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Chris Barnet

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IASI = Infrared Atmospheric Sounding Interferometer. CrIS = Cross-track Infrared Sounder ... to be diagonal, for apodized interferometers (e.g. IASI) this is ... – PowerPoint PPT presentation

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Title: Chris Barnet


1
The Challenges in using Atmospheric Trace Gas
Products from Thermal Sounders
  • Chris Barnet
  • NOAA/NESDIS/STAR
  • (the office formally known as ORA)
  • AIRS Science Team Member
  • NPOESS Sounder Operational Algorithm Team Member
  • GOES-R Algorithm Working Group Chair of Sounder
    Team
  • May 11, 2006
  • Carbon Fusion, Edinburgh

Mitch Goldberg AIRS IASI Science Team, Climate
Products Walter Wolf Near Real Time Processing
Distribution to Users Lihang Zhou Regression
Retrieval Near Real Time Web Page Eric Maddy
CO2 retrieval, tuning, vertical averaging
functions. Xiaozhen Xiong CH4 retrieval Xingpin
Liu Re-processing, Statistics, Product web-page
2
Topics
  • Introduction to our plans to use operational
    sounders to retrieve carbon products.
  • Example of CO Product
  • Example of CH4 Product Validation Efforts
  • Example of CO2 Product Validation Efforts
  • Inter-comparison of AIRS trace gas products.

3
Acronyms
  • Infrared Instruments
  • AIRS Atmospheric Infrared Sounder
  • IASI Infrared Atmospheric Sounding
    Interferometer
  • CrIS Cross-track Infrared Sounder
  • HES Hyperspectral Environmental Suite
  • Microwave Instruments
  • AMSU Advanced Microwave Sounding Unit
  • HSB Humidity Sounder Brazil
  • MHS Microwave Humidity Sensor
  • ATMS Advanced Technology Microwave Sounder
  • AMSR Advanced Microwave Scanning Radiometer
  • Imaging Instruments
  • MODIS MODerate resolution Imaging
    Spectroradiometer
  • AVHRR Advanced Very High Resolution Radiometer
  • VIIRS Visible/IR Imaging Radiometer Suite
  • ABI Advanced Baseline Imager
  • Other
  • CALIPSO Cloud-Aerosol Lidar and Infrared
    Pathfinder Satellite Observations
  • EUMETSAT EUropean organization for exploitation
    of METeorological SATellites

4
NOAA/NESDIS 20 year StrategyUsing Existing
Operational Sounders.
  • Now Develop and core test trace gas algorithms
    using the Aqua (May 4, 2002) AIRS/AMSU/MODIS
    Instruments
  • Compare products to in-situ (e.g., ESRL/GMD
    Aircraft, JAL, INTEX, etc.) to characterize error
    characteristics.
  • The A-train complement of instruments (e.g.,
    MODIS, AMSR, CALIPSO) can be used to study
    effects of clouds, surface emissivity, etc.
  • 2006 Migrate the AIRS/AMSU/MODIS algorithm into
    operations with METOP (2006,2011,2016)
    IASI/AVHRR. Study the differences between
    instruments, e.g., effects of scene and clouds on
    IASIs instrument line-shape.
  • 2009 Migrate the AIRS/IASI algorithm into
    operations for NPP (2009?) NPOESS (2012?,2015?)
    CrIS/ATMS/VIIRS. These are NOAA Unique Products
    within the NOAA NDE program.
  • 201? Migrate AIRS/IASI/CrIS algorithm into
    GOES-R HES/ABI

5
AIRS Was Launched on the EOS Aqua Platform May 4,
2002
MODIS
AMSU-A1(3-15)
AMSU-A2(1-2)
AIRS
HSB
Delta II 7920
Aqua Acquires 325 Gb of data per day
6
AIRS has a Unique Opportunity to Explore Test
New Algorithms for Future Operational Sounder
Missions.
Apr. 28, 2006
12/18/2004
5/4/2002
9/2008
7/15/2004
7
In 2007 we will have IASI AIRS making global
measurements, 4/day
  • Initial Joint Polar System An agreement between
    NOAA EUMETSAT to exchange data and products.
  • NASA/Aqua in 130 pm orbit
  • EUMETSAT/IASI in 930 am orbit (July 2006)
  • NPOESS/CrIS in 130 pm orbit (2009?)

