THE
COMMUNITY
NOAH
LAND-SURFACE MODEL (LSM)
N: National Centers for Environmental Prediction (NCEP)
O: Oregon State University (Dept of Atmospheric Sciences)
A: Air Force (both AFWA and AFRL - formerly AFGL, PL)
H: Hydrologic Research Lab - NWS (now Office of Hydrologic Dev -- OHD)
This document is filename
README_2.2.doc at
ftp://ftp.ncep.noaa.gov/pub/gcp/ldas/noahlsm/ver_2.2
Collaborators:
Mike Ek, Dag Lohmann, Fei Chen, George Gayno, Brian Moore, Hua-Lu Pan, John
Schaake, Victor Koren, Qingyun Duan, Ying Lin, Pablo Grunmann, Dan Tarpley,
Tilden Meyers, Curtis Marshall, Larry Mahrt, Jinwon Kim, Paul Rusher
08
Mar 99: Ver_1.1
27
Jul 99: Ver_2.0
23
Oct 00: Ver_2.1
25
Mar 01: Ver_2.2
1.0
Introduction
2.0
Model Heritage
3.0
Directory Contents and Quick-Start Guide to
Execution
4.0
Subroutine Summary and Calling Tree
5.0
Control File Contents and Function
6.0
Input Atmospheric Forcing File
7.0
LSM Initial Conditions
8.0
Specifying Model Parameters
9.0
Execution Output Files
10.0
Issues
to be Addressed in Future Releases
11.0
Technical References
12.0
Revisions History (pending)
1.0 INTRODUCTION
This
User’s Guide provides execution guidance for and physical description of the
public version of the community NOAH LSM.
This version of the NOAH LSM is a stand-alone, uncoupled, 1-D column
version used to execute single-site land-surface simulations. In this traditional 1-D uncoupled mode,
near-surface atmospheric forcing data is required as input forcing (see Sec
6.0). This LSM simulates soil moisture
(both liquid and frozen), soil temperature, skin temperature, snowpack depth,
snowpack water equivalent (and hence snowpack density), canopy water content,
and the energy flux and water flux terms of the surface energy balance and
surface water balance. See Sec 11 for
the lineage of key technical references.
The
public server directory in which this User’s Guide resides also contains the
complete, self-contained NOAH LSM source code file, input control file, input
atmospheric forcing file, and example execution-time LSM output files for a
full one-year 1998 simulation. This
simulation is valid at the Champaign, Illinois surface-flux site (40.01 N,
88.37 W) of NOAA/ARL investigator Tilden Meyers. See Sec 3 for a “Quick-Start” guide to executing the NOAH LSM
code in this directory to duplicate the cited 1998 simulation at this
site. To execute NOAH LSM simulations
at other sites for other initial times, study Secs 5 through 8.
This
Version 2.2 of the NOAH LSM is the most current public-release version at the
time of posting of this User’s Guide (see date cited at top). It is the version currently executing in the
NCEP realtime Land Data Assimilation System - LDAS (Mitchell et al.,
2000). Related ancestors of the NOAH
LSM are used in a) the NCEP-OH submissions to PILPS-2a, 2c, 2d, 2e, b) the
operational coupled NCEP mesoscale Eta model (Chen et al., 1997) and its
companion Eta Data Assimilation System (EDAS) (Rogers et al., 1996), and c) the
coupled NCEP global Medium-Range Forecast model (MRF) and its companion Global
Data Assimilation System (GDAS). The operational
coupled Eta/EDAS suite is the source of the multi-year Eta/EDAS GCIP archive at
NCAR, going back to April 01, 1995 (http://www.emc.ncep.noaa.gov
/mmb/gcp/access.perm.html).
(Reminder:
See Sec 3 for a “Quick-Start” guide to executing the NOAH LSM.)
2.0 MODEL HERITAGE
Beginning
in 1990, and accelerating after 1993 under sponsorship from the GEWEX/GCIP
Program Office of NOAA/OGP via collaboration with numerous GCIP Principal
Investigators (PIs), the Environmental Modeling Center (EMC) of the National Centers for
Environmental Prediction (NCEP) joined with the NWS Office of Hydrology (OH)
and the NESDIS Office of Research and Applications (ORA) to pursue and refine a
modern-era LSM suitable for use in NCEP operational weather and climate prediction
models. Early in this effort, NCEP
carried out an intercomparison of four LSMs, including 1) a simple bucket
model, 2) the OSU LSM (known as the
CAPS model in some PILPS studies), 3) the SSiB model, and 4) the Simple Water
Balance model (SWB) of OH. The results
of this intercomparison were reported in Chen et al. (1996, see references
therein for the four cited LSMs). As a
result of the good performance of the OSU LSM in this study and pre-existing
hands-on experience with this LSM by various EMC staff members, including
Hua-Lu Pan and Ken Mitchell, EMC chose the OSU LSM for further refinement and
implementation in NCEP regional and global coupled weather and climate models
(and their companion data assimilation systems). The results of the cited LSM intercomparison
and the initial EMC refinements to the OSU LSM were reported in Chen et al.
(1996).
At
the beginning of the EMC LSM effort in 1990, the OSU LSM already had a 10-year
history. Its initial development was
carried out by OSU in a series of three papers (Mahrt and Ek, 1984; Mahrt and
Pan, 1984; and Pan and Mahrt, 1987). As
the EMC LSM effort unfolded during the 1990's, a series of NCEP extensions to
the OSU LSM were a) added by EMC and its GCIP collaborators and b) tested and
validated in both uncoupled and coupled studies (see review of these in
Mitchell et al, 1999, 2000). At NCEP,
the LSM was first coupled to the operational NCEP mesoscale Eta model on 31 Jan
96, with significant Eta LSM refinements subsequently implemented on 18 Feb 97,
09 Feb 98, and 03 Jun 98. Recently in
1999, with a) the new addition and testing of frozen soil and patchy snow cover
physics in the uncoupled LSM used for the NCEP-OH submission to PILPS-2d
(Valdai, Russia), and b) the growing number of external user requests for
access to and use of the NCEP LSM (e.g. GCIP PIs), we decided the NCEP LSM had
advanced to a stage appropriate for formal public release (first in March 99).
Most
recently in 2000, given a) the advent of the "New Millenium", b) a
strong desire by EMC to better recognize its LSM collaborators, and c) a new
NCEP goal to more strongly pursue and offer "Community Models", EMC
decided to coin the new name "NOAH" for the LSM that had emerged at
NCEP during the 1990s. With our choice
of the "NOAH" acronym, already defined at the top of this User's
Guide, we in EMC strive to explicitly acknowledge both the multi-group heritage
and informal "community" useage of this LSM, going back to the early
1980’s. Since its beginning then at
Oregon State University, the evolution of the present NOAH LSM herein has
spanned significant ongoing development efforts by the following groups:
NCEP/EMC: NCEP Environmental Modeling Center
(EMC)
(Mitchell, Chen,
Ek, Lin, Marshall, Janjic, Manikin, Lohmann, Grunmann, Pan)
OSU:
Oregon
State University
(Mahrt, Pan, Ek,
Kim, Rusher)
HL: NWS Hydrology Lab - formerly
Office of Hydrology
(Schaake, Koren,
Duan)
AFWA:
Air Force Weather Agency -
formerly AFGWC
(Moore, Mitchell,
Gayno)
AFRL: Air Force Research Lab - formerly
AFGL and PL
(Mitchell, Hahn,
Chang, Yang)
In
addition to “in-house” NOAH LSM development and validation by the above
organizations, the following external PIs (primarily GCIP), have also performed
valuable validations of the NOAH LSM and its immediate NCEP 1990's
predecessors:
E.H.
