The kinetic temperature, Tk, and carbon dioxide, CO2 density, are key parameters that characterize the energetics and dynamics of the mesosphere and lower thermosphere (MLT) region. The Sounding of ...the Atmosphere using Broadband Emission Radiometry (SABER) instrument on-board the Thermosphere-Ionosphere-Mesosphere-Energetics and Dynamics (TIMED) satellite has been providing global, simultaneous measurements of limb radiance in 10 spectral channels continuously since late January 2002. In this paper we (1) present a methodology for a self-consistent simultaneous retrieval of temperature/pressure, Tk(p), and CO2 volume mixing ratio (VMR) from the broadband infrared limb measurements in the 15 and 4.3μm channels, and (2) qualitatively describe the first results on the CO2 VMR and Tk obtained from application of this technique to the SABER 15 and 4.3μm channels, including issues, which demand additional constraints to be applied.
The self-consistent two-channel retrieval architecture updates parameters at all altitudes simultaneously, and it is built upon iterative switching between two retrieval modules, one for CO2 and one for Tk. A detailed study of sensitivity, stability and convergence was carried out to validate the algorithm. The Tk/CO2 VMR distribution can be reliably retrieved without biases connected with this non-linear inverse problem starting with an initial guess as far as ±20% of CO2 VMR and ±15K from the solution (as global shift, or somewhat larger if only local deviations are considered).
In polar summer toward high latitudes the retrieved CO2 VMR profile shows a local peak around 90km. We discuss details of this feature and show that: (a) it is not an algorithm artifact or instability, (b) additional a priori constraints are needed in order to obtain a physical profile and to remove this peak, and (c) several possibilities are explored as to uncover the real cause of this feature, but no firm conclusion can be reached at this time.
This algorithm has been applied to all available daytime SABER measurements since 2002, and the first results of the mean CO2 VMR profiles and their distribution is discussed. In particular, the CO2 VMR profiles depart from a well mixed value at altitudes of 65–70km during equinoxes at high and mid-latitudes, but in the summer hemisphere solstice period the SABER data is more consistent with a well mixed VMR conditions extend up to 87–90km especially toward high latitudes.
•SABER 15 and 4.3μm channels are strongly coupled.•The 2-channel algorithm is stable and self-consistent.•Mean CO2 VMR profile appears to be well mixed up to 80–85km.•A CO2 90km peak in polar summer is a persistent but unexplained feature.•CO2 VMR decay depends on latitude and season.
We present geometry-based corrections to estimates of the Bjorken energy density in a broad range of heavy-ion collision energies (from RHIC to the LHC) considering non-circular shape of the nuclei ...overlap area in case of events selected in 0–5
centrality classes. We compare the updated Bjorken energy excitation function, obtained in our study for these very central
A
–
A
collisions, to the previously obtained ones. We also present and discuss the relevant energy dependencies of pion, kaon and proton contributions to the Bjorken energy density that are also estimated in our study.
Despite significant advances in atmospheric measurements and modeling, clouds' response to human-induced climate warming remains the largest source of uncertainty in model predictions of climate. The ...launch of the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite in 2006 started the era of long-term spaceborne optical active sounding of Earth's atmosphere, which continued with the CATS (Cloud-Aerosol Transport System) lidar on board the International Space Station (ISS) in 2015 and the Atmospheric Laser Doppler Instrument (ALADIN) lidar on board Aeolus in 2018. The next important step is the Atmospheric Lidar (ATLID) instrument from the EarthCARE (Earth Clouds, Aerosols and Radiation Explorer) mission, expected to launch in 2024.
Interaction cross sections and charged pion spectra in p+C interactions at 31 GeV/c were measured with the large-acceptance NA61/SHINE spectrometer at the CERN SPS. These data are required to improve ...predictions of the neutrino flux for the T2K long-baseline neutrino oscillation experiment in Japan. A set of data collected during the first NA61/SHINE run in 2007 with an isotropic graphite target with a thickness of 4% of a nuclear interaction length was used for the analysis. The measured p+C inelastic and production cross sections are 257.2 {+-} 1.9 {+-} 8.9 and 229.3 {+-} 1.9 {+-} 9.0 mb, respectively. Inclusive production cross sections for negatively and positively charged pions are presented as functions of laboratory momentum in ten intervals of the laboratory polar angle covering the range from 0 up to 420 mrad. The spectra are compared with predictions of several hadron production models.
Measurements of
K
∗
(
892
)
0
resonance production via its
K
+
π
-
decay mode in inelastic
p+p
collisions at beam momenta 40 and 80
GeV
/
c
(
s
NN
=
8.8
and 12.3
GeV
) are presented. The data were ...recorded by the NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. The
template
method was used to extract the
K
∗
(
892
)
0
signal. Transverse momentum and rapidity spectra were obtained. The mean multiplicities of
K
∗
(
892
)
0
mesons were found to be
(
35.1
±
1.3
(
stat
)
±
3.6
(
sys
)
)
·
10
-
3
at 40
GeV
/
c
and
(
58.3
±
1.9
(
stat
)
±
4.9
(
sys
)
)
·
10
-
3
at 80
GeV
/
c
. The NA61/SHINE results are compared with the
Epos1.99
and Hadron Resonance Gas models as well as with world data. The transverse mass spectra of
K
∗
(
892
)
0
mesons and other particles previously reported by NA61/SHINE were fitted within the Blast-Wave model. The transverse flow velocities are close to 0.1–0.2 of the speed of light and are significantly smaller than the ones determined in heavy nucleus-nucleus interactions at the same beam momenta.
Context. The thermal structure of Titan’s thermosphere is determined by the balance between several heating and cooling processes. These processes must be accurately modeled to correctly interpret ...the available measurements and enhance our understanding of the formation and evolution of this atmosphere. One of the most important thermospheric cooling process for Titan is emission in the HCN rotational band. Aims. We aim to determine the validity of local thermodynamic equilibrium (LTE) for the HCN rotational distribution in the thermosphere of Titan and the impact of its breakdown on the HCN radiative cooling rate in the thermosphere. Methods. A general non-LTE radiative transfer code for rotational lines based on the accelerated lambda iteration (ALI) was used to calculate the excitation of HCN rotational levels in Titan’s atmosphere. These level populations were then used to calculate the associated cooling rate. Results. We show that the common assumption in the models of Titan’s thermospheric energy balance, namely the LTE distribution of rotational lines of HCN, is generally not valid above about 1100 km, or ~0.025 nbar, which will affect the derived thermospheric cooling rates. The effect of non-LTE is to reduce the cooling rate to 15% of the LTE value at around the exobase altitudes depending on the given density of HCN and collisional partners (N2, CH4, H2, and electrons). Since collision state-to-state quenching rates of HCN rotational levels are poorly known, a sensitivity analysis of our results to these rates is also presented.