Rainfall and temperature attributes on the lesotho–drakensberg escarpment edge, southern africa
Rainfall and temperature attributes on the lesotho–drakensberg escarpment edge, southern africa
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DOI：
10.1111/j.1468-0459.2008.00337.x
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发表时间：
2008-03
期刊：
影响因子：
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通讯作者：
W. Nel;P. Sumner
中科院分区：
文献类型：
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作者：
W. Nel;P. Sumner
摘要。莱索托-德拉肯斯堡及其相关悬崖位于非洲东南部边界附近，是坦桑尼亚地块以南非洲山脉的最高山脉。在悬崖顶和邻近的高峰，气候通常被解释为边缘冰缘，但在这些高度很少有资料，特别是降雨量和温度的记录。位于悬崖边缘的两个临时野外观测站的气候数据提供了当代地表气候条件，其中一个观测站是非洲南部有记录以来降雨量最高的观测站。二一年至二五年的年平均雨量分别为：沙尼关山顶767.8毫米（整整三年）和森提纳峰753.2毫米（整整两年）；这些数值低于同期在山麓记录的数值。尽管由于轻微的干旱期，降雨量略低于该地区的长期平均降雨量，但数据显示，早期估计的悬崖上每年1000毫米到2000毫米的降雨量太高了。然而，在萨尼山口测量到的平均气温为5.8°C，在悬崖顶的估计范围内。冬季空气和土壤表面的霜冻循环频繁，但夏季土壤中没有霜冻循环，并且没有测量到长时间的地表-土壤冻结。因此，温度证实了先前假设的边缘冰周性质，但降水数据表明环境比预期的更干燥。因此，需要重新考虑古环境情景，特别是基于稍微夸大的当代降水值的外推而得出的关于前冰川作用的论点。
Abstract. Located near the southeastern limit of Africa, the Lesotho‐Drakensberg and associated escarpment is the highest range of African mountains south of the massifs in Tanzania. At the escarpment summit and on the adjacent high peaks, the climate is generally interpreted as marginal periglacial yet few data, specifically rainfall and temperature, exist on record at these altitudes. Climatic data from two temporary field stations on the escarpment edge, one of which is the highest rainfall station yet on record in southern Africa, provide contemporary surface‐climate conditions. Mean annual rainfall recorded between 2001 and 2005 averages 767.8 mm at Sani Pass summit (three complete years), and 753.2 mm on Sentinel Peak (two complete years); these values are less than those recorded for the same period in the mountain foothills. Even though rainfall is slightly below long‐term rainfall averages for the area due to a marginally dry spell, the data show that earlier estimates of between 1000 mm and 2000 mm rainfall per annum on the escarpment are too high. A measured mean air temperature of 5.8°C at Sani Pass, however, falls within the range estimated for the escarpment summit. Frost cycles in air and at the soil surface are frequent in winter, but absent in soil for summer, and no long‐duration surface‐soil freeze was measured. Temperatures thus confirm the marginal periglacial nature as postulated for previously, but precipitation data indicate a dryer environment than anticipated. Palaeoenvironmental scenarios, notably arguments for former glaciation based on extrapolations from somewhat exaggerated contemporary precipitation values, thus require re‐consideration.