Berbery and Rasmusson: U.
Maryland (ARM/CART)
C.
Marshall and Crawford U.
Oklahoma (OU Mesonet)
I.
Yucel and Shuttleworth: U. Arizona (ARM/CART, AZNET)
A.K.
Betts: Atmospheric
Res Inc (ISLSCP/FIFE)
C.D.
Peters-Lidard, Wood Princeton
U. (TOPLATS
extensions)
L.
Hinkelman and Ackerman: Penn State U. (ARM/CART)
T.H.
Chen, W. Qu, Henderson-Sellers, et al. RMIT (PILPS-2a)
E.
Wood, Lettenmaier, Liang, Lohmann: Princeton
U. (PILPS-2c)
A.
Schlosser, A.G. Slater, Robock, et al.
U. Maryland (PILPS-2d)
R.
Angevine NOAA/AL (Flatland Exp)
See
Sec 11 for technical references on the above external validations.
Lastly,
one crucial collaborator deserves special
mention, namely the NESDIS Office of Research and Applications (Tarpley,
Gutman, Ramsay), which has been the source of critical global surface
fields of a) vegetation greenness and its seasonality and b) realtime snow
cover, plus important GOES, satellite-based, hourly surface validation fields
of c) land surface skin temperature and
d) solar insolation, both on a 0.50-degree lat/lon CONUS grid.
3.0
DIRECTORY CONTENTS AND QUICK-START GUIDE TO EXECUTION
The
directory /pub/gcp/ldas/noahlsm/ver_2.2 on anonymous server ftp.ncep.noaa.gov
contains fifteen files as follows: 1)
this User’s Guide (file README_2.2.doc), 2) a complete self-contained NOAH-LSM
source code file, 3-4) the latter file split for the User's convenience into
two mutually exclusive files representing a) "driver" routines and b)
"physics" routines, 5) an input control file that defines model
configuration and provides initial conditions, 6) an input atmospheric forcing
file, 7) a doc file describing the source and valid period/location of this
forcing file, 8-10) an input "namelist" file triad that allows input
of non-default physical parameters, 11-15)
five execution-time output files, resulting from an entire one-year 1998
simulation valid near the Champaign, Illinois surface-flux site of Tilden
Meyers of NOAA/ARL. This site is
located at the lat/lon coordinates of
(40.01 N, 88.37 W). The15
filenames are:
Filename Contents
1
-- README_2.2.doc This User's Guide
2
-- NOAHLSM_SRC_VER_2.2.f
Self-contained NOAH LSM source
code
3
-- DRIVER_SRC_VER_2.2.f "DRIVER"
family of routines from file 2 above
4
-- SFLXALL_SRC_VER_2.2.f "PHYSICS"
family of routines from file 2 above
5
-- controlfile_ver_2.2 Input control file
6
-- obs98.dat.Z Input near-surface atmospheric
forcing file
7
-- CHAMP_IL.doc Observing site description
8
-- namelist_filename.txt 1-line 50-char name of namelist-read
input file
9
-- soil_veg_namelist_ver_2.2 namelist-read
input file
10- namelist_chg_example alternate
namelist-read input file
11- PRTSCREEN.TXT.Z Execution “print * “ screen output
12- DAILY.TXT.Z Execution Output File 1
13- HYDRO.TXT.Z Execution
Output File 2
14- THERMO.TXT.Z Execution
Output File 3
15- OBS_DATA.TXT.Z Execution Output Data File 4
All
files are text files, except files README_2.2 and CHAMP_IL, which are MS Word
files. Download all 15 files to your
workstation. Proceed with a NOAH LSM
execution test as described below.
Compile/load
file NOAHLSM_SRC_VER_2.2.f . This file
is the complete NOAH LSM source code.
It is Fortran 90 compatible and compiles free of warning and error
messages using “f90” on SGI Origin 2000 Workstations. The Unix command “f90 NOAHLSM_SRC_VER_2.2.f” will create the
executable “a.out”. Lets assume here
that we rename “a.out” to “lsm.x”.
To
prepare to execute lsm.x, first uncompress the “.Z” files with the Unix
uncompress command.
The
uncompress yields file “obs98.dat” and five upper-case “*.TXT” files. These TXT files are lsm.x execution-time output files. Move these “TXT* files to
a separate sister directory for later comparison to the equivalent output files
from your own local lsm.x execution.
The
four lower-case files given by filenames
controlfile_ver_2.2
obs98.dat
namelist_filename.txt
soil_veg_namelist_ver_2.2
are
the four input files required during the execution of lsm.x. The “controlfile” (see Sec 5) contains model
configuration variables such as number and thickness of soil layers, number and
length of time steps, initial date/time of the simulation, lat/lon location of
the simulation site, initial conditions for all state variables, and
site-specific land classifications (integer indexes for vegetation-type,
soil-type, and surface-slope category).
The
file obs98.dat (see Sec 6) contains one year’s worth (1998) of 30-min observed
atmospheric forcing data and independent observed verification data (e.g. surface
energy fluxes and soil temperature) valid at the Champaing, Illinois
surface-flux site operated and maintained by Tilden Meyers of NOAA/ARL. The site is located at the lat/lon
coordinates of (40.01 N, 88.37 W).
Now
invoking “lsm.x >PRTSCREEN.TXT” will launch and complete the 1998 one-year
LSM simulation for the aforementioned Illinois site, producing the same 5
“*.TXT” output files that you obtained originally from the NCEP server. Normal termination of the execution is
marked by the termination message “STOP: 0”.
Since all the “*.TXT” files are ascii files, one can and should confirm
that the 5 output files from the local simulation agree very closely with the
originally downloaded output files from NCEP.
The
output file PRTSCREEN.TXT contains the output from “Print *” write statements
in the
MAIN
program. In this Version 2.2, these are
the block of three “Print *” statements located within the time-step loop in the
PROGRAM MAIN source shortly
after the return from CALL SFLX . These
three Print * statements output the time step counter and the small surface
energy balance residual during each of the first 50 time steps and then every
50 time steps thereafter.
The
other four output files are the execution output data files of greater interest
and their contents are described in Sec 9.
One
important degree of freedom regarding these remaining four output files must be
cited here. The unit numbers for these
output files are 43, 45, 47, and 49, which are explicitly assigned in PROGRAM
MAIN (via variable names NOUT1, NOUT3, NOUT5, and NDAILY). The sign of these assigned unit numbers
controls whether the output is ascii or binary. The sign of all four unit numbers is determined by a signed
parameter (IBINOUT) read-in from the control file (see Sec 5). When the sign of IBINOUT is positive
(negative), the format of these four output files is binary (ascii). When the output format is ascii (binary)
then the extension *.TXT (*.GRS, meaning GrADS-readable) appears on the
generated filename. The ascii choice
(negative unit number sign) was invoked in the default control run you obtain
from the server.
4.0 SUBROUTINE SUMMARY AND CALLING TREE
Below,
we split up the subroutine calling tree into that portion associated with
PROGRAM MAIN in the "Driver family" of subroutines (file
DRIVER_SRC_VER_2.2.f) and that portion associated with the "Physics
family" of subroutines (file SFLXALL_SRC_VER_2.2.f), comprised of physics
"sub-driver" routine SFLX and all subordinate subroutines.
