Changes between Version 37 and Version 38 of Branches/Driver_Improvements

Timestamp:

2016-06-03T13:57:40+02:00 (8 years ago)

Author:

jpolcher

Comment:

--

Branches/Driver_Improvements

@@ -121 +121 @@
 The ORCHIDEE trunk version of May 2016 is used for these tests. All forcing are used at a 900s time-step and the model is configured to output through XIOS at this same time step. This ensures that all the post-processing done XIOS on the forcing variables ORCHIDEE outputs is negligible compared to the assumptions on the time axis in the forcing.
 
-From the forcing files a small region (lon=-10.3:5.3 lat=35.3:45.3) was extracted to reduce computing time and ensure that the original data set could easily be compared to the model output.
+From the forcing files a small region (lon=-10.3:5.3 lat=35.3:45.3) was extracted to reduce computing time and ensure that the original data set could easily be compared to the model output. The year 2006 was used, except for WFD which does not cover this period so 1996 was used.
 
 Orchideedriver needs some information on the time representativeness of the data for its interpolations. The CF convention proposes to put this information into the attribute "cell_methods". This information is not used by dim2driver.
@@ -191 +191 @@
 == Conclusions ==
 
-
+For all the low frequency forcing (less frequent than hourly) dim2driver does to provide the correct forcing to ORCHIDEE. This is due to the fact that we use instantaneous values for scalars and averages for fluxes. Some more detailed conclusions are apparent from these tests.
+
+- Two categories of forcing emerge because of their different conventions as to the placement of the mean values : ERA based (WFDEI, GSWP) or NCEP based (CRUNCEP, PGF). WFD is a little particular here.
+
+- The attribute "cell_methods" is needed in the files so that the drivers can perform correct time interpolations.
+
+- The phasing of the diurnal cycle of the atmospheric variables is important in defining the potential evaporation.
+
+- As demonstrated by the figures below the correct treatment of the diurnal cycle in orchideedriver results in much more comparable potential evaporation in ORCHIDEE. Or in other words dim2driver introduces differences which are not physical.
+
+ [[Image( CompareForcing_driver-4.png, width=40%)]] [[Image( CompareForcing_dim2-4.png, width=40%)]]
+
+- dim2driver generally underestimates potential evaporation.
+
+- Should a forcing have its fluxes centred on the time interval of averaging, perhaps dim2driver would behave correctly. 
+
+