SO 2 data from the Ozone Monitoring Instrument (OMI) N. Krotkov 1, A. Krueger 2, K. Yang 1, S. Carn 2,P. K. Bhartia 3, P. F. Levelt 4 1. Goddard Earth Sciences and Technology (GEST) Center, UMBC, USA 2. Joint Center for Earth Systems Technology (NASA/UMBC), UMBC, USA 3. Laboratory for Atmospheres, NASA Goddard Space Flight Center, USA 4. KNMI, Netherlands

Bottom-up inventory of Global Sulfur emissions Northern Hemisphere Southern Hemisphere Global Marine and Terrestrial DMS Volcanic SO Explosive degassing Passive degassing 5-10 Biomass Burning Fossil Fuel Use and Industry TOTAL (S, Tg) [Bluth et al., 1993; Pyle et al., 1996; Graf et al., 1997; Andres & Kasgnoc, 1998]

Total Ozone Mapping Spectrometer (TOMS): NASA, Nimbus-7, Meteor-3M, ADEOS, Earth Probe –launches 1978, 1991, 1996, 1996 –955 km orbit (Nimbus-7) –1206 km orbit (Meteor-3; 82.5° inc.) –502 km orbit (Earth Probe ) 740 km after December 1997 Sensor Characteristics –scanning monochrometer with 6 spectral bands between to µm –cross-track scan mirror with ~2500 km swath width (±51°) –spatial resolution: km (depending on altitude of spacecraft) –onboard solar diffuser Only 6 UV wavelengths limit detection to large volcanic eruptions:

NASA EOS Aura Launched July 15, 2004  Is the stratospheric ozone layer recovering?  What are the processes controlling air quality?  How is the Earth’s climate changing? HIRDLS TES MLS OMI

Ozone Monitoring Instrument The NASA EOS Aura platform, launched on July 15, 2004, carries the Ozone Monitoring Instrument (OMI) Joint Dutch-Finnish Instrument with Duch/Finish/U.S. Science Team PI: P. Levelt, KNMI Hyperspectral wide FOV Radiometer nm 13x24 km nadir footprint (highest resolution from space ! ) Swath width 2600 km ( contiguous coverage ) Radicals: Column O 3, NO 2, BrO, OClO O 3 profile ~ 5-10 km vert resolution Tracers: Column SO 2, HCHO Aerosols (smoke, dust and sulfates) Cloud top press., cloud coverage Surface UVB Tropospheric ozone 13 km (~2 sec flight) ) 2600 km 12 km/24 km (binned & co-added) flight direction » 7 km/sec viewing angle ± 57 deg 2-dimensional CCD wavelength ~ 580 pixels ~ 780 pixels

Backscattered UV (BUV) algorithm uses Ozone and SO2 spectral features in reflected Sunlight Cloud Surface Atmosphere Mostly Stratospheric (Total Ozone) Stratospheric Or tropospheric (SO2)

The OMI algorithm needs assumption altitude profile of SO 2 OMI directly measures integrated slant column absorption (SC+  ) along line of sight by fitting spectral lines Total SO2[molecules/cm2]= (SC+  )/AMF

Air mass factor (AMF) depends on a-priori SO2 profile, surface albedo, total ozone, geometry and aerosols and clouds.

OMI SO 2 data publicly released in 2006 The operational OMI SO 2 product contains retrieved SO 2 amounts for 3 separate SO 2 vertical profiles: Explosive eruption clouds [15 km altitude, large SO 2 loading, >50 DU] – NEW Linear Fit algorithm Passive volcanic degassing [5 km altitude, – NEW Linear Fit algorithm Anthropogenic SO 2 pollution; low altitude volcanoes [<3 km altitude (PBL), low SO 2 loading] - New AMF, background correction

2 year OMI SO 2 data ( )

SO 2 emissions from lignite-burning power plants in the Balkan region SO 2 enhancements observed by GOME in February 1998 [Eisinger and Burrows, GRL 1998]. SO 2 enhancements detected by OMI in February 2005

