Opened 3 months ago

Last modified 4 weeks ago

#883 new defect

Discontinuity in seasonal GPP timeseries in the tropics

Reported by: mmcgrath Owned by: somebody
Priority: major Milestone: ORCHIDEE 4.2
Component: Biogeochemical processes Version: trunc
Keywords: Cc:


In the comparisons of reference simulations for 2.2, 3.0, and 4.1, an apparent discontinuity appears in the TAG4.1 timeseries that is not present in the other two. The GPP is very high in January (80 Pg) and very low in December (50 Pg), showing a decreasing trend at the end of the year.

One would expect cyclical behavior, where if the trend in December is pointing downward, the value in January is lower, or at least around the same level. ORC2.2 and ORC3 also show decreasing trends at the end of the year, but the January value is lower than the December value.

A problem in phenology counters is suspected, perhaps because of the fact that half of the tropics are north of the equator and half are south (this jump is not noticed in northern lands).

This is r7692 (essentially what was tagged as 4.1), and appeared in an FG2 run. It also appears in LAI, NPP, NBP, and NPP/GPP ratio, but seems simplest to address in GPP.

Attachments (1)

gpp_s_t.png (88.7 KB) - added by mmcgrath 3 months ago.
Comparison of GPP for 2.2, 3.0, and 4.1 in tropical lands.

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Change History (2)

Changed 3 months ago by mmcgrath

Comparison of GPP for 2.2, 3.0, and 4.1 in tropical lands.

comment:1 Changed 4 weeks ago by bguenet

Nicolas Viovy will have a look to the simulations

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