Daytime ozone and temperature variations in the mesosphere: A comparison between SABER observations and HAMMONIA model

The scope of this paper is to investigate the latest version 1.07 SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) tropical ozone from the 1.27 μm as well as from the 9.6 μm retrieval and temperature data with respect to daytime variations in the upper mesosphere. For a better understanding of the processes involved we compare these daytime variations to the output of the three-dimensional general circulation and chemistry model HAMMONIA (Hamburg Model of the Neutral and Ionized Atmosphere). The results show good agreement for ozone. The amplitude of daytime variations is in both cases approximately 60% of the daytime mean. During equinox the daytime maximum ozone abundance is for both, the observations and the model, higher than during solstice, especially above 80 km. We also use the HAMMONIA output of daytime variation patterns of several other different trace gas species, e.g., water vapor and atomic oxygen, to discuss the daytime pattern in ozone. In contrast to ozone, temperature data show little daytime variations between 65 and 90 km and their amplitudes are on the order of less than 1.5%. In addition, SABER and HAMMONIA temperatures show significant differences above 80 k

Infrared Detectors Overview in the Short Wave Infrared to Far Infrared for CLARREO Mission

There exists a considerable interest in the broadband detectors for CLARREO Mission, which can be used to detect CO2, O3, H2O, CH4, and other gases. Detection of these species is critical for understanding the Earth?s atmosphere, atmospheric chemistry, and systemic force driving climatic changes. Discussions are focused on current and the most recent detectors developed in SWIR-to-Far infrared range for CLARREO space-based instrument to measure the above-mentioned species. These detector components will make instruments designed for these critical detections more efficient while reducing complexity and associated electronics and weight. We will review the on-going detector technology efforts in the SWIR to Far-IR regions at different organizations in this study

Characterization of a Double Mesospheric Bore Over Europe

Observations of a pair of mesospheric bore disturbances that propagated through the nighttime mesosphere over Europe are presented. The observations were made at the Padua Observatory, Asiago (45.9\ub0N, 11.5\ub0E), by the Boston University all-sky imager on 11 March 2013. The bores appeared over the northwest horizon, approximately 30 min apart, and propagated toward the southeast. Using additional satellite and radar data, we present evidence indicating the bores originated in the mesosphere from a single, larger-scale mesospheric disturbance propagating through the mesopause region. Furthermore, the large-scale mesospheric disturbance appeared to be associated with an intense weather disturbance that moved southeastward over the United Kingdom and western Europe during 10 and 11 March

Far-Infrared Spectroscopy of the Troposphere (FIRST): Flight Performance and Data Processing

The radiative balance of the troposphere, and hence global climate, is dominated by the infrared absorption and emission of water vapor, particularly at far-infrared (far-IR) wavelengths from 15-50 μm. Current and planned satellites observe the infrared region to about 15.4 μm, ignoring spectral measurement of the far-IR region from 15 to 100μm. The far-infrared spectroscopy of the troposphere (FIRST) project, flown in June 2005, provided a balloon-based demonstration of the two key technologies required for a space-based far-IR spectral sensor. We discuss the FIRST Fourier transform spectrometer system (0.6 cm-1 unapodized resolution), its radiometric calibration in the spectral range from 10 to 100 μm, and its performance and science data from the flight. Two primary and two secondary goals are given and data presented to show the goals were achieved by the FIRST flight

Ozone-Temperature Diurnal and Longer Term Correlations, in the Lower Thermosphere, Mesosphere and Stratosphere, Based on Measurements from SABER on TIMED

