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GEMPlot User-Guide

cmac994

GEMPlot User Guide

GEMPlot is a graphic user interface (GUI) for GEMPAK the General Meteorology Package an analysis, display, and product generation package for meteorological data provided by UCAR (Unidata).

Features of GEMPlot:
- Plots and retrieves Model Analysis from the Iowa State GEMPAK Archive
- Plots and retrieves Reanalysis data from NCDC
- Plots and retrieves global GFS 0.5 degree analysis from NCDC
- Perform Objective Analysis and produce surface isobar, isotherm, isodrosotherm,and isallobar analysis.
- Plot model soundings and cross-section at a variety of upper air stations across the CONUS
- Selection of upper air meteorological plots includes but is not limited to: Isotach Analysis, Absolute Vorticity Analysis, 12 hour Height change, Temperature Advection, Vorticity Advection, and Q-vector Analysis.
- Selection of surface meteorological plots includes but is not limited to: Pressure Tendency Analysis, Surface Pressure Analysis, and Surface Temperature Analysis

Background

---THIS IS IMPORTANT---

  1. The Iowa State GEMPAK Archive has model analysis back to 2002. From 2007 – Present GFS, NAM, and RUC analysis is available. Between 2002 – 2007 RUC, ETA, and THIN model analysis is available. The ETA was the predecessor to the NAM and I believe the THIN may be the AVN (now GFS) model. If you try to plot model analysis prior to 2002 the program will not work and will likely give you a nasty error this is because there is no model analysis that can be download from the Iowa State GEMPAK

  2. If you seek to plot Global data the GFS 0.5 degree resolution model analysis will be used. It is archive back to March of 2004 on NCDC and is not available before this time period. k Archive prior to 2002.

  3. If you seek to plot Global data the GFS 0.5 degree resolution model analysis will be used. It is archive back to March of 2004 on NCDC and is not available before this time period.

  4. If you seek model analysis prior to 2002 select the option for Reanalysis data. The Reanalysis data is from NCDC and is the 32km resolution North American Regional Reanalysis (NARR). Reanalysis data is available back to 1979.

  5. Objective Analysis can be performed from surface observation and upper air observation GEMPAK files from the Iowa State GEMPAK Archive. Surface Observations are available back to 1933 and upper air observations are available back to 1946 thus surface objective analysis can be performed back to 1946

*WARNING: GEMPlot is not perfect.There may be some unworked issues with the code as there are hundreds of plots that can be made using GEMPlot using more than a half century of data. I myself have not plotted them all and so I cannot guarantee that everything will work. That said if you get an error or identify a problem feel free to email me at cmcnicholas@ou.edu or just come see me in class.

Installation

  1. To install GEMPlot download the source file from sourcefourge at http://sourceforge.net/projects/gemplot/

  2. Once you have GEMPlot downloaded go to the directory (cd into the directory) in which it downloaded

  3. Unzip the GEMPlot.tar.gz file by running the command "tar -xzvf GEMPlot.tar.gz" this will create a folder called GEMPlot, cd into this folder

  4. Before running GEMPlot ensure that you source Gemenviron (or Gemenviron.profile)!!! This is very important as if you do not GEMPAK will not run. From the OU linux lab computers this can be done by typing in the command: source /usr/local/nawips/Gemenviron

  5. To run GEMPlot and begin plotting meteorological data run the command ./GEMPlot.bash You will need to run this command whenever you would like to start the program. Don't forget to run gpend after you finish plotting for the day!

  6. The program will save your files as a postscript “.plt” file and as a pdf. If you would like to convert your pdf to a .png file or .jpeg file just simply run the command "convert filename.pdf filename.png". Also if you'd like to rotate your plot (from portrait to landscape) you can run the command: "convert filename.plt -rotate 90 filename.plt"

Acknowledgements
- The meteorological data displayed by GEMPlot is provided by the Iowa State GEMPAK Archive (courtesy of Iowa State University) and the National Climatic Data Center.