Changes between Version 45 and Version 46 of OMI_observation_modules

Timestamp:

Apr 29, 2024, 12:34:00 PM (3 weeks ago)

Author:

lnerger

Comment:

--

OMI_observation_modules

@@ -63 +63 @@
                                           !   (0) Cartesian, (1) Cartesian periodic
                                           !   (2) simplified geographic, (3) geographic haversine function
-     INTEGER :: ncoord                    !< Number of coordinates use for distance computation
+                                          !   (10) Cartesian 2+1D factorized, (11) Cartesian periodic 2+1D factorized
+                                          !   (12) simplified geographic 2+1D factorized
+                                          ! (13) geographic haversine function  2+1D factorized
+     INTEGER :: ncoord                    !< Number of coordinates use for distnce computation
      INTEGER, ALLOCATABLE :: id_obs_p(:,:) !< Indices of process-local observed field in state vector
      ...
@@ -264 +267 @@
  - 2: Approximate geographic distance in meters with horizontal coordinates in radians (latitude: -pi/2 to +pi/2; longitude -pi/+pi or 0 to 2pi)
  - 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)
-
-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.
+With 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
+ - 10: Cartesian distance 2D+1D factorized in 3 dimensions
+ - 11: Cartesian distance 2D+1D factorized in 3 dimensions with periodicity (Needs specification of thisobs%domainsize(ncoord))
+ - 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. 
+ - 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.
+
+**Notes:**
+- 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.
+- 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.
+- 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.
 
 See `/models/lorenz96_omi/` for an example using case 1 with periodicity in one dimension.