Elastic deformation of the Australian continent induced by seasonal water cycles and the 2010–2011 La Niña determined using GPS and GRACE

Abstract

The solid Earth deforms elastically in response to changes in atmospheric, water, and ice mass load. I present geodetic (Gravity Recovery and Climate Experiment and GPS) observations of continental deformation at seasonal and interannual scales, responding to water and atmospheric cycles in Australia. In the southern summer, the central part of the Australian continent rises by a few millimeter and the north-south perimeter lengthens by ~1 mm, induced by atmospheric unloading. In winter, the continent subsides and the perimeter shortens due to atmospheric loading. In autumn, increased soil moisture and groundwater result in 7 mm of subsidence in northern Australia and produce a positive slope trending southward. This trend reverses in spring. The La Niña precipitation in 2010–2011 produced widespread subsidence of >10 mm, followed by gradual uplift of 10 mm over the next 3–4 years, as water storage depletes slowly through evapotranspiration. The geodetic measurements find significant imbalance in the water cycle budget in Australia over 2010–2015.