4.1 The Driver Routines
Briefly
the ten main steps of the MAIN program are:
1)
read
in control file ( model configuration, site characteristics, and initial conditions)
2)
open
output file unit numbers
3)
invoke
time-step loop (including optional spin-up loop if indicated by control file)
4)
read
atmospheric forcing data and change its sign and units as expected by SFLX
5)
interpolate
monthly-mean surface greenness and albedo to julian day of time step
6)
assign
downward solar and longwave radiation from input forcing
7)
calculate
actual and saturated specific humidity from input atmospheric forcing
8)
assign
wind speed from input forcing
9)
invoke
LSM physics (CALL SFLX) to update state variables / sfc fluxes over one time
step
10)
write simulation output data each time step to four output files
The
section in driver PROGRAM MAIN associated with each of the above ten steps is
clearly delineated with comment line "DRIVER STEP n".
NOTE:
The section of PROGRAM MAIN for Step 6 includes optional code (presently
commented out) for calculating the downward radiation from the input air
temperature and humidity if the input forcing file does not provide it.
NOTE: The section of PROGRAM MAIN for Step 8
includes optional code (presently commented out) for invoking a User-provided
routine to calculate the surface exchange coefficient for heat (Ch) in place
of the default scheme.
-
READCNTL:
read control file (including LSM initial conditions and site characteristics)
-
-----------
Begin optional Multi-year Spin-Up Loop: if invoked by control file
-------------
-
---------------------------------------
Begin: Time Step Loop -------------------------------------
-
READBND
: read atmospheric forcing data
(and observed validation variables)
-
MONTH-D: interpolate monthly albedo and veg
greenness to current julian day
-- JULDATE:
determine julian day for current time
-
QDATAP: calculate actual and saturated
specific humidity
-- E (function) calculate vapor pressure
-
DQSDT
(function): slope of sat specific humidity wrt air temp (needed in PENMAN)
-- DQS (function)
intermediate value for routine dqsdt
-
SFLX: call to family of physics routines (see Sec
4.2) **** key call ****
-
PRTDAILY: write daily total values to output file 1 (once a day only)
-
PRTHYDF: write LSM water related
variables to output file 2 (every
time step)
-
PRTHMF: write LSM energy related
variables to output file 3 (every time
step)
-
PRTBND: write out input atmospheric forcing to output file 4 (every time step)
-
-------------------------------
End: Time Step Loop
----------------------------------------------
-
------------------------End:
Optional Multi-year Spin-Up Loop---------------------------------
-
STOP
0
4.2 The SFLX Family of Subroutines
The SFLX family of subroutines contain the physics of the LSM and is rather self-contained. Each user should become familiar with the argument list of SFLX. This argument list is thoroughly documented at the top of subroutine SFLX. Once becoming familiar with the argument list, users could if they so choose create their own MAIN driver program with reasonably little effort. Calling SFLX each time step updates and returns all the LSM state variables and all the surface energy balance and surface water balance terms. In using SFLX in a coupled atmospheric model, the output arguments needed from SFLX are:
ETA - latent heat flux
H - sensible heat flux
T1 - skin temperature (from which to
calculate upward longwave radiation)
ALBEDO - (including snowpack effects) for
calculating upward solar radiation
REDPRM
-- set land-surface parameters
-- set soil-type dependent parameters
-- set veg-type dependent parameters
-- set other land-surface parameters
SFCDIF
-- calculate surface exchange
coefficient for heat/moisture
CSNOW
– (function): compute thermal conductivity of snow
SNO_NEW
– update snow depth and snow density to account for new snowfall
TDFCND
– compute soil thermal diffusivity
CANRES
– compute canopy resistance
NOPAC – this path invoked if ZERO
snowpack on ground and zero snowfall (frozen precip)
-- surface skin
temperature updated via surface energy balance
SMFLX – compute a) surface water
fluxes and b) layer soil moisture update
DEVAP-
compute direct evaporation from top soil layer
TRANSP
– compute transpiration from vegetation canopy
SRT
– compute time-rate-of-change of soil moisture
WDFCND – compute hydraulic conductivity and diffusivity
SSTEP
– forward time-step integration of soil moisture rate-of-change
ROSR12 – tri-diagonal matrix solver
SHFLX
– compute a) ground heat flux and b) layer soil temperature update
HRT
– compute time-rate-of-change of soil temperature
TDFCND – compute soil thermal diffusivity (dependent on
soil moist.)
TBND – determine
soil layer interface temperature
SNKSRC –(function) compute heat sink/source from soil ice
phase change
TDFCND –
compute soil thermal diffusivity
FRH2O –
(function) calculate subzero unfrozen soil water
HSTEP
– forward time step integration of soil temperature rate-of-change
ROSR12 – tri-diagonal matrix solver
-
surface
skin temperature updated via surface energy balance
-
new
patchy snow cover treatment in above
-
snowmelt
computed if thermal and available energy conditions warrant
CSNOW – see above
TRANSP
– see above
SRT
– see above
WDFCND – see above
SSTEP
– see above
ROSR12 – see above
TDFCND – see above
SNOWPACK – update snow depth and
snow density owing to snow compaction
SHFLX
– see above
HRT
– see above
TDFCND – see above
TBND – see above
SNKSRC – see above
TDFCND –
see above
FRH2O –
see above
HSTEP
– see above
NOTES on SFLX Calling Tree:
1 –
Both the NOPAC and SNOPAC branches treat freezing processes within soil
2 –
Calling sequences under NOPAC and
SNOPAC via SMFLX and SHFLX are very similar
3
–
Snowpack physics in SNOPAC are treated mainly “in-line”, before calls to
SMFLX/SHFL
4
–
SHFLX and subordinates do heat fluxes and soil temperature update
5
–
SMFLX and subordinates do water fluxes and soil moisture update
-- SMFLX operates independently of the soil
thermodynamics (SHFLX) and can stand
alone,
requiring only inputs of precipitation and potential evaporation
-- SHFLX cannot operate independently of soil
hydraulics, unless thermal conductivity
dependence on soil moisture dependence is removed (in routine TDFCND)
5.0
CONTROL FILE CONTENTS AND FUNCTION
The
filename of the control file is “controlfile_ver_2.2”. The user may want to have a printout of the
control file handy (about one page) when reviewing the comments below.
The
control file is read-in early in the MAIN program and provides inputs of the
following types of information: a)
valid location and start date/time of simulation, b) model configuration,
c)
name of input forcing file, d) integer indexes for land-sfc classes for the
site, e ) initial values of all the model state variables.
NOTE: The control file does not provide model physical parameters,
except for the lower boundary condition on the soil temperature (which should
be assigned the value of the annual mean sfc air temperature for the simulation
location). Physical parameters are set
in subroutine REDPRM and many of these parameters are dependent in REDPRM on
the veg-type index and soil-type index read from the control file.
The control file consists of
30 data lines that contain the following:
Line
01: LAT - simulation site latitude (positive N from equator, hundredths
of a degree)
Line
02: LON - simulation site longitude (positive W from Greenwich,
hundredths of a degree)
Note: The above serve only to document the valid
site of the input forcing data.
The physics do not use the above,
since forcing data provides downward solar radiation.
Above would be needed by a MAIN
driver that had to calculate downward solar radiation
Line
03: IBINOUT - either positive interge "1", or negative integer
"-1".
Negative sign invokes ascii text
output files with extension *.TXT
Postive
sign invokes binary output files with extension *.GRS -denoting GrADS readable
Line
04: JDAY - Integer Julian Day (1-366) of start of forcing data (start of
simulation)
Line
05: TIME - 4-digit "hhmm" integer time of day (local) at start
of forcing data,
hh is 2-digit hour (0-23) and mm is 2-digit minute
(0-59).
