venice {VGAM} | R Documentation

## Venice Maximum Sea Levels Data

### Description

Some sea levels data sets recorded at Venice, Italy.

### Usage

    data(venice)
    data(venice90)

### Format

`venice` is a data frame with 51 observations on the following 11 variables. It concerns the maximum heights of sea levels between 1931 and 1981.

year

  a numeric vector.

r1,r2,r3,r4,r5,r6,r7,r8,r9,r10

  numeric vectors; `r1` is the highest recorded value, `r2` is the second highest recorded value, etc.

`venice90` is a data frame with 455 observations on the following 7 variables.

year, month, day, hour

  numeric vectors; actual time of the recording.

sealevel

  numeric; sea level.

ohour

  numeric; number of hours since the midnight of 31 Dec 1939 and 1 Jan 1940.

Year

  numeric vector; approximate year as a real number. The formula is `start.year + ohour / (365.26 * 24)` where `start.year` is 1940. One can treat `Year` as continuous whereas `year` can be treated as both continuous and discrete.

### Details

Sea levels are in cm. For `venice90`, the value 0 corresponds to a fixed reference point (e.g., the mean sea level in 1897 at an old palace of Venice). Clearly since the relative (perceived) mean sea level has been increasing in trend over time (more than an overall 0.4 m increase by 2010), therefore the value 0 is (now) a very low and unusual measurement.

For `venice`, in 1935 only the top six values were recorded.

For `venice90`, this is a subset of a data set provided by Paolo Pirazzoli consisting of hourly sea levels from 1940 to 2009. Values greater than 90 cm were extracted, and then declustered (each cluster provides no more than one value, and each value is at least 24 hours apart). Thus the values are more likely to be independent. Of the original `(2009-1940+1)*365.26*24` values about 7 percent of these comprise `venice90`.

Yet to do: check for consistency between the data sets. Some external data sets elsewhere have some extremes recorded at times not exactly on the hour.

### Source

Pirazzoli, P. (1982) Maree estreme a Venezia (periodo 1872–1981). Acqua Aria, 10, 1023–1039.

Thanks to Paolo Pirazzoli and Alberto Tomasin for the `venice90` data.

### References

Smith, R. L. (1986) Extreme value theory based on the r largest annual events. Journal of Hydrology, 86, 27–43.

Battistin, D. and Canestrelli, P. (2006). La serie storica delle maree a Venezia, 1872–2004 (in Italian), Comune di Venezia. Istituzione Centro Previsione e Segnalazioni Maree.

### See Also

`guplot`, `gev`, `gpd`.

### Examples

    ## Not run:
    matplot(venice[["year"]], venice[, -1], xlab = "Year",
            ylab = "Sea level (cm)", type = "l")

    ymat <- as.matrix(venice[, paste("r", 1:10, sep = "")])
    fit1 <- vgam(ymat ~ s(year, df = 3), gumbel(R = 365, mpv = TRUE),
                 data = venice, trace = TRUE, na.action = na.pass)
    head(fitted(fit1))

    par(mfrow = c(2, 1), xpd = TRUE)
    plot(fit1, se = TRUE, lcol = "blue", llwd = 2, slty = "dashed")

    par(mfrow = c(1,1), bty = "l", xpd = TRUE, las = 1)
    qtplot(fit1, mpv = TRUE, lcol = c(1, 2, 5), tcol = c(1, 2, 5),
           llwd = 2, pcol = "blue", tadj = 0.1)

    plot(sealevel ~ Year, data = venice90, type = "h", col = "blue")
    summary(venice90)
    dim(venice90)
    round(100 * nrow(venice90) / ((2009 - 1940 + 1) * 365.26 * 24), digits = 3)

    ## End(Not run)

[Package VGAM version 1.0-4 Index]