Challenges in the Use of Satellite Measurements for Studies of Tropospheric Ozone

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1 Challenges in the Use of Satellite Measurements for Studies of Tropospheric Ozone Jack Fishman, John K. Creilson, Amy E. Wozniak, R. Bradley Pierce and Doreen O. Neil Atmospheric Sciences Research NASA Langley Research Center Hampton, VA Joint NASA/EPA Workshop on Air Quality and Related Climate Change Issues Research Triangle Park, NC September 14-16, 2004

2 Tropospheric ozone from satellite measurements is derived by subtracting two large numbers to calculate the tropospheric ozone residual (TOR) Some challenges: How do we know what we are seeing is truly in the troposphere? How are TOR amounts validated? How useful are data with very little vertical resolution? How do TOR amounts relate to surface ozone concentrations? These are good questions: This talk will provide insight into the first two points Schematic Diagram Showing How Tropospheric Ozone Residual (TOR) is Derived ~55 km 0-18 km Surface TOMS Total Ozone Calculate ~ 300 DU ~ 270 DU Stratospheric Ozone Profile Derived from SAGE or SBUV Tropopause (determined from NCEP analysis) Tropospheric Residual 300 DU -270 DU -30 DU The latter two require additional studies to provide good answers

3 How do we know what we are seeing is in the troposphere? Striking Similarity Between Global Distributions of TOR and Tropospheric NO 2 June-August Climatological TOR Distribution in Dobson Units (DU) QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture Tropospheric NO 2 Distribution from SCIAMACHY (10 15 molec. cm -2 )

4 How do we validate TOR measurements? Comparison of Satellite TOR with Ozonesonde Measurements at two Mid-latitude Sites Hohenpeissenberg TOR Hohenpeissenberg Ozonesonde Wallops Island Ozonesonde Wallops Island TOR R = 0.98 R = 0.96 Regression of Ozonesonde and TOR Monthly Difference R = 0.87 TOR data are from 9 latitude by 11 longitude boxes (81 grid points) centered near the two sites [Creilson et al., 2003]

Agreement with SCO Derived from SAGE Profiles Climatology from ~7000 SAGE profiles

5 How do we validate TOR measurements? Stratospheric Column Ozone (SCO) Derived from SBUV/TOMS TOR Technique In Good Agreement with SCO Derived from SAGE Profiles Climatology from ~7000 SAGE profiles SBUV-derived TOR uses stratospheric ozone profiles after application of empirical correction of Fishman et al. [2003] and lack the vertical resolution of SAGE profiles which are in excellent agreement with ozonesonde data. Difference (color bar) Climatology from ~800,000 SBUV profiles

Year June 1984 - Strong La Niña Year Interannual variability of TOR is strongly correlated

6 Dobson Units How do we know what we are seeing is in the troposphere? Examine Interannual Variability of TOR Observed over West Africa June Strong El Niño Year June Strong La Niña Year Interannual variability of TOR is strongly correlated to ENSO cycle R = 0.78 What can be said about the interannual variability of stratospheric ozone over this same region?

7 How do we know what we are seeing is in the troposphere? Stratospheric ozone over west Africa strongly correlated with quasi-biennial oscillation (QBO) Distribution of TOR over same region highly correlated with El Niño/Southern Oscillation (ENSO) R = 0.72 R = 0.78 R = 0.36 R = 0.26 Correlation of TOR with QBO is much less significant Correlation of SCO with ENSO is not significant

How do satellite measurements of a tropospheric integral

Case Study Suggests Transport from Northern U.S. Leads to Pollution Episode in Southern U.

coast Unique transport situation carries offshore pollution

8 How do satellite measurements of a tropospheric integral relate to surface O 3? Case Study Suggests Transport from Northern U.S. Leads to Pollution Episode in Southern U.S. Pollution from northern states pools off North Carolina coast Unique transport situation carries offshore pollution to southern states from Fishman and Balok [1999, JGR, 104, pp. 30,319]

9 The Next Challenge: Coupling Satellite Measurements with Models for Air Quality Applications

Regional Air Quality Modeling System (RAQMS) A NASA Langley/UW-Madison Cooperative Research Effort* RAQMS

Assimilation Scientific Understanding *RAQMS includes online chemistry from the NASA LaRC unified

and UWNMS (regional non-hydrostatic) dynamical cores RAQMS [Pierce et al.

10 Regional Air Quality Modeling System (RAQMS) A NASA Langley/UW-Madison Cooperative Research Effort* RAQMS Ozone Prediction February 27, 2001 Public Impact Regional Prediction Satellite Data Products Global Assimilation Scientific Understanding *RAQMS includes online chemistry from the NASA LaRC unified (troposphere/stratosphere) chemical mechanism driven by the UW-Hybrid (global isentropic/sigma coordinates) and UWNMS (regional non-hydrostatic) dynamical cores RAQMS [Pierce et al., JGR, 2003] is a nested global- to regional-scale meteorological and chemical modeling system for assimilating and predicting the chemical state of the atmosphere (air quality).

