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Query Endpoint

Base URL: http://modms.devops.arabiaweather.com/q

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Query Parameters

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Fields

Specify which variables to retrieve using the fields parameter: 
fields=time | location | MODEL.VAR
  • time: Timestamp for each data point
  • location: Geographic coordinates (latitude, longitude)
  • MODEL.VAR: Model variable in format MODEL.LEVEL.VARIABLE
Multiple fields: Separate with | (pipe with spaces)

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Time Range

Specify time range using the time parameter: 
time=[start TO end]
time=[now TO timestamp]
time=[start TO end STEP interval]
Formats:
  • Unix timestamp: 1762355295
  • now: Current time
  • STEP: Time interval for interpolation (e.g., 60 minutes)

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Location

Specify geographic location using the location parameter: 
location=(latitude, longitude)
Format: (lat, lon) with decimal degrees

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Variable Format

Variables follow the pattern: MODEL.LEVEL.VARIABLE Examples:
  • GFS.ATM.TCDC - GFS total cloud cover
  • GEM.GND2M.TMP - GEM 2m temperature
  • UK10.GND10M.UGRD - UK10 10m U-wind component
  • ICON.SFC.APCP.HR - ICON hourly precipitation
Common Models:
  • GFS - Global Forecast System
  • GEM - Global Environmental Multiscale
  • UK10 - UK Met Office
  • ICON - ICOsahedral Nonhydrostatic
  • WRFME - WRF Middle East
  • EC25 - ECMWF
  • AIFS - AIFS model

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Model Run Specification

You can specify a particular model run using the @ syntax: ModMS (Main Server):
  • MODEL.LEVEL.VARIABLE - Uses the latest available run
  • MODEL@model-run.LEVEL.VARIABLE - Specifies a specific model run (e.g., GFS@2218)
MAMS (Archive Server):
  • MODEL@timestamp.LEVEL.VARIABLE - Must use Unix timestamp format (e.g., GFS@1766577600)
Important: MAMS requires timestamp format (MODEL@timestamp), while ModMS supports both model-run format (MODEL@model-run) and timestamp format.
Examples:
  • ModMS: GFS@2218.ISO200HPA.UGRD (model run format)
  • MAMS: GFS@1766577600.ISO200HPA.UGRD (timestamp format)
  • ModMS: GFS.ISO200HPA.UGRD (uses latest available run)

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Mathematical Expressions

ModMS supports complex mathematical expressions in queries using the muparser library and custom functions.

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Basic Math Operations

Standard arithmetic operations:
  • + - Addition
  • - - Subtraction
  • * - Multiplication
  • / - Division
  • % - Modulo (via mod() function)
  • ^ - Power

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Comparison Operators

  • == - Equal
  • != - Not equal
  • > - Greater than
  • < - Less than
  • >= - Greater than or equal
  • <= - Less than or equal
  • && - Logical AND
  • || - Logical OR (via or() function)

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Conditional Expressions

Ternary operator for conditional logic: 
condition ? value_if_true : value_if_false
Example: 
(LSM.LSM == 0 && speed(GFS.GND10M.UGRD, GFS.GND10M.VGRD) > 7) ? 100 : 0

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Built-in Functions

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Aggregation Functions

min(value1, value2, ...)
  • Returns minimum value, ignoring NaN
max(value1, value2, ...)
  • Returns maximum value, ignoring NaN
avg(value1, value2, ...)
  • Returns average of values, ignoring NaN
median(value1, value2, ...)
  • Returns median value (up to 15 values), ignoring NaN

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Model Merging Functions

merge(value1, value2, ...)
  • Returns first non-NaN value from left to right
  • Used to combine multiple model sources with fallback
cmerge(time, value1, lastTime1, value2, lastTime2, ...)
  • Time-weighted merge based on model freshness
  • First parameter is current time
  • Then pairs of (value, last_available_time)
  • Weights models by how recent their data is

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Wind Functions

speed(u, v)
  • Calculates wind speed from U and V components
  • Formula: sqrt(u² + v²)
dir(u, v)
  • Calculates wind direction from U and V components
  • Returns direction from north in degrees (0-360)

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Meteorological Functions

rh(temp, dewpoint)
  • Calculates relative humidity from temperature and dewpoint
  • Both parameters in Kelvin
dpt(temp, rh)
  • Calculates dewpoint from temperature and relative humidity

