The AIRS (Atmospheric Infraread Sounder) Instrument
  • Hyperspectral Infrared Sounder on the EOS-AQUA platform - 1:30pm polar orbit - operational since Sept. 2002.
  • Grating spectrometer with 2378 low noise channels
  • High resolution IR channels $\sim 0.5-2.0\,\wn$ from $650\wn$ to $2665\wn$ ($3.7-15.4\, \um$)
  • 15 Km footprint - very stable - with well characterized radiances. \begin{columns} \column{.55\linewidth}
  • Other groups focus in Higher Troposphere
  • We go to the Mid Trop by using particular channels:
  • Narrow ``Q branch'' at $791.75\wn$
  • Broad ``R branch'' around $2400\wn$
  • Atmospheric state from ECMWF
  • Land Emmissivity from Borbas/Seemann (http://cimss.ssec.wisc.edu/iremis)
    Atmospheric Co2 sensitivity jacobians (weighing function)
  • Peak sensitivity around $500\mb$
    • Calibration with GlobalView
  • Use NOAA's GlobalView site data set (http://www.esrl.noaa.gov)
  • Focus on Mid Trop airplane sites - 11 total.
  • For simpler comparison, take the highest altitude flight only (usually 5000m - 8000m).

    • GlobalView BCN site CO2 time seriesGlobalView CO2 time series for all hight altitude sites
  • For each site:
  • $\sigma\approx 7\ppm$ - AIRS radiance noise
    UMBC AIRS calibration distribution - daytimeUMBC AIRS calibration distribution - nighttime
  • Uncertainty of mean $\approx 0.02\ppm$ ($10^4$ obs)
  • Calibration - {\it mean} of all sites
  • Daytime - $373.22 \ppm$
  • Nighttime - $373.55 \ppm$
  • Calibration $\sigma \approx 1.3\ppm$
    • AIRS Global Time Series - Rates
  • Data aggregated in $4\mydeg$ boxes.
  • Observed growth rate of $\approx 2.28\pm 0.07 \mathrm{ppm/year}$
  • Geographic rates exhibit significant geographical variability
    UMBC AIRS CO2 Regional Growth Time seriesUMBC AIRS Global CO2 Growth Rate Map
  • Seasonal Cycle Amplitude $\approx 3-4\ppm$, and Peak - March / September
    UMBC AIRS Global CO2 Seasonal oscilation Amplitude - peak maximumUMBC AIRS global CO@ Seasonal oscilation Phase - peak month
    • AIRS Seasonal Means
  • Mean from 2003 to 2007 - Seasonal patterns evident.
    UMBC AIRS Winter Co2 retrieval - all yearsUMBC AIRS Spring Co2 retrieval - all years

    UMBC AIRS Summer Co2 retrieval - all yearsUMBC AIRS Fall Co2 retrieval - all years
  • Empty boxes - overzealous data filtering (working on it)
    • AIRS Comparison with CarbonTracker (Year of 2007)
  • 2008 NOAA's CarbonTracker Assimilated Transport Model (http://www.esrl.noaa.gov/gmd/ccgg/carbontracker/)
  • Use GlobalView calibration sites, plus surface models
  • Integrated with local AIRS weighing functions

    • UMBC AIRS CO2 Winter 2007 retrieval MapCarbonTracker CO2 Winter 2007
  • Much more outflow from Asia into Indian ocean than CarbonTracker
    UMBC AIRS CO2 Spring 2007 retrieval MapCarbonTracker CO2 Spring 2007

    UMBC AIRS CO2 Summer 2007 retrieval MapCarbonTracker CO2 Summer 2007
  • Spring/Summer - Very similar
    UMBC AIRS CO2 Fall 2007 retrieval MapCarbonTracker CO2 Fall 2007
  • Fall - Far lower CO2, esp in SH (less transport/higher uptake?)
    • AIRS \cd detects Anthropogenic \cd fluxes
  • During Fall season, flux is down, except for Anthropogenic.
  • Using less restrictive data filter. $1\mydeg$ box.
  • Europe - see Germany, Sweden
    UMBC AIRS Anthropogenic signal - EuropeCarbonTracker Fossil Fuel CO2 emissions- Europe
  • USA (East Coast)
    UMBC AIRS Anthropogenic signal - USACarbonTracker Fossil Fuel CO2 emissions- USA