Trace Gas Retrievals from the GeoTASO Aircraft Instrument during DISCOVER-AQ

Caroline Nowlan, Xiong Liu, Cheng Liu, Gonzalo Gonzalez Abad, Kelly ChanceHarvard-Smithsonian Center for Astrophysics, Cambridge, MA

James Leitch, Joshua Cole, Tom Delker, Bill Good, Frank Murcray, Lyle Ruppert, Dan Soo Ball Aerospace, Boulder, CO

Chris Loughner, Melanie Follette-Cook, Scott Janz, Matt Kowalewski, Ken PickeringNASA GSFC, Greenbelt, MD

GeoTASO

New test-bed instrument for the geostationary TEMPO (scheduled for launch 2018-2019) and GEO-CAPE (Decadal Survey) satellite instruments

First flights happened during DISCOVER-AQ on NASA Falcon Texas 2013 (6 flight days) Colorado 2014 (12 flight days)

GeoTASO Measurements

Measures with 2 detector arrays UV: 280 – 410 nm (O3, HCHO, SO2)

Visible: 416 – 690 nm (NO2, O3, aerosols) 2-D CCD array detector

One dimension across flight track and one in wavelength dimension

Resolution at surface: ~500x500 m2 (NO2, HCHO, O3)

~1x1 km2 (SO2) We retrieve slant columns using nearby zenith-sky

reference spectra, then convert to vertical columns with air mass factor from a radiative transfer code (VLIDORT, Spurr et al., 2006) using CMAQ at 4x4 km2 resolution

Current Status

Texas campaign: NO2 vertical columns available UV radiance calibration needs refinement

Colorado campaign: NO2 and SO2 slant columns available for 4 of 12 days

To come: Ozone profiles, NO2 vertical columns, HCHO, more flights to process

First Houston data should be up on DISCOVER-AQ data archive by the end of May.

Contact: cnowlan@cfa.harvard.edu

DISCOVER-AQ Texas 2013

Houston:09/13, 09/14, 09/18, 09/24GeoCAPE ocean color

flight: 09/17

OMI underflight: 09/16

Transit out (GA power plants): 09/12

Transit back (NC power plants): 09/24

(NO2 data in red are currently available.)

DISCOVER-AQ Colorado 2014

Transit back (power plants, Kansas City, St. Louis): 08/13

Transit out (power plants): 07/25

Denver: 07/29, 07/31, 08/01, 08/02, 08/06, 08/08, 08/10, 08/11

West Colorado power plants: 08/09 Plateville Oil &

Gas:08/03

(NO2 data in red are currently available.)

NO2 over Houston (Cloud-free ground pixels)

VerticalColumn

13 Sept 201310:00-11:30AM

18 Sept 20139:00-11:45AM

24 Sept 201310:00-11:45AM

14 Sept 20132:00-5:00PM

NO2 over Downtown Houston13 September 2013

VerticalColumn

GeoTASO NO2 vs PANDORA NO2 Houston Urban Flights

Cloud-free observations

Small bias, possible causes to be investigated:• Aerosols not

currently included in radiative transfer model for air mass factor calculation

• Effects from zenith sky observations or background offset removal using clean observations over water

GeoTASO NO2 vs EPA AQS NO2 Houston Urban Flights

Lamsal et al. (2008) method is often used to infer surface mixing ratio from satellite measurements: Scale satellite vertical column density (VCD)

using a model to get surface concentration (S).

GeoTASO NO2 vs EPA AQS NO2 Houston Urban Flights

GeoTASO NO2 (500x500 m2) vs GCAS NO2 on B-200 (250x500 m2)

Close flights on 13 September 2013 show very similar NO2

Both analyzed with GeoTASO algorithm

NO2 over Denver, Raster Scans2 August 2014

8:00 – 11:30 AM LOCAL TIME 2:00 – 4:00 PM LOCAL TIMESlantColumn

08/13/2014: Overpass of Labadie Power Station, Missouri

Photo by J.B. Forbes

GeoTASO measured coincident slant columns of NO2 and SO2 downwind from Missouri’s largest coal-burning power plant, on transit back to Virginia

Future Work

O3 profile work in preparation for TEMPO mission Formaldehyde retrieval optimization Aerosol sensitivities in air mass factor Process rest of Colorado data Improvements to UV calibration for Houston campaign Comparisons with GCAS, P-3B and satellites

Responsibility for GeoTASO transferring this year from Ball Aerospace to NASA Goddard (Scott Janz)