IGG-SLR-HYBRID: High-resolution temporal gravity fields from satellite laser ranging
**************************************************************************************

   Author:            Anno Löcher
   Date of this file: 16 November 2020 
   
Content and usage
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   IGG-SLR-HYBRID is a series of monthly gravity field solutions from satellite laser 
   ranging using a hybrid parametrization including spherical harmonic coefficients and 
   empirical orthogonal functions from GRACE. 

   Time span covered:   November 1992 - June 2020
   Temporal resolution: monthly
   Spatial resolution:  SH degree 60 (degree 1 not solved)
   Satellites used:     Lageos 1, Lageos 2, Ajisai, Starlette, Stella (from November 1993)
   
   The solutions are provided as monthly sets of spherical harmonic coefficients in ICGEM 
   format. File naming convention is "IGG-SLR-HYBRID_SX+YE_YEAR-MONTH.gfc". The following 
   solutions are provided:   
      
   ==================================================================================
    Subdirectory            |   SH degrees  |  Number of EOFs  |     SH degrees
                            |   estimated   |     applied      |    used in EOFs
   ==================================================================================
    IGG-SLR-HYBRID_S0+6E    |      none     |        6         |        2-60
   -------------------------|---------------|------------------|---------------------
    IGG-SLR-HYBRID_S2+6E    |        2      |        6         |        3-60
   -------------------------|---------------|------------------|---------------------
    IGG-SLR-HYBRID_S3+6E    |      2-3      |        6         |        4-60
   -------------------------|---------------|------------------|---------------------
    IGG-SLR-HYBRID_S4+6E    |      2-4      |        6         |        5-60
   -------------------------|---------------|------------------|---------------------  
    IGG-SLR-HYBRID_S5+4E    |      2-5      |        4         |        6-60
   -------------------------|-------------------------------------------------------- 
    IGG-SLR-HYBRID_EnsMean  |          weighted mean of above solutions
   -------------------------|-------------------------------------------------------- 
   
Reference
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   When using this data, please cite the following publication which provides all informations 
   about the approach and the models used: 

   Anno Löcher and Jürgen Kusche: A hybrid approach for recovering high-resolution temporal 
   gravity fields from satellite laser ranging. Journal of Geodesy. DOI: 10.1007/s00190-020-01460-x

Contact
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   If you have any questions regarding these solutions please contact: 

   Anno Löcher
   Institute of Geodesy and Geoinformation 
   Nussallee 17
   D-53115 Bonn
  
   loecher@geod.uni-bonn.de