5 is the wind speed at a measurement height of 13.5 m above the surface and Ri is a reduced Richardson number given byRi=g��Tz/TwUz2.(7)Here g is the acceleration due STI571 to gravity, ��T is the air/sea temperature www.selleckchem.com/products/MDV3100.html difference, Tw is the water temperature, and Uz is the wind speed at a measurement Inhibitors,Modulators,Libraries height of z. For our purposes, we will neglect atmospheric stability effects and use Ri = 0. We will Inhibitors,Modulators,Libraries also neglect the along-wind/cross-wind asymmetry and use the average variance in both axes.We estimate the solar zenith angle ? using an approximation from Meeus [10] and the longitude, latitude, day of the year, and time of day. The details are presented in Inhibitors,Modulators,Libraries Appendix A.To estimate the Fresnel reflection coefficient, we use the following approximation for the index Inhibitors,Modulators,Libraries of refraction of sea water:n=1.
39855?1.
64��10?4��+1.09��10?7��2,(8)where �� is the wavelength in nm. Over the range of wavelengths from 400 nm to 700 nm, our approximation to the index of refraction varies Inhibitors,Modulators,Libraries from 1.350 to 1.337, Inhibitors,Modulators,Libraries and the resulting values for the reflection at normal incidence from 0.0222 to 0.0208. Inhibitors,Modulators,Libraries For this wavelength range and a temperature range of 0 �C 20�� C, the maximum error in normal-incidence reflectivity produced by the use of this formula is about 0.5% of the true value calculated from the tabulated refractive indices of Austin and Halikas [7,11]. The Fresnel reflection coefficient for an incidence angle �� is taken from Born and Wolf [12]:RF(��)=tan2[��?sin?1(sin��n)]2tan2[��+sin?1(sin��n)]+sin2[��?sin?1(sin��n)]2tan2[��+sin?1(sin��n)].
(9)The contribution from foam is estimated assuming that foam acts as a Lambertian reflector.
The observed radiance can then be approximated as:LF=ESUN(?)RFOAMP(FOAM)/��,(10)where RFOAM is the reflectivity of Inhibitors,Modulators,Libraries foam, and P(FOAM) is the probability encountering foam at any point on the surface. The reflectivity of foam depends on a number of factors, including thickness and age. Whitlock, et al. [13] measured a maximum reflectivity of 0.55 for new, thick foam in the laboratory. Using Entinostat this number as a calibration factor, Koepke [14] measured an average value for oceanic foam of 0.22. Frouin, et al. [15] made measurements in the surf zone, and obtained reflectivities of 0.2 to 0.
6 out to about 650 nm, and decreasing values from there into the near infrared. Moore, et al. [16] measured the foam in a ship wake, and obtained Carfilzomib a wide range of values up to 0.
75, with decreasing reflectance at wavelengths Ixazomib purchase longer than about 600 nm under all conditions. The measurement conditions of Koepke are the most similar to those of interest here, and we will use his results.The fractional foam coverage, P(FOAM), has also been measured a number of times. sellckchem Using a least-squares fit to a number of data sets, Monahan and O’Muircheartaigh obtained the relationship [17]P(FOAM)=2.95��10?6U103.52.