Dear Ferret users,
I am trying to write a script to map out areas that have the following climate conditions within this coordinate (x =2:15, y=4:14). The gridded NC files data contains 51 ensemble members from ECMWF under the auspices of the GCRF African-SWIFT Research Project. Although there is no relative humidity in the data, other parameters such as specific humidity, mean sea level pressure and temperature in which relative humidity can be derived are present. The data could be viewed from the screenshot attached below which are Plv-24in-ecmwf, sfc-24in-ecmwf and sfc-24mn-ecmwf .
http://web.csag.uct.ac.za/~lawal/S2S_rt_data/ECMWF/
Below is how I arrived at relative humidity;
From the three set of data using this relationship RH = ((Q * msl)/(0.622 * es))
Where Q: is specific humidity (kg kg**-1) in Plv-24in-ecmwf,
msl: Mean sea level pressure (Pa) in sfc-24in-ecmwf
es: Saturated vapour pressure given as: es = 6.1094 * exponential value^((17.625 * sfc-temp)/( sfc-temp + 243.04)).
FILL RH[l=1:10@ave, m=1:51@ave, x = 2:15, y=4:14]; go land 7 " " 7
However, the other two variables needed for my script is inside the data directly
V wind is contained in Plv-24in-ecmwf while sfc-24mn-ecmwf contains 2 metre temperature.
Threshold
|
| V wind | Relative Humidity | Surface Temperature |
White colour | No cause for alarm | + ve | > 40 | > 21 |
Ash colour | Mild | – ve | < 40 | 21 – 24 |
Yellow colour | Moderate | – ve | < 40 | 24 – 27 |
Brown colour | Severe | – ve | < 40 | 27 – 30 |
Red colour | Danger | – ve | < 40 | > 30 |
Could someone or anybody that has done similar work help me with a script to link the above three climate variables in order to have a single map like the vigilance map attached below.
Best regards
Aliyu Abubakar Sadiq
Attachment:
Screenshot from 2020-09-30 16_30_44.png
Description: PNG image
Attachment:
Map.PNG
Description: PNG image
