Arctic fjords represent one of the most challenging environments in the world for weather prediction and climate models. PhD candidate Tiina Kilpeläinen has identified the main challenges for the weather prediction models. Kilpeläinen will defend her thesis on September 15 at UNIS.

Press release from the University of Bergen and UNIS

Arctic fjords represent one of the most challenging environments in the world for weather prediction and climate models. This is due to complex interactions between the large-scale weather conditions, land, sea, sea ice and surrounding topography consisting of mountains, valleys and glaciers.

Tiina Kilpeläinen (right) performing fieldwork for her PhD thesis. (Photo: Tor deLange).

In her thesis, Kilpeläinen describes some special characteristics of the lowest part of the atmosphere over fjords in Svalbard. The main research topics are 1) the exchange of energy between the atmosphere and sea, 2) vertical structure of temperature, humidity and wind, 3) spatial variability of the meteorological variables and 4) identifying the main challenges for the weather prediction models.

During her PhD study, Kilpeläinen has collected data using weather masts and tethered balloons at the coasts of fjords in Svalbard. In addition, she has made high-resolution simulations of the meteorological conditions over Svalbard fjords with a weather prediction model.

Kilpeläinens investigations show that the vertical profiles of temperature, humidity and wind over Arctic fjords are complex and therefore challenging for the weather prediction models to capture. Layers with a temperature and humidity increase with height are commonly found over Svalbard fjords, often even on multiple levels. A weather prediction model does not realistically capture these layers, which leads to fairly large errors in the modeled surface variables. Further, she found that a wind maximum at a low altitude is also a typical feature over Arctic fjords. The height of this wind maximum depends on the sea-ice conditions, being highest when sea ice is present.

In her thesis, Kilpeläinen points out that due to the complex topography and the surface types (sea ice and water), spatial variability of meteorological variables within a fjord is very large and can reach levels comparable to the temporal variability. Hence, a high horizontal resolution in the order of 1 km is needed in the weather prediction models to realistically simulate all the significant small-scale processes taking place in a fjord environment.

Dissertation
Tiina Kilpeläinen will defend her PhD thesis ”The Atmospheric Boundary Layer over Arctic Fjords” on Thursday September 15 at 10:15.

She will give a trial lecture entitled “The influence of clouds on weather and climate in the Arctic” on Wednesday September 14 at 15:15.

Both lectures will take place in the auditorium “Lassegrotta” at UNIS.

About the candidate
Tiina Kilpeläinen was born in 1982 in Kajaani, Finland. She completed her Master's degree in meteorology at the University of Helsinki, Finland in 2006.

In May 2007 she enrolled as a PhD candidate at UNIS and the University in Bergen.