The range of shear exponents and turbulence intensities used is typical for the majority of sites for typical turbine hub heights nowadays.  

You can also check the IEC 61400-1 standard (ed.3), which gives alpha of 0.11 or 0.2 (depending on the load case), as well as prescriptions for turbulence intensity for different turbine types; the latter serve as approximate expectations for intensity as a function of wind speed.

To see some joint statistics between turbulence intensity and shear exponent at a number of sites, as well as derivations/theory connecting shear exponent to turbulence intensity and stability (and wind speed), check out my paper from the 2014 "Science of Making Torque from the Wind" conference.  I have attached it here, since there are a few typos in the version published online by AIP. 

I think you can calculate it using:

I = 0.16 (Re_DH) ^ (-1/8)

Christian and Mark, thanks for the reply. But, If you check the attached paper, you will see that the authors have provided the wind turbine power curves for different ranges of shear exponents and turbulent intensities. I know how to calculate the shear exponent and turbulent intensity for a series of wind data, but, the question here is how they have come up with wind turbine power curves at different shear exponent and turbulent intensity values.

Also, Mark C. Kelly's paper is very helpful if one wants to find the relation between these two variables; but, it is different than what is presented in Fig. 2 and 3 in the Honrubia paper.

UPDATE: I figured it out and will shortly upload the results here. However I have one more question to make sure I am calculating the TI correctly:

I just have the 10-min measured wind speeds and used this to calculate the Turbulent Intensity. For instance, I have:

00:00  V1

00:10  V2

00:20  V3

00:30 V4

00:40 V5

00:50 V6

01:00 V7

.    .     .

.    .     .   

.    .     .

TI = (Standard Deviation)/Mean Wind Speed

I have averaged every 6 wind speed values for calculating the standard deviation and mean wind speed. Now, when I want to plot the TI vs time, is it correct that at each time, I use the averaged values of the previous 6 wind speed data? Meaning the TI @ 1:00 will be the value obtained from previous six wind speeds.

For each 10min wind speed record (U_10min) you need the corresponding 10min wind speed standard deviation (U_stdev_10min). This is usually taken from 1 or 2 Hz data sampling. Then, you divide U_stdev_10min with the corresponding U_10min to estimate turbulence intensity for this record. The 1-2 Hz sampling is necessary to capture the energy spectrum.

Your method calculates only the stochastic variability of hourly wind speed.

Yiannis,

I agree with you. But, please take a look at the attached figure for the turbulent intensity vs wind speed in the attachment. While the TI values were not calculated using the 1-2 Hz sampling data, it still shows an acceptable distribution. Hence, I was wondering if I can say that the stochastic variability of hourly wind speed shown in this figure gives us a correct understanding on the expected turbulent intensity distribution?

I just wanted to add that I checked the wind speed data measurements and found that  the 1-2 Hz frequency in sampling data were followed. Hence, the provided figure for the turbulence intensity at different wind speeds is represent the actual turbulence intensity values that we were looking for, and it is not the stochastic variability of hourly wind speed.

Please find a part of the obtained results from this study in this poster:

Conference Paper The Impact of Mid-Atlantic Meteorological Controls on Offsho...

The shape - distribution of the attached figure has no meaning from a quantitative point of view. Y axis does not represent T.I., but dimensionless hourly wind speed standard deviation. This quantity is useful only for uncertainty analysis techniques, i.e. a completely different topic . Moreover, both hourly wind speeds and 1-2 Hz wind speeds have the same distribution, due to the linear behaviour of averaging. Thus, the corresponding result is obvious. On the other hand, this linear behaviour is not true for wind speed petrurbations which determine T.I. estimation.

Yiannis, Thanks for the reply. Good news (for me!) is I checked with the folks who measured the wind speed by LIDAR. They said the data I was using were obtained with 1-2 Hz frequency and they had provided me clean data rather than raw ones. Also, if you read the poster I have attached in the previous comment, the meteorological description of the weather pattern at the site at different case studies (different days and different times during different days) are in agreement with the obtained TI and alpha variations. I was wondering if this is enough for making sure the procedure is correct or we need to do further wind measurements and analysis. 

I am calculating the equivalent wind speed and plan to go to the next phase which is wind turbine design based on the wind assessment analysis. Hence, the numbers of this phase play and important role.

Thank  you in advance for your time and helpful comments.