Daytime temperatures in Clay in Soil texture

[N.Suzuki]

I am currently studying the heat island of Bangkok, Thailand as part of a Southeast Asian urban climate research.

This study uses WRF versions 4.2.2 and 4.3.3.
Also, Noah LSM and Single layer UCM are used.

I have run simulations on many cases, but the simulations do not reproduce the daytime and surface temperatures correctly.
In particular, daytime temperatures cause a high-temperature bias in clayey soils.

As an example, I share the following figures:
(a) Soil category (top layer) as simulated by WRF
(b) Surface temperature at 11:00 local time on June 19, 2022 (Himawari 8 satellite observation)
(c) Surface temperature at the same time simulated by WRF (Inside the black line indicates the urban area)

These symptoms appear only during the day and are not seen at night.

These results occur even if the initial condition and physical scheme are changed.
Also, when Clay was changed to Loam for testing purposes, the high temperature in the upper left corner of the area disappeared.

This high-temperature bias in clayey soils occurs mainly in the Southeast Asian region, including Manila, Philippines, Kuala Lumpur, Malaysia, and Ho Chi Minh City, Vietnam.

Please let us know if you have any remedies to improve this high-temperature bias.

Best regards,

 

[haiqingsong]

You may need to use observed soil textures for WRF simulations.

 

[rdumais63]

Since you are using Noah could it be that certain soil properties that are set in the SOILPARM.TBL need modification for these soils in your study area? WRF/run/SOILPARM.TBL at master · wrf-model/WRF

 

[rdumais63]

Here is an article that might address this a bit? Updated soil map and soil hydrologic parameters for WRF and their influences over North China during the warm season

 

[N.Suzuki]

Thank you for your many responses.
Upon investigation, we found that this was due to the low resolution of soil conditions.

Thank you so much.