Growth rates of stratospheric HCFC-22

International audienceThe Michelson Interferometer for Passive Atmospheric Sounding onboard ENVISAT (MIPAS-E) offers the opportunity to detect and spectrally resolve many atmospheric minor constituents affecting atmospheric chemistry. In this paper, we describe an algorithm produced to retrieve HCFC?22 profiles from MIPAS-E measurements made in 2003 and present results from this scheme between 300 and 50 mb. By comparison with ATMOS (AT?3) version 3 data, we find a mean Northern Hemisphere mid-latitude (20?50° N) HCFC?22 growth rate between 1994 and 2003 of 5.4±0.7 pptv/yr in the lower stratosphere (LS) and a mean LS Southern Hemisphere growth rate (60?80°S) of 6.0±0.7 pptv/yr in the same period. We test the feasibility of using a global data set to estimate the chemical lifetime of HCFC?22 in the LS and we derive this for two regions; 20?50° N (259±38 years) and 60?80° S (288±34 years). From these data we note a global LS lifetime of 274±25 years, significantly longer than previous estimates

Seasonality of Peroxyacetyl nitrate (PAN) in the upper troposphere and lower stratosphere using the MIPAS-E instrument

The Michelson Interferometer for Passive Atmospheric Sounding onboard ENVISAT (MIPAS–E) offers the opportunity to detect and spectrally resolve many atmospheric minor constituents affecting atmospheric chemistry. In this paper, we retrieve global, seasonal PAN volume mixing ratio (vmr) data from MIPAS-E measurements made in January, March, August and October 2003 and present results from this scheme between approximately 300 and 150 hPa. The total error on a single PAN retrieval is better than 20% outside the tropics and better than 50% in the tropics where uncertainties in water vapor dominate the total error budget. We observe clear differences in the seasonal cycle of PAN in our data, linked closely to biomass burning regions and growing seasons. Highest Northern Hemisphere mid-latitude PAN vmrs were observed in August (300–600 pptv on average) compared with the January and October data (less than 250 pptv on average). In the March 2003 data we observe highest PAN vmrs in the tropics with evidence of vmrs between 600 and 1000 pptv over Eastern Asia and over the Central Pacific at 333 hPa. The vertical distribution of PAN as a function of latitude (i.e. the zonal mean) highlights the strong inter-annual variability of PAN in the upper troposphere and lower stratosphere (UTLS), most pronounced poleward of 40° N (up to 400 pptv over the year). The variability of PAN in the tropical UTLS is also significant and we derive a variability of up to 250 pptv in the averages between January and October 2003. These results represent the first seasonal observations of PAN in the UTLS

Long-term prevalence and predictors of prolonged grief disorder amongst bereaved cancer caregivers: A cohort study

Context: The short-term impact of prolonged grief disorder (PGD) following bereavement is well documented. The longer term sequelae of PGD however are poorly understood, possibly unrecognized, and may be incorrectly attributed to other mental health disorders and hence undertreated. Objectives: The aims of this study were to prospectively evaluate the prevalence of PGD three years post bereavement and to examine the predictors of long-term PGD in a population-based cohort of bereaved cancer caregivers. Methods: A cohort of primary family caregivers of patients admitted to one of three palliative care services in Melbourne, Australia, participated in the study (n = 301). Sociodemographic, mental health, and bereavement-related data were collected from the caregiver upon the patient\u27s admission to palliative care (T1). Further data addressing circumstances around the death and psychological health were collected at six (T2, n = 167), 13 (T3, n = 143), and 37 months (T4, n = 85) after bereavement. Results: At T4, 5% and 14% of bereaved caregivers met criteria for PGD and subthreshold PGD, respectively. Applying the total PGD score at T4, linear regression analysis found preloss anticipatory grief measured at T1 and self-reported coping measured at T2 were highly statistically significant predictors (both p \u3c 0.0001) of PGD in the longer term. Conclusion: For almost 20% of caregivers, the symptoms of PGD appear to persist at least three years post bereavement. These findings support the importance of screening caregivers upon the patient\u27s admission to palliative care and at six months after bereavement to ascertain their current mental health. Ideally, caregivers at risk of developing PGD can be identified and treated before PGD becomes entrenched

Radical anterior decompression and fusion for cervical spondylotic myelopathy

Sixty-seven patients with cervical spondylotic myelopathy were treated by radical anterior decompression and anterior spinal fusion. Of the 51 patients followed post-operatively for an average of 4.02 years, 34 obtained complete or partial relief, nine were unchanged and two deteriorated. Early complete anterior decompression and spinal fusion led to the most favourable results.published_or_final_versio

Cloud clearing techniques over land for land surface temperature retrieval from the Advanced Along Track Scanning Radiometer

