Changes between Version 38 and Version 39 of DevelopmentActivities/ORCHIDEE-DOFOCO

Timestamp:

2013-01-21T11:50:47+01:00 (11 years ago)

Author:

mmcgrath

Comment:

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DevelopmentActivities/ORCHIDEE-DOFOCO

@@ -30 +30 @@
         * The new scheme was compared against the old one in v1.9.6.0, and the results are qualitatively similar, but not identical
         * A 20 layer model was tested against the single layer model, giving small differences (a few percent, relative, at midday)
-        * We tried to optimize the single scattering and forward efficiency values in the n-layer case to reproduce the average albedo in the 1-layer case, but a simple optimization scheme is only able to make very small gains and takes an order of magnitude more time...it appears that the n-layer albedo values cannot be optimized with respect to both the 1-layer direct and diffuse albedo to within 1% of each value in the general case, though it often works when the sun is high in the sky
+        * We tried to optimize the single scattering and forward efficiency values in the n-layer case to reproduce the average albedo in the 1-layer case, but a simple optimization scheme is only able to make very small gains and takes an order of magnitude more time...it appears that we might be able to optimize the diffuse and direct TOC albedo to match the 1-layer case, but it could take thousands of steps for a simple compass search (four function evals per step), even adjusting the step length during the optimization....maybe try a generalized set search and vary the step directions as well?
         * Inclusion of the new snow albedo gives realistic trends, with the total albedo spiking after snowfalls and showing diurnal variation with leaves are present, but being flat at other times (the solar angle is incorporated through the use of Pgap, which mostly depends on the canopy)
         * I made use of single scattering albedos that Juliane got from Bernard's inversion scheme for 20 tree species, running tests with the min and max values for single scattering albedo and forward scattering efficiency for both VIS and NIR bands...the MUE for the overal albedo varies by 0.01 to 0.04 albdo units depending on the spectrum, showing that we should take this into account