wrf.interplevel and wrf.vinterp results in very high values for vertical temperature gradients

[israt246]

Hello, I am trying to calculate the vertical temperature gradient between the surface and 1 km AGL.
I did the following:

temp2m= wrf.getvar(wrfnc,'T2') #wrfnc is the WRF output file for a specific hour
tk= wrf.getvar(wrfnc,'tk') # Temperature in Kelvin
height_agl= wrf.getvar(wrfnc,'height_agl') # Model Height for Mass Grid (AGL) in m
temp_1km = wrf.interplevel(tk, height_agl, 1000) # tempertaure interpolated to 1000 m above AGL

Then I caculate dthe temperature gradient between surace and 1 km AGL as follows:
del_T1= temp_1km-temp2m # kelvin
del_h1= 998 #1000 m- 2 m
Temp_gradient= -(del_T1/del_h1)*1000 # -dT/dz (K/km)

I am getting very high values for temperature gradient between surface and 1 km above ground level, and I am not sure if they are meteorologically correct. I have attached a screenshot of the values.

I also tried using wrf.vintep as follows:
temp_1km = wrf.vinterp(wrfnc, field=tk, vert_coord="ght_agl", interp_levels=[1], extrapolate=True,field_type="tk")
The document (https://wrf-python.readthedocs.io/en/main/user_api/generated/wrf.vinterp.html) says ’ght_agl’= grid point height agl [km], so I set the interp_levels as 1 km. But I similar results with slight difference.