scientimate.windvelz1toz2#
Uz2_PowerLaw, Uz2_LogLaw, Uz2_LogLaw_Charnock = scientimate.windvelz1toz2(Uz1, z1, z2=10, alpha=1/7, z0=0.005, alpha_Charnock=0.0145)
Description#
Convert wind velocity from first height, z1 (m), to second height, z2 (m), (e.g. 10 (m)) above surface
Inputs#
- Uz1
Wind velocity at z1 Height in (m/s)
- z1
First Height (e.g. sensor height) in (m)
- z2=10.0
Second Height that wind velocity is converted to in (m)
- alpha=1/7
- Exponent of power law velocity profile, Uz1/Uz2=(z1/z2)**(alpha)water: alpha=1/11.5, open area: alpha=1/9.5, suburban area: alpha=1/7, urban area: alpha=1/5
- z0=0.005
- Surface roughness in logarithmic velocity profile in (m), U/Ustar=(1/0.41)*ln(z/z0)water: z0=0.005 (m), open area: z0=0.02 (m), suburban area: z0=0.3 (m), urban area: z0=2 (m)
- alpha_Charnock=0.0145
- Charnock (1955) parameters to calculate ocean surface roughness, z0=alpha_Charnock*(Ustar^2/g)Charnock (1955): alpha_Charnock=0.012, Garratt (1977): alpha_Charnock=0.0145, Wu (1980): alpha_Charnock=0.0185
Outputs#
- Uz2_PowerLaw
- Wind velocity at height of z2 above surface in (m/s)calculated from power law velocity profile
- Uz2_LogLaw
- Wind velocity at height of z2 above surface in (m/s)calculated from logarithmic velocity profile
- Uz2_LogLaw_Charnock
- Wind velocity at height of z2 above surface in (m/s)calculated from logarithmic velocity profileusing Charnock (1955) relationship for wind over ocean
Examples#
import scientimate as sm
import numpy as np
Uz2_PowerLaw,Uz2_LogLaw,Uz2_LogLaw_Charnock=sm.windvelz1toz2(8,15,10)
Uz1=10.*np.random.rand(100)
Uz2_PowerLaw,Uz2_LogLaw,Uz2_LogLaw_Charnock=sm.windvelz1toz2(Uz1,15,10,1/7,0.005,0.0145)
References#
Charnock, H. (1955). Wind stress on a water surface. Quarterly Journal of the Royal Meteorological Society, 81(350), 639-640.
Garratt, J. R. (1977). Review of drag coefficients over oceans and continents. Monthly weather review, 105(7), 915-929.
Wu, J. (1980). Wind-stress coefficients over sea surface near neutral conditions—A revisit. Journal of Physical Oceanography, 10(5), 727-740.