Dear all,
I am currently attempting to use MEGAN v3.2. However, I am encountering an issue in the megcan process when trying to read the ‘LAT’ variable from the LAI file. The format of the LAI file that I used in MEGAN v2.1 is as follows.
I would appreciate any advice you could provide.
Additionally, I would be grateful if you could explain how to use the MCIP file to handle LAI in this context.
Heo Min
Looking at the ncdump of this file (in particular, variable TSTEP), I see that it is NOT an I/O API file,.
Where did it come from?
I would remind you from the I/.O API Home Page:
The Models-3 I/O API is A programming interface, not a data format !!
I/O API files are not synonymous with “netCDF files” !!
Instead, netCDF is one of four (and a half) distinct lower layers on which the data and metadata structures for I/O API files are currently available; additional lower layers have been incorporated at times in the past, and may very well be incorporated at various times in the future. Attempts to treat the I/O API as “just a data format” have consistently failed in all cases because the persons attempting to do so have not fully understood the I/O API data structures embedded in these files.
This file is a NetCDF3 classic format file that I created manually to utilize MODIS LAI data. The TSTEP is set to 46 to represent 8-day intervals for the LAI variable.
And so: it is not an I/O API file, as required by Megan.
As the Home Page states, manual creation of such files has universally failed because you don’t understand the embedded data structures.
Could you kindly provide an example of the ncdump output for the LAI input data used in MEGANv3.2?
ncdump -h MAP/LAI3_SE_US.ncf
netcdf LAI3_SE_US {
dimensions:
TSTEP = UNLIMITED ; // (1 currently)
DATE-TIME = 2 ;
LAY = 1 ;
VAR = 48 ;
ROW = 163 ;
COL = 163 ;
variables:
int TFLAG(TSTEP, VAR, DATE-TIME) ;
TFLAG:units = “<YYYYDDD,HHMMSS>” ;
TFLAG:long_name = "TFLAG " ;
TFLAG:var_desc = "Timestep-valid flags: (1) YYYYDDD or (2) HHMMSS " ;
float LAI01(TSTEP, LAY, ROW, COL) ;
LAI01:long_name = "LAI01 " ;
LAI01:units = "nondimension " ;
LAI01:var_desc = “” ;
float LAI02(TSTEP, LAY, ROW, COL) ;
LAI02:long_name = "LAI02 " ;
LAI02:units = "nondimension " ;
LAI02:var_desc = “” ;
float LAI03(TSTEP, LAY, ROW, COL) ;
LAI03:long_name = "LAI03 " ;
LAI03:units = "nondimension " ;
LAI03:var_desc = “” ;
float LAI04(TSTEP, LAY, ROW, COL) ;
LAI04:long_name = "LAI04 " ;
LAI04:units = "nondimension " ;
LAI04:var_desc = “” ;
float LAI05(TSTEP, LAY, ROW, COL) ;
LAI05:long_name = "LAI05 " ;
LAI05:units = "nondimension " ;
LAI05:var_desc = “” ;
float LAI06(TSTEP, LAY, ROW, COL) ;
LAI06:long_name = "LAI06 " ;
LAI06:units = "nondimension " ;
LAI06:var_desc = “” ;
float LAI07(TSTEP, LAY, ROW, COL) ;
LAI07:long_name = "LAI07 " ;
LAI07:units = "nondimension " ;
LAI07:var_desc = “” ;
float LAI08(TSTEP, LAY, ROW, COL) ;
LAI08:long_name = "LAI08 " ;
LAI08:units = "nondimension " ;
