wiki:LEM

The Met Office Large Eddy Model

Introduction

The Met Office Large Eddy model is also known as a cloud resolving model. Version 2.3 was developed at the Met Office in 2001. The repository here contains version 2.4 obtained from Adrian Hill in March 2011. The LEM is no longer being actively developed. It has been superseded by the Met Office/NERC Cloud Model (MONC), currently in development (access to the Met Office Science Repository Service is required).

The repository here is structured as follows,

  • trunk contains the releases and updates from the Met Office
  • branches/self_sp is a version that runs on a single processor machine
  • branches/archer is a version that runs on ARCHER

The code is designed to be hosted on a local computer and run on a remote computer. The local computer needs a C compiler and the remote computer needs a Fortran compiler.

The LEM code consists of core code and a set of corrections. The "nupdate" tool, which is part of the LEM, merges the core code with the corrections to produce the source code for compilation. This is then sent to the remote computer for compiling and linking and running. The user interacts with the LEM via a script called lemsub.

Pre-requisites

You will need the following,

  • a C compiler,
  • a Fortran 90 compiler,
  • GCOM 3.8, if you need to run on multiple processors.

Installation

Follow the procedure out lined in Installation and Basic Running. In addition to the instructions given there, you need to build "nupdate". This needs a C compiler. Thus, execute

. ./setup_LEM 
cd $LEM/SOURCE/update0.4.9
make

You also need to create ~/LEM_runs on the remote computer.

Ensure that you have an SSH agent running and that you've loaded your pass phrase (ssh-add).

Finally,

cd $LEM/JOBS/test1 
lemsub test1 0001

and select S and hit return to launch.

The code builds under gfortran with the "-std=legacy" option. On ARCHER, the code builds with the Cray compiler; this is selected via the ftn wrapper script provided by Cray.

User Guide and Scientific Documentation

The documentation can be found at the official Met Office Large Eddy Model web site.

W. McGinty, 8-Dec-2015

Last modified 2 years ago Last modified on 12/08/15 15:21:24