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Theoretical and Applied Climatology

, Volume 124, Issue 1–2, pp 425–449 | Cite as

Search for an astronomical site in Kenya (SASKYA) using climate reanalyses and high-resolution meteorological model data

  • Edward GrahamEmail author
  • Richard Vaughan
  • David A. H. Buckley
  • Koi Tirima
Original Paper

Abstract

The goal of the Search for an Astronomical Site in Kenya (SASKYA) project is to identify the best possible site(s) in Kenya for astronomical optical observation, using ERA-interim climate reanalyses and high-resolution UK Met Office Africa Limited Area meteorological model (Africa-LAM) data. This initial search focusses on a selection of 13 candidate mountain peaks across Kenya. A mixture of 30 years (1981–2010) of relatively coarse-grained ERA-interim reanalyses data and 12 months’ (2011–2012) of much higher resolution UK Met Office Africa-LAM data were used to determine the best possible sites. Cloud cover, precipitable water vapour (specific humidity), vertical velocity, aerosol loadings and wind data were analysed. The results confirm that many sites in Kenya are reasonably cloud free, with estimated photometric night fractions of possibly 50 % at the best sites. Significant seasonal inter-annual and inter-decadal variations in cloud cover can be expected, however. Average precipitable water vapour (PWV) values are uncomfortably high, but periods of much lower PWV can be expected during favourable conditions in the dry seasons. Long-term vertical velocities (as a proxy to determine areas of improved “seeing” conditions) indicate that good astronomical viewing conditions are likely to be dependent on the season and wind direction across Kenya. Finally, after full consideration of the climatological data, a trade-off is expected between the best possible site in climatological terms, and the practicalities of installing remote equipment in isolated, inaccessible areas with little or no infrastructure.

Keywords

Cloud Cover Rift Valley Precipitable Water Vapour Candidate Site Total Cloud Cover 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgments

The ECMWF ERA-interim data used in this study/project have been provided by ECMWF and have been obtained from the ECMWF data server. The UK Met Office (UKMO) Limited Area Model for Africa (Africa-LAM) was kindly made available by the UK Met Office, through the British Atmospheric Data Centre (BADC). This research was funded by the Kenya–South Africa Joint Science and Technology Research programme. A grant by the Carnegie Trust for the Universities of Scotland enabled Dr. E. Graham of the University of the Highlands and Islands to travel to South Africa in December 2012 and participate in discussions with the SASKYA team, leading to the decision to install astronomical site testing equipment at Warges and Mount Kulal. Dr. Graham is grateful for the support of the Carnegie Trust in this regard.

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Copyright information

© Springer-Verlag Wien 2015

Authors and Affiliations

  • Edward Graham
    • 1
    Email author
  • Richard Vaughan
    • 3
  • David A. H. Buckley
    • 2
  • Koi Tirima
    • 4
  1. 1.Lews Castle CollegeUniversity of the Highlands and IslandsStornowayScotland
  2. 2.South African Astronomical ObservatoryCape TownSouth Africa
  3. 3.InCA Nairobi LtdNairobiKenya
  4. 4.Inoorero CentreInoorero UniversityNairobiKenya

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