121 research outputs found

    A model-based approach to adjust microwave observations for operational applications: results of a campaign at Munich Airport in winter 2011/2012

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    In the frame of the project "LuFo iPort VIS" which focuses on the implementation of a site-specific visibility forecast, a field campaign was organised to offer detailed information to a numerical fog model. As part of additional observing activities, a 22-channel microwave radiometer profiler (MWRP) was operating at the Munich Airport site in Germany from October 2011 to February 2012 in order to provide vertical temperature and humidity profiles as well as cloud liquid water information. Independently from the model-related aims of the campaign, the MWRP observations were used to study their capabilities to work in operational meteorological networks. Over the past decade a growing quantity of MWRP has been introduced and a user community (MWRnet) was established to encourage activities directed at the set up of an operational network. On that account, the comparability of observations from different network sites plays a fundamental role for any applications in climatology and numerical weather forecast. <br><br> In practice, however, systematic temperature and humidity differences (bias) between MWRP retrievals and co-located radiosonde profiles were observed and reported by several authors. This bias can be caused by instrumental offsets and by the absorption model used in the retrieval algorithms as well as by applying a non-representative training data set. At the Lindenberg observatory, besides a neural network provided by the manufacturer, a measurement-based regression method was developed to reduce the bias. These regression operators are calculated on the basis of coincident radiosonde observations and MWRP brightness temperature (TB) measurements. However, MWRP applications in a network require comparable results at just any site, even if no radiosondes are available. <br><br> The motivation of this work is directed to a verification of the suitability of the operational local forecast model COSMO-EU of the Deutscher Wetterdienst (DWD) for the calculation of model-based regression operators in order to provide unbiased vertical profiles during the campaign at Munich Airport. The results of this algorithm and the retrievals of a neural network, specially developed for the site, are compared with radiosondes from Oberschleißheim located about 10 km apart from the MWRP site. Outstanding deviations for the lowest levels between 50 and 100 m are discussed. Analogously to the airport experiment, a model-based regression operator was calculated for Lindenberg and compared with both radiosondes and operational results of observation-based methods. <br><br> The bias of the retrievals could be considerably reduced and the accuracy, which has been assessed for the airport site, is quite similar to those of the operational radiometer site at Lindenberg above 1 km height. Additional investigations are made to determine the length of the training period necessary for generating best estimates. Thereby three months have proven to be adequate. The results of the study show that on the basis of numerical weather prediction (NWP) model data, available everywhere at any time, the model-based regression method is capable of providing comparable results at a multitude of sites. Furthermore, the approach offers auspicious conditions for automation and continuous updating

    Forecast indices from a ground-based microwave radiometer for operational meteorology

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    Abstract. Today, commercial microwave radiometer profilers (MWRPs) are robust and unattended instruments providing real-time, accurate atmospheric observations at ~ 1 min temporal resolution under nearly all weather conditions. Common commercial units operate in the 20–60 GHz frequency range and are able to retrieve profiles of temperature, vapour density, and relative humidity. Temperature and humidity profiles retrieved from MWRP data are used here to feed tools developed for processing radiosonde observations to obtain values of forecast indices (FIs) commonly used in operational meteorology. The FIs considered here include K index, total totals, KO index, Showalter index, T1 gust, fog threat, lifted index, S index (STT), Jefferson index, microburst day potential index (MDPI), Thompson index, TQ index, and CAPE (convective available potential energy). Values of FIs computed from radiosonde and MWRP-retrieved temperature and humidity profiles are compared in order to quantitatively demonstrate the level of agreement and the value of continuous FI updates. This analysis is repeated for two sites at midlatitude, the first one located at low altitude in central Europe (Lindenberg, Germany) and the second one located at high altitude in North America (Whistler, Canada). It is demonstrated that FIs computed from MWRPs well correlate with those computed from radiosondes, with the additional advantage of nearly continuous updates. The accuracy of MWRP-derived FIs is tested against radiosondes, taken as a reference, showing different performances depending upon index and environmental situation. Overall, FIs computed from MWRP retrievals agree well with radiosonde values, with correlation coefficients usually above 0.8 (with few exceptions). We conclude that MWRP retrievals can be used to produce meaningful FIs, with the advantage (with respect to radiosondes) of nearly continuous updates

