spectral UV from Helioclim-3 Ultraviolet-A and Ultraviolet

   Ultra-Violet from HC3 - Inputs - Outputs - Automatic access - Bibliography

Ultra-Violet from HC3

   This service provides spectral radiation values computed from the satellite-derived solar radiation database HelioClim-3 version 5 over a horizontal plane. The geographical coverage corresponds to the Meteosat satellite field of view, i.e. covers Europe, Africa, Atlantic Ocean, Middle East. Spatial resolution is 3 km at Nadir and is increasing as soon as we get away from this point (see illustration on the right hand side). Temporal coverage of data is 2004-02-01 up to current day-1. Time reference is UT. (The full period of data (2004 to current day-1) is available on-demand.)

The service provides time series of UV-A (315–400 nm) and UV-B (280–315 nm), and UV total data.
Data are irradiances in W/m².

Bibliography: the algorithm of conversion from total radiation (i.e. spectrally integrated) into UV-A, -B or total is described in Wald 2012 (see list of publications below). Aculinin et al. 2016 provide an interesting comparison of several methods.

Inputs

• Latitude and longitude: enter the values in decimal degrees (we advise 3 or 4 digits after comma), or directly click on the map to select your point, or you can also use the "Search Address" tool on the top of the map.
• Altitude: enter the altitude, or let us use our default high resolution elevation database SRTM (spatial resolution 90 m, uncertainty 10 m) by letting the default "Automatic" value.
• Start date and End date: format yyyy-mm-dd.
  NB: Please pay attention to ask for complete months when asking for monthly values. If incomplete, the given monthly value results from an interpolation based on the selected days.
• Time step: "15 min", "30 min", "hour", "day".
• Time reference: "UT" (universal time).
• Compute relief shadows: take into account (or not) the shadowing effect due to the far horizon.
• Output format: CSV

Outputs

1. Date: format DD-MM-YYYY
2. Time: format hh:mm
3. UVA: Irradiation in UV-A (315-400 nm) over the period on horizontal plane (-999 if not data)
4. UVB: Irradiation in UV-B (280-315 nm) over the period on horizontal plane (-999 if no data)
5. UV: Irradiation in UV (280-400 nm) over the period on horizontal plane (-999 if no data)

Bibliography Spectral

(In alphabetic order and and reverse chronological order)

Content: coefficient to derive PAR ground albedo from broadband ground albedo.

Content: data BOUSSOLE

Content: Coeff to derive PAR from GHI optimized for Cyprus.

Content: in addition to the description of CAMS McClear, this article provides a very restrictive algorithm to select clear sky instants. It consists of two successive filters. The first one is a constraint on the amount of diffuse irradiance with respect to the global irradiance since the direct irradiance is usually prominent in the case of clear sky. The second filter analyses the temporal variability of the global irradiance. If there is no cloud, the sky should be clear and steady for a long period.

Content: UV and Migraines

Content: Article which proposes an alternative of quality check for spectral radiation values.
https://doi.org/10.1594/PANGAEA.879722 proposes for free in-situ measurements for 3 sites (2 very close) close to Ostrava, in Czech Republic:

• BGOU S1: lat=49.82754°, 18.32618°, 10 min data in UTC, end of interval, averages. Data from 2014-07-01-00-00 to 2016-12-31-22-50.
• BGOU S2: idem except data start on 2014-07-02-08-00
• NB: PHI (proche BGOU) provides meteo variables and air-pollutant information at a 1h time step.
• CHMI S3: lat=49.82521°, 18.15932°, 10 min data in UTC, end of interval, averages. Data from 2014-07-07-13-00 to 2016-12-31-22-50.

Spectral bands: UVB: 280-315 nm, UVA 315-400 nm, PAR 400-700 nm, 510-700 nm, 600-700 nm, 610-680 nm, 690-780 nm, broadband 400-1100 nm.

Interesting citations in this article:

• "Moreover, diffuse radiation is know for having a different blue/red ratio compared to direct radiation (Navratil et al. 2007)."
• "We have adapted the approach of Korany et al. (2016) which applies to measurements of global and diffuse total irradiances."
• "Some values are greater than the corresponding irradiance at TOA. These values were usually connectly with partly cloudy weather, when multiple scattering on the cloud edges could increase incident solar irradiation (Mims and Frederick, 1994)."

Content: During the oral presentation given in Chile, the assessment has been extended to 6 sites (Lille, Provence, La Réunion, Kishinev, Reading and Uruguay)

Content: Coeff to derive PAR from GHI optimized for Nigeria.

Content: the Kato bands do not exactly fit the PAR spectral ranges and a spectral resampling is necessary. The authors have developed a resampling method which determine several 1-nm spectral bands whose atmospheric transmissivities are correlated to those of the Kato bands and then use these transmissivities in a linear interpolation process to compute the PAR irradiance. The technique has been numerically validated. The authors conclude that the technique estimates direct and global with very high accuracy. 

Content: authors compared atmospheric transmissivities obtained by the Kato et al. approach against those obtained by spectrally resolved computations using two Radiative Transfer Models (RTMs) in each of the 32 Kato Bands. These calculations were performed for a set of 200 000 realistic atmospheres and clouds. These authors found that the Kato et al. approach offers very accurate estimates of irradiances in all 12 Kato bands covering PAR-range.

Top of page