negative water table depth (ZWT) with opt_run=5

[xiao.zh]

Hi all,
I ran a simulation with opt_run = 5 and obtained negative values for water table depth (ZWT), see Fig below(first output, simulation starts at 2013-01-01_00:00:00). ZWT in wrfinput is zero.

As I understand it, ZWT is defined as positive downward.

When using opt_run = 1, ZWT remains positive in my simulation.

I’m wondering whether the negative ZWT values with opt_run = 5 are correct?

 

[xiao.zh]

ZWT is negative with opt_run=5.
I found it in "THE COMMUNITY NOAH-MP LAND SURFACE MODELING SYSTEM TECHNICAL DESCRIPTION VERSION 5.0.pdf".
Page 177 said:

 

[Ming Chen]

I looked at the related codes in NoahMP, and I believe that ZWT should be positive downward. I have no answer why the model yields negative value of ZWT when running with option 5. I have forwarded your question to our expert. Hope we can figure out what is wrong in this case.

 

[cenlinhe]

ZWT direction is defined in an opposite way in option = 1 and 5.
In option=1, ZWT > 0
In option.=5, ZWT<0

 

[xiao.zh]

I looked at the related codes in NoahMP, and I believe that ZWT should be positive downward. I have no answer why the model yields negative value of ZWT when running with option 5. I have forwarded your question to our expert. Hope we can figure out what is wrong in this case.

Hi Ming,
ZSOIL is set to be negative:

opt_run=5, in SUBROUTINE SHALLOWWATERTABLE:
ZWT should be negative.


opt_run=1, in SUBROUTINE GROUNDWATER:
ZWT should be positive.

 

[xiao.zh]

ZWT direction is defined in an opposite way in option = 1 and 5.
In option=1, ZWT > 0
In option.=5, ZWT<0

Yes, thanks

 

[Ming Chen]

Thank you for the clarification ! @cenlinhe @xiao.zh.