    Forecast indices from a ground-based microwave radiometer for operational meteorology

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    Today, commercial microwave radiometer profilers (MWRPs) are robust and unattended instruments providing real-time, accurate atmospheric observations at ~ 1 min temporal resolution under nearly all weather conditions. Common commercial units operate in the 20–60 GHz frequency range and are able to retrieve profiles of temperature, vapour density, and relative humidity. Temperature and humidity profiles retrieved from MWRP data are used here to feed tools developed for processing radiosonde observations to obtain values of forecast indices (FIs) commonly used in operational meteorology. The FIs considered here include K index, total totals, KO index, Showalter index, T1 gust, fog threat, lifted index, S index (STT), Jefferson index, microburst day potential index (MDPI), Thompson index, TQ index, and CAPE (convective available potential energy). Values of FIs computed from radiosonde and MWRP-retrieved temperature and humidity profiles are compared in order to quantitatively demonstrate the level of agreement and the value of continuous FI updates. This analysis is repeated for two sites at midlatitude, the first one located at low altitude in central Europe (Lindenberg, Germany) and the second one located at high altitude in North America (Whistler, Canada). It is demonstrated that FIs computed from MWRPs well correlate with those computed from radiosondes, with the additional advantage of nearly continuous updates. The accuracy of MWRP-derived FIs is tested against radiosondes, taken as a reference, showing different performances depending upon index and environmental situation. Overall, FIs computed from MWRP retrievals agree well with radiosonde values, with correlation coefficients usually above 0.8 (with few exceptions). We conclude that MWRP retrievals can be used to produce meaningful FIs, with the advantage (with respect to radiosondes) of nearly continuous updates

    Possibilità di differenziazione degli elettrodi cocleari nelle misurazioni radiologiche della posizione intracocleare e dell'angolo cordo-facciale

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    Con l'incremento del numero di impianti cocleari effettuati, il controllo di qualità è divenuto sempre più importante. Oltre alle misurazioni biofisiche intraoperatorie ci si può avvalere dell'imaging radiologico. Una nuova tecnica utilizzata in questo campo è il Cone Beam CT (CBCT). Nel presente studio sono stati valutati 65 casi (35 Nucleus Contour AdvanceCochlear; 30 Flex SoftMedEl) studiati mediante CBCT (Accu-I-tomo F17, Morita, Kyoto, Japan). Nello specifico sono stati rilevati: l'angolo di inserzione, l'altezza dell'impianto, la distanza dell'elettrodo dalla parete mediale o laterale, l'angolo tra la corda del timpano e il nervo facciale e la posizione precisa del filo dell'elettrodo nell'angolo cordo-facciale. È stato inoltre possibile valutare la differenza tra il decorso peri-modiolare e laterale degli elettrodi. I dati presentati dimostrano l'accuratezza e il vantaggio della CBCT nella visualizzazione di piccole strutture grazie al ridotto numero di artefatti da indurimento del fascio. Inoltre nel 75% dei pazienti è stato possibile visualizzare l'angolo tra la corda del timpano e il nervo facciale. È stato possibile notare differenze significative fra i vari tipi di elettrodo in funzione del tipo di rapporto con il nervo facciale. In conclusione mediante la CBCT è possibile ottenere una visualizzazione precisa e dettagliate misurazioni della posizione intracocleare dei diversi elettrodi. È persino possibile la corretta valutazione della posizione dell'elettrodo rispetto all'angolo cordo- facciale. La CBCT è quindi, dal nostro punto di vista, un utile strumento per il controllo intra e post-operatorio degli impianti cocleari

    Abstracts from the 8th International Conference on cGMP Generators, Effectors and Therapeutic Implications

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    This work was supported by a restricted research grant of Bayer AG

    Dosisoptimierung in der radiologischen Diagnostik der chronischen Rhinosinusitis

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