The analysis of mutual ozone-temperature variations can provide useful information on their interdependencies relative to the photochemistry and dynamics governing their behavior. Previous studies have mostly been based on satellite measurements taken at a fixed local time in the stratosphere and lower mesosphere. For these data, it is shown that the zonal mean ozone amounts and temperatures in the lower stratosphere are mostly positively correlated, while they are mostly negatively correlated in the upper stratosphere and in the lower mesosphere. The negative correlation, due to the dependence of photochemical reaction rates on temperature, indicates that ozone photochemistry is more important than dynamics in determining the ozone amounts. In this study, we provide new results by extending the analysis to include diurnal variations over 24 hrs of local time, and to larger spatial regimes, to include the upper mesosphere and lower thermosphere (MLT). The results are based on measurements by the SABER instrument on the TIMED satellite. For mean variations (i.e., averages over local time and longitude) in the MLT, our results show that there is a sharp reversal in the correlation near 80 km altitude, above which the ozone mixing ratio and temperature are mostly positively correlated, while they are mostly negatively correlated below 80 km. This is consistent with the view that above -80 km, effects due to dynamics are more important compared to photochemistry. For diurnal variations, both the ozone and temperature show phase progressions in local time, as a function of altitude and latitude. For temperature, the phase progression is as expected, as they represent migrating tides. For day time ozone, we also find regular phase progression in local time over the whole altitude range of our analysis, 25 to 105 km, at least for low latitudes. This was not previously known, although phase progressions had been noted by us and by others at lower altitudes. For diurnal variations, we find that between about 40 and 65 km, the ozone amounts and temperatures are mostly negatively correlated or neutral, while below approx. 40 km they are mostly positively correlated or neutral. The correlations are less systematic and less robust than for correlations of the mean. At altitudes above approx.65 km, the correlations are more complex, and depend on the tidal temperature variations. For the diurnal case, consideration needs to be given to transport by thermal tides and to the efficacy of response times of ozone concentrations and temperature to each other

Correction to "Energy Transport in the Thermosphere During the Solar Storms of April 2002"

We present corrected computations of the infrared power and energy radiated by nitric oxide (NO) and carbon dioxide (CO2) during the solar storm event of April 2002. The computations in our previous paper underestimated the radiated power due to improper weighting of the radiated power and energy with respect to area as a function of latitude. We now find that the radiation by NO during the April 2002 storm period accounts for 50% of the estimated energy input to the atmosphere from the solar storm. The prior estimate was 28.5%. Emission computed for CO2 is also correspondingly increased, but the relative roles of CO2 and NO remain unchanged. NO emission enhancement is still, far and away, the dominant infrared response to the solar storms of April 2002

Quasi 2D electronic states with high spin-polarization in centrosymmetric MoS2_2 bulk crystals

Time reversal dictates that nonmagnetic, centrosymmetric crystals cannot be spin-polarized as a whole. However, it has been recently shown that the electronic structure in these crystals can in fact show regions of high spin-polarization, as long as it is probed locally in real and in reciprocal space. In this article we present the first observation of this type of compensated polarization in MoS$_2$ bulk crystals. Using spin- and angle-resolved photoemission spectroscopy (ARPES) we directly observed a spin-polarization of more than 65% for distinct valleys in the electronic band structure. By additionally evaluating the probing depth of our method we find that these valence band states at the $\overline{\text{K}}$ point in the Brillouin zone are close to fully polarized for the individual atomic trilayers of MoS$_2$, which is confirmed by our density functional theory calculations. Furthermore, we show that this spin-layer locking leads to the observation of highly spin-polarized bands in ARPES since these states are almost completely confined within two dimensions. Our findings prove that these highly desired properties of MoS$_2$ can be accessed without thinning it down to the monolayer limit

Energy transport in the thermosphere during the solar storms of April 2002

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94816/1/jgra17969.pd

Development of a Geomagnetic Storm Correction to the International Reference Ionosphere E-Region Electron Densities Using TIMED/SABER Observations

Auroral infrared emission observed from the TIMED/SABER broadband 4.3 micron channel is used to develop an empirical geomagnetic storm correction to the International Reference Ionosphere (IRI) E-region electron densities. The observation-based proxy used to develop the storm model is SABER-derived NO+(v) 4.3 micron volume emission rates (VER). A correction factor is defined as the ratio of storm-time NO+(v) 4.3 micron VER to a quiet-time climatological averaged NO+(v) 4.3 micron VER, which is linearly fit to available geomagnetic activity indices. The initial version of the E-region storm model, called STORM-E, is most applicable within the auroral oval region. The STORM-E predictions of E-region electron densities are compared to incoherent scatter radar electron density measurements during the Halloween 2003 storm events. Future STORM-E updates will extend the model outside the auroral oval