Near real time ash cloud

Near real-time weather data and volcanic ash dispersal in the North Atlantic Andrew Zolnai Cambridge UK blog.zolnai.ca Abstract Newly available internet technologies allow freely available government data mash-ups help track weather patterns in real time. This allows for example to ascertain the weather risk across the north Atlantic, and help track weather and flight disruptions associated with ongoing Icelandic volcanic eruptions. Such developments will encourage citizen geographers to monitor their environment. Introduction The Eyjafjallajokull volcano is situated on the south coast of Iceland astride the mid-Atlantic oceanic ridge. Its eruption has been spewing ash into the atmosphere more or less continuously since late April 2010. It had a major impact on air traffic in the north Atlantic, affecting flights from North America as well as those across northern Europe. The only respite is provided when the wind bears ash away from the continent towards the uninhabited Arctic region. It is therefore critical to be able to follow the dispersal of ash in near-real time, in order to try and anticipate it impact in the near future. Whilst government meteorological offices have been providing advisories and the news media followed its consequences, new tools allow the public to follow this themselves. Here are simple tools available for free on the internet, as well as freely accessible government data sources in order to do this. Data Sources US National Oceanic and Atmospheric Administration (NOAA) Goddard Space Flight Center (GSFC) hosts web mapping services (WMS) of near-real time cloud cover data worldwide. They also carry sulphur dioxide (SO2) and carbon monoxide (CO) readings, as reflective of ash dispersal hard to see in the visible spectrum. These can be displayed for the current and up to six previous day in near real time using WMS on a mapping system described in the next paragraph. The US Geological Survey (USGS) also produced an Open File Report (OFR) that describe the plate tectonic boundaries and the volcanoes along them. These are available in Keyhole Mark-up Language (KML) and have been exported to a spreadsheet for correction (global data often posted as east E and W longitude are more often read as positive and negative, respectively, and data across the antemeridian or date line are often repeated or misread by software and data systems). Tools These data can be posted individually straight from source, either as NOAA WMS in any browser or USGS KML in Google Earth. A web GIS service is used here to spatially register and correctly stack the data together into what is called a mash-up. It is the combination of several datasets that provides the power to link, track and even predict complex weather phenomena.

Vector web service The service used is a free Geographic Information System (GIS) on the web called GIS Cloud posted on www.giscloud.com. Data can be freely viewed anonymously, a free login can be created, and data can be freely posted with certain terms and conditions (please review the website for details). The mash-up can be found under Google Fusion > NOAA Cloud or directly under http://bit.ly/ansAbe. Near-real time weather data are posted together with their origin, and freely usable under the NOAA and USGS terms & conditions. Note that data posted here are original vectors and images. Raster web service The same data can be posted on ESRI’s free GIS viewer ArcGIS Explorer (AGX). The data file has been posted on the new Arcgis.com repository http://bit.ly/bkdntd - double-clicking the icon will download the NMF file and launch it in ArcMap or AGX desktop , whichever you have. Note that at time of posting, ArcGIS Explorer online http://explorer.arcgis.com/ could not access this type of file. Usage The original screenshot of the ash cloud over England is posted on my blog http://bit.ly/ajU8IR giscloud.com ArcGIS Explorer SO2 readings clearly indicate where the as plume went early May 2010. The blog also show a video created from snapshots of the cloud cover in the visible light spectrum, taken late May after the second air traffic disruption – it is also posted on YouTube http://bit.ly/b4Iz85. Conclusion This shows how easy it can be to post weather and geographic data freely available from government websites, by using free GIS software on the internet: Can’t you thus view, analyse and post near-real time data relevant to your specific geography and to your particular sphere of interest? We hope this will inspire you to become citizen geographers surveying your environment! References NOAA WMS, current: Goddard Earth Sciences Data and Information Services Center, Atmospheric Infrared Sounder (AIRS) Near-Real-Time, http://disc.sci.gsfc.nasa.gov/services/ogc_wms USGS, 2009: Open File Report 2009-1133, Preliminary Spreadsheet of Eruption Source Parameters for Volcanoes of the World, http://pubs.usgs.gov/of/2009/1133/of2009-1133_text.pdf

Near real time ash cloud

by Andrew Zolnai

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