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UV monitoring products derived from satellite measurements
J. Kujanpaa1, K. Lakkala1, A. Arola1, A. Lindfors1, N. Kalakoski1, A. Heikkila1, J. Tamminen1
(1) Finnish Meteorological Institute, [email protected]
AbstractUV products derived from satellite data arecomplementary to traditional ground-basedmeasurements. On the one hand satellites haveglobal coverage and provide data for regionsuncovered by the ground-based UV measurementnetwork, but on the other hand ground-basedmeasurements are needed to validate the satelliteproducts. As opposed to the direct ground-basedmeasurements, the satellite products areindirectly obtained by radiative transfermodelling using as main inputs: total ozonecolumn, cloud and aerosol optical properties,surface albedo and pressure. The FinnishMeteorological Institute (FMI) is currentlyresponsible for the following three satelliteproducts using different satellite data.
EUMETSAT offline UV product• operational data available with 2-3 days delay
from https://acsaf.org/•daily doses and maximum dose rates of UV-B
and UV-A radiation•different biological weighting functions•photolysis rates, solar noon UV index•quality control flags
Surface UV data record: June 2007- May 2017•Combines observations from GOME-2/Metop-A
and GOME-2/Metop-B• Surface UV albedo and aerosol optical thickness
from daily MODIS data• Surface pressure data from
ECMWF/ERA-Interim
Comparison of UV data record withground based data
Sodankyla 67◦N, 27◦E:
0 1 2 3 4 5
Brewer CIE Daily Dose [kJ/m 2 ]
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Sodankyla 2007-2017
0 50 100 150
Brewer CIE Maximum Dose rate [mW/m 2 ]
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GO
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-2 C
IE M
axim
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/m2]
Sodankyla 2007-2017
Jokioinen 61◦N, 23◦E:
0 1 2 3 4 5
Brewer CIE Daily Dose [kJ/m 2 ]
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Jokioinen 2007-2015
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Brewer CIE Maximum Dose rate [mW/m 2 ]
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Jokioinen 2007-2015
Helsinki 60◦N, 24◦E:
0 1 2 3 4 5
Brewer CIE Daily Dose [kJ/m 2 ]
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Helsinki 2016-2017
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Brewer CIE Maximum Dose rate [mW/m 2 ]
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Helsinki 2016-2017
OMI UV product
•Ozone Monitoring Instrument (OMI) aboard theNASA EOS-Aura satellite
•Launched on 15 July 2004
• 2D CCD detector allows- measurement of UV-VIS spectra simultaneouslyin across track dimension- ground pixel size 13 x 24 km2
•Built by Dutch Space with subcontractors VTTand Patria, Finland
•UV product processed at FMI•Direct broadcast data from SAMPO:
- Satellite Measurements from Polar Orbit- sampo.fmi.fi
•Archived data from NASA:- https://disc.gsfc.nasa.gov/
Global surface UV radiation (OMUVB)
Products, L2, L2 gridded, L3 (daily):
• Irradiance (overpass time and local noon)• 305,310,324,380 nm [W/m2 /nm]•Erythemally weighted (290-400 nm) irradiance
[W/m2]•Erythemal daily dose [J/m2]•Products processed and archived at FMI
Comparison of UV data with groundbased data
0 1 2 3 4 5 6Brewer UV index
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OM
I op
UV
inde
x
2004-2018y =0.88x +0.33r² =0.84N =2322
FIG. Preliminary results: FMI’s Brewer UV indexand OMI overpass UV index ratio in Sodankyla2004-2018 (March-October).
The OMI data was donwnloaded from the Auravalidation center at avdc.gsfc.nasa.gov (Hovila etal.2014). Brewer measurements within 5 minutesfrom the overpass time of the satellite wereselected. During this time window changes in thecloud cover are frequent and influence thecomparison results.
ReferencesHovila et al. 2014, OMI/Aura Surface UVB Irradiance and ErythemalDose Daily L2 Global Gridded 0.25 degree x 0.25 degree V3, NASAGoddard Space Flight Center, Goddard Earth Sciences Data andInformation Services Center (GES DISC), Accessed: 5 September 2018,10.5067/Aura/OMI/DATA2028
TROPOMI surface UV product•Tropospheric Ozone Monitoring Instrument
(TROPOMI)• aboard the Copernicus Sentinel-5 precursor
satellite• launched on 13 October 2017
Photo: ESA
• FMI is responsible for the development andprocessing of the surface UV product.
•part of the Finnish Sentinel Collaborative GroundSegment in Sodankyla, Finland
• in-kind contribution to the S5P/TROPOMIproduct family by the FMI
•Part of EU Copernicus Program- Provides input data to Copernicus AtmosphericMonitoring Service
•Continues the OMI UV record
Product DescriptionThe algorithm builds on the heritage of thecorresponding OMI and EUMETSAT AC SAFalgorithms.
The TROPOMI surface UV product includes thefollowing UV quantities: the UV irradiance at 305,310, 324, and 380 nm; the erythemally weightedUV; the vitamin-D weighted UV. Each of these areavailable as (i) daily dose or daily accumulatedirradiance, (ii) overpass dose rate or irradiance,and (iii) local noon dose rate or irradiance. Inaddition, all quantities are available correspondingto actual cloud conditions and as clear-sky values
Comparison of UV data with groundbased data
TROPOMI overpass time UV index against Brewerspectrophotometer measurements in Sodankyla(67.37N, 26.63E) from 6 February to 16 March 2018.The UV index is very low during this time periodbut still the values agree well.
The Brewer spectroradiometer #037 measures totalozone and UV radiation at Sodankyla since 1988.
AcknowledgmentsWe thank the AC SAF project of the EUMETSAT for providing data usedin this poster.
