Class: WrfForecast::Threshold::RainThreshold

Inherits:
BaseThreshold show all
Defined in:
lib/wrf_forecast/threshold/rain_threshold.rb

Overview

This class determines the significant rain thresholds for a forecast day. That means that this class can only work correctly if the data represents a time span of up to 24 hours. The indicators and thresholds are bases on the climate indicators of the german (weatherservice):

  • strong rain: the hourly rain sum exceeds 15 mm per hour

  • heavy rain: the hourly rain sum exceeds 25 mm per hour

  • extreme rain: the hourly rain sum exceeds 40 mm per hour

  • continous rain: the rain sum over 24 hours exceeds a total of 30 mm

Instance Attribute Summary

Attributes inherited from BaseThreshold

#indicators

Instance Method Summary collapse

Methods inherited from BaseThreshold

#add_indicator, #change_indicator, #initialize

Constructor Details

This class inherits a constructor from WrfForecast::Threshold::BaseThreshold

Instance Method Details

#check_data_values(data_values) ⇒ Object (private)

method to check if the data sample offers enough data for the indicators if we dont have 24 values we do not have hourly rain for the day

Raises:

  • (ArgumentError) —

    if the data values are not sufficient



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# File 'lib/wrf_forecast/threshold/rain_threshold.rb', line 47

def check_data_values(data_values)
  if (data_values.size < 24)
    raise ArgumentError, "Error: Not enough hourly data available for a forecast day."          
  end
end

#determine_indicators(data_values) ⇒ Object (private)

method to determine the indicators based on the input data

Parameters:

  • data_values (Array) —

    the input values



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# File 'lib/wrf_forecast/threshold/rain_threshold.rb', line 29

def determine_indicators(data_values)
  sum = 0
  rain_hours = 0
  data_values.each { |value|
    change_indicator(:strong_rain, true, value > 15.0)
    change_indicator(:heavy_rain, true, value > 25.0)
    change_indicator(:extreme_rain, true, value > 40.0)
    rain_hours += 1 if (value > 1.5) # hourly rain > 1.5 mm required for continous rain check
    sum += value
  }

  change_indicator(:continous_rain, true, (sum > 30.0 && rain_hours > 6))
  nil
end

#initialize_indicators ⇒ Object (private)

initialization of the required indicators



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# File 'lib/wrf_forecast/threshold/rain_threshold.rb', line 19

def initialize_indicators
  add_indicator(:strong_rain, false, I18n.t("threshold.rain.strong_rain"))
  add_indicator(:heavy_rain, false, I18n.t("threshold.rain.heavy_rain"))
  add_indicator(:extreme_rain, false, I18n.t("threshold.rain.extreme_rain"))
  add_indicator(:continous_rain, false, I18n.t("threshold.rain.continous_rain"))
  nil
end