UV dose: availability of cloud modification data

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Cloud-modified UV dose data

The UV dose is the effective UV irradiance (given in kJ/m2) reaching the Earth's surface integrated over the day and taking the attenuation of the UV radiation due to clouds into account. For comparison sake the UV dose assuming cloud-free conditions is also given.

The cloud data is compiled from geostationary Meteosat Second Generation (MSG) satellite observations -- available in principle once every 15 minutes since 19 January 2004 -- provided by the MSG Cloud Physical Properties (CPP) algorithm.

Because we compute the daily UV dose, we need cloud data over the full day. Once and a while one or more quarters of an hour of MSG data are missing or are incomplete. Though we can fill in missing quarters on the basis of persistence (i.e. using the data from the preceeding quarter), we do not want to have data gaps that are 1 hour (4 quarters) or longer.

See this page for more details on the cloud modification applied.

For days with large data gaps in the MSG data or no MSG data at all we can therefore not compute the cloud-modified UV dose. The following graph and table show when this has occurred -- these overviews are updated manually on an irregualar basis.

 
Days of missing MSG CPP cloud-modification data

 
year total missing days (MM/DD)
2017 0 --   [ last updated: 21 July ]
2016 3 05/11, 06/10, 10/15
2015 3 04/28, 11/15, 12/24
2014 2 03/26, 07/28
2013 3 02/06, 08/18, 09/21
2012 3 01/19, 08/31, 12/07
2011 26 01/05, 02/02, 02/05, 02/06, 02/21, 02/22, 02/24,
02/28, 03/09, 03/16, 03/19, 03/20, 03/21, 03/28,
04/01, 04/10, 04/12, 04/19, 05/13, 05/14, 05/15,
05/16, 05/19, 08/11, 09/04, 09/05
2010 6 03/18, 04/20, 07/14, 08/19, 09/11, 11/24
2009 10 01/04, 02/04, 04/17, 05/16, 07/08, 08/05, 08/15,
08/21, 11/05, 11/09
2008 13 05/13, 05/20, 09/24, 10/14, 10/15, 11/25, 11/29,
11/30, 12/01, 12/02, 12/09, 12/10, 12/22
2007 4 06/05, 06/25, 08/17, 08/31
2006 9 01/09, 01/10, 01/11, 01/12, 01/21, 05/18, 09/23,
09/24, 09/25
2005 11 01/10, 01/11, 01/12, 01/13, 03/12, 03/15, 03/18,
04/18, 04/20, 05/29, 06/20
2004 17 01/19, 01/20, 01/21, 03/28, 04/08, 06/23, 06/30,
08/12, 09/29, 10/04, 10/05, 10/06, 10/07, 10/12,
10/13, 11/16, 12/09
[ first MSG data recorded on 19 Jan. ]

 


last modified: 04 August 2017
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