seas (version 0.5-2)

lars: Read and write data from LARS-WG file formats

Description

Read and write data from the LARS-WG stochastic weather generator file formats; also convert to a format for HELP

Usage

# read synthetic or observed *.st file
read.lars(stfile, year.offset = 0)
# write observed climate data (*.st and/or *.sr)
write.lars(x, stfile, datfile, site, lat, lon, alt)
# experimental functions (may not work great; or at all!)
lars2help(infile, outfile, year.offset, site)
write.lars.scenario(file, x1, x2, name = "anomaly")

Arguments

stfile

file name with *.st extension; this is a ‘site file’ for LARS-WG which contains meta-data for the climate data, and has the location of the the climate data file; for write.lars, if this variable is NA or FALSE, this file will not be written (however, datfile must be defined)

datfile

file name with either *.sr or *.dat extension; contains climate data, as described by stfile; this does not need to be set if stfile is defined, as this datum is found in the st file

file

file name with a *.sce extension; this is a ‘scenario’ file with absolute and relative changes of climate data

infile

input file

outfile

output file

x

data.frame of climate data

x1

same as x

x2

same as x

year.offset

offset of years between what is contained in the data files and what is needed in R to produce a reasonable ‘Date’; this is required, for example, if synthetic data are produced that start from an arbitrary year ‘1’ but represent climate from the year ‘2000’

site

same as ‘[SITE]’ in st file; if missing, this will try to read from attr(x$name); this is the same as a ‘region’ for HELP

name

scenario name

lat

same as ‘LAT’ in st file; if missing, this will try to be read from attr(x$latitude)

lon

same as ‘LON’ in st file; if missing, this will try to be read from attr(x$longitude)

alt

same as ‘ALT’ in st file; if missing, this will try to be read from attr(x$elevation)

Details

These functions interface with the LARS-WG files (Version 4.0), which is a stochastic weather generator by Mikhail Semenov.

The climate data files used with LARS-WG have two parts: (1)~a ‘site file’ with a st extension, containing the meta-data; and (2)~a data file with a *.sr or *.dat extension, containing all the data. The variable names are translated according to the following table:

seas	LARS-WG
year	‘YEAR’
yday	‘JDAY’
t_min	‘MIN’
t_max	‘MAX’
preicp	‘RAIN’
solar	‘RAD’
sun	‘SUN’
pet	‘PET’

To write climate data from R to a LARS-WG file, the data.frame names need to match those in the seas-side of the table.

Data exported from write.lars always has legal (according to the Gregorian calendar) and increasing sequence of days (even if there are gaps in x$date). Missing data values are written as -99.

Synthetically generated data from LARS-WG use a 365-day calendar, and may need to be converted to a Gregorian calendar, which can be done using conv365toGregorian.

lars2help and write.lars.scenario are experimental functions to translate data between LARS and HELP (see write.help for more info).

References

LARS-WG was can be downloaded for academic and research uses from http://www.rothamsted.bbsrc.ac.uk/mas-models/larswg.php

Semenov, M.A. and Barrow, E.M. 1997. Use of a stochastic weather generator in the development of climate change scenarios. Climate Change, 35 (4), 397--414, 10.1023/A:1005342632279

See Also

write.help, read.sdsm, summerland example synthetic data, conv365toGregorian

Examples

# NOT RUN {
stfile <- system.file("extdata", "summerland.st", package="seas")
print(stfile)
summ <- read.lars(stfile, year.offset=1960)
head(summ)
str(summ)

# plot temperature
summ$t_mean <- rowMeans(summ[, c("t_min", "t_max")])
seas.temp.plot(summ)

# plot solar radiation
seas.var.plot(summ, "solar")

# plot precipitation
summ.ss <- seas.sum(summ)
image(summ.ss)
plot(seas.norm(summ.ss))
# }