mackp {gamair}

Prediction grid data for 1992 mackerel egg model

Description

This data frame provides a regular grid of values of some predictor variables useful for modelling mackerel egg abundances. Its main purpose is to enable mackerel egg densities to be predicted over a regular spatial grid within the area covered by the 1992 mackerel egg survey (see mack), using a fitted generalised additive model.

Usage

data(mackp)

Format

A data frame with 5 columns. Each row corresponds to one spatial location within the survey area. The columns are as follows:

lon

Longitude of the gridpoint in degrees east

lat

Latitude of the gridpoint in degrees north.

b.depth

The sea bed depth at the gridpoint.

c.dist

The distance from the gridpoint to the 200m sea bed depth contour.

salinity

Salinity interpolated onto the grid (from mack measurements).

temp.surf

Surface temperature interpolated onto grid (from mack data).

temp.20m

Temperature at 20m interpolated from mack data.

area.index

An indexing vector that enables straightforward copying of the other variables into a matrix suitable for plotting against longitude and lattitude using image(). See the example below.

Details

The grid is defined on a series of 1/4 degree lon-lat squares.

References

Borchers, D.L., S.T. Buckland, I.G. Priede and S. Ahmadi (1997) "Improving the precision of the daily egg production method using generalized additive models". Can. J. Fish. Aquat. Sci. 54:2727-2742.

Examples

## example of how to use `area.index' to paste gridded info.
## into a square grid (of NA's) for plotting
data(mackp)
lon<-seq(-15,-1,1/4);lat<-seq(44,58,1/4)
zz<-array(NA,57*57)
zz[mackp$area.index]<-mackp$b.depth
image(lon,lat,matrix(zz,57,57))