Urban Cooling_ T air calculate error

[zhongan.wang]

hello,

I have encountered problems with air temperature calculation in the Cooling model.
I got the Tair_nomix (seems correct),but their has no value for Tair.
The column in the aoi.shp is Null for avg_tmp_v and avg_tmp_an.

T_air_nomix(left) T_air(right)

Is there any possible way to solve this condition? thanks

[dave]

Hi @zhongan.wang , I think the same issue just came up over here Urban Cooling _ nan values (new) - #8 by dave

@dave

I think the critical thing here is that the extent of the LULC extends beyond the Area of Interest by at least the distance of the “max blending distance”. When this is not the case, the nodata values from the edges of the LULC seem to creep deep into the AOI during the convolution steps. (This is evident in nodata appearing in intermediate/T_air.tif ). I think we may be able to improve the model’s behavior there, but for now you found a good workaround by using a larger LULC.

Do you think this is the same problem?

[zhongan.wang]

thanks @dave for your reply,

I had tried your solution earlier, it can calculate T air well for small area.

But still can’t works when I put all my study area in. The aoi.shp already clips for 1500m from the edges lulc raster, and my air blending area set for only 100m. The result as below.

• The one in the middle is the success one (for a town scale).
• The pink line is the edge of area of interest.
• The black polygon is the Tair rater; grayscale is Tair nomix raster.
• The bottom one are lulc raster.

As the T air shows a rectangular area, does it means the lulc raster need to cover all rectangular extent area of aio.shp?

thanks alot

[dave]

Hi @zhongan.wang , thanks for following up. There may indeed be a problem with the convolution step that creates T_air.tif from T_air_nomix.tif and how it handles nodata pixels. I haven’t had time yet to reduce the problem to a small reproducible example, but it’s on my todo list.

@zhongan.wang

As the T air shows a rectangular area, does it means the lulc raster need to cover all rectangular extent area of aio.shp?

I think it should be okay if the lulc raster has nodata values outside the bounds of the AOI shape, but due to a bug, that may be a problem. I’ll try to learn more about what is happening soon.