These plots are normally used for plotting the estimated concentration surface (whatSurface = 3) but can be used to explore the estimated surfaces for the log of concentration or for the standard error (in log space) which is what determines the bias correction. The plots are often more interpretable when the time limits for the plot are less than a decade. To explore changes over a long time period it is best to do this multiple times, for various time slices of 2 years (for example) or to use the function plotDiffContours.

Although there are a lot of optional arguments to this function, most are set to a logical default.

Obtaining a plot that provides good insight it is useful to experiment with several of the arguments such as yearStart, yearEnd, qBottom, qTop, and contourLevels.

Data come from named list, which contains a Sample dataframe with the sample data, a Daily dataframe with the daily flow data, and an INFO dataframe with metadata.

plotContours(eList, yearStart, yearEnd, qBottom = NA, qTop = NA,
whatSurface = 3, qUnit = 2, contourLevels = NA, span = 60,
pval = 0.05, printTitle = TRUE, vert1 = NA, vert2 = NA, horiz = NA,
tcl = 0.03, flowDuration = TRUE, customPar = FALSE, yTicks = NA,
tick.lwd = 1, usgsStyle = FALSE, lwd = 2, cex.main = 1,
cex.axis = 1, color.palette = colorRampPalette(c("white", "gray", "blue",
"red")), ...)

## Arguments

eList named list with at least the Daily and INFO dataframes, and surfaces matrix numeric value for the starting date for the graph, expressed as decimal year (typically whole number such as 1989.0) numeric value for the ending date for the graph, expressed as decimal year, (for example 1993.0) numeric value for the bottom edge of the graph, expressed in the units of discharge that are being used (as specified in qUnit). NA will choose a "pretty" lower limit nearest to the 5% of discharge. If yTicks are specified, then the first value of yTicks becomes the lowest discharge shown on the figure. numeric value for the top edge of the graph, expressed in the units of discharge that are being used (as specified in qUnit). NA will choose a "pretty" upper limit nearest to the 95% of discharge. If yTicks are specified, then the last value of yTicks becomes the highest discharge shown on the figure. numeric value, can only accept 1, 2, or 3; whatSurface=1 is yHat (log concentration), whatSurface=2 is SE (standard error of log concentration), and whatSurface=3 is ConcHat (unbiased estimate of concentration), default = 3. object of qUnit class. printqUnitCheatSheet, or numeric represented the short code, or character representing the descriptive name. numeric vector containing the contour levels for the contour plot, arranged in ascending order, default is NA (which causes the contour levels to be set automatically, based on the data) numeric, it is the half-width (in days) of the smoothing window for computing the flow duration information, default = 60 numeric, the probability value for the lower flow frequency line on the graph logical variable if TRUE title is printed, if FALSE not printed numeric, the location in time for a black vertical line on the figure, yearStart

## Examples

yearStart <- 2002
yearEnd <- 2010
qBottom <- 0.5
qTop<- 20
clevel <- seq(0,2,0.25)
eList <- Choptank_eList
plotContours(eList, yearStart, yearEnd, qBottom, qTop,
contourLevels = clevel)
plotContours(eList, yearStart, yearEnd, qBottom, qTop = 50,
contourLevels = clevel, flowDuration = FALSE)
colors <- colorRampPalette(c("white","black"))
plotContours(eList, yearStart, yearEnd, qBottom, qTop = 50,
contourLevels = clevel, color.palette = colors,
flowDuration = FALSE)