Dear Luo Yi,
question 1: As far as I know, DSSAT uses the 'Civil Twilight' for
calculation of daylength.
question 2: It´s just a matter of definition. Under
http://aa.usno.navy.mil/faq/docs/RST_defs.html#top you´ll find definitions
of astronomical, nautical and civil twilight.
Hope this helps.
Greetings
Jans
At 04:09 PM 11/10/2006, you wrote:
>Dear researchers,
>
>In the subroutine
> CALL CSCER040 (FILEIOCS, RUN, TN, RN, RNMODE, !Command line
> & ISWWAT, ISWNIT, IDETO, IDETG, IDETL, FROP, !Controls
> & SN, ON, RUNI, REP, YEAR, DOY, STEP, CN, !Run+loop
> & SRAD, TMAX, TMIN, CO2, RAIN,
>!Weather
> & *TWILEN*, WINDSP, SOILTEMP, EO,
>!Weather
> & NLAYR, DLAYR, DEPMAX, LL, DUL, SAT, BD, SHF, !Soil states
> & SNOW, SW, NO3, NH4, !H2o,N states
> & YEARPLT,
>!Pl.date
> & EOP, TRWUP,
>!Resources
> & LAI, KCAN, KEP, !States
> & RLV, NFP, PORMIN, RWUMX, CANHT, !States
> & UNO3, UNH4, UH2O, !Uptake
> & SENC, SENN, SENLIG, !Senescence
> & CRESC, CRESN, CRESLIG, !Residue
> & STGDOY,
>!Stage dates
> & DYNAMIC)
>!Control
>
>The variable TWILEN corresponds to the internal variable DAYLT. DAYLT means
>daylength. The daylength is calculated by subroutine DAYLEN() in the
>weathr.for file. TWILEN is calculated by the subroutine TWILIGHT() that is
>also in the weathr.for file.
>
>Questions:
>1. does the CSCER040 need to use the TWILEN here as the day length?
>2. what are the difference between day length and twilength?
>
>Cheers,
>
>
>--
>Dr. Luo Yi, Professor
>=============================================================
>Ecohydrological Model Development and Integrated Watershed Management
>
>Institute of Geographic Science and Natural Resources Research(IGSNRR)
>Chinese Academy of Sciences (CAS)
>
>Datun Road, Anwai, Chaoyang District, 100101, Beijing, China
>[log in to unmask], [log in to unmask]
>+86-10-64888920 (Tel.) +86-10-64888920 (Fax)
>=============================================================
__________________________
Jans Bobert
Stavangerstrasse 23
10439 Berlin
Germany
fon +49 (0)30 43734861
e-mail: [log in to unmask]
|
