Ozone and Air Quality. Some Selected Research Projects in the Chemical Sciences Division

Transcription

1 Ozone and Air Quality Some Selected Research Projects in the Chemical Sciences Division Joost de Gouw & Christoph Senff 1. Research approach and tools 2. Ozone precursor emissions 3. Nighttime chemical transformation 4. Land-sea breeze circulation 5. Ozone regional transport 6. Nighttime transport in low-level jet Joost Christoph

2 Ozone - Air Quality Research in CSD Atmospheric Measurements Laboratory Measurements Atmospheric Models Interplay between different approaches is one of the keys to success Collaboration with GSD and PSD on (forecasting) models Collaboration with GMD on ozone measurements

3 Tools for Field Measurements Used by CSD Platforms NOAA WP-3 NOAA Twin Otter NOAA Ron Brown In-situ Measurements (WP-3 and Ron Brown) Ozone precursors and radiation Radicals By-products of ozone chemistry Remote Measurements (Twin Otter and Ron Brown) Ozone lidar Doppler wind lidar

4 ESRL Regional Air Quality Field Studies New England 1993, 2002, 2004 CCOS 2000 ITCT 2002 Southeast 1995, 1999 Ongoing Local Studies Focus of many of today s talks East Texas 2000, 2006

5 VOC Emissions from Petrochemical Industries E VOC, ktons/year Houston metro area 40 TX 30 Latitude W.A. Parish Ship Channel TX City E NOx, ktons/year Houston has a severe ozone problem due to emissions from the petrochemical industry 29.0 Sweeny Longitude Freeport B Freeport A Choc. Bayou Work by: Joost de Gouw, Carsten Warneke, Tom Ryerson 0 NOAA performed the Texas Air Quality Studies in 2000 and 2006

6 Ethene Emissions From Industrial Point Sources NOAA WP-3 prevailing wind direction TexAQS 2000: Ethene is one of the main reactive VOCs A laser photo-acoustic instrument was developed for fast-response measurements during TexAQS 2006

7 Ethene Emissions From Industrial Point Sources Ethene flux from Freeport: Ozone (ppbv) Gaussian plume model Sweeny Freeport 30 Measured O 3 Predicted O 3 - Reported VOC emissions Predicted O 3 - Corrected VOC emissions longitude (deg) Gaussian model and analysis: M. Trainer - NOAA ESRL Emissions are severely underestimated in inventories developed by the State of Texas As a result, rapid ozone production in industrial plumes is underestimated by models

8 Verification of Isoprene Emissions Inventories Rainforest Boreal forest Deciduous forest Isoprene: large sources ~35% of all VOC emissions high reactivity midday lifetime <1 hour Reliable estimates of the emissions is key in ozone models Work by: Carsten Warneke, Joost de Gouw

9 Validation of Isoprene Emission Inventories ICARTT 2004 SOS 1999 TEXAQS 2006 Warneke et al. [in preparation] Inventories constructed from land-use data and emission factors depending on vegetation type Here: validate U.S. emission inventories using aircraft data

10 Validation of Isoprene Emission Inventories Example from 1 research flight over NE Texas: NOAA WP-3 OK TX AR LA Isoprene (pptv) Model Measurement Warneke et al. [in preparation] Measurements: 1-sec PTR-MS data Scatter due to real atmospheric variability Model: EPA BEIS3.13 inventory ECMWF temperature and radiation Measurements agree with inventory within factor of ~2

11 Nighttime Chemical Processing Work by: Steve Brown, Bill Dubé, Hendrik Fuchs, Roberto Sommariva

12 Diurnal Nitrogen Oxide Cycles Free Troposphere Free Troposphere 1.5 km Daytime Boundary Layer Residual Layer O 3 NO VOC OH O 3 RO 2 OH NO NO 2 HNO 3 hν O % of NO x tied up as NO 3, N 2 O 5 at night NO 3, N 2 O 5 losses determine how much NO x available the next day NO 3 is a strong oxidant for VOCs O 3 NO 2 NO 2 NO 3 N 2 O 5 H 2 O Het HNO m Nocturnal Boundary Layer DMS Sea Salt Soil NO Bio VOC VOC, NO x SO 2, PM DMS Sea Salt Soil NO Bio VOC VOC, NO x SO 2, PM NO x, VOC,O 3 transformed at night