Note: Except for use of JDAY to to temporal
interpolation of monthly greenness and albedo read-in later below, the above
JDAY and TIME serve only to document the valid start date/time of the input forcing data. The physics do not use the above, since
forcing data provides downward solar radiation. Above would be needed by a MAIN driver that had to calculate
downward solar radiation
Line
06: NCYCLES – number of times the integration will cycle through the
input forcing data
(useful for multi-year spin-up runs,
wherein input forcing file spans one complete year)
Line
07: SYDAYS - number of days in spin-up year (either 365 or 366)
(relevant only if NCYCLE is 2 or
greater)
Line
08: L2nd_data: logical variable: value of .true. or .false.
if TRUE: then NCYCLES must be
set to 2 or greater, and thus invokes spin-up runs of
NCYCLE-1 spin-up years with first
forcing file given below, followed by 1 final cycle
(not necessarily full year)executed
from second forcing file below and representing the
final
production run period. Will write
output only during final cycle, unless two forcing
files have
the same name, then will write output from each cycle
if FALSE: then only first
named forcing file is used, still for the number of cycles given
by NCYCLE, and will write output
from every cycle
Note:
The true option for L2nd_data is useful for multi-year "PILPS-type"
spin-up runs
For
forcing files spanning only a partial year, L2nd_data should be false and
NCYCLE=1
Line
09: NRUN is the total number of simulation time steps per cycle.
Line
10: DT – floating point length of time step (secs) used in physical
integration
Note: DT should NOT be larger than one hour (3600
secs)
Note: There must be one forcing data record in
forcing file for each time step
Line
11: NSOIL - integer number of soil layers
Note:
NSOIL must be 2 or greater, NOT to exceed 20, strongly recommend at least 4
Line
12: Z – height in meters above ground of atmospheric forcing data
Note: In observed forcing data, the height of the
temperature/humidity observation (e.g. 2 m) is often different from the height
of the wind observation (e.g. 10 m ).
When that is the case, we recommend using the height of the wind
observation for Z.
Line
13: SLDPTH - thickness values for the NSOIL soil layers in meters (chosen by user), starting with the
uppermost layer and proceeding downward
Note: We recommend that each succeeding soil layer
downward not exceed 3 times the thickness of the soil layer above it. For the common 4-layer configuration, we
recommend
Layer 1: 10 cm (.10 m)
Layer 2: 30 cm (.30 m)
Layer 3: 60 cm (.60 m)
Layer 4:100 cm (1.0 m)
Note: The physical equations in the LSM predict
the soil moisture/temperature state variables at the midpoint of each model
soil layer.
NOTE:!! Sum total of all soil layer thicknesses
should not exceed about 2/3 of depth parameter ZBOT. The
lower boundary condition TBOT of soil temperature is applied at the depth
specified by parameter ZBOT, whose current default value of -3.0 meters is set
in routine REDPRM (ZBOT follows negative sign convention for soil depth), but
this default can be changed via the optional NAMELIST I/O in REDPRM. (A more appropriate value of the default
value for ZBOT would probably by -8.0, likely to be adopted in future
versions.)
Line
14: - filename of the first input
forcing file (up to 72 characters)
Line
15: - filename of the second input forcing
file (up to 72 characters)
Note:
see above discussion of logical variable "L2nd_data
Note:
the two forcing files may be the same name (used for both spin-up and
production years)
NOTE !! : User should contact NCEP Point of Contact given at top of Page 1 for recommended values for Lines 12-18
Line
16: SOILTP - soil type integer index (range 1-9), see definitions in
routine REDPRM
Line
17: VEGTYP veg type integer index (range 1-13), see definitions in
routine REDPRM
Line
18: SLOPTYP sfc slope integer index (range 1-9), see definitions in
routine REDPRM
Note:
SLOPTYP is a sfc slope category (flat, steep, mixed, etc) used in the bottom
drainage
Line
19: ALBEDO – 12 monthly values of surface albedo fraction (snow-free)
for simulation site
Note:
LSM physics will internally add snow cover effects to ALBEDO
Line
20: SHDFAC - 12 monthly values
of green vegetation fraction for simulation site
NOTE !! See contact point at top of this User's Guide to get monthly
vegetation greenness values for your simulation site of interest.
NCEP
now sets monthly SHDFAC using the global database and publication of
Gutman, G. and A. Ignatov, 1998: The
derivation of the green vegetation fraction from
NOAA/AVHRR for use in
numerical weather prediction models.
International Journal
of Remote Sensing, 19,
1533-1543.
This
latter work provides a 5-year, monthly mean, global database of green
vegetation fraction at 0.144 degree resolution, obtained from NDVI. The authors forcefully argue that the two
AVHRR channels that are used to derive NDVI do NOT provide sufficient degrees
of freedom to derive BOTH vegetation greenness and LAI independently. They instead argue for embracing all the
seasonality of vegetation in the greenness fraction and holding the LAI at a
fixed constant annual value in the range of 1-5 (thus LAI becomes a tuning
parameter). NCEP has obtained
reasonable behavior with LAI=3.
Line
21: SNOALB – maximum albedo expected over deep snow
Robinson, D.A., and G. Kukla, 1985: Maximum surface
albedo of seasonally snow-
Covered Lands in the Northern Hemisphere. J. Climate
Appl. Meteor., 23, 1626-1634
(See Fig. 4 therein for depiction from digital
database).
Line
22: ICE – Flag to invoke sea-ice
physics (always set to 0 for land-mass simulations)
Note: The integer flag “ICE” forces branch to sea-ice physics in LSM.
Be aware that this ICE flag has
no bearing on soil ice physics in NCEP LSM.
Line 23: TBOT – set to the climo annual mean sfc air temperature (K) for the modeled site
.
Note: TBOT serves as the annually fixed, soil-temperature bottom-boundary condition at a soil depth of ZBOT. ZBOT is currently set at a default 3-meter depth (-3.0) in routine REDPRM. ZBOT is the assumed nominal soil depth where the amplitude of the soil-temperature annual cycle is near zero (e.g. about double the e-folding depth in the soil of the annual cycle of surface air temperature).
Initial conditions for all state variables follows:
Line 24: T1 – initial skin temperature (K). Can be set to initial air temperature. Model physics
rapidly spins this up in first few 2-3 time steps.
Line 25: STC (1-NSOIL): initial soil temperature (K), in each soil layer
Line 26: SMC (1-NSOIL): initial volumetric total soil moisture (liquid and frozen) in each layer
(usually in the range .1-.43)
Note: Initial SMC should not exceed soil saturation (porosity), as set in routine REDPRM for given soil class.
Line 27: SH2O (1-NSOIL): initial volumetric liquid soil moisture (unfrozen) in each layer
Note: initial SH2O must not exceed porosity, nor exceed initial SMC
NOTE: During conditions of no soil freezing, SH2O=SMC in each layer.
NOTE: Initializing soil ice (case of SH2O less than SMC) is very difficult. Recommend starting the model run in the warm season and letting the physics spin-up soil ice, or running multi-year spin-up cycles.
Line 28: CMC – initial canopy water content (m). Set to zero as physics rapidly spins this up.
Line 29: SNOWH – initial snow depth (m)
Line 30: SNEQV – initial water equivalent (m) of above snowdepth. If not observed, dividing
SNOWH by 5 gives a nominal initial value.
6.0 ATMOSPHERIC FORCING FILE
As is typical with many off-line, uncoupled LSMs, the NCEP LSM requires the following near-surface atmospheric forcing data, preferably at 30-minute time intervals (or interpolated to
30-minute time intervals or smaller from say 1-6 hour interval observations -- Aside note: for observation intervals longer than 1-hour, the incoming surface solar insolation needs to be interpolated with a solar zenith angle weighting, in order to capture the full amplitude of the diurnal solar insolation).
