Mid-winter lower stratosphere temperatures in the Antarctic vortex: comparison between observations and ECMWF operational model.

International audienceRadiosonde temperature profiles from Belgrano (78° S) and other Antarctic stations have been compared with European Centre for Medium-Range Weather Forecasts (ECMWF) data during the winter of 2003. Results show a bias in the operational model which is height and temperature dependent, being too cold at layers peaking at 80 and 25?30 hPa, and hence resulting in an overestimation of the predicted potential PSC areas. Here we show the results of the comparison by considering the possibility of a bias in the sondes at extremely low temperatures and discuss the potential implications that this bias might have on the ozone depletion computed by Climate Transport Model based on ECMWF temperature fields

Antarctic ozone variability inside the polar vortex estimated from balloon measurements

Thirteen years of ozone soundings at the Antarctic Belgrano II station (78° S, 34.6° W) have been analysed to establish a climatology of stratospheric ozone and temperature over the area. The station is inside the polar vortex during the period of development of chemical ozone depletion. Weekly periodic profiles provide a suitable database for seasonal characterization of the evolution of stratospheric ozone, especially valuable during wintertime, when satellites and ground-based instruments based on solar radiation are not available. The work is focused on ozone loss rate variability (August–October) and its recovery (November–December) at different layers identified according to the severity of ozone loss. The time window selected for the calculations covers the phase of a quasi-linear ozone reduction, around day 220 (mid-August) to day 273 (end of September). Decrease of the total ozone column over Belgrano during spring is highly dependent on the meteorological conditions. Largest depletions (up to 59%) are reached in coldest years, while warm winters exhibit significantly lower ozone loss (20%). It has been found that about 11% of the total O₃ loss, in the layer where maximum depletion occurs, takes place before sunlight has arrived, as a result of transport to Belgrano of air from a somewhat lower latitude, near the edge of the polar vortex, providing evidence of mixing inside the vortex. Spatial homogeneity of the vortex has been examined by comparing Belgrano results with those previously obtained for South Pole station (SPS) for the same altitude range and for 9 yr of overlapping data. Results show more than 25% higher ozone loss rate at SPS than at Belgrano. The behaviour can be explained taking into account (i) the transport to both stations of air from a somewhat lower latitude, near the edge of the polar vortex, where sunlight reappears sooner, resulting in earlier depletion of ozone, and (ii) the accumulated hours of sunlight, which become much greater at the South Pole after the spring equinox. According to the variability of the ozone hole recovery, a clear connection between the timing of the breakup of the vortex and the monthly ozone content was found. Minimum ozone concentration of 57 DU in the 12–24 km layer remained in November, when the vortex is more persistent, while in years when the final stratospheric warming took place "very early", mean integrated ozone rose by up to 160–180 DU

Maksimivoimalaitteen toistolaskurin algoritmin kehitystyö

Insinöörityön aiheena oli kehittää ranteessa pidettävään maksimivoimalaitteeseen voimailuliikkeiden toistot tunnistava algoritmi. Laitteen aikaisempi versio toistolaskurista oli epäluotettava, koska se ei pystynyt tunnistamaan haluttua voimailuliikettä, vaan toistoksi tunnistettiin mikä tahansa tarpeeksi suuri kiihtyvyys. Tavoitteena oli kehittää algoritmi, joka kiihtyvyysanturin tietojen perusteella osaisi tunnistaa suoritetut voimailuliikkeiden toistot sekä erottaa väärät liikkeet oikeista. Algoritmin kehitystyössä käytettiin apuna langallista analogista kiihtyvyysanturia, jonka kiihtyvyystiedot tallennettiin AD-muuntimen ja LabVIEW-ohjelman avulla tietokoneelle. Varsinainen algoritmin kehitystyö tehtiin Matlab-ohjelmalla. Koska kyseessä oli tuotekehitystyö, ei valmiita ratkaisuja ollut olemassa. Tästä seurasi se, että monet asiat täytyi kokeilemalla todeta joko toimiviksi tai toimimattomiksi. Lopputuloksena saatiin algoritmi, joka tietyin rajoituksin tunnistaa suoritetun voimailuliikesarjan toistot sekä jättää huomioimatta väärät liikkeet ja liian epäpuhtaasti suoritetut toistot

Is elective surgery during the COVID-19 pandemic safe? A multi-center prospective study in a high incidence area

