Latest National Slow Down Day Donegal updates here:

first_img RELATED ARTICLESMORE FROM AUTHOR News, Sport and Obituaries on Monday May 24th DL Debate – 24/05/21 Pinterest Important message for people attending LUH’s INR clinic Facebook Previous articleKey meeting to determine fate of Letterkenny-Inishowen bus serviceNext articleFears over time sensitive funding for Donegal Islands News Highland Pinterest There’s an increased Garda presence across Donegal today as National Slow Day is underway in earnest. The latest update of speed detections from Donegal Gardai today include:Motorist clocked speeding 119km/h in a 100 zone near Ballintra.Truck travelling at 89 km/h in a 100 zone near Newtowncunningham Donegal. Harps come back to win in Waterford Arranmore progress and potential flagged as population grows Google+center_img Twitter WhatsApp Twitter Homepage BannerNews Facebook Google+ By News Highland – October 18, 2019 Latest National Slow Down Day Donegal updates here: WhatsApp Loganair’s new Derry – Liverpool air service takes off from CODAlast_img read more

A decadal satellite record of gravity wave activity in the lower stratosphere to study polar stratospheric cloud formation

first_imgAtmospheric gravity waves yield substantial small-scale temperature fluctuations that can trigger the formation of polar stratospheric clouds (PSCs). This paper introduces a new satellite record of gravity wave activity in the polar lower stratosphere to investigate this process. The record is comprised of observations of the Atmospheric Infrared Sounder (AIRS) aboard NASA’s Aqua satellite from January 2003 to December 2012. Gravity wave activity is measured in terms of detrended and noise-corrected 15 µm brightness temperature variances, which are calculated from AIRS channels that are the most sensitive to temperature fluctuations at about 17–32 km of altitude. The analysis of temporal patterns in the data set revealed a strong seasonal cycle in wave activity with wintertime maxima at mid- and high latitudes. The analysis of spatial patterns indicated that orography as well as jet and storm sources are the main causes of the observed waves. Wave activity is closely correlated with 30 hPa zonal winds, which is attributed to the AIRS observational filter. We used the new data set to evaluate explicitly resolved temperature fluctuations due to gravity waves in the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis. It was found that the analysis reproduces orographic and non-orographic wave patterns in the right places, but that wave amplitudes are typically underestimated by a factor of 2–3. Furthermore, in a first survey of joint AIRS and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) satellite observations, nearly 50 gravity-wave-induced PSC formation events were identified. The survey shows that the new AIRS data set can help to better identify such events and more generally highlights the importance of the process for polar ozone chemistry.last_img read more