*APR Section

18MAY25
Type
Optional Section

Description
Change default A Priori settings[1]

Structure
Multiple, optional PARAM=VALUE fields, any order, generally applicable. Optionally followed by a series of subsections defining parameters for particular retrieved species.
Structure
PARAM=[value] Applicable to all retrievals
PARAM=[value]
...
RTV1[2] Applicable to retrieved species RTV1
    PARAM=[value]
    ...
RTV2 Applicable to retrieved species RTV2
    PARAM=[value]
    ...
... etc

Parameter Type Description Units Range Default[3]
ACVFIL C A Priori Covariance file [none]
CORREL R Correlation length km ≥0 50 km
PCT_SD R Percentage SD % ≥0 100 %
RELAX R Relaxation factor ≥0 0.0
VALUE R A Priori value [various] ≥0 0.0
ABS_SD R Absolute SD [various] ≥0 TEM: 10 K
POI: 0.1 km
OFF: NESR
LIN: 0.01
SCA: 0.01
QAD: 0.01
Type: R=Real; C=character string

Notes
  1. The hierarchy for retrieved species RTVi is
    • Use value specified in subsection for RTVi
    • Use value specified in general subsection
    • Use default values (set in module asdcon_dat.f90)

  2. RTVn has to be one of RTV items listed in the *RTV section, except that CFCs are referenced only by 'F' number instead of chemical formula.

  3. Default values are set in module asdcon_dat.f90

Example
*APR CORREL=0 ! Uncorrelated A Priori for all species PCT_SD=100 ! Set default 100% SD for VMR,PRE retrievals CH4 ! Change CH4 only .. PCT_SD=10 ! .. change to 10% uncertainty