paper.md
In hddtools: Hydrological Data Discovery Tools

title: 'hddtools: Hydrological Data Discovery Tools' authors: - affiliation: 1 name: Claudia Vitolo orcid: 0000-0002-4252-1176 date: "27 December 2016" output: pdf_document bibliography: paper.bib csl: hydrology-and-earth-system-sciences.csl tags: - open data - hydrology - R affiliations: - index: 1 name: European Centre for Medium-range Weather Forecasts

Summary

The hddtools [@hddtoolsCRAN] (hydrological data discovery tools) is an R package [@R-base] designed to facilitate access to a variety of online open data sources relevant for hydrologists and, in general, environmental scientists and practitioners. This typically implies the download of a metadata catalogue, selection of information needed, formal request for dataset(s), de-compression, conversion, manual filtering and parsing. All those operation are made more efficient by re-usable functions.

Depending on the data license, functions can provide offline and/or online modes. When redistribution is allowed, for instance, a copy of the dataset is cached within the package and updated twice a year. This is the fastest option and also allows offline use of package's functions. When re-distribution is not allowed, only online mode is provided.

Datasets for which functions are provided include: the Global Runoff Data Center (GRDC), the Scottish Environment Protection Agency (SEPA), the Top-Down modelling Working Group (Data60UK and MOPEX), Met Office Hadley Centre Observation Data (HadUKP Data) and NASA's Tropical Rainfall Measuring Mission (TRMM).

This package follows a logic similar to other packages such as rdefra [@rdefraJOSS] and rnrfa [@rnrfa]: sites are first identified through a catalogue (if available), data are imported via the station identification number, then data are visualised and/or used in analyses. The metadata related to the monitoring stations are accessible through the functions: catalogueGRDC(), catalogueSEPA(), catalogueData60UK() and catalogueMOPEX(). Time series data can be obtained using the functions: tsGRDC(), tsSEPA(), tsData60UK(), tsMOPEX() and HadDAILY(). Geospatial information can be retrieved using the functions: KGClimateClass() returning the Koppen-Greiger climate zone and TRMM() which retrieves global historical rainfall estimations.

The retrieved hydrological time series (e.g. using tsData60UK()) can be used to feed hydrological models such as fuse [@fuseGitHub; @fuseJOSS], topmodel [@topmodel] and hydromad [@Andrews20111171; @hydromad].

For more details and examples, please refer to the help pages and vignette.