). The emission by NO is indicative of the conversion of solar energy to infrared radiation within the atmosphere and represents a “natural thermostat” by which heat and energy are efficiently lost from the thermosphere to space and to the lower atmosphere. We describe the SABER observations at 5.3 μm and their interpretation in terms of energy loss. The infrared enhancements remain only for a few days, indicating that such perturbations to the thermospheric state, while dramatic, are short‐lived.
[1] The dramatic solar storm events of April 2002 deposited a large amount of energy into the Earth's upper atmosphere, substantially altering the thermal structure, the chemical composition, the dynamics, and the radiative environment. We examine the flow of energy within the thermosphere during this storm period from the perspective of infrared radiation transport and heat conduction. Observations from the SABER instrument on the TIMED satellite are coupled with computations based on the ASPEN thermospheric general circulation model to assess the energy flow. The dominant radiative response is associated with dramatically enhanced infrared emission from nitric oxide at 5.3 mm from which a total of $7.7 Â 10 23 ergs of energy are radiated during the storm. Energy loss rates due to NO emission exceed 2200 Kelvin per day. In contrast, energy loss from carbon dioxide emission at 15 mm is only $2.3% that of nitric oxide. Atomic oxygen emission at 63 mm is essentially constant during the storm. Energy loss from molecular heat conduction may be as large as 3.8% of the NO emission. These results confirm the ''natural thermostat'' effect of nitric oxide emission as the primary mechanism by which storm energy is lost from the thermosphere below 210 km.
The SABER instrument was launched onboard the TIMED satellite in December 2001. Vertical profiles of kinetic temperature (Tk) are derived from broadband measurements of CO2 15 μm limb emission, in combination with measurements of CO2 4.3 μm limb emission used to derive CO2 volume mixing ratio (vmr). Infrared emission from the CO2 ro‐vibrational bands are in non‐local thermodynamic equilibrium (non‐LTE) in the mesosphere and lower thermosphere (MLT), requiring new radiation transfer and retrieval methods. In this paper we focus on Tk and show some of the first SABER observations of MLT Tk and compare SABER Tk profiles with rocket falling sphere (FS) measurements taken during the 2002 summer MaCWAVE campaign at Andøya, Norway (69°N, 16°E). The comparisons are very encouraging and demonstrate a significant advance in satellite remote sensing of MLT limb emission and the ability to retrieve Tk under extreme non‐LTE conditions.
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