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, lienertc@ethz.ch

http://RETICAH.ethz.ch