UGAMP Offline Trajectory Code (Version 3) ========================================= John Methven, Department of Meteorology, University of Reading, PO Box 243, Earley Gate, Reading, RG6 6BB, UK. Email: J.Methven@reading.ac.uk References for the code itself and papers establishing its accuracy: *************** UGAMP_tech44.ps *************** Methven, J. (1997) Offline trajectories: Calculation and accuracy. Tech. Report 44, 18pp., U.K. Univ. Global Atmos. Modelling Programme, Dept. of Meteorol., Univ. of Reading, Reading, U.K. Methven, J., Evans, M., Simmonds, P. and Spain, G. (2001) Estimating relationships between air-mass origin and chemical composition. J. Geophys. Res., 106, 5005-5019. Methven, J., Arnold, S.R., O'Connor, F.M., Barjat, H., Dewey, K., Kent, J., Brough, N. (2003) Estimating photochemically produced ozone throughout a domain using flight data and a Lagrangian model. J. Geophys. Res., 108(D9), 4271, doi:10.1029/2002JD002955. (see also publications in http://www.met.rdg.ac.uk/~swrmethn ) The following files should enable you to run the Offline trajectory code on some sample ECMWF spectral analyses. Please email me if you intend to use this trajectory code in your research and also notify me of any publications that incorporate results from this trajectory model. ******************** user_guide3_2001.pdf ******************** A minimalist guide to using the code which describes the parameters of the model (changed before compilation) and the variables which can be changed after compilation through the use of FORTRAN NAMELISTs in the jobdecks. It was written in 2001 so the details about the filepaths for the code, jobdecks and programme library at CSAR, Manchester, are out of date. However, all of these files do exist at CSAR but on the computer "wren" in /ohome/lrjm4/outside/offline_3 (26/2/2004). ********* era40.job ********* A sample UNIX jobdeck which puts the program together using the "nupdate" function, creates the NAMELISTs, compiles the program and then executes it. The nupdate function pulls together subroutines from a program library and applies some modifications by editting various lines. This is a good way to maintain the programme because the programme library remains fixed for all users (at version 3) and any user modifications or bug fixes are incorporated by nupdate. If you wish to use Offline in this way then you should use the programme library at CSAR or email me about using it on your own computer system. Otherwise use the jobdeck below. *************** era40_nonup.job *************** A sample UNIX jobdeck which specifies filepaths, creates the NAMELISTs, compiles the program "off3_era40.f" and executes it. You will need to change the filepaths and FORTRAN compilation line to be appropriate for your computer system. ************ off3_era40.f ************ The FORTRAN source code which was put together by nupdate using "era40.job". It includes the latest standard updates including bug fixes, four-digit years and coping with ERA-40 data. ************ trajplot.pro ************ An IDL program to plot trajectories contained in one trajectory file. All you need to do is to edit the file and at the beginning of the main program set lcomputer=1 for running on a PC (Windows) or lcomputer=0 for running on a UNIX computer. Then start up IDL and enter .run trajplot Answer the questions and then a window should appear. You can plot trajectories on a map using the `traj' button or draw any two variables against each other using the `x vs y' button (for example height versus time along trajectory). You can change the variables on the x and y axes using the drop down menus on the top row of buttons. You can change the limits of the map by editting the four values on the second row down corresponding to: min(latitude), min(longitude), max(latitude), max(longitude). You can change the x-axis using the first two values on the third row. The first number refers to the starting value for the axis and the second number corresponds approximately to the range/30. Finally you can also select different colour scales and reverse them if desired. ************ rdftread.pro ************ An IDL procedure that is called by trajplot to read the trajectory data files. You can edit this to select filepaths for the location of trajectory data on your computer. Different values of IDATA can be used to specify different directories. Examples are given in rdftread.pro. If you choose to do this you must also change the value given for IDATA in trajplot.pro . The default (IDATA=1) expects the trajectory data to be in the current directory. ************** traj2003080112 ************** A sample trajectory file output by executing "era40_nonup.job". In this example the trajectories are 4 days long but if you run the sample code as it is then your output will be trajectories that are 2 days long. The trajectories are integrated backwards in time from the "arrival date" 12UTC 1 Aug 2003. ****************** spamYYYYMMDDHH.grb ****************** The spectral analyses on ECMWF model eta-levels at T159L60 resolution (in the same format as the whole of ERA-40) for one time: year YYYY, month MM, day DD, hour HH (UTC). These are read and used by the Offline trajectory code as the calculation proceeds. Look in "user_guide3_2001.pdf" for ways in which you could use other input data to drive the trajectory model. Note that if you request specific humidity as a trajectory attribute then you will also need the ECMWF ggamYYYYMMDDHH.grb data files (since q is always a grid-point field in the current ECMWF analysis system).