2010_2023_RelativeHumidity_ERA5_FourirerProcess_1k

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

ERA5:  Relative Humidity

The imagery summarises some key environmental indicators, incorporating seasonal dynamics, for The European and North African extent.This series of ERA5  data, processed according to Scharlemann et al (2008), has been updated to include imagery for 2010-2023.

Process:

Image values were extracted from ERA5(  Relative Humidity) 1 km imagery for 2010-2023.  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 outputs recorded the mean, minimum, and maximum of the time series, and error 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)  Sea pixels were masked with a VIIRS land/sea layer . The E4Warning study region was a subset of global images. Idrisi rasters were converted to GeoTIFF format in order to give data users more flexibility.

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

File names:

The 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 RH in mmALL D1,D2,D3,Da PercentagesALL E1,E2,E3 PercentagesALL P1,P2.P3 Months*100. (Jan=100)

Projection + EPSG code:Latitude-Longitude/WGS84 (EPSG: 4326)Spatial extent:north: 82:00:30Nsouth: 18Nwest: 32:00:30Weast: 70E

Spatial resolution:30 arc seconds (approx. 1000 m)

Temporal resolution:Monthly  from 2010 to 2023

Pixel values

Percent * 10 (scaled to Integer; example: value 738 = 73.8 %)

Source: 

 Monthly time series of spatially enhanced relative humidity for Europe at 30 arc seconds resolution (2000 - 2023) derived from ERA5-Land data: https://zenodo.org/records/12699259

Software used: 

Codes are written in Python and C++The software used for map production is ESRI ArcMap 10.8

License: CC-BY-SA 4.0Processed by:ERGO (Environmental Research Group Oxford) https://ergoonline.co.uk/ )