LAI08:var_desc = “” ;
float LAI09(TSTEP, LAY, ROW, COL) ;
LAI09:long_name = "LAI09 " ;
LAI09:units = "nondimension " ;
LAI09:var_desc = “” ;
float LAI10(TSTEP, LAY, ROW, COL) ;
LAI10:long_name = "LAI10 " ;
LAI10:units = "nondimension " ;
LAI10:var_desc = “” ;
float LAI11(TSTEP, LAY, ROW, COL) ;
LAI11:long_name = "LAI11 " ;
LAI11:units = "nondimension " ;
LAI11:var_desc = “” ;
float LAI12(TSTEP, LAY, ROW, COL) ;
LAI12:long_name = "LAI12 " ;
LAI12:units = "nondimension " ;
LAI12:var_desc = “” ;
float LAI13(TSTEP, LAY, ROW, COL) ;
LAI13:long_name = "LAI13 " ;
LAI13:units = "nondimension " ;
LAI13:var_desc = “” ;
float LAI14(TSTEP, LAY, ROW, COL) ;
LAI14:long_name = "LAI14 " ;
LAI14:units = "nondimension " ;
LAI14:var_desc = “” ;
float LAI15(TSTEP, LAY, ROW, COL) ;
LAI15:long_name = "LAI15 " ;
LAI15:units = "nondimension " ;
LAI15:var_desc = “” ;
float LAI16(TSTEP, LAY, ROW, COL) ;
LAI16:long_name = "LAI16 " ;
LAI16:units = "nondimension " ;
LAI16:var_desc = “” ;
float LAI17(TSTEP, LAY, ROW, COL) ;
LAI17:long_name = "LAI17 " ;
LAI17:units = "nondimension " ;
LAI17:var_desc = “” ;
float LAI18(TSTEP, LAY, ROW, COL) ;
LAI18:long_name = "LAI18 " ;
LAI18:units = "nondimension " ;
LAI18:var_desc = “” ;
float LAI19(TSTEP, LAY, ROW, COL) ;
LAI19:long_name = "LAI19 " ;
LAI19:units = "nondimension " ;
LAI19:var_desc = “” ;
float LAI20(TSTEP, LAY, ROW, COL) ;
LAI20:long_name = "LAI20 " ;
LAI20:units = "nondimension " ;
LAI20:var_desc = “” ;
float LAI21(TSTEP, LAY, ROW, COL) ;
LAI21:long_name = "LAI21 " ;
LAI21:units = "nondimension " ;
LAI21:var_desc = “” ;
float LAI22(TSTEP, LAY, ROW, COL) ;
LAI22:long_name = "LAI22 " ;
LAI22:units = "nondimension " ;
LAI22:var_desc = “” ;
float LAI23(TSTEP, LAY, ROW, COL) ;
LAI23:long_name = "LAI23 " ;
LAI23:units = "nondimension " ;
LAI23:var_desc = “” ;
float LAI24(TSTEP, LAY, ROW, COL) ;
LAI24:long_name = "LAI24 " ;
LAI24:units = "nondimension " ;
LAI24:var_desc = “” ;
float LAI25(TSTEP, LAY, ROW, COL) ;
LAI25:long_name = "LAI25 " ;
LAI25:units = "nondimension " ;
LAI25:var_desc = “” ;
float LAI26(TSTEP, LAY, ROW, COL) ;
LAI26:long_name = "LAI26 " ;
LAI26:units = "nondimension " ;
LAI26:var_desc = “” ;
float LAI27(TSTEP, LAY, ROW, COL) ;
LAI27:long_name = "LAI27 " ;
LAI27:units = "nondimension " ;
LAI27:var_desc = “” ;
float LAI28(TSTEP, LAY, ROW, COL) ;
LAI28:long_name = "LAI28 " ;
LAI28:units = "nondimension " ;
LAI28:var_desc = “” ;
float LAI29(TSTEP, LAY, ROW, COL) ;
LAI29:long_name = "LAI29 " ;
LAI29:units = "nondimension " ;
LAI29:var_desc = “” ;
float LAI30(TSTEP, LAY, ROW, COL) ;
LAI30:long_name = "LAI30 " ;
LAI30:units = "nondimension " ;
LAI30:var_desc = “” ;
float LAI31(TSTEP, LAY, ROW, COL) ;
LAI31:long_name = "LAI31 " ;
LAI31:units = "nondimension " ;
LAI31:var_desc = “” ;
float LAI32(TSTEP, LAY, ROW, COL) ;
LAI32:long_name = "LAI32 " ;
LAI32:units = "nondimension " ;
LAI32:var_desc = “” ;
float LAI33(TSTEP, LAY, ROW, COL) ;
LAI33:long_name = "LAI33 " ;