Air temperature
at height Z above ground
Air humidity
at height Z above ground
Surface pressure
at height Z above ground
Wind speed
at height Z above ground
Surface downward longwave radiation
Surface downward solar radiation
Precipitation
For
the example one-year LSM simulation provided with this User’s Guide, we were
extremely fortunate to benefit from the collaboration of GCIP-sponsored PI
Tilden Meyers of NOAA/ARL, who operates a flux site located just south of
Champaign, IL (40.01 N lat, 88.37 W lon).
The
site characteristics and observing instrumentation are described in the MS Word
document
CHAMP_IL,
provided by courtesy of Tilden Meyers, and available in same directory as this
User’s Guide.
The
1998 forcing file from the above flux site is available as filename “obs98.dat”
in the same directory as this User’s Guide.
This file contains one record for each 30-minute observation time and
the file spans the entire calendar year of 1998 (hence 2 X 24 X 365 = 17520
records). Each 30-min record provides
the following 33 observed variables (including the 7 required LSM forcing
variables, marked by “**”), listed in the order they appear in each record of
the file:
jday Julian
Day
time LST,
half hour ending
w_speed propeller anemometer (10
meters, Bondville ISIS)
w_dir wind
direction (10 meters, Bondville ISIS)
** Ta air temperature (C), at 3 m
** RH relative humidity at 3 m (list continued)
** Pres surface pressure in mb
** Rg incoming solar radiation (W/m2)
Par_in incoming
visible radiation (0.4‑0.7 um) in uE/m2/s
Par_out outgoing
or reflected visible light
Rnet net
radiation (W/m2)
GHF soil
or ground heat flux (W/m2)
** rain total rain for half hour (inches)
wet wetness
sensor (in voltage with higher values indicating wetness)
IRT surface
or skin temp (C)
2_cm soil
temp at 2 cm (C)
4_cm soil
temp at 4 cm
8_cm soil
temp at 8 cm
16_cm soil
temp at 16 cm
32_cm soil
temp at 32 cm
64_cm soil
temp at 64 cm
** u_bar average wind vector speed at 6-meters (m/s)
u’w’ kinematic
shear stress (m2/s2)
u’2 streamwise
velocity variance (m2/s2)
v’2 crosswind
velocity variance (m2/s2)
w’2 vertical
velocity variance(m2/s2)
H sensible
heat flux (W/m2)
LE latent
energy flux (W/m2)
CO2 CO2
flux (mg CO2/m2/s)
** LW_in
downwelling longwave from sky (W/m2)
sm_5 soil
volumetric water content at 5 cm zone (after November 19 1997)
sm_20 soil
volumetric water content at 20 cm zone (after November 19 1997)
sm_60 soil
volumetric water content at 60 cm zone (after November 19 1997)
In the LSM, program MAIN
reads in all 33 of the above variables at each time step via the call to subroutine
READBND, which also fills in occasional missing observations. Missing obs are very sparse and virtually
always involve missing values of the wind speed (u_bar at 6 m), for which the
READBND software substitutes (w_speed at 10 m). Finally, the last section of routine READBND performs unit
conversions on “rain”, “Ta”, and “Pres” to convert them to the units expected
in the call to SFLX .
In addition to the
LSM-required atmospheric forcing variables in the above list, the other
variables in the list represent either a) independent validation data or b)
useful initial conditions for the LSM state variables. LSM initial conditions are discussed in the
next section.
At each time step in the
MAIN program, after the return from the physics update in CALL SFLX, useful LSM
validation data from the above observation file is written out to validation
output file OBS_DATA.TXT via call to routine PRTBND (e.g. LE, H, GHF, RNET,
IRT, and the layer by layer soil moisture and temperature).
7.0 LSM INITIAL CONDITIONS
2 –
SH2O: liquid volumetric soil
moisture in each soil layer
3 –
STC: temperature
in each soil layer
4 –
T1: skin temperature
5 –
CMC: canopy water content
6–
SNOWH: snow depth
7 -
SNEQV: water-equivalent snow
depth
Typically,
a number of these state variables are not observed at a given validating
observation site. The following initial
variables were not available in the site observation file (obs98.dat):
SNEQV,
SNOWH, CMC, nor SMC (and SH2O) below 60 cm
Since
January 1998 was mild (El’Nino) at the given site, we assumed a) zero snow
cover (SNOWH=0.0, SNEQV=0.0) and b) zero soil ice (SMC=SH2O), plus we set
CMC=0.
While
we in general found the physical behavior of the observed data in file
obs98.dat to be very good, inspection of the observed soil moisture at the 20 and 60 cm levels showed them to be
virtually time invariant over the entire year, despite substantial wetting and
drying periods. Hence their accuracy is
very suspect.
It is typical for LSM simulations at a particular observation site to be hampered by non-observed
(e.g.
snowdepth, frozen soil moisture, deep soil moisture ) or ill-observed initial state variables (.e.g. soil
moisture). Facing this dilemma, the
Project for Intercomparison of Land-Surface Process Schemes (PILPS) has come to
urge modelers to use a one-year spin-up protocol, whereby the simulation for a
desired period (1998 here) is preceded
by a spin-up year (say 1997 in this case) where the spin-up year forcing is
repeated several years to allow the LSM to essentially achieve
equilibrium.
Tilden
Meyers provided us with the 1997 forcing data for his site, and we proceeded to
execute the PILPS-recommended spin-up protocol to provide all initial soil
states for the one-year 1998 production run provided in this directory.
Specifically,
in a prior run using the same model configuration as in the control file given
here and using L2nd_data = .false., NCYCLES= 10, and the aforementioned 1997
forcing file we call "obs97.dat", we executed a 10-year spin-up run
over the 1997 annual cycle in order to derive initial conditions of soil state
and snow state (turned out zero snowpack, because of warm fall and early winter
in 1997) for the 1998 production run provided here in the directory with this
User's Guide. In practice, a full
10-years of spin-up is not needed. We
generally recommend 3-5 years of spin-up.
8.0 SPECIFYING MODEL PARAMETERS
The
vast majority of the NOAH LSM land-surface parameters are set in subroutine
REDPRM. However, the assignment of some
land-surface parameters have not yet been “collected” into the REDPRM setting
and remain buried deep in the LSM code.
We feel these exceptions are primarily parameters of secondary or
tertiary importance. A few exceptions
may be some parameters used in the snowpack physics, such as the parameter that
controls the amount of supercooled water allowed in the soil over a range of
sub-freezing temperatures. We are
working to identify such parameters and bring them into the REDPRM setting in a
future release.
In
a broader sense, one should also consider the number (NSOIL) and thickness
(SLDPTH) of the soil layers (especially thickness
of top soil layer) specified in the control file to be adjustable
parameters.
Before
proceeding further in this section, the reader should have on hand a copy of
the subroutine REDPRM.
In
REDPRM, we define the NAMELIST named "/SOIL_VEG/", which includes ALL
the parameters defined in REDPRM, including parameter arrays whose elements
depend on soil type, vegetation type, or slope type. Moreover, this namelist includes three variables that
respectively define the number of classes (up to a maximum of 30) that we carry
for soil type, vegetation type, and slope type. With the powerful and robust flexibility of the namelist
construct, we can even make wholesale changes to the soil and vegetation
classification scheme used and the soil and vegetation parameters associated
with the change in classification. Thus
via the namelist read, we can change as little as one single universal
parameter, or multiple- element parameter arrays associated with a
classification, or the number of classification categories themselves, or a
combination of these, all without any recompiling of source code.
