Effects of the spatial scales in the initial conditions of numerical weather forecasts
Student Seminar Series
Department of Atmospheric & Oceanic Sciences
presents
a talk by
Minh-Tri Nguyen
MSc student
Effects of the spatial scales in the initial conditions of numerical weather forecasts
Despite numerous improvements in technology, there are still many differences between the numerical weather forecasts and the observations of the weather, especially in precipitation. Although many factors could explain these differences, we focus on the spatial scale of the initial conditions: is it more important to have accurate state variables at the small scales or at the large scales? To obtain some insight into this question, the case of a squall line event is studied in numerical experiments by removing successively more and more of the small scales in the initial conditions. Here, rather than filtering one by one each field of the state variable, such as the temperature and the wind fields, the potential vorticity (PV) field is filtered and the piecewise PV inversion technique (Davis and Emanuel, 1991) is used to obtain the initial state variable fields. The filtered initial conditions are then used to simulate the squall line event using the Weather and Research Forecasting model (WRF). In this seminar, we will outline our methodology and present comparison of the simulated rain rates with those from the radar observations.