AIRS Global Daily Ammonia Products

J. Warner1, Z. Wei1, L. L. Strow2, S. Hannon2, R. Yang1

J. Walker3 1 Dept. of Atmospheric and Oceanic Sciences, UMCP 2 Dept. of Physics and JCET, UMBC 3 US EPA, Research Triangle Park, NC

*Funded by NASA’s The Science of Terra and Aqua Program (NNX11AG39G) and the Atmospheric Composition Program (NNX07AM45G).

Why Ammonia •  Global ammonia (NH3) emissions have been increasing due

to the dramatically increased agricultural livestock numbers together with the increasing use in nitrogen fertilization (Sutton et al., 1993).

•  Atmospheric ammonia has impacts to the ecosystems on both local scales, acidification and eutrophication, and global (transboundary) scales through formation of fine ammonium containing aerosols.

•  Measurements with daily and large global coverage are challenging and have been lacking partly because the lifetime of NH3 is relatively short and partly because it requires high sensitivity for the retrievals that can be only obtained from areas with high thermal contrasts near the surface (Clarisse et al., 2010).  

Methodology •  Retrievals using the Optimal Estimation (OE) technique.

•  AIRS Cloud Cleared Radiances are used (CCR).

•  AIRS L2 products other than NH3 are used in the Forward Model (FM) SARTA.

•  Error Covariance matrices and a priori profiles are computed from MOZART climatology.

Contributions of Scott Hannon for AIRS Ammonia Products

•  Added NH3 coefficients into AIRS forward model SARTA… •  Developed AIRS NH3 sensitivities based on the Brightness Temperatures (BT), which we used in the proposal to NASA.

AIRS Ammonia signals from BT fitting (2004/05/05-20) using pure clear scenes

AIRS NH3 spectral RMS Signals (top) and Errors (bottom)

•  MOZART climatology shows know emission sources. •  Zonal mean time series indicate in the tropics emission peaks in the winter season and in the mid-latitudes peaks in the summer. •  MOZART NH3 fields have not been validated (private communication with L. Emmons).

AIRS NH3 A priori with covariance derived from MOZART climatology

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NH3 mean profile from High emission area

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NH3 mean profile from Moderote emission area

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NH3 mean profile from Low emission area

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Determination of a priori Example  on  20060304  

        •     

•   Used  to  iden5fy  different  emission  signals.  

€

Rstrong − RweakNEdT

AIRS NH3 VMRs (pptv) at 840hPa and DOFS for May 1-31, 2009

AIRS  NH3  VMRs   AIRS  NH3  DOFS    

•  High NH3 identifies all known sources. •  DOFS 0.3 to greater than 1.0.

AIRS NH3 VMR (ppt) at 840hPa for 20090501--20090531

15 30 45 60 75 90 105 120 135 150 165 180 -165-150-135-120-105 -90 -75 -60 -45 -30 -15

15 30 45 60 75 90 105 120 135 150 165 180 -165-150-135-120-105 -90 -75 -60 -45 -30 -15

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AIRS NH3 DOFs for 20090501--20090531

15 30 45 60 75 90 105 120 135 150 165 180 -165-150-135-120-105 -90 -75 -60 -45 -30 -15

15 30 45 60 75 90 105 120 135 150 165 180 -165-150-135-120-105 -90 -75 -60 -45 -30 -15

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Current Issues CCR  with  Cloud  Frac5on=1.0   CCR  with  Cloud  Frac5on=0.0  

•  CCR verses L1 clear radiances •  Selection of a priori

AIRS NH3 VMR (ppt) at 840hPa for 20090501--20090531

15 30 45 60 75 90 105 120 135 150 165 180 -165-150-135-120-105 -90 -75 -60 -45 -30 -15

15 30 45 60 75 90 105 120 135 150 165 180 -165-150-135-120-105 -90 -75 -60 -45 -30 -15

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300.0 570.0 840.0 1110.0 1380.0 1650.0 1920.0 2190.0 2460.0 2730.0 3000.0

AIRS NH3 VMR (ppt) at 840hPa for 20090501--20090531

15 30 45 60 75 90 105 120 135 150 165 180 -165-150-135-120-105 -90 -75 -60 -45 -30 -15

15 30 45 60 75 90 105 120 135 150 165 180 -165-150-135-120-105 -90 -75 -60 -45 -30 -15

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Comparisons with MOZART NH3 AIRS  NH3  VMRs  w/  Cloud  Frac5on=0  

MOZART  NH3  at  912hPa     MOZART-4 NH3 VMR (pptv) monthly mean at 840hPa for 200905

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MOZART  NH3  at  840hPa    

AIRS NH3 VMR (ppt) at 840hPa for 20090501--20090531

15 30 45 60 75 90 105 120 135 150 165 180 -165-150-135-120-105 -90 -75 -60 -45 -30 -15

15 30 45 60 75 90 105 120 135 150 165 180 -165-150-135-120-105 -90 -75 -60 -45 -30 -15

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Remaining – Validation with In Situ Measurements

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NH3: AIRS RETR. V.S. Insitu

•  Twenty five in situ surface sites from US EPA. •  NOT good! Yet!

Remaining – Inter-comparison

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(10.40°, −60.82°): solzen=24.9°, land=0.0, DOF−airs=0.64, DOF−tes=0.46

AIRS FGAIRS RETTES FGTES RET

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Summary •  AIRS captures global NH3 emission sources due to natural

and anthropogenic activities with good accuracies. •  AIRS DOFS for NH3 ranges from 0.3 to greater than 1.0

over emission regions. •  More efforts are needed in the selection of spectral

channels and to reduce noise possibly due to cloud and/or surface effects, as well as the selection of a priori profiles.

•  Carry out comparisons to models such as GEOS-Chem, GMI, and CMAQ.

•  More Validations with in situ measurements •  Inter-comparing with other satellite sensors, i.e., TES

and IASI NH3.