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Consensus Functions

consensus(value1, value2, ...)
  • Finds longest chain of similar values and returns average
  • Used for model ensemble consensus
consensusT(threshold, value1, value2, ...)
  • Consensus with threshold - groups values above/below threshold
  • First parameter is threshold value
consensusL(maxDiff, value1, value2, ...)
  • Linear consensus with maximum difference parameter
  • First parameter is maximum allowed difference
confidenceGT(threshold, value1, value2, ...)
  • Returns confidence (0-1) that values are above threshold
confidenceBT(threshold, value1, value2, ...)
  • Returns confidence (0-1) based on threshold comparison

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Filter Functions

filter(value, currentTime, maxTime)
  • Returns value only if currentTime is less than maxTime, else NaN
filter(value, currentTime, minTime, maxTime)
  • Returns value only if minTime is less than or equal to currentTime and currentTime is less than maxTime, else NaN

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Utility Functions

nearest(target, value1, value2, ...)
  • Returns value closest to target
nearestxy(target, x1, y1, x2, y2, ...)
  • Returns y-value whose x-value is closest to target
or(value1, value2, ...)
  • Logical OR - returns first truthy value
fzero(x1, y1, x2, y2, ...)
  • Finds zero crossing point between data points
mod(value, divisor)
  • Modulo operation

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Unit Conversion

conv("unit1>unit2", value)
  • Converts between units using UDUNITS library
  • Example: conv("kelvin>celsius", GFS.GND2M.TMP)

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Query Capabilities

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1. Single Model Queries

Query data from a single model: 
GFS.GND2M.TMP - 273.15

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2. Multi-Model Merging

Combine multiple models with fallback: 
merge(WRFME.ISO850HPA.TMP, GFS.ISO850HPA.TMP) - 273.15

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3. Model Averaging

Average values from multiple models: 
avg(GFS.ISO500HPA.TMP, UK10.ISO500HPA.TMP) - 273.15

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4. Model Median

Get median from multiple models: 
median(speed(EC25.GND10M.UGRD, EC25.GND10M.VGRD), 
       speed(GFS.GND10M.UGRD, GFS.GND10M.VGRD), 
       speed(ICON.GND10M.UGRD, ICON.GND10M.VGRD))

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5. Conditional Calculations

Use conditional logic based on conditions: 
(LSM.LSM == 0 && speed(GFS.GND10M.UGRD, GFS.GND10M.VGRD) > 7 && 
 GFS.GND2M.RH < 60 && GFS.SFC.APCP.HR <= 0) ? 
 (min(speed(GFS.GND10M.UGRD, GFS.GND10M.VGRD) / 7 * 0.5, 1.0) * 
  GFS.GND2M.RH < 40 ? 100 : (GFS.GND2M.RH * -2.5 + 200)) : 0

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6. Derived Variables

Calculate derived meteorological variables: 
speed(GFS.GND10M.UGRD, GFS.GND10M.VGRD)
dir(GFS.GND10M.UGRD, GFS.GND10M.VGRD)
rh(GEM.GND2M.TMP, GEM.GND2M.DPT)

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7. Time-Based Filtering

Filter values based on time constraints: 
filter(GFS.SFC.APCP.HR, time, GFS.RUNTIME + 72)

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8. Time-Weighted Merging

Merge models based on data freshness: 
cmerge(time, EC25.GND10M.UGRD, EC25.LASTTIME, 
       ICON.GND10M.UGRD, ICON.LASTTIME, 
       GFS.GND10M.UGRD, GFS.LASTTIME)

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9. Ensemble Consensus

Get consensus from multiple model runs: 
consensus(EC25.SFC.APCP.HR*1000, UK10.SFC.TPRATE.HR, 
          GFS.SFC.APCP.HR, ICON.SFC.TPRATE.HR)

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10. Unit Conversions

Convert between units: 
GFS.GND2M.TMP - 273.15  // Kelvin to Celsius
GFS.MSL.PRMSL / 100     // Pascal to Hectopascal

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Time Step Interpolation

The STEP parameter enables time interpolation to get data at regular intervals: Syntax: 
time=[start TO end STEP interval]
Interval Units:
  • minutes - Minutes (e.g., 60 minutes for hourly)
  • hours - Hours
  • days - Days
Example: 
time=[now TO 1766620800 STEP 60 minutes]
This returns data points every 60 minutes between now and the end timestamp, interpolating values from available model timesteps.
Use STEP when you need regular time intervals (e.g., hourly data) but the model only provides data at irregular timesteps.

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URL Encoding

When constructing URLs manually, remember to URL-encode special characters:
  • Space: %20
  • Pipe: %7C or | (usually works)
  • Comma: %2C or , (usually works)
  • Parentheses: %28 ( and %29 )