Name
Erik Johansson
Swedish Meteorological Institute, Sweden

Title
Towards Improved Understanding of the Vertical Structure of Cloud Radiative Heating and Cooling effects

Time and place
Thursday 28 January 2015, 14.15
Room C609, Arrhenius Laboratory, 6th floor

Abstract

The main purpose of this study is to investigate and document the vertical structure of clouds and their corresponding cloud radiative heating and cooling (CRH/C). We focus on two areas that are dynamically and radiatively different where we know that CRH/C plays an important role at least locally.

Paper I focuses on India and the summer monsoon. Here we investigate CRH/C of the three main cloud types associated with the monsoon: high clouds, stratiform clouds and deep convective clouds. To capture the whole transition of the monsoon monthly values during the time period May to October are analysed. We also investigate the difference between active and break periods of the monsoon during these months. It is found that during this time period, stratiform clouds heat the middle troposphere while they cool the upper troposphere, with the largest contribution during June, July and August. Deep convective clouds warms the middle and upper troposphere while they cool the tropical tropopause layer and the atmosphere at the cloud base. High clouds warm the upper troposphere and lower stratosphere, with the largest impact in May and July, while they tend to cool the surface.

Paper II focuses on Water Vapour Intrusions (WWI) into the Arctic. Strong WWI can, together with transport of sensible heat affect the sea ice melt. We examine four different geographical sectors and investigate the CRH/C, surface temperatures and circulation patterns during winter and summer months. Our results shows that WWIs leads to an increase in cloudiness and surface warming during both winter and summer, where the corresponding CRH/C will mainly cool the upper troposphere and warm the lowermost part of the troposphere. The impact on the lower part of the atmosphere during winter is strongest for WWI coming from the Pacific Ocean, followed by the Barents/Kara Seas. WWIs from the Atlantic ocean will create an significant local warming in the Fram Strate where a large portion of the sea ice is transported out of the Arctic.

Welcome!