18 - use case: phenology data

Located here: ftp://opendata.dwd.de/climate_environment/CDC/observations_germany/phenology

This example uses data in the subfolder annual/crops/hist

phenocrop_base <- paste0(sub("climate$", "phenology", dwdbase), 
                        "/annual_reporters/crops/historical/")
# pheno_urls <- indexFTP("", base=phenocrop_base, dir="Pheno")
kohl_url <- "PH_Jahresmelder_Landwirtschaft_Kulturpflanze_Weisskohl_1951_1990_hist.txt"# 9 MB
kohl_file <- dataDWD(base=phenocrop_base, url=kohl_url, joinbf=TRUE, 
                     dir=localtestdir(), read=FALSE) 
kohl <- read.table(kohl_file, sep=";", header=TRUE)