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To investigate changes in the ozone (O 3) chemical production regime over the contiguous United States (CONUS) with accurate knowledge of concentrations of its precursors, we applied an inverse modeling technique with Ozone Monitoring Instrument (OMI) tropospheric nitrogen dioxide (NO 2) and total formaldehyde (HCHO) retrieval products in the summers of 2011, 2014, and 2017, years in which United States National Emission Inventory were based. The inclusion of dynamic chemical lateral boundary conditions and lightning-induced nitric oxide emissions significantly account for the contribution of background sources in the free troposphere. Satellite-constrained nitrogen oxide (NO x) and non-methane volatile organic compounds (NMVOCs) emissions mitigate the discrepancy between satellite and modeled columns: the inversion suggested 2.33–2.84 (1.07–1.34) times higher NO x over the CONUS (over urban regions) and 0.28–0.81 times fewer NMVOCs emissions over the southeastern United States. The model-derived HCHO/NO 2 column ratio shows gradual spatial changes in the O 3 production regime near urban cores relative to previously defined threshold values representing NO x and VOC sensitive conditions. We also found apparent shifts from the NO x -saturated regime to the transition regime (or the transition regime to the NO x -limited regime) over the major cities in the western United States. In contrast, rural areas, especially in the east-southeastern United States, exhibit a decreased HCHO/NO 2 column ratio by −1.30 ± 1.71 with a reduction in HCHO column primarily driven by meteorology, becoming sensitive to VOC emissions. Results show that incorporating satellite observations into numerical modeling could help policymakers implement appropriate emission control policies for O 3 pollution. • Top-down estimated NO x and NMVOCs emissions enable us to have accurate knowledge of the ozone chemical regime. • The dynamic lateral boundary conditions and lightning-induced emission improve the model performance in the upper atmosphere. • Many urban regions have shifted to NOx-limited condition, while the southeastern U.S. becomes sensitive to VOC emissions. [ABSTRACT FROM AUTHOR]

Abstract: The evolution of the particle background at an altitude of ~540 km during the time interval between 1996 and 2007 is studied using the particle monitor of the High Energy X-ray Timing Experiment on board NASA''s Rossi X-ray Timing Explorer. A special emphasis of this study is the location and strength of the South Atlantic Anomaly (SAA). The size and strength of the SAA are anti-correlated with the 10.7 cm radio flux of the Sun, which leads the SAA strength by ~1 year reflecting variations in solar heating of the upper atmosphere. The location of the SAA is also found to drift westwards with an average drift rate of about 0.3°/yr following the drift of the geomagnetic-field configuration. Superimposed to this drift rate are irregularities, where the SAA suddenly moves eastwards and where furthermore the speed of the drift changes. The most prominent of these irregularities is found in the second quarter of 2003 and another event took place in 1999. We suggest that these events are previously unrecognized manifestations of the geomagnetic jerks of the Earth''s magnetic field. [Copyright &y& Elsevier]

Abstract: In recent years, radio ray tomography of the ionosphere has developed into a very useful technique for the study of the ionosphere. Compact generalized singular value decomposition (CGSVD) is used to study the feasibility of using the International Reference Ionosphere (IRI) model as a regularization profile for ionospheric tomography experiments. TEC data obtained from a meridional chain of three LEO satellite receivers located in Alaska, USA are used for reconstruction of the poleward edge of the mid latitude ionosphere and the high latitude ionosphere. Results show that the IRI has the potential of becoming a useful regularization profile for computerized tomographic reconstruction of the ionosphere. The error estimates for reconstructed images with IRI and Chapman as regularization profiles show that the IRI is a better profile to use under quiet and moderate geomagnetic conditions. Under severe geomagnetic conditions, the IRI and Chapman regularization profiles produce reconstructed images of comparable quality. It has also been observed that the foF2 values obtained from reconstructed images that use the IRI as a regularization profile are closer to measured values than those obtained from the images reconstructed with the Chapman regularization profile. [Copyright &y& Elsevier]

Abstract: We have designed and built an instrument to measure and monitor the “nightglow” of the Earth’s atmosphere in the near ultraviolet (NUV). In this paper we describe the design of this instrument, called NIGHTGLOW. NIGHTGLOW is designed to be flown from a high altitude research balloon, and circumnavigate the globe. NIGHTGLOW is a NASA, University of Utah, and New Mexico State University project. A test flight took place from Palestine, Texas on July 5, 2000, lasting about 8h. The instrument performed well and landed safely in Stiles, Texas with little damage. The resulting measurements of the NUV nightglow are compared with previous measurements from sounding rockets and balloons. [Copyright &y& Elsevier]

The Upper Atmosphere Research Satellite (UARS) was the first satellite to be launched under the Earth Observing System (EOS) science program of multi-mission observing systems of the National Aeronautics and Space Administrations (NASA). The EOS program was conceived to advance the understanding of the Earth-Atmosphere system on the global scale. The UARS was launched in September 1991 with ten instruments dedicated entirely to increase the understanding of chemistry and dynamics of the Earth''s stratosphere and mesosphere. After 10 years of successful data collection (far exceeding the originally projected lifetime of 3 years), the official mission ended in September 2001. However, seven instruments aboard UARS are still operational and six regularly take measurements. It is expected that the UARS will overlap the Earth Observing System (EOS) Aura satellite (to be launched in early 2004) for several months before the end of the UARS mission. The UARS data and atmospheric chemistry and dynamics data from other satellites are archived at the NASA Goddard Earth Sciences Distributed Active Archive Center (GES DAAC) and are available free to the public and science user community. The UARS data and related documents may be accessed through the GES DAAC website (http://daac.gsfc.nasa.gov). This paper gives an overview of the UARS data products. Detailed information on UARS instruments, mission highlights and related publications are available from the UARS project website (http://umpgal.gsfc.nasa.gov) [Copyright &y& Elsevier]