One
exercises the above flexibility through the input filename called
"namelist_filename.txt", which is read-in by routine REDPRM. This 1-line 50-char text file provides the
name of the namelist file, which the routine REDPRM then reads in as well. By this mechanism, one can carry multiple namelist
files (providing different parameter sets) in the same execution
directory. The contents of the 1-line
file "namelist_filename.txt" thus acts as a pointer to the namelist
file you wish to read-in during a given execution.
Every
namelist file so pointed to must begin with the following syntax:
$SOIL_VEG
LPARAM = .FALSE.$
or
$SOIL_VEG
LPARAM = .TRUE.$
with
the latter followed by at least one or more defined parameter values.
We
recall that the beginning of Sec 3 listed all the filenames in the directory
/ver_2.2with this User's Guide (README_2.2.doc). Inspecting the contents of filename
"namelist_filename.txt" therein, we find that this file points to the
filename ""soil_veg_namelist_ver_2.2". On inspection we find the contents of this file to be
$SOIL_VEG
LPARAM = .FALSE.$ ,
hence
ALL the default values of the parameters defined in REDPRM will be retained
unchanged.
If
the contents of "namelist_filename.txt" instead pointed to filename
"namelist_chg_example", then we find on inspection that the contents
of the latter file are
$SOIL_VEG
LPARAM = .TRUE.$
$SOIL_VEG
NROOT_DATA = 3,3,3,3,3,3,2,2,2,2,0,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 $
$SOIL_VEG
Z0_DATA(7) = 0.15 $
$SOIL_VEG REFKDT_DATA = 1.0 $
In the above example, our execution will
utilize 1) new values for all the elements of array NROOT, 2) a new value for
the 7-th element of the array of roughness lengths (this element corresponding
to veg class #7, or perennial grassland), and 3) a new value for the scalar
surface runoff parameter REFKDT.
Below, we will review ALL the parameters
defined in REDPRM. All these parameters
are included in the NAMELIST /SOIL_VEG/, which is specified in routine REDPRM
as
NAMELIST
/SOIL_VEG/ SLOPE_DATA, RSMTBL, RGLTBL, HSTBL, SNUPX,
&
BB, DRYSMC, F11, MAXSMC, REFSMC, SATPSI, SATDK, SATDW,
&
WLTSMC, QTZ, LPARAM, ZBOT_DATA, SALP_DATA, CFACTR_DATA,
&
CMCMAX_DATA, SBETA_DATA, RSMAX_DATA, TOPT_DATA,
&
REFDK_DATA, FRZK_DATA, BARE, DEFINED_VEG, DEFINED_SOIL,
&
DEFINED_SLOPE, FXEXP_DATA, NROOT_DATA, REFKDT_DATA, Z0_DATA,
&
CZIL_DATA, LAI_DATA, CSOIL_DATA
In the above
list, there are five kinds of land-surface parameters,
reviewed in order below.
a)
single
universal values
b)
values
dependent on the soil class index (default categories are 1- 9)
c) values
dependent on the vegetation class index (default categories are 1-13)
d) values
dependent on the surface slope index (default categories are 1-7)
e)
parameters specifying the numbers of vegetation, soil, and slope classes
A)
Universal values (14) (current default value in
this release listed)
CZIL = 0.20: Zilintikevich parameter (range 0.0 - 1.0), recommended range 0.2 - 0.4
Note: CZIL is a tuneable parameter, which controls the ratio of the roughness length for heat to the roughness length for momentum, and is known as the Zilintikevich coefficient. This parameter effectively allows tuning of the aerodynamic resistance of the atmospheric surface layer. Increasing CZIL increases aerodynamic resistance. For a full description and example impacts of this primary parameter, see the article by
Chen, F, Z. Janjic, and K. Mitchell, 1997: Impact of the atmospheric surface-layer
parameterizations in the new land-surface scheme of the NCEP mesoscale Eta model.
Boundary-Layer Meteor., 85, 391-421
REFDK=2.0E-6: a parameter used with REFKDT below to compute sfc runoff parameter KDT
REFKDT = 3.0: surface runoff parameter (nominal range of 0.5 – 5.0)
NOTE: REFKDT is a tuneable parameter that significantly impacts surface infiltration and hence the partitioning of total runoff into surface and subsurface runoff. Increasing REFKDT decreases surface runoff. See next publication:
Schaake, J., V. Koren, Q.-Y. Duan, K. Mitchell, and F. Chen, 1996: Simple water
balance model for estimating runoff at different spatial and temporal scales.
J. Geophysical Res., 101, No. D3.
NOTE: REFDK corresponds to the saturation hydraulic conductivity Ksat for silty clay loam. If the latter parameter value is changed, then REFDK must be equated to that new value.
ZBOT = -3.0 m: nominal depth of TBOT: lower boundary condition on soil temp (range 3-20m)
(see discussion of ZBOT in discussion of TBOT in notes below Lines 13 and 23 of Control File in Section 5.0)
FXEXP = 2.0: bare soil
evaporation exponent
SBETA= -2.0:used to compute veg
canopy effect on ground heat flux as a function of greenness
CSOIL = 1.26E+6: soil heat
capacity (J/m**3/K)
SALP = 2.6:shape parameter used
in function to infer percent area snow cover from snow depth
CFACTOR = 0.5: exponent used in function for canopy water
evaporation
CMCMAX =0.0005 (m): maximum canopy water capacity used in canopy
water evaporation
FRZK=0.15 a base reference value
(for light clay soil type) of parameter for the frozen-soil freeze factor
representing the ice content threshold above which frozen soil is impermeable
RSMAX=5000 (s/m) maximum stomatal
resistance used in canopy resistance routine CANRES
TOPT= 298(K) optimum air
temperature for transpiration in canopy resistance routine CANRES
RTDIS: array specifying vertical
root distribution, i.e. the fraction of total root mass present
in each soil layer
Note: RSMAX and TOPT are not yet functions of
vegetation class.
Note: Presently, RTDIS is set universally (not
dependent on vegetation class) and assumes a
uniform root
distribution throughout the specified number of root layers for the given
vegetation class.
B) Soil-class
dependent parameter arrays (10)
Routine REDPRM applies 9
soil texture classes. These classes are
defined near the top of routine REDPRM.
The parameters dependent on soil class are:
SMCMAX: maximum volumetric soil moisture (porosity)
SMCREF: soil moisture threshold for onset of some
transpiration stress
SMCWLT: soil moisture wilting point at which
transpiration ceases
SMCDRY: top layer soil moisture threshold at which
direct evaporation from soil ceases
DKSAT: saturated soil hydraulic conductivity
PSISAT: saturated soil matric potential
B: the “b” parameter in hydraulic functions
DWSAT: saturated soil water diffusivity
QUARTZ: quartz content, used to compute soil
thermal diffusivity
FRZFACT: a
parameter used with FRZK to compute the value of parameter FRZX
Note: if soil parameters
such as SMCMAX and SMCREF or soil classification scheme are
changed, then parameters FRZK and FRZFACT
must be changed
C) Vegetation-class dependent parameters arrays (7)
Routine
PRMVEG applies the 13 “SiB” vegetation classes. These classes are described in the comment block at the top of
routine PRMVEG. The seven veg-class
dependent parameters are:
Z0:
(m)
roughness length
RCMIN (s/m) : minimal stomatal resistance used in canopy
resistance of routine CANRES
RGL: radiation stress parameter used in F1 term in canopy resistance
of routine CANRES
HS: coefficient used in vapor pressure deficit term F2 in canopy
resistance of routine CANRES
LAI: presently set to universal
value of 3.0 across all vegetation classes
Note:
seasonality of vegetation greenness carried by fraction of green vegetation
(SHDFAC)
NROOT: number of soil layers from
top down reached by roots
SNUP: the water-equivalent
snowdepth upper threshold at which
1)
100
percent snow cover is achieved for given veg class
2) maximum snow albedo is achieved for given
veg class
D) Surface-slope dependent parameter arrays (1)
Routine
REDPRM embodies 7 categories of surface slope.
