Scheduled Downtime
On Friday 21 April 2023 @ 5pm MT, this website will be down for maintenance and expected to return online the morning of 24 April 2023 at the latest

geogrid : land use classification.

D

Dipson11

Member
hello, I am trying to plot the land use classification for a city. can I leave geo_data_res='default' as it is? In tutorials it says we can use geo_data_res='nlcd2011_9s + default' for selecting a dataset. So, do I have to change it to geo_data_res='modis + default' if I want to see the landuse classification from modis?

My purpose is to generate the landuse classification of the city so Im thinking of running the geogrid first and then vislualizing 'geo_em.d01.nc' using ncview, is it a right approach or do you suggest any other tools?

Thank you
 

USGS and MODIS Land Use​

By default, the geogrid program interpolates land use categories from MODIS IGBP 21-category data. However, an alternative set of land use categories based on the USGS land-cover classification may be selected. Although MODIS-based data contain 21 categories of land use, these categories are not a subset of the 24 USGS categories. See Land Use and Soil Categories in the Static Data for a listing of the specific land use categories for either data set.

24-category USGS-based land use data may be selected instead of the MODIS data at run-time using the geog_data_res variable in the &geogrid namelist record by prefixing each resolution of static data with the string usgs_lakes+. For example, in a two-domain configuration, where geog_data_res would ordinarily be specified as

geog_data_res = 'default', 'default',

it should instead be specifed as

geog_data_res = 'usgs_lakes+default', 'usgs_lakes+default',



This change instructs the geogrid program to look in each entry of the GEOGRID.TBL for a resolution of static data denoted by ‘usgs_lakes’, and if such a resolution is not available, to instead look for a resolution denoted by the string following the ‘+’. Thus, for the GEOGRID.TBL entry for the LANDUSEF field, the USGS-based land use data, identified with the string ‘usgs_lakes’, would be used instead of the ‘default’ resolutions (or source) of land-use data in the example above; for all other fields, the ‘default’ resolutions would be used for the first and second. As an aside, when none of the resolutions specified for a domain in geog_data_res is found in a GEOGRID.TBL entry, the resolution denoted by ‘default’ will be used.

Note
To change from the default 21-class MODIS land-use data, the ‘num_land_cat’ variable must be set to ‘21’ in the ‘physics’ namelist record in the WRF namelist.input file. For 24-class USGS data, ‘num_land_cat’ should be set to 24.
Click to expand...
 
Hey , william. Thank you very much for your suggestion. I want to use WRF- Urban canopy model (UCM) with a single canopy layer. I am bit confused because in the documentation it says that WRF version acounts for 3 urban classes in the usgs and MODIS describing "low density residential", "high density rsidential" and " Industrial commercial", which are 31,32 and 33. I read an article og WRF-URBAN 4.3: local climatic zones and it states that we can now incorporate 11 urban classes by injecting LCZ. when I tried LCZ generator it has 17 classes (1,2,3,4,5,6,7,8,9,10,A,B,C,D,E,F,G), how does it incorporate?

SInce I am doing my analysis for a small city. Do you think i should use the default 3 urban classes ?geog_data_res = 'default' or geog_data_res = 'LCZ + default'


Thank you very much.
 
Dipson11 said:
Hey , william. Thank you very much for your suggestion. I want to use WRF- Urban canopy model (UCM) with a single canopy layer. I am bit confused because in the documentation it says that WRF version acounts for 3 urban classes in the usgs and MODIS describing "low density residential", "high density rsidential" and " Industrial commercial", which are 31,32 and 33. I read an article og WRF-URBAN 4.3: local climatic zones and it states that we can now incorporate 11 urban classes by injecting LCZ. when I tried LCZ generator it has 17 classes (1,2,3,4,5,6,7,8,9,10,A,B,C,D,E,F,G), how does it incorporate?

SInce I am doing my analysis for a small city. Do you think i should use the default 3 urban classes ?geog_data_res = 'default' or geog_data_res = 'LCZ + default'


Thank you very much.
Click to expand...
Good morning,

I will admit that urban is by far one of my worst areas when it comes to WRF.

There are so many variables that come into play with urban schemes and the small resolution needed for it. So instead of guessing i'll have to defer you to the NCAR staff @kwerner and @Ming Chen
 
You must log in or register to reply here.
Top