Geodetic Constraints on the Qinghai-Tibetan Plateau Present-Day Geophysical Processes

Abstract

The Qinghai-Tibetan Plateau is the largest and the highest area in the world with distinct and competing surface and subsurface processes. The entire Plateau has been undergoing crustal deformation and accompanying isostatic uplift as a result of the Cenozoic collision of the Indian and Eurasian continents. Regional secular surface mass changes include the melting of mountain glaciers and ice caps, and permafrost layer degradation due to global warming. There is also a plausible effect of glacial isostatic adjustment due to the removal of a possible Pleistocene ice-sheet. In this article, we present an assessment of the sizes and extents of these competing interior and exterior dynamical processes, and their possible detections using contemporary space geodetic techniques. These techniques include, in addition to GPS, satellite radar altimetry over land, and temporal gravity field measurements from the Gravity Recovery and Climate Experiment (GRACE) satellite mission. These techniques are complementary: land satellite altimetry, similar to GPS, is sensitive only to surface uplift, whereas GRACE is sensitive to both surface uplift and mass changes inside the Earth. Each process may dominate the others in a particular region. Our analysis shows that GRACE data are more sensitive (than GPS or land altimetry) to hydrologic and meteorology signals, some of which are larger than the combined effect of geodynamic processes and permafrost degradation.

Groundwater storage changes in the Tibetan Plateau and adjacent areas revealed from GRACE satellite gravity data

“…The signal amplitudes become smaller from south to north in the Tibetan Plateau. These patterns are simi- (Rodell et al, 2004) and CPC data (Fan and van den Dool, 2004), (b) ICESat-1 based glacier measurements (Gardner et al, 2013), (c) monthly GLDAS (CLM/NOAH/MOSIC/VIC) data (Rodell et al, 2004), (d) ICESat-1 lake measurements (Zhang et al, , 2013, (e) one ALD model (Oelke and Zhang, 2007;Erkan et al, 2011) and (f) ICE-6G_C(VM5a) model (Argus et al, 2014;Peltier et al, 2015). A, B, C and D denote positions of the hydrology signals, which will be compared to those when Gaussian filter is used (Fig.…”

Response of Tibetan Plateau lakes to climate change: Trends, patterns, and mechanisms

“…Permafrost degradation due to increasing active-layer thickness has occurred in the TP, but the observations have mainly been made along the Qinghai-Tibet railroad (Luo et al, 2016;Wu et al, 2014;Yang et al, 2010). Based on regional modeling of the active-layer depth over the TP, a rough estimate of the amount of water released from permafrost degradation can be made (Erkan et al, 2011;Oelke and Zhang, 2007;Xiang et al, 2016). In addition, the contribution of melting ground ice to the surface water stream in the source area of the Yellow River, in the northeast TP, has been estimated at 13.2−16.7% by hydrological separation from a stable isotopic method (Yang et al, 2019).…”

Lake volume and groundwater storage variations in Tibetan Plateau's endorheic basin

“…A regional modeling of active-layer depth (ALD) over the TP has been performed for 1980-2001[Oelke and Zhang, 2007. The ALD data in the Inner TP were extracted from previous studies [Erkan et al, 2011;Oelke and Zhang, 2007]. Part of the meltwater from permafrost degradation may be stored as ground ice in the active layer; the released water is estimated using the model from Xiang et al [2016].…”