see Presentation (2.6 MByte)

TherMap Thermal Maps

Use of Topographic Radar Scans to Identify Thermal Hotspots in Alpine Areas

Contents „ „

History and present state of thermal maps The TherMap approach Topography – Irradiance – Temperature „ Thermal Take-Off Spots „

„ „

Model validation Conclusions

May 06

B. Sigrist - TherMap OSTIV 2006, Eskilstuna/SE

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“Flashlight Analogy” of 1955

Hans Nietlisbach

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B. Sigrist - TherMap OSTIV 2006, Eskilstuna/SE

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Example of an Existing Thermal Map

Thermikkarte Deutschland Considers neither daytime nor season

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B. Sigrist - TherMap OSTIV 2006, Eskilstuna/SE

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Topographic Approach by TherMap Topographic data model

Topography of a region

Date and daytime

Irradiance map (W/m2)

Surface properties

Temperature map (heating effect)

Regional meteorology

Thermal map (?)

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B. Sigrist - TherMap OSTIV 2006, Eskilstuna/SE

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A. Topography SRTM 90 m Satellite Radar Data

These are tables indicating the elevation of the surface of the earth every 90 Topographic meters Topographic Map Map Example: Example: Elevation Elevation Map Map

Used to generate computed maps

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B. Sigrist - TherMap OSTIV 2006, Eskilstuna/SE

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B. Irradiance The intensity of solar radiation (W/m2) „ „

at a given location, date and time

PVGIS © European Communities, 2002-2006 Šúri M., Huld T.A., Dunlop E.D. (2005). PVGIS: a web-based solar radiation database for the calculation of PV potential in Europe. International Journal of Sustainable Energy, 24, 2, 55-67.

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B. Sigrist - TherMap OSTIV 2006, Eskilstuna/SE

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(1) Basic Irradiance = Projection of solar vector on normal vector

Normal vector

Solar vector

Parabolic approximation line

Tangent

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B. Sigrist - TherMap OSTIV 2006, Eskilstuna/SE

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(2) Irradiance is diminished as light penetrates the atmosphere ~1.3 kW/m2 before entering atmosphere

Depending on • Solar elevation • Altitude • Turbidity

Present TherMap assumption: 12 km visibility (for turbidity) In reality locally and seasonally variable May 06

B. Sigrist - TherMap OSTIV 2006, Eskilstuna/SE

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(3) Irradiance per air column is scaled by the slope of the surface (solar pannel)

Sun

Air column

Irradiated surface

IIhh = = IIss // cos cos αα Horizontal surface

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α

Slope angle

B. Sigrist - TherMap OSTIV 2006, Eskilstuna/SE

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Example:

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Irradiance, Jura-Gruyères/CH, May 6, 1100 MEZ

B. Sigrist - TherMap OSTIV 2006, Eskilstuna/SE

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C. Temperature Temperature increase due to cumulative effect of solar irradiation minus radiation losses

Solar Engineering Handbook Part 2, “Temperature Theory”, ed. 2003, Meteonorm, http://www.meteotest.ch/en/mn_dl?w=ber

On a sunny day the Temperature is peaking about 2 hours after the Irradiance peak May 06

B. Sigrist - TherMap OSTIV 2006, Eskilstuna/SE

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Irradiance - Temperature

Temperature: Approximation by a timephased smoothing model Irradiance 0.6 0.5 0.4 0.3 0.2

Smoothing model with smoothing factor a = 0.1 to 0.6

0.1 6

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Irradiance - Temperature

Time of day (hour)

6.00

8.00

10.00

12.00

14.00

16.00

18.00

20.00

Present best fit: Smoothing model with time-phased smoothing factor a = 0.2 x 0.9(hr-12)

Hour

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B. Sigrist - TherMap OSTIV 2006, Eskilstuna/SE

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Effects diminishing Temperature increase

y t i s n e d h n t i o i w t a s et she g Ve ini d im p e ! s lo

Albedo of snow covered surfaces (seasonal)

Forest belt from 900 – 1500 m

Seasonally climbing and descending vegetation May 06

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Example:

Temperature, Valais/CH, May 6th

1100h 1300h MEZ 1700hMEZ MEZ 1500h MEZ

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Thermal Take-Off Spots (von Kalckreuth’s rule) Thermals climb along slope until angle drops below 30 degrees

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Example: Take-Off Spots on Overlay Temperature Map (Sisteron May 6, 1300 MEZ)

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Model Validation „ „

„

Expert advice Overlayed IGC logfiles of flights on days with „ few and high clouds „ unstable atmosphere (temperature increase leading to thermals) „ (if possible) comments by the pilots Regions: Alps, Jura, Black Forest/DE

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B. Sigrist - TherMap OSTIV 2006, Eskilstuna/SE

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Validation: Net Vario Vario Net Vario Speed

Polar curve

Actual Vario

Actual speed

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June 28 Engadin June 28

Validation Examples

June 28

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Conclusions „

„

TherMap model seems to be valid for topographically highly differentiated areas, such as the Alps Mixed results for topographically smoother regions, such as the Jura: „ „

„

(+) Irradiance (~) Temperature

Not sufficient for still smoother regions

May 06

OK

~

X

B. Sigrist - TherMap OSTIV 2006, Eskilstuna/SE

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Note on Irradiance Maps in “Smooth” Areas Thermal map

The Thesimilarity similarity would wouldseem seemto to justify justifyfurther further research research

Irradiance map

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B. Sigrist - TherMap OSTIV 2006, Eskilstuna/SE

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Next Steps „

„

Internet publication: Maps, forum, services R&D on „ „ „ „ „ „

May 06

Secondary IR effects (lakes, ice, vegetation, satellite IR scans) Variation of turbidity Temperature model Secondary aerodynamic effects Refined flight tracking (wind drift, ground tracks) Extention to non-Alpine regions

d n a Help e c i v d A ! e m o c l e W

B. Sigrist - TherMap OSTIV 2006, Eskilstuna/SE

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Thank You

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