Institute for Marine and Atmospheric Research (IMAU)

Ice and Climate

 

Research

Automatic Weather Stations

The relation between meteorological quantities and the mass balance of a glacier surface is a critical element in modelling the reaction of different glaciers to climate change. To get a better hold on the processes that determine this interaction, IMAU has conducted a number of detailed meteorological field studies and deployed several automatic weather stations (AWS) on glaciers, ice caps and ice sheets. Since 1991, IMAU has deployed several AWS on different glaciers in different climate regimes. The stations are designed to work for long periods without being serviced and offer the opportunity to measure meteorological variables in remote areas and in harsh weather conditions.

The main purpose of these stations is to study the mass balance and energy balance at these locations in view of global climate change, sea level rise and historic climate reconstructions.

Read more about where UU/IMAU operates AWS and check out live AWS data.


Regional Climate Modeling

We use the regional atmospheric climate model RACMO over the large ice sheets of Greenland and Antarctica to study their surface mass balance and climate. The dynamical and physical core of RACMO is kept up-to-date by our partners at the Royal Netherlands Meteorological Institute (KNMI), while at IMAU we developed and integrated into RACMO a snow routine for use over land ice. The snow routine currently treats snow grain size growth (for prognostic albedo calculations), vertical heat conduction, densification of the firn, percolation and refreezing of meltwater, transport, sublimation and erosion/deposition of drifting snow and meltwater runoff. All these components are interactively coupled to the atmospheric part of RACMO.

RACMO has proven capable of realistically simulating the surface mass balance (SMB) of the Greenland and Antarctic ice sheets. RACMO data are frequently used by glaciologists to study the regional mass balance of a glacier basin or the interaction of meltwater runoff with basal sliding and frontal melt.

Read more about the most recent model runs and available data.


Ice dynamics and GPS

A well-known phenomenon in glacier dynamics is the existence of a relation between the glacier velocity and available amount of melt water. This relation is of particular importance when estimating the reaction of glaciers and ice sheets to climate change. In order to better understand this relation, detailed flow velocity and mass balance information is crucial as well as ice flow models of various complexity.

For the observational part, IMAU developed a low cost stand-alone single-frequency GPS unit to perform year round ice velocity observations in addition to mass balance measurements using stakes and sonic altimeters. Modelling efforts are concentrated on simple flow line models for process studies and the 'Parallel Ice Sheet Model' PISM for more realistic experiments.


Ice sheets, climate and sea level

Ice sheets play an important role in the climate system. They contribute to sea level on time scales of years to 100.000 years and they are important for the interpretation of paleo data. Sea level variations are studied over the entire Cenozoicum with comprehensive numerical flow models covering the four major ice sheets on Earth, (Antarctica, Greenland, Eurasia and the Northern American ice sheet complex) and considering their mutual interaction via regional sea level variations. Results are used for the interpretation of marine and ice cores.


Glacier length variations and climate reconstruction

Knowledge of past glacier fluctuations provides insight into glacier dynamics and the sensitivity of glaciers to climate change. In addition, historical glacier fluctuations can be used to reconstruct past climate fluctuations and the contribution of glaciers to the sea-level rise observed since the middle of the 19th century. For many regions of the world information of glacier fluctuations over the past centuries has become available, mostly in the form of measured and reconstructed glacier length fluctuations.

At IMAU we have compiled a data set of world-wide glacier length fluctuations, including measurements as well as reconstructions. At present, the data set has 380 records. All records start before 1950 and cover at least 4 decades. There are records from all continents, but there are no records from the Canadian and Russian Arctic.

Information on glacier fluctuations can be used to reconstruct past climate variations. Taking the reponse charateristics of each individual glacier into account, we have reconstructed global temperature anomalies over the past four centuries (see figure). This reconstruction provides a fully independent confirmation of earlier proxy-based temperature reconstructions of pre-instrumental temperature history.


Morteratsch

In October 1995 IMAU placed an Automatic Weather Station (AWS) on the snout of the Morteratschgletscher, a glacier in the Bernina Alps, Switzerland. The aim of this project was (and is) to obtain a multi-annual dataset of meteorological quantities from the lower part of a valley glacier, and to study the relation between mass balance and climate. The Morteratschgletscher was selected for this project because of good accessibility, appropriate size, and typical valley-glacier geometry. Logistics are simple and relatively cheap, because a helicopter base is just a few minutes away (Samedan). The Morteratschgletscher is a great tourist attraction, but this never led to serious problems with the instruments.

Hans Oerlemans is the principal investigator on this project and hosts a website with background information, data examples and numerous pictures.


International Polar Year

The Polar Regions have profound significance for the Earths climate and ultimately environments, ecosystems and human society. However we still know remarkably little about many aspects of the polar climate and its interactions. We do know that the three fastest warming regions on the planet in the last two decades have been Alaska, Siberia and parts of the Antarctic Peninsula, showing us that the Polar Regions are highly sensitive to climate change.

The recent technological developments such as earth observation satellites, autonomous vehicles and molecular biology techniques offer enormous opportunities for a quantum step upwards in our understanding of polar systems, and hence IPY 2007-2008 was initiated. On the following website information can be found on the IMAU projects related to the IPY.