Using the MAPL Orbital Component with SatSim

The MAPL_OrbGridComp module is a gridded component that creates satellite ground tracts. From these tracks, masks on the input grid are created. These masks represent which grid cell boxes were passed over by the satellite in a timestep of the model. The component has been integrated in the GEOS5 GCM and is a child of the AGCM gridded component and creates masks on the atmospheric grid at each timestep in the model run. The mask represents the ground track or swath of the particular satellite between the current model time and the current model time plus the heartbeat. For example, if the model heartbeat is 30 minutes and we start the model at 21z, at the first timestep the masks exported by MAPL_OrbGridComp represent the ground track or swath seen between 21:00 and 21:30. At the 2nd timestep the exports now represent the track or swath between 21:30 and 22:00. Thus far the MAPL_OrbGridComp module has been interfaced with the SatSim gridded component. Exports of the SatSim component can be masked and the masked fields can be output via the History as an export of SatSim. To use this capability the user must provide two resource files that follow the standards of ESMF resource files. The first is MAPL_OrbGridComp.rc, which defines the satellites and the swath of the instruments to simulate in the model run. An example MAPL_OrbGridComp.rc is shown below:

#                            ----------------
#                            Mask Definitions
#                            ----------------
verbose: .false.
debug: .false.
Nominal_Orbits::
#                              Swath
# Instrument   Satellite       (km)      Halo              Long Name
# ----------  -----------   ----------  ------    ---------------------------------------------------
   TERRA       TERRA               0       0         Orbital Mask for TERRA (Satellite Sub-point)
   MOPITT      TERRA             616       0         Orbital Mask for MOPITT
   ASTER       TERRA              60       0         Orbital Mask for ASTER
   MODIS_T     TERRA            2330       0         Orbital Mask for MODIS TERRA
   MISR        TERRA             380       0         Orbital Mask for MISR
#
   AQUA        AQUA                0       0         Orbital Mask for AQUA (Satellite Sub-point)
   AIRS        AQUA             1650       0         Orbital Mask for AIRS
   AMSR_E      AQUA             1445       0         Orbital Mask for AMSR-E
   MODIS_A     AQUA             2330       0         Orbital Mask for MODIS AQUA
#
   AURA        AURA                0       0         Orbital Mask for AURA (Satellite Sub-point)
   HIRDLS      AURA             3000       0         Orbital Mask for HIRDLS
   OMI         AURA             2600       0         Orbital Mask for OMI
   TES         AURA              180       0         Orbital Mask for TES
#
   CALIPSO     CALIPSO             0       0         Orbital Mask for CALIPSO
   CLOUDSAT    CLOUDSAT            0       0         Orbital Mask for CLOUDSAT
::

The file must have a Nominal_Orbits label. Following the label each line has the following text entries.

Instrument - This is the name that will be used for the export state created by GEOS5

Satellite - This is the satellite name. Currently the valid satellites are TERRA, AQUA, AURA, CALIPSO, and CLOUDSAT.

Swath - This the the size of the swath in kilometers. Note the ACTUAL SWATH SIZE IS TWICE THIS since this is the size of the swath on either side of the groud track. If this is 0 you will just get the ground track of the actual satellite.

Halo - This allows one to had a halo around the swath where the number is the number of extra grid points to swath outside of the generated sattellite swath

Long Name - this parameter is not read but you can place additional text after the Halo for information

The second resource file you need is called SatSim.rc and describes which exports of SatSim to mask with the possible masks produced by the MAPL_OrbGridComp module. An example SatSim.rc is shown below:

Masked_Exports::
MDSOPTHCKWTRLG MISR MASK_MDSOPTHCKWTRLG
MDSOPTHCKTTLLG MISR MASK_MDSOPTHCKTTLLG
::

The file must have a Masked_Exports label. Following the label each line has the following three entries in the following order.

1. Name of export in SatSim. This is the name of the export in SatSim you want to mask.

2. Name of the mask to apply to export. This must be one of the instrument names in the corresponding MAPL_OrbGridComp.rc file.

3. Name of new variable. This is what the new masked export will be name. The variable of this name can now be exported via the History from the SatSim component like any of the native exports of SatSim.

Finally any mask defined in the MAPL_OrbGridComp.rc file can be exported in History as a standard 2D field with the same name as the instrument from the 'ORBIT' component. For example to output TERRA and MOPITT masks defined in the example MAPL_OrbGridComp.rc define a collection with the fields attribute like so:

collection_name.fields: 'TERRA'  ,  'ORBIT' ,
                        'MOPITT' ,  'ORBIT' ,
::