Polar Budget Diagnostics
The polar regions are of particular interest for climate research due to their unique sensitivity to ongoing warming. In the Arctic, surface warming is amplified through numerous feedback mechanisms while in Antarctica, rapid and effective heat uptake is modifying the oceanic heat content. Our group performs detailed diagnostics of the polar energy and water budgets to develop an understanding of these regions sensitivities and their role in the global climate system.
Developing a process-based understanding of the energy budget within these regions is crucial to understand past changes while also providing a benchmark for global climate models which have persisting errors in the representation of the polar regions.
We are members of national and international research associations that support us, most notably the International Arctic Science Committee (IASC), the Association of Polar Early Career Scientists (APECS), the Austrian Polar Research Institute (APRI) and the Vienna International Network for Atmsopheric Research (VINAR). Recently we started engaging in the preparation of the 5th International Polar Year (IPY5), with the intensive observation period scheduled for 2032/33.
Arctic Energy and Water Budgets
The Arctic climate system is shaped by a complex interplay between the atmosphere, ocean, sea ice and land. Our group investigates the coupled Arctic energy budget, including surface energy fluxes, atmospheric and oceanic heat transports, and the storage of energy within the ocean, atmosphere and sea ice. By considering these components together, we can assess how energy enters, leaves and is redistributed within the Arctic climate system and how changes in one component are connected to changes in others.
We combine satellite and in-situ observations with atmospheric and ocean reanalyses to derive observationally constrained estimates of the individual budget components and assess their consistency. These estimates also provide a benchmark for evaluating climate models, including large ensembles from CMIP6, helping us identify systematic biases and assess how realistically models represent the processes governing Arctic climate.
Our analyses also extend to the Arctic water budget, connecting precipitation and evaporation with river runoff and exchanges of liquid water and sea ice through the Arctic gateways. Together, energy and water budget diagnostics provide a process-based perspective on interactions between the different components of the Arctic climate system.
Arctic water (left) and energy (right) budgets from observationally constrained reference estimates (black/white) and the CMIP6 multi-model mean (red). The budgets combine exchanges through the atmosphere, ocean and surface with changes in energy and water storage. Adapted from Winkelbauer et al. (2024).
Polar Radiative Budgets
The polar radiative budgets are undergoing rapid changes at both the surface and at the top-of-atmosphere. As snow and ice covered areas are reducing, these regions are absorbing more sunlight (shortwave radiation) and as these regions warm they begin to emit more thermal (longwave) radiation. The relative partitioning between these components is nontrivial and is a focus of ongoing research.
We utilize a range of satellite based observations to characterize the ongoing changes to the Arctic radiative budgets. The NASA Clouds and the Earth’s Radiant Energy System (CERES) project provides robust observations of both top-of atmosphere and surface radiative fluxes since 2001. In the Arctic, while reducing sea ice is associated with increasing solar absorption, thermal emission trends are changing at the same rate resulting in an unchanging net energy budget (the Arctic energy imbalance remains unchanged). In Antarctica however, thermal emission remains unchanged under variable solar absorption leading to an increasing energy imbalance, with the Southern Ocean modulating heat uptake in the Antarctic region through effective heat uptake.
Annual accumulated thermal emission and solar absorption in the Arctic (left) and Antarctic (right) regions as measured by NASA CERES project. Notable years are labeled. Edited from Prince and L'Ecuyer (2024) DOI: 10.1175/JCLI-D-23-0294.1
Spectral Thermal Emission
As satellite technology develops, new sensors are providing novel observations of Earth's radiative transfer. The NASA Polar Radiant Energy in the Far InfraRed Experiment (PREFIRE) mission, launched in 2024, consists of two 6U CubeSats in near-polar orbit each carrying a miniaturized IR spectrometer providing the first global observations of Earth's completed spectrally resolved emission spectra (from 5 to 50 µm). The NASA PREFIRE mission focuses on characterizing top-of-atmosphere thermal emission in the polar regions. We examine the polar, spectral atmospheric greenhouse effect through PREFIRE observations with a focus on the role of highly variable water vapor concentrations in the polar regions.
Distributions of the spectral Arctic summer greenhouse parameter (G) as retrieved by the NASA PREFIRE mission. Values shown for the month of July for all-sky (blue) and clear-sky (orange) observations with the monthly mean shown as coloured points.