8
Spectral Coverage of Thermal Sounders (Example
Radiances AIRS, IASI, CrIS)
AIRS, 2378 Channels
IASI, 8401 Channels
CrIS 1305
CO2
O3
CH4
CO2
CO
9
Thermal sounder forward modelExample upwelling
radiance term
Absorption coefficients, ?, for a any spectrally
active molecular species, i, (e.g., water, ozone,
CO2, etc.) must be computed.
Each channel samples a finite spectral region
? is a strong function of pressure, temperature,
and interaction with other species.
Full radiative transfer equation includes
surface, down-welling, and solar reflection terms.
Inversion of this equation is highly non-linear
and under-determined.
Vertical temperature gradient is critical for
thermal sounding.
10
Retrieval is a minimization of cost function,
optimized for the instrument
Covariance of observed minus computed radiances
includes instrument noise model and spectral
spectroscopic sensitivity to components of X that
are held constant (Physics a-priori information).
Covariance of product (e.g., CO, CH4, CO2) can be
used to optimize minimization of this
underdetermined problem. Currently we are using
minimum variance approach (C ?I) due to lack of
knowledge of correlations.
Derivative of the forward model is required to
minimize J.
11
Utilization of thermal product requires knowledge
of vertical averaging
  • Thermal instruments measure mid-tropospheric
    column
  • Peak of vertical weighting is a function of T
    profile and water profile and ozone profile.
  • Age of air is on the order of weeks or months.
  • Significant horizontal and vertical displacements
    of the trace gases from the sources and sinks.
  • Solar/Passive instruments (e.g., SCIA, OCO)
    laser approaches measure a total column average.
  • Mixture of surface and near-surface atmospheric
    contribution
  • Age of air varies vertically.

12
Sounding Strategy in Cloudy ScenesCo-located
Thermal Microwave ( Imager)
  • Sounding is performed on 50 km a field of regard
    (FOR).
  • FOR is currently defined by the size of the
    microwave sounder footprint.
  • IASI/AMSU has 4 IR FOVs per FOR
  • AIRS/AMSU CrIS/ATMS have 9 IR FOVs per FOR.
  • ATMS is spatially over-sampled can emulate an
    AMSU FOV.

AIRS, IASI, and CrIS all acquire 324,000 FORs
per day
13
Thermal Sounder Core Products(on 45 km
footprint, unless indicated)
14
Trace Gas Product Potential from Operational
Thermal Sounders
Product Available Now
In Work
Held Fixed
Haskins, R.D. and L.D. Kaplan 1993
15
Retrieval of Atmospheric Trace GasesRequires
Unprecedented Instrument Specifications
  • Need Large Spectral Coverage (multiple bands)
    High Sampling (currently, we use 1680 AIRS and 14
    AMSU channels in our algorithm)
  • Increases the number of unique pieces of
    information
  • Ability to remove cloud and aerosol effects.
  • Allow simultaneous retrievals of T(p), q(p),
    O3(p).
  • Need High Spectral Resolution Spectral Purity
  • Ability to isolate spectral features ? vertical
    resolution
  • Ability to minimize sensitivity to interference
    signals..
  • Need Excellent Instrument Noise Instrument
    Stability
  • Low NE?T is required.
  • Minimal systematic effects (scan angle
    polarization, day/night orbital effects, etc.)