Elective surgery; COVID-19 pandemicCirugía electiva; Pandemia de COVID-19Cirurgia electiva; Pandèmia de COVID-19Objective: The aim of this study was to describe the evolution of patients admitted for elective orthopaedic surgery during the immediate post-COVID-19 peak of the pandemic. Methods: This is a multi-center, observational study conducted in 8 high complexity hospitals of Catalonia, one of the highest COVID-19 incidence areas in Spain. We included patients ≥18 years of age undergoing elective surgery (total knee or hip arthroplasty, knee or hip revision arthroplasty, shoulder or knee arthroscopy, hand or wrist surgery, forefoot surgery, or hardware removal) after the COVID-19 peak (between May 5th and June 30th, 2020). The main exclusion criterion was a positive result for SARS-CoV-2 PCR within the 7 days before the surgery. The primary outcomes were postoperative complications within 60 days (+/-30) or hospital readmission due to a COVID-19 infection. Following the recommendations of the International Consensus Group (ICM), elective surgeries were re-started when the nationwide lockdown was lifted. Before the surgery, patients were contacted by phone to rule out any exposure to confirmed COVID-19 cases, a reverse transcription-polymerase chain reaction (PCR) assay was performed in all patients 48-72 hours before hospital admission, and they were asked to maintain home confinement until the day of the surgery. Results: 675 patients were included: 189 patients in the arthroplasty group (28%) and 486 in the ambulatory surgery group (72%). Mean [SD] age was 57.6 [15.3] years. The mean Charlson Comorbidity Index score was 2.21 (SD = 2.01, Min = 0, Max = 13). A total of 84 patients (12.75%) obtained an American Society of Anesthesiologists (ASA) score ≥ 3, showing no association between the ASA score and the risk of developing COVID-19 symptoms at follow-up (χ 2 (4) = 0.77, P = 0.94). The mean occupation rate of hospital beds for COVID-19 patients was 13% and the mean occupation rate of critical care beds for COVID-19 patients was 27% at the time of re-introducing elective surgeries. These were important rates to consider to decide when to reintroduce elective surgeries after lockdown. Surgical time, time of ischemia and intra-operative bleeding were not related with a higher risk of developing COVID-19 post-operatively (χ 2 (1) = 0.00, P = 0.98); (χ 2 (2) = 2.05, P = 0.36); (χ 2 (2) = 0.37, P = 0.83). Only 2 patients (0.3 %) presented with a suspected COVID-19 infection at follow-up. None of them presented with pneumonia or required confirmation by a reverse transcription PCR assay. Hospital re-admission was not needed for these patients. Conclusion: The risk of developing COVID-19 during the immediate post-COVID-19 peak in a region with a high incidence of COVID-19 has not been proved. These data suggest that elective orthopaedic surgeries can be resumed when assertive and strict protocols are followed

The spatial scale of ozone depletion events derived from an autonomous surface ozone network in coastal Antarctica

To probe the spatial extent of tropospheric ozone depletion events during Antarctic spring, a network of 10 autonomous ozone monitors was established around the Dronning Maud Land sector of Antarctica for a full calendar year. Together with manned stations in the area, the network covered a ~1200 km stretch of coast, as well as a transect ~300 km inland and to ~2000 m above sea level (a.s.l.). Here we present results from the spring period (August to October 2008). While some ozone depletion events were evident at only a single site, implying localised ozone destruction, others were evident across the network. The fact that, on occasions, ozone depletion events were observed at all coastal sites simultaneously, suggests the depleted air mass had a scale of at least 1200 km. As the ozone-poor air was advected from the Weddell Sea sea ice zone, the data imply that large areas over the Weddell Sea sea ice zone are significantly depleted in ozone on occasions during Antarctic spring

Behavior of NO2 and O3 columns during the eclipse of February 26, 1998, as measured by visible spectroscopy

Observations of the NO2 and O3 columns using zenith-viewing differential absorption spectroscopy in the visible range (450–540 nm) were carried out at Izaña Observatory (Tenerife, 28°N, 16°W, 2370 m above sea level.) during the eclipse of February 26, 1998 (95% occultation over the station). Ozone has been retrieved using two different spectral ranges to minimize the effect of the continuous change of the solar spectrum shape as the Sun is being occulted. Small variations before the maximum phase in agreement with previous observations are found, but because of the change in the shape of the solar spectrum, it cannot conclusively be determined whether the ozone changes are real or due to interferences with changing Fraunhofer lines. The difficulties in observing small changes of absorbing gases during solar eclipse when using remote sensing technique that uses the solar UV and visible radiation as the source are discussed. NO2 displays an increase in phase with the degree of solar occultation, as compared to a non eclipse day of 1.55±0.09. A simple model assuming that changes over short times scales are only due to changes in photodissociation, using O3 and temperatures obtained from an ozone sounding station close to the observatory, reproduces the observed variation when the NO2 bulk is assumed to be at an altitude of 28 km. Correction for differences between local solar zenith angle (SZA) and the SZA where the absorption takes place is taken into account.This work has been possible thanks to the support of the UE through the SCUVS-3 Project (ENV-4-CT95-0089)