The MIPAS instrument on board Envisat, in Earth orbit, the PFS and OMEGA instruments on Mars Express, and VIRTIS on board Venus Express are currently providing a dataset of limb measurements of the ...CO2 atmospheric fluorescence emission at 4.3 - mu m from the upper atmosphere of the three planets. These measurements represent an excellent dataset to perform comparative studies between the terrestrial planets' upper atmospheres, and also to test our theoretical understanding of these emissions. In order to exploit these datasets, we apply a set of non-local thermodynamic equilibrium (non-LTE) models developed at the IAA/CSIC, in Granada, Spain, to a selection of data. In general, the models can explain the main spectral features of the measurements, and also the altitude and solar zenith angle variations. However, the simulations for Mars and Venus give an incorrect ratio of the emissions at two wavelengths, 4.4 and 4.32 mu m . In order to explain this deficiency, a revision of the most uncertain non-LTE energy transfer parameters has been performed. The quenching rate of nu 3 quanta of high-energy CO2 states by CO2 itself could reduce the model-data discrepancy if increased by a factor 2-4, still within its current uncertainty range. This factor, however, is subject to the uncertainty in the thermal structure. A number of simulations with the non-LTE models were also used to study and compare the role of radiative transfer in this spectral region in the three terrestrial planets. Sensitivity studies of density and temperature are also presented, and they permit an analysis of how the differences between the planets and between the three instruments affect their sounding capabilities.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
► The optical depth of the martian atmosphere determines the brightness of shadows. ► We estimate the optical depth from the brightness of shadows in orbiter images. ► It is best to use images taken ...in colors between yellow and red. ► Two case studies suggest an accuracy of ±15% or better between yellow and red.
The difference in brightness between shadowed and sunlit regions in space images of Mars is a measure of the optical depth of the atmosphere. The translation of this difference into optical depth is what we name the “shadow method”. Our analysis of two HRSC data-sets and a HiRISE data-set indicates that it is possible to estimate the optical depth with the shadow method. In colors between yellow and red the accuracy may be around ±15%, and in some cases ±8–10%. In other colors we found larger errors.
We came to these results in two steps. First, we investigated in how far shadow method retrievals are proportional to the true optical depth. To this end we analyzed about 150 locations in Valles Marineris that were imaged by HRSC. Whereas the studied region spans about 8
km in altitude we were able to study the relation between altitude and shadow-method retrievals. Retrievals from five HRSC panchromatic (675
±
90
nm) stereo images yielded scale-heights with an average of 12.2
±
0.7
km, which is very close to the expected local pressure scale height. Many studies have shown that the scale-height of optical depth and pressure commonly are similar. This indicates that the shadow method retrievals are on average close to proportional to the optical depth, because otherwise these would probably not yield a correct scale-height. HRSC’s red image yielded very similar results, but the blue, green, and NIR images did not.
Next, we compared optical depth measurements by the two MER rovers with shadow method retrievals from orbiter images of the rover exploration sites. Retrievals with the shadow method appear systematically smaller than the rover measurements; dividing the retrievals by a “correction factor” yields an estimate of the real optical depth. Retrievals from three HRSC panchromatic stereo images of a region near the Spirit rover yielded a correction factor of 0.63
±
0.09 when the sunlit comparison regions were at varying and more or less arbitrary distances from the shadows and 0.71
±
0.06 when these were close together. Twenty retrievals from a HiRISE red (650
±
100
nm) image of the Opportunity exploration site similarly yielded 0.68
±
0.09. The results from these two case studies suggest that the shadow method has an accuracy of about ±15% or around ±8–10% in the best cases.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