LAI33:units = "nondimension " ;
LAI33:var_desc = “” ;
float LAI34(TSTEP, LAY, ROW, COL) ;
LAI34:long_name = "LAI34 " ;
LAI34:units = "nondimension " ;
LAI34:var_desc = “” ;
float LAI35(TSTEP, LAY, ROW, COL) ;
LAI35:long_name = "LAI35 " ;
LAI35:units = "nondimension " ;
LAI35:var_desc = “” ;
float LAI36(TSTEP, LAY, ROW, COL) ;
LAI36:long_name = "LAI36 " ;
LAI36:units = "nondimension " ;
LAI36:var_desc = “” ;
float LAI37(TSTEP, LAY, ROW, COL) ;
LAI37:long_name = "LAI37 " ;
LAI37:units = "nondimension " ;
LAI37:var_desc = “” ;
float LAI38(TSTEP, LAY, ROW, COL) ;
LAI38:long_name = "LAI38 " ;
LAI38:units = "nondimension " ;
LAI38:var_desc = “” ;
float LAI39(TSTEP, LAY, ROW, COL) ;
LAI39:long_name = "LAI39 " ;
LAI39:units = "nondimension " ;
LAI39:var_desc = “” ;
float LAI40(TSTEP, LAY, ROW, COL) ;
LAI40:long_name = "LAI40 " ;
LAI40:units = "nondimension " ;
LAI40:var_desc = “” ;
float LAI41(TSTEP, LAY, ROW, COL) ;
LAI41:long_name = "LAI41 " ;
LAI41:units = "nondimension " ;
LAI41:var_desc = “” ;
float LAI42(TSTEP, LAY, ROW, COL) ;
LAI42:long_name = "LAI42 " ;
LAI42:units = "nondimension " ;
LAI42:var_desc = “” ;
float LAI43(TSTEP, LAY, ROW, COL) ;
LAI43:long_name = "LAI43 " ;
LAI43:units = "nondimension " ;
LAI43:var_desc = “” ;
float LAI44(TSTEP, LAY, ROW, COL) ;
LAI44:long_name = "LAI44 " ;
LAI44:units = "nondimension " ;
LAI44:var_desc = “” ;
float LAI45(TSTEP, LAY, ROW, COL) ;
LAI45:long_name = "LAI45 " ;
LAI45:units = "nondimension " ;
LAI45:var_desc = “” ;
float LAI46(TSTEP, LAY, ROW, COL) ;
LAI46:long_name = "LAI46 " ;
LAI46:units = "nondimension " ;
LAI46:var_desc = “” ;
float LAT(TSTEP, LAY, ROW, COL) ;
LAT:long_name = "LAT " ;
LAT:units = “” ;
LAT:var_desc = "Latitude " ;
float LONG(TSTEP, LAY, ROW, COL) ;
LONG:long_name = "LONG " ;
LONG:units = “” ;
LONG:var_desc = "Longitude " ;
// global attributes:
:IOAPI_VERSION = "ioapi-3.2: $Id: init3.F90 120 2019-06-21 14:18:20Z coats $ " ;
:EXEC_ID = "???????????????? " ;
:FTYPE = 1 ;
:CDATE = 2022003 ;
:CTIME = 231209 ;
:WDATE = 2022003 ;
:WTIME = 231209 ;
:SDATE = 0 ;
:STIME = 0 ;
:TSTEP = 10000 ;
:NTHIK = 1 ;
:NCOLS = 163 ;
:NROWS = 163 ;
:NLAYS = 1 ;
:NVARS = 48 ;
:GDTYP = 2 ;
:P_ALP = 30. ;
:P_BET = 60. ;
:P_GAM = -100. ;
:XCENT = -100. ;
:YCENT = 37. ;
:XORIG = -743500. ;
:YORIG = -1376500. ;
:XCELL = 9000. ;
:YCELL = 9000. ;
:VGTYP = 0 ;
:VGTOP = 0.f ;
:VGLVLS = 0.f, 0.f ;
:GDNAM = "SE_US " ;
:UPNAM = "CNVT_LAI " ;
:VAR-LIST = "LAI01 LAI02 LAI03 LAI04 LAI05 LAI06 LAI07 LAI08 LAI09 LAI10 LAI11 LAI12 LAI13 LAI14 LAI15 LAI16 LAI17 LAI18 LAI19 LAI20 LAI21 LAI22 LAI23 LAI24 LAI25 LAI26 LAI27 LAI28 LAI29 LAI30 LAI31 LAI32 LAI33 LAI34 LAI35 LAI36 LAI37 LAI38 LAI39 LAI40 LAI41 LAI42 LAI43 LAI44 LAI45 LAI46 LAT LONG " ;
:FILEDESC = "Converted from MEGAN input text file" ;
:HISTORY = "" ;
}
You might run into additional problems when you try to mix and match MEGAN 2.1 with MEGAN version 3.2 that’s in CMAQ.
Thank you for your response. It was helpful !