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Methods to improve Real-Time Visualization and Exploration of Precipitation and Temperaturein Web-Cartography
ICC 2009, Santiago de Chile
Christophe Lienert, ETH Zurich
Overview
Motivation User needs and objectives Methodology – automated workflows for P and T Map results Discussion and Conclusion
Motivation > a changing climate
More intense, frequent precipitation and flood events Statistically show: very rare events become rare events Precipitation sees a seasonal shift from summer to winter Shift of the 0°C line > decisive for flooding in spring / autumn
Motivation > damage reduction
Improve preparedness before floods, enhance monitoring More assets and values lie in flood-prone areas Increase of risks and damages (2005: 3 Mia CHF)
User Needs & Objectives
RADAR
TEMPERATUREDISTRIBUTION
EXTRACTION OF0°C ISOTHERM
TEMPERATUREPOINT GAUGES
INTERSECTION - Visual enhancements- Show attributes- toggle views
BETTER ASSESSMENTSof catchment‘s disposition to flooding
Real
-tim
e ge
nera
tion
Precipitation Radar and Temperature Interpolation
Radar today > integrated, multi-parameter, quantitative Difficulties: instrumental, meterological factors affect accuracy main advantage: spatial extent of prec. fields clearly visible
Temperature data > often inavailable in higher altitudes Difficulties: interpolation accuracy in mountainous topography
1h data ≠ 1day data spatial variability depends on temporal variability
main advantage: altitude is the main distribution factor
Precipitation radar maps > existing examples
Radar > from stand-alone in the 1960s to user-oriented quantitative monitoring products, storm-tracking, now-casting
Radar > uncertainties due to instrumental and meteorological factors
Radar > main advantage: spatial extent of precipitation field Temperature > accuracy of interpolation depending on
observation accuracy, point density and Discussion and Conclusion
No quantitative color scheme Too many classes
Too coarse Way too many classes
Visual Improvements Radar
Radar > continuous, quantitative data [mm] or [in] Reduce number of data classes Use sequential color scheme, vary lightness Apply visual smoothing for more genuine representations
Temperature maps > existing examples
No legend, no clear allocation
No areal interpolation
Visual Improvements Temperature
Temperature > continuous quantitative data [°C] or [°K] Use diverging color schemes Contrast hue, vary lightness for + and - values Use point symbolizations AND
interpolated surfaces AND extracted isolines
Taking advantages of web-mapping
…to avoid representational conflicts radar vs. temperature Web-maps > Data exploration with interactive methods! Web-maps > central calculations, visualizations on the client
Methodology > real time workflow radar
Methodology > real time workflow temperature
Interpolated temperature surface- Display of legend on mouseover- Display of ommited gauges
Temperature surface + framed rectangles- Display of time series, attributes on click- Red and blue rectangles on gauge sites
Interactive, radar image- re-classifed, re-colored, bilinear smoothing- Legend directly displayed in ‚raster‘ tab
smoothed radar image + 0°C isotherm -highlighting of area above 0°C- attributes directly displayed in ‚vector‘ tab
Framed rectangles for point temperature data- tooltip function on mouseover- attributes and legends directly displayed in ‚vector‘ tab
Discussion
Visual problems: Complex workflows exception handling Other ways of handling missing/faulty data?
Data problems: Other interpolation methods? Calculation of real-time environmental lapse rate? Inclusion of longitudinal lapse rate? Solar radiance?
Conclusion
Visual Improvements of real time radar possible in real-time! (inappropriate class numbers, illegible coloring, coarse resolution data)
Visual improvements of point temperature data (framed rectangles)
Real-time interpolation of temperature points (iso-line and statistical surface)
Distribution of maps over the web (Combined views, interactive exploration methods, remote assessment)
Thank you for your attention!
Christophe Lienert, ETH Zurich, [email protected]
http://RETICAH.ethz.ch