1. Satellite observations of atmospheric methane and their value for quantifying methane emissions
Jacob, D.J., A.J. Turner, J.D. Maasakkers, J. Sheng, K. Sun, X. Liu, K. Chance, I. Aben, J. McKeever, and C. Frankenberg,  Atmos. Chem. Phys.,16,  , doi: /acp , 2016. 

2. Observing methane from space
Solar backscatter (SWIR) Thermal emission (TIR) Lidar (SWIR)
Wavelength [µm]
SWIR methane absorption bands
1.65 µm allows “proxy method” from combined CO2 retrieval
2.3 µm allows CO retrieval

3. Solar back-scatter instruments for observing methane from space
Agency
Data period
Pixel size
[km2]
Return time
Band
[µm]
Precision
Past/present
SCIAMACHY
ESA
3060
6 days
1.65
1.5 %
GOSAT
JAXA
2009-
1010
3 days (sparse)
0.6 %
GHGSat
GHGSat, Inc.
2016-
0.05x0.05
targets
1-10%
Future
TROPOMI
2017-
77
1 day
2.3
0.6%
GOSAT-2
2018-
10x10
both
0.3%
geoCARB
NASA
selected
45
2 hours
1.0%
Proposed
CarbonSat
proposed
22
5-10 days
0.4%
GeoFTS
3x3
0.2%
G3E
2x3
0.5%
CHRONOS
4x4
1 hour

4. Methane observations from SCIAMACHY and GOSAT
Dry column average mixing ratio XCH4

5. New gridded version of EPA US methane inventory
Inventory with 0.1ox0.1o monthly resolution and scale-dependent error characterization
for use as prior estimate in inverse analyses
2012
Maasakkers et al. [2016]

6. Comparing EPA and EDGAR inventories for south-central US
EDGAR v4.2 has large errors, compromising inverse analyses and their interpretation
Maasakkers et al. [2016]

7. Observing methane from space in the future
Observing methane from space in the future. This animation illustrates the capabilities of different satellite instruments to map methane emissions from the Barnett Shale region of northeast Texas. This region features major methane emissions from oil/gas production, livestock, and landfills. The animations show two days of observations by GOSAT (2009-present), TROPOMI (2017 launch), and the geostationary GCIRI (proposed to NASA). During those two days, GOSAT has only one observation over the region. TROPOMI provides complete daily mapping at 1:30 pm local time but can be blocked by clouds. GCIRI provides complete hourly mapping with high pixel resolution, enabling notably the detection of so-called "super-emitters". The slide illustrates the tremendous future potential of TROPOMI and geostationary observations for mapping methane emissions. From Melissa Sulprizio and Daniel Jacob (Harvard).

8. Detectability of regional and point sources of methane
 Instrument
Averaging time required
to quantify regional source
(Q =72 tons h-1 over 300300 km2)
Single-pass point source
detection threshold
[tons h-1]
SCIAMACHY
1 year 68
GOSAT
7.1
TROPOMI
Single pass (1 day)
4.2
GCIRI/geoCARB
Single pass (1-2 hours)
4.0
GHGSat NA
0.25
Cumulative pdf of point sources reporting to
GHGRP
Cumulative pdf of 10×10 km2 emission pixels across US

9. Some recommendations for the future
Combine SWIR and TIR retrievals to resolve vertical distribution of methane
- Improve detectability and data interpretation for the Arctic
Fly geostationary mission with staring sub-km capability over source regions
- Detect point sources, “super-emitters”, cloudy wetlands
Improve global bottom-up inventories for inverse analyses
Improve quality and interpretation of inversions, top-down/bottom-up partnership
Develop combined satellite + suborbital observing systems for source regions
- Suborbital perspective essential for monitoring multitude of point sources