2015_Min_RelativeHumidity_Modis_FourirerProcess

This is a set of images produced by Temporal Fourier Analysis (TFA) of Modis minimum Relative humidity data:

Modis: Minimum Relative Humidity

The imagery summarises some key environmental indicators, incorporating seasonal dynamics, for The European and North African extent.This series of Modis  data, processed according to Scharlemann et al (2008), has been updated to include imagery for 2015.

Process:

Image values were extracted from MODIS( Min Relative Humidity) 5 km imagery for 2015.  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 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 and the images were projected from sinusoidal to geographic (WGS84). 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 Modis 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)

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