Showing posts from February, 2010

Weather Research and Forecasting Model Explained (Part 3) - System Architecture and Parallelism

WRF ,as mentioned in part 1 and part2, is a system designed for both operational and research purposes, and to run on systems from conventional laptops to super computers. The design of such a versatile system is a real challenge.
In this post we will explore some of the WRF's Software Framework design and explain the functionality of the different layers of the system. Also we'll discuss how the system handles parallelism in different hardware environments.
Software Framework Architecture[1][2]:
(The following functionalities doesn't include parallelism handling)

 Figure1: Hierarchical WRF Software Design As it appears in Figure 1, the system design has 3 layers: The Driver Layer:
It defines and allocates domains and associates them in a nest hierarchy. It also manages the flow of a system run as it's responsible for stepping the time for the loop mentioned in part1. And it's responsible for I/O operations.  The Mediation Layer:
It interfaces between the two othe…

Weather Research and Forecasting Model Explained (Part 2) - Nesting and System Components

In the part 1 we introduced WRF and discussed the meteorological basics of Advanced Research WRF. In this part we discuss the concept of nesting and explain different system parts of WRF. But first we'll define two basic terms.
Grid: Raw atmospheric data layed out as a discrete grid for an area of the map.
Figure 1 [1] Grid examples Domian: A model created by processing grid information and making it ready for processing by WRF Model.
Nesting is a way of getting high resolution data from low resolution data.That's achieved by introducing more grid or grids to the initial state. Those finer grain grids force the need for more high resolution data. That data is obtained by interpolating data from coarse grain grids or could be user input.
Figure 2 [1] Nested grid WRF System Components:

Figure3 [1] WRF system components As it appears in figure 1, the system has 3 main components: Preprocessor (WPS), the WRF Model and Post Processor. The WPS is responsible for preparing the inp…

Weather Research and Forecasting Model Explained (Part 1) - Weather Prediction Basics

My goal here is to give a simple overview of the WRF for computer science students.
The Weather Resarch and Forecasting (WRF, pronounced "worf") model is an open-source numerical weather prediction (NWP) and atmospheric simulation system designed for both research and operational applications [1]. This system was developed as joint effort between National Center of Atmospheric Research, National Oceanic and Atmospheric Administration (NOAA), Air Force Weather Agency and others. In this post ,and the posts to follow, I'll try to explain the WRF from two different perspectives, the first being Meteorology and the second being Computer Science.
I am here concerned with the Advanced Research WRF (ARW) subset of WRF.
Weather Prediction Basics:
Weather Prediction means to predict the state of the atmosphere in terms of (pressure, temperature, speed of wind, etc). Our atmosphere is controlled by flow and the conditions of the air across the planet and by predicting that flow we …