MZAsurfCn2

MATLAB

[cn2,Wg,Lin] = MZAsurfCn2(DATE,lat,lon,alt,press,temp,wind,windAlt, ...
                       param,value, ...)

Description

Applies bulk modeling methods to estimate the ground level Cn2 value.

Parameters

Parameters	Description
DATE [datetime]	Date of observation. Can be a Matlab datetime object of a date vector. If not a datetime object, GMT is assumed. Ignored if ground level solar irradiance is given.
lat [scalar]	Latitude of observation point (deg). Ignored if ground level solar irradiance is given.
lon [scalar]	Longitude of observation point (deg). Ignored if ground level solar irradiance is given.
alt [scalar]	Altitude for Cn2 estimate (m AGL).
press [scalar]	Observed station pressure (Pa).
temp [scalar]	Observed temperature (K).
wind [scalar]	Observed wind speed (m/s).
windAlt [scalar]	Altitude (AGL) at which the wind speed is measured.
param [char]	Parameter name
value [various]	Parameter value Possible param/value options are: 'CloudCondition' - Observed cloud conditions in a 3x2 matrix. Column 1 holds the fractional cloud coverages at each layer, column 2 holds the cloud layer altitude in ft AGL. Defaults to no clouds. 'SolarIrradiance' - Ground level solar irradiance (W/m^2) 'MinSolarIrr' - Minimum value for ground level solar irradiance. Use to possibly override the NaN return when solar irradiance is low. May still get NaN under low wind conditions. NOTE: The model does not support Cn2 estimation under these conditions. 'Terrain' - Description of the site terrain (case insensitive) or surface [albedo, evap const, surface roughness (m)]. Defaults to [0.17,0.5,0.0014]. Possible terrain values: 'open ocean', [0.06,1.0,0.001] 'conifer forest', [0.11,1.0,1.1] 'deciduous trees', [0.165,1.0,1.25] 'green grass', [0.25,1.0,0.0014] 'grass soil', [0.21,0.6,0.007] 'bare soil', [0.17,0.2,0.01] 'desert sand', [0.4,0.0,0.0003] 'fresh asphalt', [0.04,0.0,0.00002] 'worn asphalt', [0.1,0.0,0.00002] 'old concrete', [0.27,0.0,0.00002] 'new concrete', [0.55,0.0,0.00002] 'ocean ice', [0.6,0.5,0.00001] 'fresh snow', [0.06,1.0,0.002]

Return Values

Return Values	Description
cn2 [scalar]	Estimate of ground level Cn2 (m^{-2/3}).
Wg [scalar]	Solar irradiance at the ground (W/m^2).
Lin [scalar]	Estimate of inner scale (m).

References

https://en.wikipedia.org/wiki/Albedo.
Bendersky et al. "Modeling and measurements of near-ground atmospheric optical turbulence according to weather for Middle East environments," Proc. SPIE, vol. 5612, pp. 350-361, 2004.
F. V. Hansen, "Surface Roughness Lengths," ARL Technical Report, ARL-TR-61, August 1993.
D. H. Tofsted, "Modeling Turbulence Generation in the Atmospheric Surface and Boundary Layers," ARL Technical Report, ARL-TR-7503, October 2015.

Examples

>> [cn2,Wg,Lin] = MZAsurfCn2([2016 7 29 12 58 0],38.818,-76.867,2, ...

1.0008e5,297.15,3.6011,10,'CloudCondition', ...

[0 0; 0.75 1000; 0.75 1400],'Terrain','green grass')

Cn2, ground level solar irradiance, and inner scale given time,

location, met data, cloud condition and terrain.

>> [cn2,~,Lin] = MZAsurfCn2([],[],[],2,1.0008e5, ...

297.15,3.6011,10,'SolarIrradiance',395.9468, ...

'Terrain',[0.25,1.0,0.0014])

Cn2 and inner scale given met data, ground level solar irradiance, and terrain albedo and evaporative constant.

Group

Turbulence Prediction Modeling

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