16
Radiances versus Products
17
Example of Carbon Monoxide Products from AIRS in
collaboration with W. Wallace McMillin Michele
McCourt University of Maryland, Baltimore County
W. McMillan (mcmillan_at_umbc.edu) AIRS
Science Team Meeting, Cal Tech, 3/8/06
UMBC
18
The CO ( O3) Product Improves Utility of the CH4
and CO2 Products
  • CO can be used to help us distinguish combustion
    sources (fossil or biomass) from other
    sources/sinks in our methane and carbon dioxide
    products.
  • CO can be used to estimate horizontal and
    vertical transport during combustion events.
  • CO (and Ozone) may help us improve atmospheric
    vertical transport models in the mid-troposphere.
  • Inter-comparison w/ aircraft (e.g., ESRL/GMD,
    INTEX-A, INTEX-B), and MOPITT products is
    in-work.
  • McMillan et al. 2005. GRL v.32
    doi10.1029/2004GL0218
  • McCourt, PhD dissertation, UMBC, 2006

19
AIRS CO and Trajectories
July 2004 Fires in Alaska
500 mb 700 mb 850 mb
20
AIRS CO and Trajectories
500 mb 700 mb 850 mb
21
AIRS CO and Trajectories
500 mb 700 mb 850 mb
22
AIRS CO and Trajectories
500 mb 700 mb 850 mb
23
AIRS CO and Trajectories
500 mb 700 mb 850 mb
24
AIRS CO and Trajectories
500 mb 700 mb 850 mb
25
AIRS CO and Trajectories
500 mb 700 mb 850 mb
26
AIRS CO and Trajectories
500 mb 700 mb 850 mb
CO from southern Alaska Fires was transported to
Europe at high altitudes (5 km)
CO from northern Alaskan fires was transported to
the lower atmosphere in SE of US
27
Example of Methane Products from AIRS
28
AIRS CH4 Kernel Functions are Sensitive to H2O(p)
T(p)
Polar
Mid-Latitude
Tropical
Isothermal vertical structure weakens sensitivity.
moisture optical depth pushes peak sensitivity
upwards.
29
Also providing the vertical information content
to understand CH4 product
CH4 total column f/ transport model (Sander
Houweling, SRON)
AIRS mid-trop measurement column
Peak Pressure of AIRS Sensitivity
Fraction Determined from AIRS Radiances
30
Comparison of CH4 product ESRL/GMD Continuous
Ground Site
Barrow Alaska
3deg. x 3deg. gridded retrieval averaged over
60-70 lat, -165 to -90 lng
31
Comparisons of AIRS product to ESRL/GMD Aircraft
Observations
ESRL/GMD aircraft profiles are the best
validation for thermal sounders since they
measure a thick atmospheric layer.
32
ESRL/GMD Flask Data from Poker Flats, Alaska
Seasonal cycle is a function of altitude
7.5 km 385 mb
5.5 km 500 mb
1.5 km 850 mb
Surface Flasks (Barrow)
33
We need to determine how much of our CH4 signal
is from stratospheric air
Dobson-Brewer circulation
UT/LS region in high latitudes has older air.
We will explore tracer correlations to unravel
surface vs stratospheric sources. (working w/ L.
Pan, NCAR)
Can depress high latitude, high altitude methane
signals in winter/spring time-frame.
34
Example of Carbon Dioxide Products from AIRS
35
LW Thermal CO2 Kernel Functions are also
Sensitive to H2O, T(p), O3(p).
Mid-Latitude TPW 1.4 cm
Polar TPW 0.5 cm
Tropical TPW 2.5 cm
moisture optical depth pushes peak sensitivity
upwards
Isothermal vertical structure weakens sensitivity
36
Also providing the vertical information content
comparing CO2 product with models
CO2 Transport Model Randy Kawa (GSFC)
AIRS mid-trop measurement column
Fraction Determined from AIRS Radiances
Averaging Function Peak Pressure
37
Preliminary Comparisons to ESRL/GMD aircraft
  • Comparison of AIRS ESRL/GMD observations..
  • Usually ? 5 hour time difference
  • Limit retrievals within 200 km of aircraft.
  • Spot vs. regional sampling
  • Retrieval is average of good retrievals
  • 3 50 rets are used in each dot.
  • ? 3.1 ppmv, correlation 0.83
  • Investigation of outliers is in-work.

