This function creates several graphics showing seasonal and annual trends for a given swmp parameter. Plots include monthly distributions, monthly anomalies, and annual anomalies in multiple formats. Anomalies are defined as the difference between the monthly or annual average from the grand mean. Monthly anomalies are in relation to the grand mean for the same month across all years. All data are aggregated for quicker plotting. Nutrient data are based on monthly averages, wheras weather and water quality data are based on daily averages. Cumulative precipitation data are based on the daily maximum.
Individual plots can be obtained if plt_sep = TRUE
. Individual plots for elements one through six in the list correspond to those from top left to bottom right in the combined plot.
Summary data for the plots can be obtained if sum_out = TRUE
. This returns a list with three data frames with names sum_mo
, sum_moyr
, and sum_mo
. The data frames match the plots as follows: sum_mo
for the top left, bottom left, and center plots, sum_moyr
for the top right and middle right plots, and sum_yr
for the bottom right plot.
Missing values can be filled using the long-term average across years for each month (fill = 'monoclim'
) or as a linear interpolation between missing values using na.approx
(fill = 'interp'
). The monthly average works well for long gaps, but may not be an accurate representation of long-term trends, i.e., real averages may differ early vs late in the time series if a trend exists. The linear interpolation option is preferred for small gaps.