Sökning: "NWP"

Visar resultat 1 - 5 av 9 avhandlingar innehållade ordet NWP.

1. 1. Toward Sequential Data Assimilation for NWP Models Using Kalman Filter Tools

   Författare :Jelena Bojarova; Rolf Sundberg; Krzysztof Podgorski; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; non-Gaussian state space models; Kalman filtering; ETKF; 3D-Var; data assimilation; NWP; Mathematical statistics; Matematisk statistik; matematisk statistik; Mathematical Statistics;

   Sammanfattning : The aim of the meteorological data assimilation is to provide an initial field for Numerical Weather Prediction (NWP) and to sequentially update the knowledge about it using available observations. Kalman filtering is a robust technique for the sequential estimation of the unobservable model state based on the linear regression concept. LÄS MER

3. 2. 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. 3. Dynamical aspects of atmospheric data assimilation in the tropics

   Författare :Nedjeljka Žagar; Erland Källén; Nils Gustafsson; Eugenia Kalnay; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; tropical data assimilation; variational methods; mass-wind coupling; Meteorology; Meteorologi;

   Sammanfattning : A faithful depiction of the tropical atmosphere requires three-dimensional sets of observations. Despite the increasing amount of observations presently available, these will hardly ever encompass the entire atmosphere and, in addition, observations have errors. Additional (background) information will always be required to complete the picture. LÄS MER

5. 4. On errors in meteorological data assimilation

   Författare :Magnus Lindskog; Erland Källen; Nils. Gustafsson; Florence Rabier; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Meteorology; Meteorologi; meteorologi; Meteorology;

   Sammanfattning : Data assimilation in Numerical Weather Prediction (NWP) optimally blends observations with atmospheric model data in order to obtain the best possible initial state for an atmospheric model prediction. Specification of error characteristics is an important part of data assimilation. LÄS MER

7. 5. Description and Analysis of Data and Errors in GPS Meteorology

   Författare :Borys Stoew; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; atmospheric water vapor; global positioning system; propagation delay; meteorology; ensemble assimilation; GPS;

   Sammanfattning : This report presents the relation between remote sensing techniques used for estimation of atmospheric water vapor content, and numerical weather prediction. The thesis makes an overview of the methods for estimation of the zenith wet/total delay (ZWD/ZTD) for radio waves in the neutral atmosphere, and a statistical description of data in relation to the sampling problem for atmospheric water vapor. LÄS MER