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APSIMInitiative / ApsimX

ApsimX is the next generation of APSIM
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SoilWat resetting U/Cona when switching summer/winter U-Cona #8112

Open KirstenVer opened 1 year ago

KirstenVer commented 1 year ago

What happened?

In absence of rainfall, APSIMX SoilWat resets U/Cona when it switches to summer U/Cona values. (The same may happen when it goes to winter U/Cona, but the example simulation had rainfall at that time, so not as noticeable.)

In the example simulation we see a sudden drop in soil water content in surface layers and accompanying spike in Es compared with parallel SWIM3 run (as part of an experiment with Model as treatment). image ErrorUConaReset.zip

What Operating System are you on?

Windows

hol353 commented 1 year ago

The problem was as artifact of the discontinuous nature of 2 stage evap. When CONA / U suddenly changed, the ES calculation when from stage 2 into stage 1 evaporation due to this test:

            // are we in stage1 ?
            if (sumes1 < U)
            {

I've added a small bit of code to reset sumes1 and sumes2 when the change over from summer/winter occurs. On the graph below you can now see that ES doesn't have a big jump up. Instead there is a small increase which is due to the changed CONA value. A new release of APSIM with this change will be available in about 30 minutes.

image

KirstenVer commented 1 year ago

Belated Thanks Dean! (missed the notification)

par456 commented 5 months ago

In the new system, when we reset U, 2nd stage evaporation is staying high leading to higher evaporation afterwards.

A new test is needed to look at fallow through winter on clay soils, after U and CONA is set from high summer to low winter values. TO Check the magnitude of the change, as it seems to be significant in some of the datacube sims.