Sökning: "tjernström"

Visar resultat 16 - 19 av 19 avhandlingar innehållade ordet tjernström.

  1. 16. The Arctic Atmosphere : Interactions between clouds, boundary-layer turbulence and large-scale circulation

    Författare :Georgia Sotiropoulou; Michael Tjernström; Joseph Sedlar; Susanne Crewell; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Arctic; mixed-phase clouds; thermodynamic structure; Arctic inversion; cloud-surface interactions; seasonal transition; IFS model; LES; atmosfärvetenskap och oceanografi; Atmospheric Sciences and Oceanography;

    Sammanfattning : Arctic climate is changing fast, but weather forecast and climate models have serious deficiencies in representing the Arctic atmosphere, because of the special conditions that occur in this region. The cold ice surface and the advection of warm air aloft from the south result in a semi-continuous presence of a temperature inversion, known as the “Arctic inversion”, which is governed by interacting large-scale and local processes, such as surface fluxes and cloud formation. LÄS MER

  3. 17. Boundary Layer Parametrization in Numerical Weather Prediction Models

    Författare :Jacob Svensson; Gunilla Svensson; Michael Tjernström; Patrick Samuelsson; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Boundary-Layer Meteorology; Numerical Weather Prediction; Turbulence parametrization; COAMPS; IFS; meteorologi; Meteorology;

    Sammanfattning : Numerical weather prediction (NWP) and climate models have shown to have a challenge to correctly simulate stable boundary layers and diurnal cycles. This aim of this study is to evaluate, describe and give suggestions for improvements of the descriptions of stable boundary layers in operational NWP models. Two papers are included. LÄS MER

  4. 18. Mesoscale dynamics and boundary-layer structure in topographically forced low-level jets

    Författare :Stefan Söderberg; Michael Tjernström; Branko Grisogono; Douw G. Steyn; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; low-level jets; boundary layer; turbulence structure; Meteorology; Meteorologi;

    Sammanfattning : Two types of mesoscale wind-speed jet and their effects on boundary-layer structure were studied. The first is a coastal jet off the northern California coast, and the second is a katabatic jet over Vatnajökull, Iceland. LÄS MER

  5. 19. Arctic Atmospheric Rivers : Eulerian and Lagrangian features, and trends over the last 40 years

    Författare :Cheng You; Michael Tjernström; Abhay Devasthale; Heikki Järvinen; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Arctic; Atmospheric river; Stratocumulus; Blocking; Turbulence; Longwave irradiance; atmosfärvetenskap och oceanografi; Atmospheric Sciences and Oceanography;

    Sammanfattning : Arctic Atmospheric rivers, termed ‘warm-and-moist intrusion’ (WaMAI) in this thesis, transporting heat and moisture into the Arctic from lower latitudes, is a key contributor to the amplified warming in the Arctic under global change (Arctic Amplification). However, the warming effect of WaMAIs and its transformation along the trajectories into high Arctic still remain unclear, as well as their relation with the large-scale atmospheric circulation. LÄS MER