These categories are described in a comment block near the top of
routine REDPRM. The parameter dependent
on slope class is:
SLOPE – a coefficient between
0.1-1.0 that modifies the drainage out the bottom of the last
soil layer. A larger surface slope implies larger
drainage
E) Classification dimension parameters (3)
Vegetation Types ("SiB-1") after
Dorman and Sellers (1989; JAM)
DEFINED_VEG = 13: the number of
SiB-1vegetation class categories, assigned as follows:
1:
BROADLEAF-EVERGREEN TREES
(TROPICAL FOREST)
2:
BROADLEAF-DECIDUOUS TREES
3:
BROADLEAF AND NEEDLELEAF TREES (MIXED FOREST)
4:
NEEDLELEAF-EVERGREEN TREES
5:
NEEDLELEAF-DECIDUOUS TREES (LARCH)
6:
BROADLEAF TREES WITH GROUNDCOVER (SAVANNA)
7:
GROUNDCOVER ONLY (PERENNIAL)
8:
BROADLEAF SHRUBS WITH PERENNIAL GROUNDCOVER
9:
BROADLEAF SHRUBS WITH BARE SOIL
10:
DWARF TREES AND SHRUBS WITH GROUNDCOVER (TUNDRA)
11:
BARE SOIL
12:
CULTIVATIONS (THE SAME PARAMETERS AS FOR TYPE 7)
13:
GLACIAL (THE SAME PARAMETERS AS FOR TYPE 11)
Soil Types
after Zobler (1986), except for quartz after Cosby et al (1984)
DEFINED_SOIL = 9: the number of
Zobler soil class categories, assigned as follows:
TEXTURE DESCRIPTION QUARTZ CONTENT
1 COARSE LOAMY SAND (0.82)
2 MEDIUM SILTY CLAY LOAM (0.10)
3 FINE LIGHT CLAY (0.25)
4 COARSE-MEDIUM SANDY
LOAM (0.60)
5 COARSE-FINE SANDY CLAY (0.52)
6 MEDIUM-FINE CLAY LOAM (0.35)
7 COARSE-MED-FINE SANDY
CLAY LOAM (0.60)
8 ORGANIC (0.40)
9 GLACIAL LAND ICE LOAMY
SAND (0.82)
Slope Types
after Zobler (1986)
DEFINED_SLOPE = 9: the number of Zobler defined slope
categories, assigned as follows:
SLOPE CLASS PERCENT
SLOPE
1 0-8
2 8-30
3 > 30
4 0-30
5 0-8 & > 30
6 8-30 & > 30
7 0-8, 8-30, > 30
8 GLACIAL ICE
9 OCEAN/SEA
9.0 EXECUTION OUTPUT FILES
There
are five execution-time output files:
PRTSCREEN.TXT: holds results from “Print * “ output via
execution command line syntax of “lsm.x
>PRTSCREEN.TXT” (i.e. capture
of “screen” print). Presently file
contains the surface energy balance residual and time-step value for first 50
time steps, then every 50 steps thereafter.
a)
DAILY.TXT: contains daily-defined output values
once-per-day, from routine PRTDAILY,
such as daily total evaporation and precipitation.
b)
HYDRO.TXT:
contains water related outputs at every "time step", from
routine PRTHYDF,
such as actual and
potential evaporation, soil moisture, snowdepth, snowmelt, runoff.
c)
THERMO.TXT:
contains energy related outputs at every "time step",from routine
PRTHMF,
such as skin temperature,
soil temperature, and all surface energy fluxes
d) OBS_DATA.TXT: output of observed input
forcing/validation data, from routine PRTBND,
such as incoming radiation, skin
temperature, soil temperature, precip, net radiation, latent,
sensible, and ground heat fluxes (i.e. this file echoes the input observation
file “obs98.dat”,
but with some units conversion for
compatibility with other model outputs)
10.0 ISSUES TO BE ADDRESSED IN FUTURE RELEASES
10.1 Technical
-- continue to seek and move tuneable parameter
values not yet embraced in the central
parameter-definition routine of REDPRM (e.g., the parameters BLIM and CK
in routine
FRH2O
that control the amount of super-cooled soil water permitted when
sub-freezing).
-- in documentation of model parameters in Sec 8,
add a superscript notation of say 1-5 to
identify
parameters of a certain physical influence (Ed, canopy resistance, surface
runoff, soil
water or
heat transfer, frozen soil, snow pack, aerodynamic resistance, soil heat
transfer).
Also,
update the Sec 8 discussion to clarify the differences in number and name of
parameters
in the
REDPRM subroutine argument list and the REDPRM NAMELIST list.
-- given improvements in Ver 2.0, 2.1, and 2.2 in
treatment and compactness of logic for
ground
heat flux
under snowpack, seek to reunify the now separate routines of NOPAC and SNOPAC
-- before first call to SFLX, check that all initial
input arguments are within expected range (e.g.
that
vegetation greenness fraction is not negative, which causes extremely spurious
behavior)
10.2 Physical
a) sooner
-- despite Ver 2.2 increase in both a) root depth
(from 1 m to 2 m) for forest vegetation
classes
and b) LAI parameter, somewhat low transpiration is still realized in summer in
mid-
latitudes
over relatively dense vegetated areas with little soil moisture stress. Canopy
resistance is apparently somewhat high.
Revisit both the values of certain canopy resistance
parameters such as RSMIN, as well as the formulation of the vapor
pressure deficit stress
-- the aerodynamic resistance embodied in the
surface exchange coefficient CH (computed in
routine
SFCDIF) appears to be a bit low (e.g. potential evaporation is somewhat too
high
compared
to NOAA pan measurements), so try increase in default CZIL value in REDPRM
from .2
to .3 (or .4, TBD by testing)
-- test explicit schemes for CH, (recent descendants
of Louis (1982)), in place of the Paulson
scheme,
to allow application of OSU/Mahrt sub-grid variability treatment for the stable
surface layer, as a way to retard the
decrease of Ch for increasing moderate
stable conditions.
-- revisit the value of the lower bound on unfrozen
water content in freezing soil conditions via
the BLIM
and CK parameters in routine FRH2O
-- use explicit soil layer state temperature,
STC(k), instead of TAVG, to compute the soil ice,
thereby
eliminating the need to calculate TSURF at top of soil column under snowpack
-- remove the equating of SMCDRY to SMCWLT in REDPRM
on the first call to REDPRM.
Rather
let the separate DATA statements in REDPRM for SMCDRY and SMCWLT
determine
whether they are specified to be equal or not
-- in the initial calculation of parameters REFSMC
and WLTSMC on the first call to REDPRM,
replace
the hardwired parameters of 3.0 and 0.5, respectively with flexible parameter
values
that can
be altered via the NAMELIST I/O in REDPRM.
