Seasonal and Diurnal Variability in Near‐Surface Air and Ground Temperature Regimes of the Alpine Zone of Mount Kenya

• Published in: Earth and space science (Hoboken, N.J.) N.J.), 2024-02, Vol.11 (2), p.n/a
• Main Authors: Downing, Timothy A., Olago, Daniel O., Nyumba, Tobias
• Format: Article
• Language: English
• Subjects: Alpine environments; Climate change; Drought; Dry season; Elevation; Equator; frost days; Heat; High temperature; lapse rate; Mountains; Radiation; Refugia; Seasonal variations; temperature regime; thermal niche; tropical alpine; Vegetation; Vegetation cover
• ISSN: 2333-5084; 2333-5084
• DOI: 10.1029/2023EA003410

Mountains near the equator have very unique temperature regimes due to the tropical latitude and alpine altitude. How climate change will impact these temperature regimes is not clear as there are so few temperature records in these environments. This study attempts to characterize the near‐surface air and ground temperature regime for the Teleki Valley (3,200–4,200 m. a.s.l) on the western slope of Mount Kenya using a set of six temperature loggers placed at 200 m elevation intervals. Temperature was recorded at 30 min intervals from September 2021 to October 2022. The mean diurnal temperature range varied from 6°C to 14°C, with maximum daily swings in excess of 25°C. There was a distinct seasonality in temperature, with a hot season during the months of January‐March, where it was roughly 3°C warmer than the coolest months. Diurnal temperature swings were also highest in March. This seasonality is driven by radiation and moisture: higher radiation during the vernal equinox combined with clear skies during the dry season made for higher temperatures. Elevation was the dominant spatial gradient determining temperature regimes, but rock and vegetation cover played a large role in modifying near‐surface air and ground temperature. The highest elevation logger (4,200 m. a.s.l), measuring ground temperature, showed muted seasonal and diurnal swings, creating for warmer temperatures than lower elevation loggers. This demonstrates the importance of thermal refugia at these high elevations. This also makes predictions of plant and animal responses to climate change difficult, as uniform upward shifts would not necessarily maintain thermal niches. Plain Language Summary Tropical alpine areas have few detailed records of climate particularly in the zone near the surface where most organisms live. This study investigated the near ground temperature regime of the Teleki Valley of Mount Kenya using loggers placed at 200 m elevation intervals. The results showed that temperature can vary considerably over short distances and over time, with marked daily and seasonal temperature patterns. Elevation, topography and cover drive these differences as do macro‐climactic factors of wind patterns and solar radiation. The implication is that biotic responses to climate change will not be straight‐forward but may be site‐ and species‐specific. Key Points Near‐surface temperature regime of the alpine zone of Mount Kenya has a seasonal element that is driven in part by solar radia