IMPORTANCE: It is estimated that only 27% of patients with acute ischemic stroke and large vessel occlusion who undergo successful reperfusion after mechanical thrombectomy are disability free at 90 ...days. An incomplete microcirculatory reperfusion might contribute to these suboptimal clinical benefits. OBJECTIVE: To investigate whether treatment with adjunct intra-arterial alteplase after thrombectomy improves outcomes following reperfusion. DESIGN, SETTING, AND PARTICIPANTS: Phase 2b randomized, double-blind, placebo-controlled trial performed from December 2018 through May 2021 in 7 stroke centers in Catalonia, Spain. The study included 121 patients with large vessel occlusion acute ischemic stroke treated with thrombectomy within 24 hours after stroke onset and with an expanded Treatment in Cerebral Ischemia angiographic score of 2b50 to 3. INTERVENTIONS: Participants were randomized to receive intra-arterial alteplase (0.225 mg/kg; maximum dose, 22.5 mg) infused over 15 to 30 minutes (n = 61) or placebo (n = 52). MAIN OUTCOMES AND MEASURES: The primary outcome was the difference in proportion of patients achieving a score of 0 or 1 on the 90-day modified Rankin Scale (range, 0 no symptoms to 6 death) in all patients treated as randomized. Safety outcomes included rate of symptomatic intracranial hemorrhage and death. RESULTS: The study was terminated early for inability to maintain placebo availability and enrollment rate because of the COVID-19 pandemic. Of 1825 patients with acute ischemic stroke treated with thrombectomy at the 7 study sites, 748 (41%) patients fulfilled the angiographic criteria, 121 (7%) patients were randomized (mean age, 70.6 SD, 13.7 years; 57 women 47%), and 113 (6%) were treated as randomized. The proportion of participants with a modified Rankin Scale score of 0 or 1 at 90 days was 59.0% (36/61) with alteplase and 40.4% (21/52) with placebo (adjusted risk difference, 18.4%; 95% CI, 0.3%-36.4%; P = .047). The proportion of patients with symptomatic intracranial hemorrhage within 24 hours was 0% with alteplase and 3.8% with placebo (risk difference, −3.8%; 95% CI, −13.2% to 2.5%). Ninety-day mortality was 8% with alteplase and 15% with placebo (risk difference, −7.2%; 95% CI, −19.2% to 4.8%). CONCLUSIONS AND RELEVANCE: Among patients with large vessel occlusion acute ischemic stroke and successful reperfusion following thrombectomy, the use of adjunct intra-arterial alteplase compared with placebo resulted in a greater likelihood of excellent neurological outcome at 90 days. However, because of study limitations, these findings should be interpreted as preliminary and require replication. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03876119; EudraCT Number: 2018-002195-40
The retrieval of NO and Tk from MIPAS upper atmospheric observation is described NO and Tk climatology is compared to models Diurnal variations of thermospheric NO are analyzed We present vertically ...resolved thermospheric temperatures and NO abundances in terms of volume mixing ratio retrieved simultaneously from spectrally resolved 5.3 m emissions recorded by the Michelson Interferometer for Passive Atmospheric Spectroscopy (MIPAS) in its upper atmospheric observation mode during 20052009. These measurements are unique since they represent the first global observations of temperature and NO for both day and night conditions taken from space. A retrieval scheme has been developed which accounts for vibrational, rotational and spin-orbit non-LTE distributions of NO. Retrieved polar temperature and NO profiles have a vertical resolution of 510 km for high Ap values, and degrade to 1020 km for low Ap conditions. Though retrieved NO abundances depend strongly on the atomic oxygen profile used in the non-LTE modeling, observations can be compared to model results in a consistent manner by applying a simple correction. Apart from this, total retrieval errors are dominated by instrumental noise. The typical single measurement precision of temperature and NO abundances are 540 K and 1030%, respectively, for high Ap values, increasing to 3070 K for Tk and 2050% for NO VMR for low Ap conditions. Temperature and NO profiles observed under auroral conditions are rather insensitive to smoothing errors related to the mapping of a priori profile shapes. However, for extra-polar and low Ap conditions, a potential systematic bias in the retrieved nighttime temperature and NO profiles related to smoothing errors has been identified from a comparison to Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIME-GCM) simulations. We have constructed a solar minimum monthly climatology of thermospheric temperature and NO from MIPAS observations taken during 20082009. MIPAS temperature distributions agree well, on average, with the Mass Spectrometer and Incoherent Scatter radar model (NRLMSISE-00), but some systematic differences exist. MIPAS temperatures are generally colder than NRLMSISE-00 in the polar middle thermosphere (mainly in the summer polar region) by up to 40 K; and are warmer than NRLMSISE-00 in the lower thermosphere around 120125 km by 1040 K. Thermospheric NO daytime distributions agree well with the Nitric Oxide Empirical Model (NOEM), based on Student Nitric Oxide Explorer (SNOE) observations. A comparison of MIPAS NO number density with the previous climatology for the declining phases of the solar cycle based on HALOE and SME data shows that MIPAS is generally larger with values ranging from 10 to 40%, except in the auroral region and at the equatorial latitudes above 130 km where the MIPAS/HALOE+SME ratio varies from 1.6 to 2. Day-night differences in MIPAS NO show daytime enhancements of up to 140% in the tropical and midlatitudes middle thermosphere. In the lower thermosphere, the diurnal amplitude is smaller and NO concentrations are generally higher during night by about 1030%, particularly in the auroral regions.
