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

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 similar to 1mm, 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 7mm of subsidence in northern Australia and produce a positive slope trending southward. This trend reverses in spring. The La Nina precipitation in 2010-2011 produced widespread subsidence of >10mm, followed by gradual uplift of 10mm over the next 3-4years, as water storage depletes slowly through evapotranspiration. The geodetic measurements find significant imbalance in the water cycle budget in Australia over 2010-2015. Plain Language Summary This study finds how the Australian continent has deformed responding to atmospheric and water cycle changes sustained over periods of long-term droughts and the heavy precipitation during the La Nina. The majority of the Australian continent was depressed by the La Nina water load in 2010-2011 and slowly rebounded afterward as the water evaporates from the continent. The geodetic measurements (like GPS and Gravity Recovery and Climate Experiment) find significant imbalance in the water cycle budget in Australia over 2010-2015.