NCM Logo
Isolines | Label High and Low pressure systems | Automated Weather Fronts

Isolines, Label Pressure Systems and Weather Fronts

Isolines

The NCM API allows to get data in order to visualize isolines for different parameters. The data about isolines is provided in the format GeoJSON, which can be easily integrated in any web-application.

http://api-mm.ncm.gov.sa/get_isolines?<fields>
FieldDescriptionExample
parameter Parameter from the available parameters in the API. Note that only one parameter can be fetched per isoline query. parameter=t_2m:C
bbox A bounding box specified by maximal and minimal latitude and longitude formatted according to bbox=<min_lon,min_lat,max_lon,max_lat> (please note the order). bbox=5.8,45.7,10.7,47.9
Optional fields
datetime A single point in time (UTC) as specified in the section Date/Time Description. datetime always refers to validdatetime. The default setting is now. datetime=2018-04-12T12:45Z
isoline_range Define an interval for which isolines shall be generated. The structure is as follows: start,end,spacing. isoline_range=-40,40,5
isoline_values Define a single value or a list of values for which isolines shall be generated. If isoline_values=5 is set for temperature, then only the 5 °C-isotherm is generated. isoline_values=0,0.5,1,1.5,2,2.5,3
resolution Set the resolution of the input data, which the calculated isolines are based on (either in degrees or pixels): <resolution_lat>,<resolution_lon> or <number_lons>x<number_lats> resolution=0.05,0.05 or resolution=400,300
source Select the desired model/source. source=mix
radius_median_filter Smoothing of isolines. Enter number between 0-10. Default is 1. radius_median_filter=1
radius_gaussian_filter Smoothing of isolines. Enter number between 0-10. Default is 3. radius_gaussian_filter=3
isoline_min_points Minimum number of points per isolines. Must be at least 2. isoline_min_points=2

Examples

Label High and Low pressure systems

The NCM API also allows to label regions of high and low pressure with the corresponding letters H and L. The data format is a GeoJSON file, which provides minima and maxima of mean sea level pressure in a given boundary box. This allows for an easy integration in any web-application.

http://api-mm.ncm.gov.sa/get_highs_lows?<fields>
FieldDescriptionExample
parameter Parameter which the labeling of highs and lows is based on. parameter=msl_pressure:hPa, parameter=geopotential_height_700hPa:m
bbox A bounding box specified by maximal and minimal latitude and longitude formatted according to bbox=<min_lon,min_lat,max_lon,max_lat> (please note the order). bbox=5.8,45.7,10.7,47.9
Optional fields
datetime A single point in time (UTC) as specified in the section Date/Time Description. datetime always refers to validdatetime. The default setting is now. datetime=2018-04-12T12:45Z
isoline_range Define an interval for which isolines shall be generated. The structure is as follows: start,end,spacing. The default setting for the parameter msl_pressure:hPa is 960, 1040, 4 (in hPa). If other units like Pa or psi are used, the interval has to be defined in the respective unit. isoline_range=1000,1020,3
isoline_values Define a single value or a list of values for which isolines shall be generated. If isoline_values=5 is set for temperature, then only the 5 °C-isotherm is generated. isoline_values=0,0.5,1,1.5,2,2.5,3
resolution Set the resolution of the input data, which the calculated isolines are based on (either in degrees or pixels): <resolution_lat>,<resolution_lon> or <number_lons>x<number_lats> resolution=0.05,0.05 or resolution=400,300
source Select the desired model/source. source=mix
radius_median_filter Smoothing of isolines. Enter number between 0-10. Default is 4. radius_median_filter=1
radius_gaussian_filter Smoothing of isolines. Enter number between 0-10. Default is 3. radius_gaussian_filter=3

Examples

Automated Weather Fronts

The NCM API allows to get automatically identified weather fronts. It distingushes between cold fronts, warm fronts, stationary fronts and upper-level fronts. Also, the direction in which the fronts are moving is provided. The data to display automated weather fronts is provided in the format GeoJSON, which can be easily integrated in any web-application.

http://api-mm.ncm.gov.sa/get_weather_fronts?<fields>
FieldDescriptionExample
datetime A single point in time (UTC) as specified in the section Date/Time Description. datetime always refers to validdatetime. datetime=2023-04-27T12:45Z
bbox A bounding box specified by maximal and minimal latitude and longitude formatted according to bbox=<min_lon,min_lat,max_lon,max_lat> (please note the order). bbox=5.8,45.7,10.7,47.9
Optional fields
source Select the desired model/source. The default setting is ecmwf-ifs. source=ecmwf-ifs, source=ncep-gfs, source=ukmo-um10

Example