Fast simulations of downward UV doses, indices and irradiances at the Earth's surface

Alternative services: http://nadir.nilu.no/~olaeng/fastrt/fastrt.html and http://zardoz.nilu.no/~olaeng/fastrt/fastrt.html

Version 2.3, Copyright © 2005 Ola Engelsen
Norwegian Institute for Air Research, Email: ola.engelsen@nilu.no

Press here for more information on FastRT and simpler versions

Download joint package for fast UV simulations and diagnosis of measured UV Spectra       Windows/DOS executables       FASTRT Changelog


Solar Geometry for Irradiance Calculations

Month Day GMT Hours Minutes Year

Latitude (degs N) Longitude (degs E)

When checked, use degrees for Solar Zenith Angle directly and ignore Date, Time, and Location


Cloudless sky: Visibility of km, Range [5-350] km. Ångström β of , Range [0.0-0.4] (AOD = βλ-1.3).

Scattered clouds: Cloud fraction of %, Range [0-100]. Cloud liquid water column of g m-2, Range [0-5000].
Press here for total cloud fractions from the NOAA AVHRR Pathfinder products.

Broken clouds (radiation enhancement): Cloud liquid water column of g m-2, Range [0-5000].

Overcast sky: Cloud liquid water column of g m-2, Range [0-5000]. (= cloud optical depth @ 360 nm * 5000/1083)
Press here for cloud columns and fractions from the ECMWF 40 Year Re-analysis (ERA-40) data set.


Total ozone column: Dobson Units (1000 * cm atm), Range [100-600]
Press here for total ozone column measurements from the TOMS satellite instruments.


Surface altitude km. Range [0.0-6.0] km

Surface albedo of Range [0.0-1.0].

Surface type:


Triangular spectral response function, Full Width Half Maximum (FWHM): nm, Range [0.05-55.0] nm, multiples of 0.05 nm

Compute surface downward irradiance for at wavelength nm, Range [290-400] nm.

Compute surface irradiances from to at steps of nm, Range [290-400nm].

Compute UV daily dose of type
(Solar zenith angle and time of day selection ignored)

Compute UV doserate of type

Print UV action spectrum of type



This work has been funded by the European Commission (EC) and the Norwegian Research Council ( NFR) through the projects UV Radiation in the Arctic: Past, Present and Future (UVRAPPF) and European Database for UV Climatology and Evaluation (EDUCE).


Ola Engelsen                                                                          NILU Phone: (+47) 77 75 03 75
Norwegian Institute for Air Research (NILU)                    NILU Fax no:(+47) 77 75 0376
N-9296 Tromsø                                                                     Office-Phone no:(+47) 77 75 03 89
Norway                                                                                  Email: ola.engelsen@nilu.no