Dear Maha,
Regards and best wishes,
Thank you for the kind mail.I wish to know from you for what purpose you need future scenarios of weather.
By definition "Weather is defined as the state or condition of the atmosphere at a particular place and given instant of time" where as the climate is "generalized weather or summation of weather conditions over a given region during comparatively longer period".
Therefore, please take up any method such a way that at least by and large the method takes the above basic principle into consideration.
My request: You are a Ph.D student!
Also, in my experience i wish to state that/ suggest you that please do
consider past weather and its effects/influence/ impact also to give any conclusions from your Ph.D work.
1.Please do not hesitate to write to me the objectives of your study
2.Kindly note that i proved over the years that "It is not only the future "climate" or "weather"that is important but also the "past weather" which is very /equally important for agricultural crops
Example:4 days of cloudy weather coupled with fall in temperature , 1-3 degree centigrade, causes sucking pests on many agricultural crops during the vegetative stage. remember ------ "THIS IS PAST WEATHER" ------
God bless you in all your endeavours for a very good Ph.D work.
Sincerely,
Murthy.
> Date: Wed, 5 Jan 2011 10:31:10 -0500
> From: [log in to unmask]
> Subject: Re: Future weather Data
> To: [log in to unmask]
>
> Dear Maha,
>
> I developed a tool that generates time series of daily weather that
> exactly match a series of monthly targets, but with statistical
> properties that are consistent with historic daily observations at a
> given location. It is described in:
>
> Hansen, J.W. and Ines, A.V.M., 2005. Stochastic disaggregation of
> monthly rainfall data for crop simulation studies. Agric. For. Meteorol.
> 131:233 246.
>
> It uses the same stochastic weather generator that I developed for the
> WeatherMan software that is part of DSSAT 4.x (described in: Hansen,
> J.W. and Mavromatis, T., 2001. Correcting low frequency variability bias
> in stochastic weather generators. Agric. For. Meteorol. 109:297-310;
> Mavromatis, T. and Hansen, J.W., 2001. Interannual variability
> characteristics and simulated crop response of four stochastic weather
> generators. Agric. For. Meteorol. 109:283-296; and Hansen, J.W., 1999.
> Stochastic daily solar irradiance for biological modeling applications.
> Agric. For. Meteorol. 94:53-63.). It uses the same parameter file that
> WeatherMan produces and uses for its unconstrained weather generator,
> but is constrained to reproduce a time series of monthly targets. This
> of course assumes that you have sufficient historic daily data to
> estimate the weather generator parameters.
>
> I have not yet implemented a user-friendly GUI version. For my own
> work, I developed a stand-alone command-line version of the parameter
> estimation tool (extracted from what I developed for WeatherMan),
> stand-alone weather disaggregation tools for DSSAT and APSIM weather
> file formats, and a version that also deals with dewpoint and wind speed
> to support variations of the Penman model of potential
> evapotranspiration (used for the SARRA-H crop models). If you are
> interested, let me know, and I can send files and instructions.
>
> Regards,
>
> Jim
>
>
> On 12/30/2010 5:14 AM, Maha Lotfy Mohamed Elsayed wrote:
> > All DSSAT group,
> >
> > I wish you a new year full of happiness, success, progress, and peace.
> >
> > I have two future weather scenarios but monthly based (from 2011 to 2082)
> > for the location here under study. Could anyone help me on how to obtain
> > the daily values?
> >
> > Thanks a lot in advance.
> >
> > Best regards,
> >
> > Maha
> >
> >
> > --
> > Maha ELSAYED
> > PhD Student, DAAPV, Università di Padova
> > Agripolis - viale dell'Università 16
> > 35020 Legnaro (PD)
> > Italy
> > Mobile: +39 3896479117
> > www.griffin.uga.edu/ageng/people_files/Elsayed.htm
> > Skype ID: maha_lotfy
> >
>
> --
> James W. Hansen, Ph.D.
> Research Scientist - Agricultural Systems, CCAFS Theme 4 Leader
> The International Research Institute for Climate and Society
> The Earth Institute, Columbia University, Lamont Campus
> 61 Route 9W, Monell Building
> Palisades, NY 10964-8000
> USA
>
> voice: +1-845-680-4410
> fax: +1-845-680-4864
> e-mail: [log in to unmask]
> WWW: http://iri.columbia.edu/cgi-bin/staff?jhansen
> Skype: j.w.hansen
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