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BFBNIB, FZAB, GIS, IJS, KILJ, NUK, OILJ, SBCE, SBMB, UL, UPUK
The temperature and ozone volume mixing ratio (VMR) profiles measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on ENVISAT are used to study the unusual Antarctic major ...stratospheric warming of 2002. The observed zonal mean temperatures show rapid poleward increase and remarkable reversal of the latitudinal gradients at 35 km or below in several days. The highest temperature increase is of 50 K or more. The zonal mean ozone VMRs also increase poleward and have maximum values of 7 ppmv in a wide region between 20 and 40 km at latitudes south of 40°S. Temperature amplitudes of zonal wave number 1 to 3 exhibit a double‐peaked structure with peaks near 25 km and 35 km. The ozone waves in the lower stratosphere are generally in phase with the corresponding temperature waves. At the onset of the warming, the wave 1 amplitudes drastically increase at 60°S–80°S, reaching maxima of ∼20 K for the temperature and ∼2 ppmv for the ozone VMR. Significant wave 3 amplitudes are also observed with maximum of 14–18 K and 1–1.5 ppmv for temperature and ozone VMR, respectively. The wave 3 amplitudes are larger than those of wave 2 by nearly a factor of 2 immediately before and after the polar vortex split. The large‐amplitude wave 1 and 3 disturbances break down in 1 or 2 days, and the wave 2 variations are enhanced and attain amplitudes comparable to those of wave 1 and 3, resulting in an apparent wave 2 warming event. These results are consistent with other observations and suggest the importance of wave 3 forcing in the major warming.
Daytime mesospheric limb emission spectra of ozone in the
4.8
μ
m
regime are analyzed with respect to vibrational excitation and relaxation processes. The data, which was obtained by the MIPAS ...(Michelson Interferometer for Passive Atmospheric Sounding) instrument on board ESA's Environmental Satellite, is simulated by means of a non-local thermodynamic equilibrium (non-LTE) model utilizing
O
3
-abundance, temperature, and pressure data from simultaneous retrievals in other spectral regions. The vibrational states of ozone depart from LTE due to the absorption of radiation from the lower atmosphere and due to the production of excited states in the
O
+
O
2
+
M
→
O
3
(
v
)
+
M
recombination reaction. The energy flow into the ozone molecule as well as the collisional relaxation are highly uncertain. Model calculations that assume ozone formation at energies larger than
5000
cm
-
1
underestimate the measured radiances by a factor of 2–3 in the 50–75
km altitude regime, if the nominal relaxation scheme is assumed. Agreement between measured and modeled radiances is achieved, if the collisional rates for the transformation of hot band stretching to bending quanta are reduced by about a factor of three, or if the quasi-nascent distribution of ozone favors vibrational states in the
3000
cm
-
1
region.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We measured the optical depth of the Martian atmosphere as a function of altitude above two opposing scree walls of the Valles Marineris, from stereo images that were taken with the High Resolution ...Stereo Camera (HRSC) of Mars Express on June 3, 2004, during orbit 471. The optical depths were measured from contrast differences between the stereo images with the so called “stereo method”. For 7 regions in the northern wall of the Valles, we estimated the optical depth and found values between 1.0 and 1.6. These regions span more than 6
km in altitude and the results show a clear relation with altitude. A fit on these results yielded a scale-height for the optical depth of 14.0
km
+
1.3/−1.1
km. The expected local pressure–scale height is smaller: 11.5–12.0
km. The difference is most likely explained by small (around 1.5%) offset errors in the intensity calibration of HRSC images. We also selected 9 regions in the opposing southern wall and from these we measured values of optical depth in the range 1.3–1.5. Our result suggests the presence of clouds above this part of the Valles because the optical depth appears almost independent of the surface altitude. Possibly these are banner clouds, forming at the edge of the canyon, that contain dust that is blown over the canyon by winds from the high plains to the South.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Rotational temperatures obtained from the O
2 Atmospheric (0–1) nightglow band and from the OH (6–2) band, with a Spectral Airglow Temperature Imager (SATI) instrument at Sierra Nevada Observatory (
...37
.
06
∘
N
,
3
.
38
∘
W
) are presented. A revision of the temperatures obtained from the Q branch of the (6–2) Meinel band has been undertaken. First, new experimental Einstein coefficients for these lines have been introduced and the temperatures derived from the Q lines (1, 2 and 3) of the (6–2) OH Meinel band have been compared to those deduced from the P lines (2 and 4) of the same band of spectra taken by a spectrograph at Boston University. The new set of SATI data has been used to analyse the seasonal behaviour of the mesospheric and lower thermospheric temperatures. Atmospheric temperatures deduced from SATI and from satellite observations with the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board the TIMED satellite, have also been compared. SABER temperatures at 95
km are slightly warmer (about 2.5
K) than SATI temperatures while at 87 km they are slightly colder (about 5.7
K). Also, similar patterns of seasonal and day to day variations are found in the temperatures retrieved from both instruments at the latitude of
37
∘
N
.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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