1. Dr. Eddy Graham UHI Research Conference Presentation Thursday 8 November 2012 SASKA: Search for an Astronomical Site in Kenya

2. 2 Why study Astronomy? 1.Aesthetic beauty! 2.Unanswered questions about “dark matter” (83% of universe) and “dark energy” (73% of mass-energy universe) 3.“Are we alone?”.. Last count on exoplanet.eu = 843 4.Humans want to “explore and extend beyond…”

3. 3 Why Astronomy, Weather and Climate? Clear skies (not even partial cloudiness) Little atmospheric water vapour Minimal turbulence… Other variables: Gentle and consistent winds; few aerosols / dust; no extreme weather (snow, hail, lightning, etc..); low night-time relative humidity; low seismic risk; nearness to infrastructure. Weather and climate are vital for successful astronomical observations:

4. 4 Twinkling stars and refraction of light Parallel wave front of stellar image gets distorted by atmosphere Atmosphere Space

5. 5 Where is Kenya?

6. 6 Kenya: Topography metres R I F T V A L L E Y Semi- Arid / Desert More Humid Mt. Kenya Mt. Kilimanjaro

7. 7 Kenya: Identification of candidate sites Mount Kulal (2293m) Warges (2688m) Mount Kenya (~4400m) Google Earth followed by site visits

8. Data Provenance: ECMWF ERA-interim 1979-2012 “reanalysis” 0.5 deg lat/lon resolution (~50km), ~ 50 levels 24 years of data, 6-hourly temporal resolution Easy to use, small file sizes (kb to mb) United Kingdom Met Office Africa Limited Area Model (“Africa-LAM”) output Very high 12km resolution, 70 levels, night-time hourly resolution run daily in real-time - archive 2010-2012 - large file sizes (2 GB per day!)

9. Analyses and Results: Cloud cover & variability (Integrated)

10. Analyses and Results: Integrated water vapour

11. Vertical velocity and height of turbulent layers -> need to go as high as possible -> surface turbulent layer is deep (2,500 to 3,000m, or more)

12. 12 Interim decision soon, South Africa (Dec 2012): Mount Kulal (2293m) Warges (2688m) Mount Kenya (~4400m) Monitoring conditions for two years. ~2017: begin construction of 1.5 to 2- metre telescope

13. Not quite ESO Paranal (Chile)… But a worthy project nonetheless: - Will provide a much-needed economic boost to Kenyan economy - Provide a dedicated research and training facility for African physics and astronomy students at home

14. 14 Thank you to sponsors! Spiral Galaxy, NGC 1232 21 Sep 1998, VLT Paranal (ESO) Hurricane Epsilon, 3 Dec 2005, NASA But 10 17 times difference in scale!!

15. Appendix 1: Seismic Risk

16. Appendix 2: TOMS 20-year aerosol index

17. 17 Appendix 3: What are “Reanalyses” ? Reanalysis Re-analyses are reconstructed weather analyses (maps) for the past (~1950s onwards) using all available weather data for the past, but using a fixed numerical meteorological model of today (avoids inhomogenities)

18. ERA40 mid-to-upper tropospheric (775 to 200 hPa) vertical velocities in range 2.5 5.0 cm /sec (i.e. gently subsiding air, turbulence less likely) H H H H H H H H Appendix 4: Vertical velocities

19. 19 Appendix 5: Prevailing windspeeds

20. Appendix 6: Global mean annual IWV

21. 21 Kenya: Identification of candidate sites Mount Kulal (2293m)

22. 22 Kenya: Identification of candidate sites OlDonyoNyiro (2752m)

23. 23 Kenya: Identification of candidate sites Mount Kenya (~4400m)

24. 24 Identification of candidate sites OlDonyoLenkiyo (2550m) Mount Kenya (~4400m) Loita Hills (2642m)

25. ERA: cloud cover data and variability Mt_Kulal OlDonyoN yiro Mt_Marsa bit Kapchol ioNdotoWargesLoita_HillsMtelo CC160.90168.82180.02461.55182.58171.27365.34421.25 St.dev110.42110.97120.811212.98119.83112.66164.57170.18 Mt_FurroliOlDonyoLenkyoSololoMt_KenyaCherangany3350m_ODY CC331.08174.53244.34141.10237.18145.41 St.dev171.02114.47139.1893.94138.2996.08 More or less same results with UK Met Office African-LAM Analyses and Results: Cloud cover & variability

26. Analyses and Results: Integrated water vapour (IWV) IWV is extremely height dependent