About the status and outlook forOMI Surface UV product

OMI Science Team Meeting

Helsinki, June 24-27, 2008

Antti Arola

Aapo left FMI about three months ago.

Since then, I have been responsible for the scientific development of OMUVB, while Simo Tukiainen

has been responsible for the processing related issues.

Puijo tower measurements

Finnish meteorological institute and Univ. of Kuopio

Current setup of measurements

Ion spectrometerAIS

Gas concentrations (NO-NOx, O3, SO2, CO)GAS

Total particle number concentrationCPC

Aerosol absorptionMAAP

Aerosol particle size distribution (0.25-32 m)ADM

Visibility, precipitationPWD

Weather parameters (T, RH, p, wind 2D)WXT

Aerosol scatteringNM

Cloud condensation nucleus (CCN) concentrationCCNC

Cloud drop size distribution (2-50 m)CDP

Aerosol particle size distribution (7-900 nm)* simultaneously in and out of cloud”

DMPS

DMPS = differential mobility particle sizer; ADM = ambient dust monitor; CPC = condensation particle counter; CDP = cloud droplet probe; CCNC = cloud condensation nuclei counter; NM = nephelometer;MAAP = multi-angle absorption photometer; WXT = weather transmitter; PWD = present weather detector;AIS = Air Ion Spectrometer

AERONET station

• AERONET sites in FinlandHyytiäläKuopioPallasHelsinki_LighthouseSodankylä

• Soon FMI campaign site in India, near Delhi

Provide a long term data set to:• Characterize aerosol optical properties• Validate Satellite & model aerosol retrievals• Synergism with Satellite obs., models sfc net

Satellite observations from A-train

Aqua

CALIPSO CloudSat

PARASOL

Aura

OMI Surface UV Algorithm and Surface UV Products

• Inherits from the TOMS UV algorithm based on look-up-tables made with various radiative transfer models.

• Calculate clear-sky surface UV irradiance

• Define cloud optical depth that gives the measured TOA radiance

• Make cloud correction using the obtained

• Absorbing aerosol correction to be added in the future

• Products:

• Erythemal dose rate both at overpass and at local solar noon (UV Index)

• Erythemal daily dose

• Irradiances at 305, 310, 324 and 380 nm both at overpass and at local solar noon

• The OMI surface UV algorithm is implemented in two separate processing systems: OMI-VFD and Global OMUVB.

OMI Very-Fast-Delivery has been operational since March 2006

OMI data is received by Direct Broadcast in Sodankylä and is processed immediately after each overpass of the Aura satellite. Distribution plots for total column ozone, UV Index and Erythemal daily dose are published within 30 minutes after the overpass at

http://omivfd.fmi.fi/index_eng.html

Global OMUVB product

Processing Status and Data Release

• OMUVB Level 2 V003 reprocessing is on-going. Years 2007 and 2008 are ready, earlier data is in progress.

• Level 2 HDF5-EOS data are available at GES DISC.

• http://disc.gsfc.nasa.gov/Aura/OMI/omuvb_v003.shtml

• AVDC provides OMUVB overpass data for over 100 sites that has been used for validation. New sites can be added (michael.m.yan@nasa.gov).

Tanskanen, A., et al. (2007), Validation of daily erythemal doses from Ozone Monitoring Instrument with ground-basedUV measurement data, J. Geophys. Res., 112, D24S44, doi:10.1029/2007JD008830.

• Brewers in Jokioinen and Sodankylä

• SUV100 network data by National Science Foundation

• Canadian Brewer network data from Meteorological Service of Canada

• Spectral UV data from Lauder and Tokyo

Corr. coeff. = 0.76Slope = 2.4

Arola, A., S. Kazadzis, N. Krotkov, A. Bais, J. Grobner, and J. R. Herman

(2005), Assessment of TOMS UV bias due to absorbing aerosols,

J. Geophys. Res., 110, D23211, doi:10.1029/2005JD005913.

Relationship suggests a correction for the absorbing aerosols:

absb

UVUV

loperationacorrected

*1

)()(

)1(* SSAAODabs

Kinne, S.: Aerosol Direct Radiative Forcing

with an AERONET touch, Atmos. Environ.,

submitted, 2007.

Parameterization allows post-correction of the TOMS operational UV data:

Conclusions• Analog to the TOMS total column ozone time-series the

surface UV time-series are continued with the OMI measurement data applying an algorithm that is similar to the TOMS UV algorithm.

• There is a need to introduce a correction for absorbing aerosols. First step is to include a monthly climatology based on global aerosol models, satellite data, and sunphotometer measurements.

• The validation effort continues, important particularly when changes to the algorithm are applied.