Extra Earth observation studies to better understand effects of climate change

The NWO honoured eight TU Delft research projects for Earth observation and planetary research. Several studies will start within the CEG faculty that will help us better understand the Earth's climate system.

Once we have a better picture of the climate system, it offers opportunities for fine-tuning models, for example. Femke Vossepoel, associate professor at TU Delft and involved in one of the honoured projects, is working on that. "For a long time there has been a desire to build a 'digital twin' (a modelled replica) of planet Earth. This would make it possible to calculate scenarios very precisely. On that basis, policymakers can make better choices to mitigate and anticipate climate change."

Puzzle pieces of the water cycle

Vossepoel's research will provide insight into meltwater from glaciers in the Alps. "That is only one part of the whole water cycle. My colleagues, in turn, are looking at other processes that converge in the entire water cycle." For example, Pavel Ditmar looks at meltwater in Greenland, Riccardo Riva's research focuses on the movements of water in the ocean, and Susan Steele-Dunne focuses on water exchange between the land and the atmosphere. These are many puzzle pieces from the water cycle that will help us better understand the Earth's climate system, and can make a 'digital twin' of Earth more realistic.

Vossepoel is pleased to see that so many projects from TU Delft (Civil Engineering and Geosciences and Aerospace Engineering) have been honoured. "We can find each other quickly and the cooperation is motivating. Satellites have become increasingly accurate in recent years and we can also interpret the signals better. This makes it possible to explore areas you can't easily get to. But it also produces a lot of different data. We need to carefully examine how we make best use of the available data infrastructure," Femke Vossepoel says.

The following projects have been assigned within the Geoscience and Remote Sensing and Geoscience and Engineering departments of CEG:

Satellite gravimetry will measure the mass of meltwater at the base of Greenland Ice Sheet

Pavel Ditmar

Current projections of future sea level rise remain rather uncertain. One of the reasons is an insufficient understanding of how ice flows in Greenland may respond to increasing air temperatures. Warm weather facilitates a temporary accumulation of meltwater at the base of ice sheet, which plays a role of lubricant, so that ice discharge into the ocean accelerates. To understand this process better, we propose to using satellite gravimetry – a unique remote sensing technique, which can sense mass re-distribution at any depth inside the Earth. In this way, we will contribute to better forecasting future sea level rise.

The oceans will tell us where their water is coming from

Riccardo Riva

The amount of water in the oceans is never constant due to its continuous exchange with the continents, where freshwater is stored in, for example, ice sheets, glaciers and groundwater systems. Direct observations of those reservoirs are sparse in both space and time, although they are crucial to understand the impact of climate change on the global water cycle and on sea level. Remarkably, freshwater fluxes redistribute over the oceans following very specific patters, known as sea-level fingerprints. This project will analyse satellite observations to detect those patterns and provide original estimates of their continental sources.

Altimeter-derived long-term global changes in ocean tides

Cornelis Slobbe

Ongoing long-term changes in ocean tides may have severe consequences for coastal environments and ecological systems. However, our understanding of these changes is limited because the observational input is just obtained from clustered and sparsely distributed coastal tide gauges where local processes dominate. By using the full record of multimission satellite radar altimeter data and hydrodynamic models, we will i) map the large-scale patterns of long-term global changes in the main tidal constituents, ii) quantify the contribution of the key drivers, and iii) assess the impact on sediment transport and other key physical processes in the Wadden Sea.

ASCAT slope: A new angle on the role of vegetation in the climate system

Susan Steele-Dunne

Vegetation plays an important, but poorly-understood role in exchanges of water and carbon between the land and atmosphere. We need to understand and model these exchanges to predict, mitigate and adapt to the impact of climate change and make smarter decisions for a sustainable future. Radar can see into vegetation and tell us about water transport from the roots to the atmosphere. We will use global satellite radar data to improve our understanding of the role of vegetation in a changing climate.

Satellite snow data for drought forecasting in the Rhone basin

Femke Vossepoel

With climate change, droughts are becoming more frequent and more intense. In the Rhone basin, droughts are having an important impact on people and agriculture. By combining satellite observations of snow cover and glaciers in the Alps and its glaciers in the model eWatercycle. For several sub-questions, we want to reduce the model in a targeted way to do calculations in an efficient way. With this we can forecast water behaviour and better estimate how much water flows into the Rhone from glaciers and snow melt, which leads to improved warnings which ultimately contribute to mitigate the negative effects of droughts.

Photo: ESA