depudm {climatol} | R Documentation |
Climatological series homogeneity studies, with missing data estimation, inhomogeneities (point errors, mean shifts and trends) detection, and graphical displays.
depudm(varcli, anyi, anyf, nm = 12, wa = 100, dz.max = 2, difumb = 0.05, leer = TRUE, a = 0, b = 1, wz=0.001, sqrtrans = FALSE, ttip = 3, refglob = FALSE, ndec = 1, pval = 0.05, graf = FALSE, auto = FALSE, verb=TRUE)
varcli |
Acronym of the name of the studied climatic variable, as in the data file name. |
anyi |
Initial year of the data present in the file (four digits) |
anyf |
Final year of the data present in the file (four digits) |
nm |
Number of series in each station. (Default=12, for monthly data). |
wa |
Shape parameter of the weighting function 1/(1+d^2/wa) ,
where d stands for distance. Low values (1-10) increase the weight of
nearby stations, while high values (>1000) take in account also the
far stations influence. Do wa=0 if you want an unweighted average of
all the stations. |
dz.max |
Threshold to accept differences between observed and estimated
data, in standard deviation units. (Only used when auto=TRUE ). |
difumb |
Maximum acceptable difference in the series average values
between missing data filling iterations. This process will stop when
the maximum difference is lower or equal to difumb . |
leer |
if TRUE , climatological data will be read from files.
(Can be set to FALSE if data have already been read in a previous
call to depudm ). |
a, b |
Parameters of the optional transformation a+b*dat to be
applied to data when read from the files. |
wz |
Scale parameter of the vertical coordinate Z . The default
value assumes that X and Y are expressed in km, while
Z is expressed in m. Can be used to change the Z weight in
inter-station distance computations. |
sqrtrans |
if TRUE , a square root transformation will be applied
to all data greater than 1. (Useful with e.g. precipitation data, to
approximate their distribution to a Gauss one). |
ttip |
Type of standardization:
|
refglob |
if TRUE , use annual averages for normalization of all
the series of each station. Incompatible with graf=TRUE . Can be
useful in arid places with frequent null precipitation mixed with high
precipitation values in other years, making quite unstable the computation
of their averages. |
ndec |
Number of decimal places of the purged data, to be saved in the file ‘VAR_AI-AF.dep’. |
pval |
If greater than 0, t-test of mean difference will be applied
to running windows of 10 and 20 terms (between samples of 5 and 10 terms),
and an overall trend test. If graf=TRUE , p-values of the t-test
will be plotted and, provided that the trend is significant (lower than
pval ), the regression line with time will be plotted as well. |
graf |
If TRUE , interactive graphs will be displayed for each
series. |
auto |
If TRUE , data whose differences to their estimated
(normalized) values are greater than dz.max will be substituted by
their estimates. |
verb |
If TRUE , progress indications will be
shown in the terminal. |
This is the main function for error correction and homogeneity testing of the
climatological series, and makes frequent calls to other subordinated
functions. The climatological series are read from files named
‘VAR_AI-AF.dat’, and the coordinates and names of the stations from
‘VAR_AI-AF.est’, where VAR
stands for any acronym of the
involved climatological variable, and AI
and AF
are the two
last digits of the initial and final year of the data. Data are stored
station by station, and chronologically within each station block. Missing
values are specified as NA
(the usual way in R). In the stations file
there will be a record (line) for each station, with structure X Y Z ID
NAME
, where X
and Y
are the UTM coordinates in km, Z
the altitude in m, ID
a station identifier, followed by the full
NAME
of the station, that must be put between double quotes if it
contains any space character (see the example files in the package's data
directory). depudm
will save the purged, filled series in files
‘VAR_AI-AF.dep’, eventually overwriting the pre-existing ones. (Rename
them if results of different calls to depudm
are to be saved). A log
of each run will also be appended in a file named ‘climatol.log’.
Objects created by this function (original data, dat.d
; normalized
data, dat.z
; estimated data, dat.e
; ...) will remain resident
in the memory space during the rest of the R session while not explicitly
removed, therefore been susceptible to apply on them all the extended
variety of statistical and graphic functions available in R.
As inhomogeneities in one series will affect other nearby series, making
them suspects of inhomogeneity even if they are good, it is advisable to
proceed step by step, beginning with a fairly high wa
(>=1000) to
only correct the most prominent errors, and successively repeat the
process with decreasing values of wa
.
Jose A. Guijarro
Climatol: Software libre para la depuración y homogeneización de datos climatológicos. IV Congress of the Spanish Climatology Society (Santander, 2-5 of November 2004).
#The two files PTOT_51-00.* of the package's data directory must be # first copied to the working directory. Then run: ## Not run: depudm("PTOT",1951,2000,b=.1,ttip=2,sqrtrans=TRUE,graf=TRUE)