Changes between Version 45 and Version 46 of OMI_observation_modules


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Timestamp:
Apr 29, 2024, 12:34:00 PM (8 months ago)
Author:
lnerger
Comment:

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  • OMI_observation_modules

    v45 v46  
    6363                                          !   (0) Cartesian, (1) Cartesian periodic
    6464                                          !   (2) simplified geographic, (3) geographic haversine function
    65      INTEGER :: ncoord                    !< Number of coordinates use for distance computation
     65                                          !   (10) Cartesian 2+1D factorized, (11) Cartesian periodic 2+1D factorized
     66                                          !   (12) simplified geographic 2+1D factorized
     67                                          ! (13) geographic haversine function  2+1D factorized
     68     INTEGER :: ncoord                    !< Number of coordinates use for distnce computation
    6669     INTEGER, ALLOCATABLE :: id_obs_p(:,:) !< Indices of process-local observed field in state vector
    6770     ...
     
    264267 - 2: Approximate geographic distance in meters with horizontal coordinates in radians (latitude: -pi/2 to +pi/2; longitude -pi/+pi or 0 to 2pi)
    265268 - 3: Geographic distance computation in meters using haversine formula with horizontal coordinates in radians (latitude: -pi/2 to +pi/2; longitude -pi/+pi or 0 to 2pi)
    266 
    267 For 0 and 1 any distance unit can be used. The computed distance will be in the same unit. For 2 and 3 the input coordinates are in radians and the distance is computed in meters. Essential is that the grid point coordinates and observation coordinates use the same unit.
     269With PDAF V2.2.1, a **2D+1D factorized localization** was introduced for 3-dimensional applications. With the factorized localization, the horizontal distance (components 1 and 2) is treated separately from the vertical direction (3rd component). This is available for both isoptropic and non-isotropic localization and activated using the choices
     270 - 10: Cartesian distance 2D+1D factorized in 3 dimensions
     271 - 11: Cartesian distance 2D+1D factorized in 3 dimensions with periodicity (Needs specification of thisobs%domainsize(ncoord))
     272 - 12: Approximate geographic distance 2D+1D factorized in meters with horizontal coordinates in radians (latitude: -pi/2 to +pi/2; longitude -pi/+pi or 0 to 2pi) and vertical in unit chosen by the user.
     273 - 13: Geographic distance computation 2D+1D factorized in meters using haversine formula with horizontal coordinates in radians (latitude: -pi/2 to +pi/2; longitude -pi/+pi or 0 to 2pi) and vertical in unit as chosen by the user.
     274
     275**Notes:**
     276- When disttype>=10 is specified with isotropic localization the weight function for the vertical direction is constant with a valu eof one. For non-isotropic localization, the weight functions can be separately specified for the vertical and horizontal directions.
     277- For 0 and 1 (likewise 10, 11) any distance unit can be used. The computed distance will be in the same unit. For 2 and 3 the horizontal input coordinates are in radians and the distance is computed in meters. Essential is that the grid point coordinates and observation coordinates use the same unit.
     278- For 3-dimensional localization, the unit of the vertical direction can be chosen by the user. However, for geographic ditances, the unit should be chosen to be 'compatible' with the unit in the horizontal (meter). When isotropic localization is used, the unit for the vertical direction can be scaled do that the length scales in the vertical and horizontal directions are the same  (this, e.g., allows to use pressure as the distance measure in the vertical in atmospheric models). For non-isotropic localization, the units can differ without scaling. In ccase of the factorized 2D+1D localization (disttype>=10), the units in the horizontal and vertical directions are independent.
    268279
    269280See `/models/lorenz96_omi/` for an example using case 1 with periodicity in one dimension.