DOI: 10.5281/zenodo.16678980
title: 2010_2024_ERA5_Precipitation_Rainfall_FourierProcessed_1k_WG

description: This is a set of images produced by Temporal Fourier Analysis (TFA) of ERA5 data:

ERA5: Total Precipitation 

The imagery summarises some key environmental indicators, incorporating seasonal dynamics, for the whole worldThis series of ERA5 data, processed according to Scharlemann et al (2008), has been updated to include imagery from 2010 to 2024. 

 

Precipitation from the ERA5 reanalysis archive supplied by the European Centre for Medium Range Weather Forecasting for 2010 - 2022. Abstract: Precipitation from the ERA5 reanalysis archive supplied by the European Centre for Medium Range Weather Forecasting. The original data is at 0.25 degree resolution and was downscaled by ERA extraction algorithms to 1km resolution, then downloaded. The daily data have been aggregated to dekadal, monthly, and annual datasets to match the outputs produced by NASA from the MODIS imagery temperature and vegetation Index datasets. The resolution was also chosen to match these MODIS datasets.

Process:

Image values were extracted from ERA5 ( Total precipitation) at 1 km resolution imagery from 2010 to 2024.  Each parameter extract dataset was then processed by a temporal Fourier processing algorithm. A stepwise system of thresholds and interpolations screened erroneous values and bridged gaps in the time series. The smoothed series was sampled at 5-day intervals and transformed into a set of sine curves describing annual, bi-annual, and tri-annual fluctuations. For each of these curves, the Fourier algorithm generated images expressing the amplitude, phase, and variance. Other output recorded the mean, minimum, and maximum of the time series, and errors measured during the Fourier transform. For a detailed description of the Fourier algorithm and its output, please see the article by Scharlemann et al., 2008 (https://doi.org/10.1371/journal.pone.0001408)  Idrisi rasters were converted to GeoTIFF format in order to give data users more flexibility. Sea pixels were masked with a VIIRS land/sea layer. 

 

This new ERA5 Dataset is used as an update and continuation of our MODIS TFA product and can be utilised in the same way. 

Projection + EPSG code:

Latitude-Longitude/WGS84 (EPSG: 4326)

Extent    -180.0000000000000000,-90.0000000000000000 : 179.9999999999998295,89.9999999999999147

File names:

The wg at the start of each file name indicates that the image covers the whole world in the E4warning  and is in geographic projection. 04 refers to the year timeline of 2010-2024.The next two characters identify the channel:20 - Monthly Total PrecipitationThe last two characters of each file name denote the output from Fourier processing:a0 - meanmn - minimummx - maximuma1 - amplitude of annual cyclea2 - amplitude of bi-annual cyclea3 - amplitude of tri-annual cyclep1 - phase of annual cyclep2 - phase of bi-annual cyclep3 - phase of tri-annual cycled1 - variance in annual cycled2 - variance in bi-annual cycled3 - variance in tri-annual cycleda - combined variance in annual, bi-annual, and tri-annual cyclesvr - variance in raw dataParameter Fourier Variable Image values areERA5  A0, A1, A2, A3, Min, Max, Vr Reflectance values  monthly total precipitation in mmALL D1,D2,D3,Da PercentagesALL E1,E2,E3 PercentagesALL P1,P2.P3 Months*100. (Jan=100)