11 Development of the Regional Air Quality Modeling System (RAQMS) Principal Investigator: R. Bradley Pierce (NASA LaRC Creativity and Innovation (C&I) Initiative: Global Climate & Environmental Quality) LaRC Co-Investigators: T. Duncan Fairlie, Jassim A. Al-Saadi, Jennifer Olson, James Crawford, Doreen O. Neil, Jack Fishman University of Wisconsin Co-Investigators: Donald R. Johnson, Matthew H. Hitchman, Gregory J. Tripoli EPA Co-Investigator: James J. Szykman UW/LaRC Cooperative Post Doc: Chieko Kittaka

12 RAQMS Modules The IMPACT chemistry module includes detailed stratospheric chemistry and has been used to assimilate stratospheric species distributions in support of stratospheric field campaigns. The module has also been used to conduct multi-year coupled simulations of the Earth s atmosphere and compares well with observed climatology. Comprehensive tropospheric chemistry is included. The UW-Hybrid global meteorological module is uniquely formulated to provide accurate prediction of the long-range transport of atmospheric trace gases (hybrid sigma-potential temperature vertical coordinates). The UWNMS regional meteorological module includes multiple interactive grid nesting, detailed cloud microphysics, radiative transfer and surface processes and is suitable for prediction of planetary boundary layer and convective exchange processes.

13 Assimilated Data Provide Much Better Information in Upper Troposphere and Lower Stratosphere Compared to Nadirviewing Satellites: Critical for Residual Techniques Vertical resolution from SBUV Vertical resolution from RAQMS

14 Current satellite technique uses information from 5 days of measurements to construct stratospheric distribution: Results in daily accuracy potentially compromised Initial model runs suggest long-term accuracy is not compromised Day-to-day TOR differences may be as large as 15 DU

Aura: Launched July 15, 2004 High Resolution Dynamics Limb Sounder

tropospheric trace gases and aerosols Microwave Limb Sounder (MLS:USA)

tropospheric trace gases Tropospheric Emission Spectrometer (TES: USA)

Monitoring Instrument (OMI: Netherlands/Finland) Measures column ozone and

15 Aura: Launched July 15, 2004 High Resolution Dynamics Limb Sounder (HIRDLS:USA/UK) Measures IR limb emission of stratospheric and upper tropospheric trace gases and aerosols Microwave Limb Sounder (MLS:USA) Measures microwave limb emission of ozone destroying chemicals and upper tropospheric trace gases Tropospheric Emission Spectrometer (TES: USA) Down looking and limb looking measurements of air pollution Ozone Monitoring Instrument (OMI: Netherlands/Finland) Measures column ozone and aerosols - continues global ozone record of TOMS HIRDLS MLS Direction of motion TES limb OMI TES nadir

16 Summary: Research Must Progress on Two Fronts Satellite Studies TOR (tropospheric O 3) from TOMS has provided a long-term data set Validation and accuracy will always be difficult to determine OMI will increase horizontal resolution to 13 x 24 km OMI should also be capable of providing same species measurements as GOME and SCIAMACHY (NO 2 and CH 2 O) previously, but with better spatial resolution TES will provide direct measurement of tropospheric O 3 Modeling Studies Successful synthesis of capabilities to simulate regional and global processes key to progress Models can be used to segregate tropospheric and stratospheric components better than using only observations Models might provide important insight relating tropospheric column measurements to surface measurements for greater relevance to air quality applications

17 Back-up Slides

18 What is RAQMS? RAQMS Regional Air Quality Modeling System Global to Regional Meteorolgical /Chemical Model for Assimilating and Predicting Air Quality UW-Hybrid University of Wisconsin Global Module Meteorological Model with Hybrid vertical coordinate UW-NMS University of Wisconsin Regional Module Non-Hydrostatic Meteorogical Modeling System IMPACT LaRC Chemical Module Interactive Modeling Project for Atmospheric Chemistry A joint effort between LaRC and the University of Wisconsin- Madison (UW) to develop a nested global- to regional-scale meteorological and chemical modeling system for assimilating and predicting chemical composition.

19 How Can We be Sure We are Seeing Tropospheric Ozone? On the global scale, there is now a compelling picture indicating a strong relationship between regional precursor emissions and the resultant tropospheric ozone distribution derived from satellite measurements QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture. TOR in Dobson Units June-August TOR Distribution Tropospheric Column NO 2 from SCIAMCHY

with ENSO and strength of monsoonal flow Relationship between TOR and

20 How do we know what we are seeing is in the troposphere? Interannual variability of TOR over Northern India Strongly Correlated with ENSO and strength of monsoonal flow Relationship between TOR and SSTA Periods of strong El Niño June Strong El Niño Year June Strong La Niña Year

21 High Pressure Dominates East Coast After Front Passes Through on July 1

22 Development of Satellite Ozone Distribution During Air Pollution Episode

23 Synoptic Situation During Middle of Air Pollution Episode

24 Origin of Air in Polluted Air Behind Front and in Clean Air Ahead of Front Origin of High Ozone behind front was NE U.S. Origin of Lower Ozone ahead of front was from the Tropics

25 Persistent Anticyclone Over Eastern U.S. Finally Breaks Down

26 Trajectories Show Origin of Pollution Over Southern States and Subsequent End of Pollution Episode

Science Results Based on Aura OMI-MLS Measurements of Tropospheric Ozone and Other Trace Gases

Science Results Based on Aura OMI-MLS Measurements of Tropospheric Ozone and Other Trace Gases J. R. Ziemke Main Contributors: P. K. Bhartia, S. Chandra, B. N. Duncan, L. Froidevaux, J. Joiner, J. Kar,