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[EnergyPlus_Support] Re: Weather file of College Station - Texas

Eman,

I took a second look at your data, and apparently something is indeed 
wrong for June at least.
I gathered data from the the two models that have been used to derive 
the current NSRDB, as well as measured data from the nearest station, 
Austin:

Month 1 2 3 4 5 6 7 8 9 10 11 12 Year
METSTAT_model (1991–2005)
Glob 2511 3061 4020 5157 5636 6238 6520 5913 4969 3859 2753 2378 4418
DNI 3124 3068 3585 4142 4072 4818 5361 4959 4441 3972 3059 3044 3970

SUNY_model (1998–2005)
Glob 3090 3730 4800 5820 5950 6510 6590 6080 5150 4480 3290 2830 4870
DNI 3519 3366 3825 4428 4482 4869 5724 5292 4644 4158 3429 3582 4283

Austin_Meas. (1985–2002)
Glob 2591 3198 4190 5126 5434 6251 6641 6098 5034 3822 2817 2332 4481
DNI 3514 3519 3983 4373 3901 5013 5808 5477 4788 4241 3571 3358 4279


METSTAT is a model that uses ground observations of clouds from 
airports. The TMY3s were generated from its results.
SUNY is a model that uses cloud data from satellite. Its results shown 
here are for a 0.1x0.1deg pixel centered at 30.55N, -96.35W.
All these results are from different sources and different periods, but 
none of them shows a low in June. Interestingly, the measurements in 
Austin rather show a low in May.

Chris


---------------------

 Hello Mr Cris;
As the DNI decrease, the diffuse increase. So I checked the weather data & find that is the case, so many thanks for the explaination, this expalins for me why the DNI is lower in June  than in January. Appreciated so much'

But still there is a point!
Why June still have minimum global  ( DNI & diffuse) than May & July.  There is a drop in the total solar radiation in June specifically. As the month before it & the month after it both have higher global radiation.

Monthly Statistics for Solar Radiation  (Direct Normal, Diffuse, Global Horizontal) Wh/m²
             Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 
Direct Avg 4311 4089 4543 4656 4756 3564 4865 4942 4264 2758 2725 4440 

Direct Max 8349 7801 8952 10104 8570 7584 8939 8220 7941 7467 7124 7395 
    Day      19   23   28   21   19   20   26    9    6   16    9   30 

Diffuse Avg 928  1376 1665 1831 2703 2531 2756 2191 1876 1541 1076 985  

Global Avg 2893 3584 4493 5028 6127 5182 6199 5724 4671 3096 2408 2938 

I wonder if  there is an explaination for that
Thank you very much
 Eman Tora


-- 
Chris A. Gueymard, PhD
Solar Consulting Services
P.O. Box 392
Colebrook, NH 03576, USA
Tel. (603) 237-8550
Fax  (603) 237-5314
http://www.SolarConsultingServices.com



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