Advanced User’s Guide Version 3.5 August, 2016 Ming Hu National Oceanic and Atmospheric Administration (NOAA)/Earth System Research Laboratory Cooperative Institute for Research in Environmental Sciences (CIRES) Chunhua Zhou, Hui Shao, Don Stark, and Kathryn Newman National Center for Atmospheric Research (NCAR) Acknowledgement This user's guide is constructed with contributions from distributed GSI developers. We give our special acknowledgement to these contributors and reviewers, including, but not limit to: National Centers for Environmental Prediction (NCEP) Environmental Modeling Center (EMC): John Derber, Russ Treadon, Mike Lueken, Wan-Shu Wu, Andrew Collard, and Ed Safford National Center for Atmospheric Research (NCAR): Xiang-Yu Huang, Syed Rizvi, Zhiquan Liu, and Arthur Mizzi National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory (ESRL): Steve Weygandt, Dezso Devenyi, Joseph Olson, and Jeff Beck Shanghai Meteorological Service: Min Sun The GSI community support and code management effort is sponsored by NOAA's Office of Oceanic and Atmospheric Research (OAR). This work is also facilitated by NCAR. NCAR is supported by the National Science Foundation (NSF). ii Foreword This document, designed for experienced users, includes advanced knowledge, features, and skills of GSI as well as details of assimilation of specific data types. Users may use as a reference for their special research topics. To read this guide, users should already read and understand the content in the GSI User’s Guide. This version of Advanced GSI User’s Guide was released with the community GSI version 3.5 in August 2016. Please note, not like the basic GSI user’s guide which is being updated every year and closely follows the GSI release code, this advanced user’s guide, as a reference, is only being updated as needed and therefore doesn’t pertain to one specific code release. There are 10 Chapters in this document: Chapter 1: Overview Chapter 2: Software Installation Chapter 3: Advanced Topics on Run and Diagnosis Chapter 4: GSI Theory Chapter 5: GSI Code Structure Chapter 6: Static Background Error Covariance Chapter 7 Observations Chapter 8: Satellite Radiance Data Assimilation Chapter 9 Radar Data Assimilation Chapter 10 GSI Applications DTC may update the content of this advanced User’s Guide, if needed, between releasees. For the latest version of this document, please visit the GSI User’s Website at http://www.dtcenter.org/com-GSI/users.v3.5/docs/index.php Please send questions and comments to: [email protected] For referencing this document, please use: Developmental Testbed Center, 2016: Gridpoint Statistical Interpolation Advanced User's Guide Version 3.5. Available at http://www.dtcenter.org/com- GSI/users.v3.5/docs/index.php, 119 pp. For referencing the general aspect of the GSI community effort, please use: Shao, H., J. Derber, X.-Y. Huang, M. Hu, K. Newman, D. Stark, M. Lueken, C. Zhou, L. Nance, Y.-H. Kuo, B. Brown, 2016: Bridging Research to Operations Transitions: Status and Plans of Community GSI. Bulletin of the American Meteorological Society, doi:10.1175/BAMS-D-13-00245.1, in press iii Table of Contents Table of Contents Chapter 1: Overview .................................................................................................................. 1 Chapter 2: Software Installation ........................................................................................... 3 2.1 Modifying the GSI Build Environment .................................................................................... 3 2.2 Understanding the Build System ............................................................................................. 3 2.2.1 Configuration Resource File ................................................................................................................ 4 2.2.2 Modification Example ............................................................................................................................ 6 Chapter 3: Advanced Topics on Run and Diagnosis ........................................................ 8 3.1 Convergence Information from File fort.220 ...................................................................... 8 3.2 Use Bundle To Configure Control, State Variables And Background Fields ............ 11 3.3 Using Observations Station Uselist And Rejection List In GSI ...................................... 12 3.3.1 Surface Observation Rejection And Use List ............................................................................. 13 3.3.2 Aircraft Observation Rejection ........................................................................................................ 14 Chapter 4: GSI Theory ............................................................................................................. 16 4.1 3DVAR Equations: ....................................................................................................................... 16 4.2 Iterations To Find The Optimal Results .............................................................................. 17 4.3 Analysis Variables ....................................................................................................................... 18 Chapter 5: GSI Code Structure .............................................................................................. 19 5.1 Main Process ................................................................................................................................. 19 5.2 GSI Background IO (for 3DVAR) ............................................................................................. 22 5.3 Observation Ingestion ............................................................................................................... 23 5.4 Observation Innovation Calculation ..................................................................................... 24 5.5 Inner Iteration ............................................................................................................................ 25 Chapter 6: Static Background Error Covariance ............................................................ 26 6.1 What Is Background Error Covariance ................................................................................ 26 6.2 Processing Of Background Error Matrix ............................................................................. 27 6.3 Apply Background Error Covariance ................................................................................... 29 Chapter 7 Observations .......................................................................................................... 31 7.1 Process BUFR/PrepBUFR Files ............................................................................................... 31 7.1.1 introduction ............................................................................................................................................. 31 7.1.2 Encode, Decode, Append A Simple BUFR File ........................................................................... 33 7.1.2.1 Decoding/Reading Data From A Simple BUFR File ......................................................................... 33 7.1.2.2 Encoding/Writing Data Into A Simple BUFR File ............................................................................ 41 7.1.2.3 Appending Data To A Simple BUFR File ............................................................................................... 44 7.1.3 Encode, Decode, Append The PrepBUFR File ........................................................................... 46 7.1.3.1 Decoding/Reading Data From A PrepBUFR File .............................................................................. 46 7.1.3.2 More Exmaples On Processing Prepbufr Files .................................................................................. 48 7.3 GSI BUFR Interface ...................................................................................................................... 49 7.3. 1 GSI Observation Data Ingest And Process Procedure .......................................................... 49 7.3.2 The BUFR Decoding In GSI Read Files .......................................................................................... 53 7.4 NCEP Generated BUFR Files ..................................................................................................... 54 7.4.1 Knowledge on NCEP BUFR/PrepBUFR Files ............................................................................. 54 7.4.2 BUFR/PrepBUFR Data Resources for Community Users .................................................... 57 7.5 Observation Error Adjustment ............................................................................................... 58 iv Table of Contents Chapter 8: Satellite Radiance Data Assimilation ........................................................... 59 8.1. Satellite Radiance Data Ingest And Distribution ............................................................. 59 8.1.1 Link Radiance BUFR Files To GSI Recognized Names ........................................................... 59 8.1.2 GSI Code To Ingest Radiance Data ................................................................................................. 62 8.1.3 Information On Ingesting And Distribution .............................................................................. 65 8.2. Radiance Observation Operator ..........................................................................................