Eliminate the DATA statements for
REFSMC
and WLTSMC in REDPRM
b) later
-- allow non-uniform root density profile and
rooting depths that varying with vegetation class
-- allow horizontally varying total depth of soil
column (e.g. vary thickness of deepest
soil layer)
-- allow vertically varying soil texture
-- add a TOPMODEL-like approach to baseflow runoff
-- allow simultaneous infiltration excess and
saturation excess surface runoff
(present
version allows only for latter)
-- reformulate canopy transpiration to include CO2
flux
-- consider adding a veg-class "tile
approach" in Driver surrounding calls to SFLX
-- consider adding a 2-layer canopy, i.e. for
treatment of melting snow under shading canopy
-- consider adding a multi-layer snowpack model
11.0 TECHNICAL REFERENCES
11.1 Model Physics
Lineage (OSU, AFGL/PL/AFRL, AFGWC/AFWA, NCEP, OH/OHD)
Original
soil hydrodynamic physics:
Marht
and Pan, 1984, Boundary Layer Meteorol, 29, 1-20.
Stability-dependent
Penman potential evaporation:
Mahrt
and Ek, 1984, J. Clim. Appl. Meteorol, 23, 222-234.
Original
soil thermodynamic physics:
Pan
and Mahrt, 1987, Boundary Layer Meteorol, 38, 185-202.
Time-integration
scheme advancements:
Kalnay
and Kanamitsu, 1988: Mon. Wea. Rev., 116, 1945-1958
Canopy
resistance advancements:
Chen,
F., K. Mitchell, et al, 1996: J.
Geophys. Res., 101, No. D3, 7251-7268 (Secs. 3.1.1-3.1.2)
Surface
infiltration advancements:
Schaake,
J., et al., 1996: J. Geophys. Res., 101, 7461-7475.
Surface-layer
turbulence advancements:
Chen,
F., Z. Janjic, and K. Mitchell, 1997, Boundary-Layer Meteorol, 85, 391-421.
Bare
soil evaporation and vegetation greenness advancements:
Betts,
A., F. Chen, K. Mitchell, and Z. Janjic, 1997: Mon. Wea. Rev., 125, 2896-2916.
Gutman,
G., and A. Ignatov, 1998: Int. J. Remote Sensing, 19, 1533-1543.
Snowpack
and frozen ground physics advancements:
Koren,
V., et al., 1999: J. Geophys. Res.,
101, No. D3, 7251-7268.
For
subsurface heat flux advancements:
Peters-Lidard,
C., M. Zion, and E. Wood, 1997: JGR, 102, No. D4, 4303-4324 (Sec. 2.1.2)
Peters-Lidard,
C., 1998: J. Atmos. Sci., 55, 1209-1224. (Sec. 2.b)
Lunardini,V.,1981:Heat
Transfer in Cold Climates. Van Nostrand Reinhold,1-731 (Sec. 4.12.1.1)
Chang,
S.,D.Hahn, C.-H.Yang, D.Norquist, and M.Ek, 1999: J. Appl. Meteorology, 38,
405-422.
11.1 OSU Heritage: 1981-1998
(OSU)
Uncoupled
Marht
and Pan, 1984, Boundary Layer Meteorol, 29, 1-20.
Mahrt
and Ek, 1984, J. Clim. Appl. Meteorol,
23, 222-234.
Pan
and Mahrt, 1987, Boundary Layer Meteorol, 38,
185-202.
OSU
1-D PBL Model User’s Guide, Version 1.0.0,1988.
OSU
1-D PBL Model User’s Guide, Version 1.0.4, 1991.
Ek,
M., and R. Cuenca, 1994, Boundary-Layer Meteorology, 70, 369-383.
11.2
Air Force Lineage: 1985-present (AFGWC,
AFGL/PL/AFRL)
Uncoupled
Mitchell,
1985 (AFGWC Tech Report)
Moore,
B., K. Mitchell, et al., 1990: 20th AMS Conf. Ag and Forest Meteorology, 7-11.
Chang,
S.,D.Hahn, C.-H.Yang, D.Norquist, and M.Ek, 1999: J. Appl. Meteorology, 38,
405-422.
Coupled
Yang,
C.-H., et al., 1989, AFGL Tech Report, GL-TR-89-0158, 262 pp.
11.3
NCEP Lineage: 1990-present (NMC,
NCEP)
Uncoupled
Chen,
F., K. Mitchell, et al., 1996: J. Geophys. Res., 101, No. D3, 7251-7268 (Secs.
3.1.1, 3.1.2)
Chen,
F., and K. Mitchell, 1999: J. Meteorol. Soc. of Japan, 77, 167-182. (GSWP
Special Issue)
Mitchell,
K., et al., 2000: 15th AMS Conf. on Hydrology, 1-4.
Coupled
Mitchell, K., 1994: 5th AMS Symposium on Global
Change Studies, 192-198.
Chen,
F., Z. Janjic, and K. Mitchell, 1997, Boundary-Layer Meteorol, 85, 391-421.
Betts,
A., F. Chen, K. Mitchell, and Z. Janjic, 1997: Mon. Wea. Rev., 125, 2896-2916.
Mitchell,
K., et al., 1999: 14th AMS Conf. on Hydrology, 261-264.
Marshall,
C., et al., 1999: 14th AMS Conf. on Hydrology, 265-268.
Mitchell,
K., et al., 2000: 15th AMS Conf. on Hydrology, 180-183.
Ek,
M., K. Mitchell, et al., 2001: 9th AMS Conf. on Mesoscale Processes, Paper
P1.10
11.4
OHD Heritage: 1995-present (OH,
HRL, OHD)
Schaake
et al., 1996: J. Geophys. Res., 101, 7461-7475.
Koren,
V., et al.,1999: J.Geophys.Res.,101,7251-7268
11.5
External Validators of NCEP NOAH
Model
Uncoupled
PILPS-2a (two papers)
PILPS-2c (three papers)
PILPS-2d (two papers)
GSWP (several papers)
Coupled
Berbery, Rasmusson, Mitchell, 1996, JGR, 101, 7305-7319.
Yarosh, Ropelewski, Mitchell, 1996, JGR, 101,
23289-23298.
Betts, Chen, Mitchell, Janjic,
1997, Mon. Wea. Rev., 125, 2896-2916.
Yucel, Shuttleworth, Washburne, Chen, 1998, Mon.
Wea. Rev., 126, 1977-1991.
Berbery, Mitchell, Benjamin,
Smirnova, Ritchie, et al., 1999, JGR, 104, 19329-19348.
Berbery and Rasmusson, 1999, Mon.
Wea. Rev., 127, 2654-2673.
Yarosh, Ropelewski, Berbery, 1999, JGR, 104,
19349-19360.
Hinkelman, Ackerman, Marchand,
1999, JGR, 104, 19535-19549.
Berbery and Collini, 2000, Mon. Wea.
Rev., 128, 1328-1346.
Fennessy and Shukla, 2000, J.
Climate, 13, 2605-2627.
Angevine and Mitchell, 2001, Mon.
Wea. Rev., in press.
Marshall, Crawford, Mitchell, Stensrud, 2001, J.
Hydrometeor., Submitted.
Berbery, 2001, J. Climate, 14, 121-137.
11.6 NESDIS/ORA Land Surface Fields for NCEP
Operational Use
Daily
N.H. 23-km snow cover:
Ramsay,
B., 1998, Hydrological Processes, 12, 1537-1546.
Annual
cycle of monthly global vegetation greenness:
Gutman,
G., and A. Ignatov, 1998, Int. J.
Remote Sensing, 19, 1533-1543.
Annual
cycle of monthly snow-free surface albedo:
Csiszar,
I., and G. Gutman, 1999, J. Geophys. Res., 104, 6215-6228.