SO 2 burdens increase over China >50% of China’s energy is derived from coal burning. SO2 emissions increased at a rate 35%/decade in China’s sulfate aerosol loading has increased by 17%/decade in [Massie, Torres and Smith 2004] 25.5 million tons of SO2 was emitted by Chinese factories in 2005 up 27% from 2000 OMI can observe SO 2 emissions in the planetary boundary layer (PBL) over China on a daily basis and is able to track individual pollution plumes outflow to Pacific. Krotkov, N, A., S. A. Carn, A.J. Krueger, P.K. Bhartia, K. Yang, Band residual difference algorithm for retrieval of SO2 from the AURA Ozone Monitoring Instrument (OMI), IEEE Transactions on Geoscience and Remote Sensing, AURA special issue, 44(5), , 2006

Ecuador/S. Colombia volcanoes PERU La Oroya copper smelter Daily SO 2 emissions (kilotons) Sept Sept 2005 Ilo copper smelter Average SO 2 map from OMI Carn, S.A., N.A. Krotkov, A.J. Krueger, K. Yang, P.F. Levelt, "Sulfur dioxide emissions from Peruvian copper smelters detected by the OMI", GRL (in print), 2007.

Atmospheric impacts of oil production (1) OMI measures SO 2 emissions from oil refineries and oil/gas fields in the Gulf States Cumulative SO 2 emissions October 2005 Unknown Iranian source

Atmospheric impacts of oil production (2) Can we use SO 2 emissions as a proxy for oil production? OMI data indicate increased output to counter high gas prices in the US in late 2005 SO 2 burden over Gulf States Jan Apr 2006

2 year OMI SO 2 data ( ) Mexico City (pollution) Popocatepetl volcano (degassing)

2 year OMI SO 2 data ( ) OMI: Nyamuragira volcano degassing South African power plants (e.g., near Johannesburg); copper smelting More than 90% of South Africa's electricity is generated by the combustion of coal Coal-fired power plants not required to use scrubbers to remove sulfur from emissions GOME SO 2, Nyamuragira volcano degassing [Eisinger and Burrows, 1998]

Average ( ) SO 2 burdens over USA, Europe and China: 25.5 million tons of SO2 was emitted by Chinese factories in 2005 up 27% from 2000 East-Aire’05 experiment

We focus on EAST-AIRE regional experiment over NE China in April SO 2 observations from instrumented aircraft flights are compared with OMI SO 2 maps. SO2 Aerosol Aircraft spirals

April 5: Heavy pollution ahead of cold front : MODIS RGB imagery courtesy of the MODIS Rapid Response Project

The comparison demonstrates that operational OMI algorithm can distinguish between heavy pollution ( April 5 ahead of cold front ):

MODIS RGB imagery courtesy of the MODIS Rapid Response Project April 7: Shenyang area behind cold front

MODIS RGB imagery courtesy of the MODIS Rapid Response Project MODIS RGB + OMI SO2 + trop winds, 7 April 2005

OMI pollution SO2 data quality 1.The OMI measurements of SO2 agree with the aircraft in situ observations of high concentrations of SO2 (ca ~2 DU) ahead of the cold front and lower concentrations behind it. This comparison demonstrates that OMI can distinguish between background SO2 conditions and heavy pollutions on a daily basis. 2.Operational SO2 data need correction for total ozone, SO2 profile, viewing geometry and aerosol effects. 3.OMI IFOV noise ~1.5DU for ideal conditions (near nadir view, no clouds). The noise is expected to decrease with new calibrations (ECS 3 data). Reprocessing of the SO2 record in summer Noise is less than 0.2 DU in yearly averaged maps. Small artifacts (local biases) are present in some areas. 5.Daily OMI bias (IFOV averaged over ~2 by 2 deg box) is positive over China (OMI higher than aircraft ) by 0.5 – 2DU. The bias needs to be corrected empirically.Off-line spectral fit algorithm features smaller bias. 6.Current algorithm Quality Flags are too conservative: reject real pollution.

The End