13 Vertical Stratification & Nighttime Chemistry NOAA WP-3 NO F(NO x ) = 3 + 2N 2 O 5 NO 2 + NO 3 + 2N 2 O 5 Residual Daytime Boundary Layer Intermediate Layer Nocturnal Boundary Layer NO x and VOC plumes occur in discrete layers at night Chemical transformation within different layers differs markedly

14 Boundary Layer Vertical Profiles Erie (BAO) Tower 300 m w/ vertical resolution ~ 0.5 m Movable carriage on outside with > 1 ton payload Studies in 2004 (fall) and 2007 (summer) High NO 3 routinely observed aloft Often associated with complex layering Surface layer commonly observed

15 Ozone Transport and Mixing Processes Local-scale transport: Land sea breeze circulation in Houston, TX Regional transport: Increasingly important as 8-hour O 3 standards are tightened Nighttime processes: Transport and mixing by low-level jet

16 Measurement tools: LIDAR & RADAR Remote Sensing Ozone Lidar: TOPAZ = Tunable Optical Profiler for Aerosol and Ozone TOPAZ lidar mounted in NOAA Twin Otter R. Alvarez II, C. Senff, et al. Ozone profiles & mixed layer height

17 Measurement tools: LIDAR & RADAR Remote Sensing Doppler Wind Lidar: HRDL = High Resolution Doppler Lidar S. Tucker, A. Brewer, et al. Wind speed & direction profiles

18 Measurement tools: LIDAR & RADAR Remote Sensing Wind Profiler Network (PSD): NOAA/ESRL Integrated Wind Profiler Observing Site TEXAQS-II East Texas Wind Profiler Network A. White et al.

19 Measurement tools: LIDAR & RADAR Remote Sensing Wind Profiler Network (PSD): AR TX TEXAQS-II East Texas Wind Profiler Network A. White et al. NOAA/ESRL Integrated Wind Profiler Observing Site Gulf of Mexico A. White, C. Senff, et al. Interactive wind profiler trajectory tool

20 Local Transport: Houston land-sea breeze recirculation Noon: offshore flow Late afternoon: flow reverses Banta et al, 2005

21 Air Quality forecast model comparison with lidar Original Emissions League City Texas City Lidar O 3 cross section MM5/Chem model (1.7 km horizontal resolution) J.-W. Bao, G. Grell, S. McKeen

22 Air Quality forecast model comparison with lidar League City Texas City Lidar O 3 cross section MM5/Chem model (1.7 km horizontal resolution) J.-W. Bao, G. Grell, S. McKeen

23 Regional Transport: Estimating ozone exported from Houston Integrate excess ozone in plume (plume O 3 background O 3 ). Southerly wind Multiply with horizontal wind speed (from wind profiler network) to yield ozone flux for each transect.

24 Regional Transport: Houston Ozone Flux 8/12/06 8/14/06 8/30/06 ~ 35 kg s -1 8/28/00 9/06/ Max. ozone flux, kg s -1 A flux of 35 kg O 3 s -1 transported out of Houston over an 8-hour day is equivalent to a 10-ppb increase in ozone over an approx. 10,000 square mile area, assuming a 2-km deep mixed layer.

25 Nighttime Transport & Mixing AR Nighttime low level jet can transport O 3 over long distances. TX Speed and directional wind shear at night are very effective in distributing O 3 over large areas. Gulf of Mexico 12-hour forward trajectories: 6 PM 6 AM LST

26 Nighttime Transport & Mixing w/o LLJ w/ LLJ Nighttime low-level jet (LLJ) structure Wind speed variance: σ u 2 TKE R. Banta, Y. Pichugina, et al.

27 Summary: Ozone - Air Quality Research in CSD Atmospheric Measurements Laboratory Measurements Atmospheric Models Atmospheric measurements of emissions, chemical and dynamical processes are an important cornerstone. Laboratory measurements and modeling studies complete CSD s ozone air quality research approach.