Found 10066 publications. Showing page 225 of 403:
2019
2004
2004
Measurement techniques used for characterization of volcanic ash clouds have been evaluated specifically with regard to applicability and limitations. This report summarizes how future infrastructure investments in Norway will be able to provide additional information about volcanic ash clouds that can be used to inform operational aviation authorities. Three main recommendations are given.
2014
Measurement of volcanic ash in Norwegian air space. WP 1.4.2 Improved detection of ash clouds. NILU OR
Water and ice clouds and temperature conditions may often influence the detection of volcanic ash affected pixels in infrared satellite images. Several methods are available for the detection of ash clouds in SEVIRI images. Manual adjustments to the methods are often needed for a given ash situation. The report describes various methods for detection of ash affected pixels. A quantitative comparison of the methods is made based on synthetic SEVIRI images from the 2010 Eyafjallajokull eruption.
2013
For retrieval of ash mass loading from infrared satellite measurements, estimates of the ash cloud temperature and the surface temperature are required. The ash cloud temperature and surface temperature may be taken from satellite measurements, weather model forecast, or deduced by satellite retrievals.
The report describes various methods to estimate the ash cloud temperatue and surface temperature. The impact of varying cloud temperature and surface temperature on the signal measured by an IR-sensor in space is investigated.
2013