Abstract
Lakes in permafrost regions are highly sensitive to changes in air temperature, snowmelt, and soil frost. In particular, the Qinghai-Tibetan Plateau (QTP) is one of the most sensitive regions in the world influenced by global climate change. In this study, we use retracked Enivsat radar altimeter measurements to generate water level change time series over Lake Qinghai and Lake Ngoring in the northeastern QTP and examine their relationships with precipitation and temperature changes. The response of water levels in Lake Qinghai and Lake Ngoring is positive with regards to precipitation amount. There is a negative relationship between water level and temperature change. These findings further the idea that the arid and high-elevation lakes in the northeastern QTP are highly sensitive to climate variations. Water level increases in Lake Qinghai in winter may indicate inputs of subsurface water associated with freeze-thaw cycles in the seasonally frozen ground and the active layer.
Highlights
The Qinghai-Tibetan Plateau, the highest plateau in the world, has an average elevation of more than 4000 m above sea level, and the permafrost over the QTP occupies about 1.5 × 106 km2, or approximately 70% of the permafrost regions in China (Oelke and Zhang 2007)
Despite of sporadic data gaps, Lake Ngoring water level time series shows that there are smaller secondary peaks around April, which could be due to seasonal snow/glacier melt in spring
In Lake Qinghai, there are counterintuitive seasonal water level increases around November/December and water level decreases around March/April
Summary
The Qinghai-Tibetan Plateau (hereafter, QTP), the highest plateau in the world, has an average elevation of more than 4000 m above sea level, and the permafrost over the QTP occupies about 1.5 × 106 km, or approximately 70% of the permafrost regions in China (Oelke and Zhang 2007). Satellite radar altimetry has been used to study water elevation changes over lakes (Morris and Gill 1994; Birkett 1995; Lee et al 2010), rivers We use retracked Environmental Satellite (Envisat) altimeter measurements to generate water level change time series over Lake Qinghai and Lake Ngoring in the northeastern QTP (Fig. 1) and examine their relationships with regard to precipitation and temperature observed by satellites. Lake Qinghai is the largest closed-basin lake in China located in the arid-semiarid area of 3194 m above sea level. It has an average depth of 21 m and a lake area of 4260 km. The lake has an elevation of 4272 m above sea level, an area of 610 km and an average depth of 17.6 m
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