38
Comparisons to JAL aircraft observations
ESRL/GMD MBL model
ESRL/GMD Marine Boundary Layer Model (surface
measurement)
AIRS CO2 retrieval from GRIDDED dataset
mid-trop thick layer measurement
Matsueda et al. 2002 aircraft single level
measurement
JAL Aircraft data provided by H. Matsueda
39
Same as before, but in-situ CO2 adjusted by
a-priori in retrieval
In-situ data is adjusted by the of a-priori in
our regularized retrieval. This depresses the
seasonal amplitude of the in-situ data and is a
gauge of our retrieval performance. Differences
should exist between single level (surface or
altitude) observations and AIRS thick layer
observations.
JAL Aircraft data provided by H. Matsueda
40
Again, to what extent does stratospheric age of
air play a role?
Surface measurements (dashed line) and model of
500 mb concentration (solid line) can differ by 5
ppm (NOTE Vert. Scale is 350-385
ppm) Brewer-Dobson effect has altitude, latitude,
and seasonal variation with a maximum in northern
winter/spring.
2004
2002
2000
Model runs of Brewer-Dobson circulation effect
are courtesy of Run-Lie Shia, Mao-Chang Liang,
Charles E. Miller, and Yuk L. Yung, California
Inst. Of Technology NASA Jet Propulsion Lab.
41
NOAA AIRS CO2 Product is Still in Development
  • Measuring a product to 0.5 is inherently
    difficult
  • Empirical bias correction (a.k.a. tuning) for
    AIRS is at the 1 K level and can affect the CO2
    product.
  • Errors in moisture of 10 is equivalent to 0.7
    ppmv errors in CO2.
  • Errors in surface pressure of 5 mb induce 1.8
    ppmv errors in CO2.
  • AMSU side-lobe errors minimize the impact of the
    57 GHZ O2 band as a T(p) reference point.
  • Bottom Line Core product retrieval problems must
    be solved first.
  • Currently, we can characterize seasonal and
    latitudinal mid-tropospheric variability to test
    product reasonableness.
  • The real questions is whether thermal sounders
    can contribute to the source/sink questions.
  • Requires accurate vertical horizontal transport
    models
  • Having simultaneous O3, CO, CH4, and CO2 products
    is a unique contribution that thermal sounders
    can make to improve the understanding of
    transport.

42
And many groups are working on AIRS CO2
algorithms
43
AIRS measures multiple gases (and temperature,
moisture and cloud products) simultaneously
CH4
  • 29 month time-series of AIRS trace gas products
    Alaska Canada Zone (60 ? lat ? 70 -165 ? lon
    ? -90)
  • July 2004 Alaskan fires are evident in CO signal
    (and CH4 ??)
  • Seasonal methane is correlated to surface
    temperature (wetlands emission?)
  • We have begun to investigate correlations that
    should exist between species (e.g., O3, CO, CH4
    interaction)

CO
CO2
O3
CH4 Tsurf
Aug.2003
Mar.2006
44
29 month time-series of AIRS productsEastern
China Zone (20 ? lat ? 45, 110 ? lon ? 130)
Correlation of CH4 with skin temperature is
significantly smaller
45
29 month time-series of AIRS productsSouth
America Zone (-25 ? lat ? EQ , -70 ? lon ? -40)
Biomass burning
Correlation of CH4 with skin temperature is
non-existent
46
For more informationhttp//www.orbit.nesdis.noaa
.gov/smcd/spb/airs/index.html
  • Trace GAS web-pages allow a quick look at the
    trace gas products as a function of geography,
    time, and comparisons with in-situ datasets.

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_at_noaa.gov
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