Changeset 2293 for palm/trunk/SOURCE/pmc_interface_mod.f90

Timestamp:

Jun 22, 2017 12:59:12 PM (7 years ago)

Author:

suehring

Message:

In anterpolation, exclude grid points used for interpolation from parent to child

File:

• palm/trunk/SOURCE/pmc_interface_mod.f90 (modified) (4 diffs)

palm/trunk/SOURCE/pmc_interface_mod.f90

@@ -26 +26 @@
 ! -----------------
 ! $Id$
+! In anterpolation, exclude grid points which are used for interpolation. 
+! This avoids the accumulation of numerical errors leading to increased 
+! variances for shallow child domains.  
+! 
+! 2292 2017-06-20 09:51:42Z schwenkel
 ! Implementation of new microphysic scheme: cloud_scheme = 'morrison' 
 ! includes two more prognostic equations for cloud drop concentration (nc)  
@@ -5421 +5426 @@
 !--    Define the index bounds iclp, icrm, jcsp and jcnm.
 !--    Note that kcb is simply zero and kct enters here as a parameter and it is
-!--    determined in pmci_init_anterp_tophat
-
+!--    determined in pmci_init_anterp_tophat.
+!--    Please note, grid points used also for interpolation (from parent to
+!--    child) are excluded in anterpolation, e.g. anterpolation is only from 
+!--    nzb:kct-1, as kct is used for interpolation. Following this approach
+!--    avoids numerical problems which may accumulate, particularly for shallow
+!--    child domain, leading to increased velocity variances. A more 
+!--    comprehensive explanation for this is still pending.
        IF ( nesting_mode == 'vertical' )  THEN
           IF ( nest_bound_l )  THEN
@@ -5439 +5449 @@
           IF ( nest_bound_l )  THEN
              IF ( var == 'u' )  THEN
+                iclp = icl + nhll + 1 + 1
+             ELSE
                 iclp = icl + nhll + 1
-             ELSE
-                iclp = icl + nhll
              ENDIF
           ENDIF
           IF ( nest_bound_r )  THEN
-             icrm = icr - nhlr
+             icrm = icr - nhlr - 1
           ENDIF
 
           IF ( nest_bound_s )  THEN
              IF ( var == 'v' )  THEN
+                jcsp = jcs + nhls + 1 + 1
+             ELSE
                 jcsp = jcs + nhls + 1
-             ELSE
-                jcsp = jcs + nhls
              ENDIF
           ENDIF
           IF ( nest_bound_n )  THEN
-             jcnm = jcn - nhln
+             jcnm = jcn - nhln - 1
           ENDIF
        ENDIF
@@ -5468 +5478 @@
 !--          For simplicity anterpolate within buildings and under elevated
 !--          terrain too
-             DO  kk = kcb, kct
+             DO  kk = kcb, kct - 1
 !
 !--             ijfc and kfc are precomputed in pmci_init_anterp_tophat