monitor_nowcast {AirMonitor}

Apply NowCast algorithm to mts_monitor data

Description

A NowCast algorithm is applied to the data in in the monitor object. The version argument specifies the minimum weight factor and number of hours to be used in the calculation.

Available versions include:

1. pm: hours = 12, weight = 0.5

2. pmAsian: hours = 3, weight = 0.1

3. ozone: hours = 8, weight = NA

The default, version = "pm", is appropriate for typical usage.

Usage

monitor_nowcast(
  monitor,
  version = c("pm", "pmAsian", "ozone"),
  includeShortTerm = FALSE
)

Arguments

monitor

mts_monitor object.

version

Name of the type of nowcast algorithm to be used.

includeShortTerm

Logical specifying whether to alcluate preliminary NowCast values starting with the 2nd hour.

Details

This function calculates each hour's NowCast value based on the value for the given hour and the previous N-1 hours, where N is the number of hours appropriate for the version argument. For example, if version = "pm", the NowCast value for Hour 12 is based on the data from hours 1-12.

The function returns values when at least two of the previous three hours have data. NA's are returned for hours where this condition is not met.

By default, the funtion will not return a valid value until the Nth hour. If includeShortTerm = TRUE, the function will return a valid value after only the 2nd hour (provided, of course, that both hours are valid).

Calculated Nowcast values are truncated to the nearest .1 ug/m3 for 'pm' and nearest .001 ppm for 'ozone' regardless of the precision of the data in the incoming mts_monitor object.

Value

A modified mts_monitor object. (A list with meta and data dataframes.)

References

https://en.wikipedia.org/wiki/Nowcast_(Air_Quality_Index)

AQI Technical Assistance Document