An hourly ground temperature dataset for 16 high-elevation sites (3493–4377 m a.s.l.) in the Bale Mountains, Ethiopia (2017–2020)

Abstract

Abstract. Tropical mountains and highlands in Africa are under pressure because of anthropogenic climate and land-use change. To determine the impacts on the afro-alpine environment and to assess the potential socio-economic consequences, the monitoring of essential climate and environmental variables at high elevation is fundamental. However, long-term temperature observations on the African continent above 3000 m are very rare. Here we present a consistent multiannual dataset of hourly ground temperatures for the Bale Mountains in the southern Ethiopian Highlands, which comprise Africa's largest tropical alpine area. The dataset covers the period from January 2017 to January 2020. To characterise and continuously monitor the mountain climate and ecosystem of the Bale Mountains along an elevation gradient from 3493 to 4377 m, ground temperature data loggers have been installed at seven sites at 2 cm depth; at four sites at 10 cm depth; and at five sites at 2, 10, and 50 cm depth. The statistical analysis of the generated time series reveals that ground temperatures in the Bale Mountains are subject to large daily fluctuations of up to 40 ∘C and minor seasonal variations on the order of 5 to 10 ∘C. Besides incoming short-wave radiation, ground moisture, and clouds at night, slope orientation and the type of vegetation coverage seem to be the main factors controlling daily and seasonal ground temperature variations. On the central Sanetti Plateau above 3800–4000 m, the mean annual ground temperature ranges from 9 to 11 ∘C. However, nocturnal ground frost down to a depth of 5 cm occurs frequently during the dry season from November to February. At the five sites where ground temperature is measured at three depths, the monitoring will be continued to trace long-term changes. To promote the further use of the ground temperature dataset by the wider research community dealing with the climate and geo-ecology of tropical mountains in eastern Africa, it is made freely available via the open-access repository Zenodo: https://doi.org/10.5281/zenodo.6047457 (Groos et al., 2022).

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

“…The lapse rate calculated in this study (−0.5°C/100 m) is somewhat less than reported in the literature: the range of values for Mount Kenya varies from 0.44 to 0.68°C/100 m depending on the data set used (Chen et al., 2018; Coe, 1967; Grab et al., 2004; Mizuno & Fujita, 2014; Omuombo et al., 2020; Winiger, 1981). Similar values have been reported for other East African mountains (Duane et al., 2008; Groos et al., 2022; Loomis et al., 2017; Wesche, 2002). The theoretical moist adiabat for East Africa is −0.55°C/100 m (Loomis et al., 2017), and generally −0.60 or −0.65°C/100 m is quoted as the standard lapse rate world‐wide (Lute & Abatzoglou, 2021; Nigrelli et al., 2018; Wang et al., 2018).…”

“…Seasonal variability in diurnal temperature regimes have been noted before in Kilimanjaro, although at lower elevation sites (2340 m); there mean daily range varied from 3.4°C in July to 9.5°C in February (Duane et al., 2008). In the Ethiopian highlands also, seasonal variations of 3–4°C have been documented (Groos et al., 2022).…”

High-resolution digital elevation models and orthomosaics generated from historical aerial photographs (since the 1960s) of the Bale Mountains in Ethiopia

“…The mean annual ground temperature ranges from 7 to 11 °C (Groos et al, 2022). The lowest and highest temperatures recorded on the Sanetti Plateau were -15 ºC and 26 ºC, respectively (Hillman, 1988), where frosts occur during all clear nights throughout the year (Groos et al, 2022). Rainfall is variable throughout the study area and ranges from 800 to 1500 mm annually (Woldu et al, 1989).…”

“…The mean monthly minimum and maximum temperatures are 5.6 °C and 21.4 °C, respectively, for an altitudinal range of 2700 to 4377 m above sea level (asl). The mean annual ground temperature ranges from 7 to 11 °C (Groos et al, 2022). The lowest and highest temperatures recorded on the Sanetti Plateau were -15 ºC and 26 ºC, respectively (Hillman, 1988), where frosts occur during all clear nights throughout the year (Groos et al, 2022).…”

The mid‐latitude hydrolaccolith of the Spanish Central System (Southern Europe): A top‐to‐bottom integration of geomatic, geophysical and sedimentary datasets for characterising a singular periglacial landform

“…The heterogeneous presence of seasonal water pools can explain the detected differences in the uplifting response during the annual evolution of the hydrolaccolith by controlling surface/subsurface temperatures (Figure 6b). gramme is needed to understand further the annual thermal regime of such periglacial landform (Groos et al, 2022;Marcos & Palacios, 2004;Palacios et al, 2003;Serrano et al, 2020;Vieira et al, 2003).…”