Evolution of the Distribution of Upper-Tropospheric Humidity over the Indian Ocean: Connection with Large-Scale Advection and Local Cloudiness

International audienceThe spatial and temporal distribution of Upper-Tropospheric Humidity (UTH) observed by the SAPHIR/Megha-Tropiques radiometer is analyzed over two sub-regions of the Indian Ocean during October-November-December over 2011-2014. The properties of the distribution of UTH were studied regarding the phase of the Madden-Julian Oscillation (active or suppressed) and the large-scale advection vs. local production of moisture. To address these topics, first a lagrangian back-trajectory transport model was used to assess the role of the large-scale transport of air masses in the intraseasonal variability of UTH. Second, the temporal evolution of the distribution of UTH is analyzed using the computation of the higher moments of its probability distribution function (PDF) defined for each time step over the domain. Results highlight significant differences in the PDF of UTH depending on the phase of the MJO. The modeled trajectories ending in the considered domain originate from an area that strongly varies depending on the phases of the MJO: during the active phases, the air masses are spatially constrained within the tropical Indian Ocean domain, while a distinct upper tropospheric (200-150hPa) westerly flow guides the intraseasonal variability of UTH during the suppressed phases. Statistical relationships between the cloud fractions and the moments of the PDFs of UTH are found to be quite similar regardless of the convective activity. However, the occurrence of thin cirrus clouds is associated to a drying of the upper troposphere (enhanced during suppressed phases) while the occurrence of thick cirrus-anvil clouds appears to be significantly related to a moistening of the upper troposphere

Estimating confidence intervals around relative humidity profiles from satellite observations: Application to the SAPHIR sounder

International audienceA novel scheme for the estimation of layer-averaged relative humidity (RH) profiles from space-borne observations in the 183.31GHz line is presented. Named ARPIA for Atmospheric Relative humidity Profiles Including Analysis of confidence intervals, it provides for each vector of observations the parameters of the distribution of the RH instead of its expectation as usually done by the current methods. The profiles are composed of 6 layers distributed between 100 and 950hPa. The approach combines the 6 channels of the SAPHIR instrument onboard the Megha-Tropiques satellite and the Generalized Additive Model for Location, Scale and Shape (GAMLSS) to infer the parametric distributions, assuming that they follow a Gaussian law. The knowledge of the conditional uncertainty is an asset in the evaluation using radiosounding profiles of RH with a dedicated bayesian method. Taking the uncertainties into account in both the ARPIA estimates and the in situ measurements yields to have biases, root-mean-square and correlation coefficients in the range -0.56% - 9.79%, 1.58% - 13.32% and 0.55 - 0.98 respectively, the largest biases being obtained over the continent, in the mid-tropospheric layers

Water vapor of the tropical atmosphere from the SAPHIR microwave sounder

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Analyse des erreurs et incertitudes dans la raie de la vapeur d'eau à 183GHz: apport de l'instrument SAPHIR

International audienceCinq sources d'incertitudes ont été évaluées de manière numérique afin de réaliser un bilan des erreurs pour chaque canal d'observation de SAPHIR. Ces erreurs sont considérées comme des intervalles de confiance autour du biais. Les résultats montrent que l'incertitude totale est la plus large pour C1 et qu'elle diminue progressivement jusque C6

L'éthique en recherche ou les éthiques en recherche ?

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High Risk of Anal and Rectal Cancer in Patients With Anal and/or Perianal Crohn’s Disease

International audienceBackground & AimsLittle is known about the magnitude of the risk of anal and rectal cancer in patients with anal and/or perineal Crohn’s disease. We aimed to assess the risk of anal and rectal cancer in patients with Crohn’s perianal disease followed up in the Cancers Et Surrisque Associé aux Maladies Inflammatoires Intestinales En France (CESAME) cohort.MethodsWe collected data from 19,486 patients with inflammatory bowel disease (IBD) enrolled in the observational CESAME study in France, from May 2004 through June 2005; 14.9% of participants had past or current anal and/or perianal Crohn’s disease. Subjects were followed up for a median time of 35 months (interquartile range, 29–40 mo). To identify risk factors for anal cancer in the total CESAME population, we performed a case-control study in which participants were matched for age and sex.ResultsAmong the total IBD population, 8 patients developed anal cancer and 14 patients developed rectal cancer. In the subgroup of 2911 patients with past or current anal and/or perianal Crohn’s lesions at cohort entry, 2 developed anal squamous-cell carcinoma, 3 developed perianal fistula–related adenocarcinoma, and 6 developed rectal cancer. The corresponding incidence rates were 0.26 per 1000 patient-years for anal squamous-cell carcinoma, 0.38 per 1000 patient-years for perianal fistula–related adenocarcinoma, and 0.77 per 1000 patient-years for rectal cancer. Among the 16,575 patients with ulcerative colitis or Crohn’s disease without anal or perianal lesions, the incidence rate of anal cancer was 0.08 per 1000 patient-years and of rectal cancer was 0.21 per 1000 patient-years. Among factors tested by univariate conditional regression (IBD subtype, disease duration, exposure to immune-suppressive therapy, presence of past or current anal and/or perianal lesions), the presence of past or current anal and/or perianal lesions at cohort entry was the only factor significantly associated with development of anal cancer (odds ratio, 11.2; 95% CI, 1.18-551.51; P = .03).ConclusionsIn an analysis of data from the CESAME cohort in France, patients with anal and/or perianal Crohn’s disease have a high risk of anal cancer, including perianal fistula–related cancer, and a high risk of rectal cancer