Opened 4 years ago

Closed 4 years ago

# Problem throughfall_by_mtc

Reported by: Owned by: maignan somebody major Anthropogenic processes

### Description

In constantes_mtc.f90, we have:

```166	  REAL(r_std), PARAMETER, DIMENSION(nvmc) :: throughfall_by_mtc  =  &  !! Fraction of rain intercepted by the canopy
167	  & (/ 30.0,   30.0,   30.0,   30.0,   30.0,   30.0,   30.0,  &        !! (0-100, unitless)
168	  &    30.0,   30.0,   30.0,   30.0,   30.0,   30.0  /)
```

In hydrol_canop, we have:

```3722	    !
3723	    !! 1.3 Limits the effect and sum what receives soil
3724	    !
3725	    precisol(:,1)=veget_max(:,1)*precip_rain(:)
3726	    DO jv=2,nvm
3727	       DO ji = 1, kjpindex
3728	          zqsintvegnew(ji,jv) = MIN (qsintveg(ji,jv),qsintmax(ji,jv))
3729	          precisol(ji,jv) = (veget(ji,jv)*throughfall_by_pft(jv)*precip_rain(ji)) + &
3730	               qsintveg(ji,jv) - zqsintvegnew (ji,jv) + &
3731	               (veget_max(ji,jv) - veget(ji,jv))*precip_rain(ji)
3732	       ENDDO
3733	    END DO
3734	    !
```

Is the comment false in constantes_mtc.f90, is throughfall_by_mtc the PERCENTAGE of rain NOT intercepted by the canopy, as implied by the name and the use in hydrol_canop? Could we add some reference for the chosen value?

### comment:1 Changed 4 years ago by aducharne

I agree about the comment in constantes_mtc.f90.

Regarding the origin of the values, I think it was introduced by Nathalie de Noblet for CMIP5. Not sure it's more than a rule of thumb to correct some biases...

Agnès

### comment:2 Changed 4 years ago by maignan

References (reported by Catherine)

Gash, J. H. C. (1979). An analytical model of rainfall interception by forests. Quarterly Journal of the Royal Meteorological Society, 105(443), 43-55.

Miralles, D. G., Gash, J. H., Holmes, T. R., de Jeu, R. A., & Dolman, A. J. (2010). Global canopy interception from satellite observations. Journal of Geophysical Research: Atmospheres, 115(D16).

Schneebeli, M., Wolf, S., Kunert, N., Eugster, W., & Mätzler, C. (2011). Relating the X-band opacity of a tropical tree canopy to sapflow, rain interception and dew formation. Remote sensing of environment, 115(8), 2116-2125.

van Dijk, A. I., Gash, J. H., van Gorsel, E., Blanken, P. D., Cescatti, A., Emmel, C., ... & Montagnani, L. (2015). Rainfall interception and the coupled surface water and energy balance. Agricultural and Forest Meteorology, 214, 402-415.

### comment:3 Changed 4 years ago by jgipsl

Change of comment has been done here in the trunk rev [4752]. New comment :
Percent by PFT of precip that is not intercepted by the canopy
P Peylin

### comment:4 Changed 4 years ago by jgipsl

• Resolution set to fixed
• Status changed from new to closed

Note that the references above concerne the interception(qsintmax) and not directly the throughfall, C. Ottle.

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