[TRNSYS-users] Sebha Weather Generation

Dear TRNSYS users

I used Type 54a to generate meteorological year depending on average meteorological data of weather records at Sebha city at the south of Libya as shown below:

Table 1

Location Number & Place Location Symbol Latitude

1SEBHA

27.02

.00

Monthly Average of daily Global Radiation on Horizontal (kJ/m²)

14796

16812

18936

21816

25128

24552

22464

21600

18360

15300

12600

Monthly Average of daily Humidity Ratio times 10,000 (kg water/kg air)

125

150

159

162

145

108

100

Monthly Average of daily Temperatures (°C)

19.1

22.4

25.9

31.6

36.7

39.2

38.6

35.4

When I run the project with the following parameters:

Table 2

No.	Parameter		Value and Reason
1	Temperature model, 1 = Stochastic, 2 = Cosine		1= near realistic random profile
2	Hourly radiation correction, 1 = Yes, 2 = No		1= daily autocorrelation effect
3	Use default number of seeds, 1 = Yes		1= default values
4	Average Wind Speed (AWS) in Jan. (m/s)		4.16
5 ?15	AWS Feb?...Nov., (m/s)	5.19, 5.35, 6.79, 6.22, 5.96, 5.45, 5.19, 5.04, 5.24, 3.96
16	AWS Dec. (m/s)		3.96
7	Altitude at Sebha city (m)		435 above sea level

I got two questionable results:

1^st - higher than normal daily ambient temperatures, and my question here is regarding, what average of daily monthly ambient temperatures I should use in table 1 above, is it the average of Maximum daily monthly ambient temperature or the average of Minimum daily monthly ambient temperatures or the average of both such as:

Average daily monthly ambient Temp. = (Average Tmax + Average Tmin)/2 ???

2^nd ? the sum of Beam and Diffuse Irradiation give not the Global Irradiation as it must be?? and The values of Beam (direct) irradiation are higher than the values of Global irradiation during summer months ( the Table 3 below contains the resulted monthly integrated values of Solar Irradiation), my question is where is the mistake?..? since :

G_h must equal (G_bh + G_dh), where: G_his the Global Horizontal Irradiance, G_bh is the Beam Horizontal Irradiance and G_dh is the Diffuse Horizontal Irradiance.

Table 3 the resulted Monthly Integrated Solar Irradiation (MJ/m²)

	Global	Direct	Diffuse
Jan	459	292	249
Feb	472	325	232
Mar	589	438	257
Apr	654	585	225
May	784	884	174
Jun	742	873	160
Jul	766	878	175
Aug	695	655	216
Sep	647	557	231
Oct	571	433	250
Nov	460	307	240
Dec	389	221	236

Note; I got the almost similar results using Type 54b with the default number of seeds in the attached project !

Thanks in advance for your help

G. Azzain

g_azzain@yahoo.com