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

Transcription

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

2 Contents History and present state of thermal maps The TherMap approach Topography Irradiance Temperature Thermal Take-Off Spots Model validation Conclusions 2

3 Flashlight Analogy of 1955 Hans Nietlisbach 3

4 Example of an Existing Thermal Map Thermikkarte Deutschland Considers neither daytime nor season 4

5 Topographic Approach by TherMap Topographic data model Date and daytime Surface properties Topography of a region Irradiance map (W/m2) Temperature map (heating effect) Regional meteorology Thermal map (?) 5

6 A. Topography SRTM 90 m Satellite Radar Data These are tables indicating Example: Elevation Map the elevation of the surface of the earth every 90 Topographic Map meters Used to generate computed maps 6

7 B. Irradiance The intensity of solar radiation (W/m2) at a given location, date and time PVGIS European Communities, 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,

8 (1) Basic Irradiance = Projection of solar vector on normal vector Tangent Normal vector Solar vector Parabolic approximation line 8

9 (2) Irradiance is diminished as light penetrates the atmosphere ~1.3 kw/m 2 before entering atmosphere Depending on Solar elevation Altitude Turbidity Present TherMap assumption: 12 km visibility (for turbidity) In reality locally and seasonally variable 9

10 (3) Irradiance per air column is scaled by the slope of the surface (solar pannel) Sun Air column I h = I s / cos α Horizontal surface α Irradiated surface Slope angle 10

11 Example: Irradiance, Jura-Gruy Gruyères/CH,, May 6, 1100 MEZ 11

12 C. Temperature Temperature increase due to cumulative effect of solar irradiation minus radiation losses Solar Engineering Handbook Part 2, Temperature Theory, ed. 2003, Meteonorm, On a sunny day the Temperature is peaking about 2 hours after the Irradiance peak 12

13 Temperature: : Approximation by a time- phased smoothing model Irradiance - Temperature Irradiance Smoothing model with smoothing factor a = 0.1 to Time of day (hour) Irradiance - Temperature Hour Present best fit: Smoothing model with time-phased smoothing factor a = 0.2 x 0.9 (hr-12) 13

14 Effects diminishing Temperature increase Albedo of snow covered surfaces (seasonal) Forest belt from m Vegetation density diminishes with slope! Seasonally climbing and descending vegetation 14

15 Example: Temperature 1100h 1300h 1700h MEZ 1500h MEZ Temperature, Valais/CH, May 6th 15

16 Thermal Take-Off Spots (von Kalckreuth s rule) Thermals climb along slope until angle drops below 30 degrees 16

17 Example: Take-Off Spots on Overlay Temperature Map (Sisteron( May 6, 1300 MEZ) 17

18 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 18

19 Validation: Net Vario Vario Net Vario Speed Actual Vario Polar curve Actual speed 19

20 June 28 Engadin June 28 Validation Examples June 28 20

21 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 OK ~ X 21

22 Note on Irradiance Maps in Smooth Areas Thermal map The The similarity would would seem seem to to justify justify further research Irradiance map 22

23 Next Steps Internet publication: : Maps, forum, services R&D on 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 Help and Advice Welcome! 23

24 Thank You 24