We present five new cloud detection algorithms over land based on dynamic threshold or Bayesian techniques, applicable to the Advanced Along Track Scanning Radiometer (AATSR) instrument and compare these with the standard threshold based SADIST cloud detection scheme. We use a manually classified dataset as a reference to assess algorithm performance and quantify the impact of each cloud detection scheme on land surface temperature (LST) retrieval. The use of probabilistic Bayesian cloud detection methods improves algorithm true skill scores by 8-9 % over SADIST (maximum score of 77.93 % compared to 69.27 %). We present an assessment of the impact of imperfect cloud masking, in relation to the reference cloud mask, on the retrieved AATSR LST imposing a 2 K tolerance over a 3x3 pixel domain. We find an increase of 5-7 % in the observations falling within this tolerance when using Bayesian methods (maximum of 92.02 % compared to 85.69 %). We also demonstrate that the use of dynamic thresholds in the tests employed by SADIST can significantly improve performance, applicable to cloud-test data to provided by the Sea and Land Surface Temperature Radiometer (SLSTR) due to be launched on the Sentinel 3 mission (estimated 2014)

MIPAS detection of cloud and aerosol particle occurrence in the UTLS with comparison to HIRDLS and CALIOP

Satellite infrared emission instruments require efficient systems that can separate and flag observations which are affected by clouds and aerosols. This paper investigates the identification of cloud and aerosols from infrared, limb sounding spectra that were recorded by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), a high spectral resolution Fourier transform spectrometer on the European Space Agency's (ESA) ENVISAT (Now inoperative since April 2012 due to loss of contact). Specifically, the performance of an existing cloud and aerosol particle detection method is simulated with a radiative transfer model in order to establish, for the first time, confident detection limits for particle presence in the atmosphere from MIPAS data. The newly established thresholds improve confidence in the ability to detect particle injection events, plume transport in the upper troposphere and lower stratosphere (UTLS) and better characterise cloud distributions utilising MIPAS spectra. The method also provides a fast front-end detection system for the MIPClouds processor; a processor designed for the retrieval of macro- and microphysical cloud properties from the MIPAS data. <br><br> It is shown that across much of the stratosphere, the threshold for the standard cloud index in band A is 5.0 although threshold values of over 6.0 occur in restricted regimes. Polar regions show a surprising degree of uncertainty at altitudes above 20 km, potentially due to changing stratospheric trace gas concentrations in polar vortex conditions and poor signal-to-noise due to cold atmospheric temperatures. The optimised thresholds of this study can be used for much of the time, but time/composition-dependent thresholds are recommended for MIPAS data for the strongly perturbed polar stratosphere. In the UT, a threshold of 5.0 applies at 12 km and above but decreases rapidly at lower altitudes. The new thresholds are shown to allow much more sensitive detection of particle distributions in the UTLS, with extinction detection limits above 13 km often better than 10<sup>−4</sup> km<sup>−1</sup>, with values approaching 10<sup>−5</sup> km<sup>−1</sup> in some cases. <br><br> Comparisons of the new MIPAS results with cloud data from HIRDLS and CALIOP, outside of the poles, establish a good agreement in distributions (cloud and aerosol top heights and occurrence frequencies) with an offset between MIPAS and the other instruments of 0.5 km to 1 km between 12 km and 20 km, consistent with vertical oversampling of extended cloud layers within the MIPAS field of view. We conclude that infrared limb sounders provide a very consistent picture of particles in the UTLS, allowing detection limits which are consistent with the lidar observations. Investigations of MIPAS data for the Mount Kasatochi volcanic eruption on the Aleutian Islands and the Black Saturday fires in Australia are used to exemplify how useful MIPAS limb sounding data were for monitoring aerosol injections into the UTLS. It is shown that the new thresholds allowed such events to be much more effectively derived from MIPAS with detection limits for these case studies of 1 × 10<sup>−5</sup> km<sup>−1</sup> at a wavelength of 12 μm

Ab initio study on the low-lying excited states of retinal

Ab initio results for the electronic spectrum of all-trans-retinal and its truncated model 3-methyl-all-trans (10-s-cis)-2,4,6,8,10-undecapentaen-1-al are presented. The study includes geometry determination of the ground state. Vertical excitation energies have been computed using multiconfigurational second-order perturbation theory through the CASPT2 formalism. The lowest singlet excited state in gas phase is predicted to be of nπ∗ character. The lowest triplet state corresponds, however, to a ππ∗ state. The most intense feature of the spectrum is due to the strongly dipole-allowed ππ∗ transition, in accordance with the observed maximum in the one-photon spectra. The vertical excitation energies of the Bu- and Ag-like states are found close, the latter ≈ 1 eV higher than the maximum in the two-photon spectra. Solvent effects and nonvertical nature of the observed maximum in the two-photon spectra are invoked in rationalizing the deviation with respect to the best present estimate for the Ag-like state. In addition, qualitative aspects of the one-bond photoisomerization about the C11 = C12 double bond of retinal are considered. The overall isomerization picture from 11-cis into all-trans-retinal, as taking place mainly along the triplet manifold, agrees with experimental [email protected] ; [email protected]