Cooling after Deforestation in Tropics

Any miscellaneous question/problem/comment related to WRF support that does not fit under any of the other category
Post Reply
Astrid
Posts: 10
Joined: Wed Jun 12, 2019 2:53 pm

Cooling after Deforestation in Tropics

Post by Astrid » Thu Oct 31, 2019 10:47 pm

Dear all,

I am fairly new to WRF, but managed to run some deforestation scenarios over Colombia to study the impact of land cover/land use change on climate in the tropics. While I was preparing my input data (ERA-Interim) and running the control and deforestation scenario (I changed the physical properties of evergreen broadleaf forest to cropland and pasture in the VEGPARM.TBL and LANDUSE.TBL) everything seemed fine.
But now when comparing the runs, surface temperature over the deforested areas are about 0.1°C - 0.3°C cooler than in the control run. All existing literature on deforestation impacts says the contrary: temperature should rise after deforestation in the tropics!

Now I am confused and a little desperate (it's my master's thesis topic), because I can't find any possible reason for that.

If anyone had some similar problem or any idea what could be the reason for this cooling, I would be very grateful.

Cheers,
Astrid

kwerner
Posts: 2287
Joined: Wed Feb 14, 2018 9:21 pm

Re: Cooling after Deforestation in Tropics

Post by kwerner » Tue Nov 12, 2019 7:27 pm

Hi Astrid,
I would first like to apologize for the delay in response. Thank you for your patience. Have you been able to make any progress with this inquiry since posting it? If not, can you attach your namelist.input file so that we can see which options you are using, and let me know which version of WRF you are using? Thanks!
NCAR/MMM

Astrid
Posts: 10
Joined: Wed Jun 12, 2019 2:53 pm

Re: Cooling after Deforestation in Tropics

Post by Astrid » Tue Nov 12, 2019 10:30 pm

Hey Kelly,
no worries! I am so glad that you have a look!

No, unfortunately not. I was trying to find good literature on the albedo of tropical agriculture and pasture to use in the VEGPARM.TBL and will run some small tests with the values I found. I use WRF Version 3.9.1.1.
Furthermore, I analyzed my radiation balance and it seems that sensible heat flux decreases over deforested areas, while it should increase in the tropics. Changes in albedo, latent heat, upward & downward shortwave and long wave fluxes and evaporation, runoff and precipitation look ok though.

So, here it comes.
Cheers!
Astrid
namelist.input
(5.84 KiB) Downloaded 29 times

kwerner
Posts: 2287
Joined: Wed Feb 14, 2018 9:21 pm

Re: Cooling after Deforestation in Tropics

Post by kwerner » Thu Nov 14, 2019 12:15 am

Hi,
I spoke to our physics specialist about this. He believes the most likely culprit for cooling is the albedo change when you remove trees. He also says that it's not completely unrealistic for deforestation to lead to cooling. I have recently seen a study that found that deforestation can cause an overall warming effect, globally, but there are some specific locations where the temperatures do decrease.
NCAR/MMM

Post Reply

Return to “Miscellaneous”