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--- intercomparisons:e6_ocean_planet [2025/09/10 19:01] – claudia
+++ intercomparisons:e6_ocean_planet [2026/03/20 17:02] (current) – claudia
@@ Line 1: / Line 1: @@
+==== Case E6: Planet with US standard atmosphere and ocean surface ====
+In this case we include the US standard atmosphere, the corresponding Rayleigh scattering optical thickness and molecular absorption profiles are provided at 450 nm.
+Below we add a water surface described by a bidirectional reflectance distribution function including the specular reflection.
+//Setup://
+  * model atmosphere US-standard, scattering optical thickness provided in file {{:intercomparisons:phase_e:tau_rayleigh_450nm_usstd.dat|}}, molecular absorption optical thicknes in {{:intercomparisons:phase_e:tau_absorption_450nm_usstd.dat|}}. The file includes 2 columns where the first is the altitude of the layer boundaries in km, and the second is the layer optical thickness (e.g. the value for 0 km corresponds to the optical thickness for the layer from 0 to 1 km).
+  * The surface is described by the ocean reflectance matrix using Mishchenko's code [[http://www.giss.nasa.gov/staff/mmishchenko/ftpcode/ocean.shadow.f|ocean.shadow.f]] (uses anti-clockwise convention for azimuth angle!)
+  * wind speed: 5 m/s
+  * mean surface slope, according to Eq. 18 in Mishchenko and Travis 1997:\\ 2$\sigma^2$ = 0.003 + 0.00512 $\cdot$ u$_{10}$, where u$_{10}$ is the wind speed in m/s
+  * refractive index of water: 1.33+0i
+  * wavelength: 450 nm
+  * Rayleigh depolarization factor: 0.03
+  * Earth radius: 6371 km
+  * Observer at 3.0e5 km distance from center of Earth at (lan, lon)=(0°, 0°)
+    * Field of view of 2.44° includes the complete planet:
+      * The result is an image with 61$\times$61 pixels with resolution 0.04°$\times$0.04°:
+      * Directions within the FOV should be randomly distributed
+      * pixel center zenith angles: //vza:// -1.2° - +1.2°, increment 0.04°
+      * pixel center azimuth angles: //vaa:// -1.2° - +1.2°, increment 0.04°
+      * Here the angles refer to the connection line between Earth center and observer.
+  * Sun position:
+    * latitude: //lat:// 0°
+    * longitudes: //lon:// 50°, 90°, 110°, 130°
+    * The longitude of the sun position corresponds to the phase angle.