Atmospheric CO2 and CH4 Measurements

Ray Nassar ray.nassar@ec.gc.ca

Climate Research Division, Environment Canada

NSERC-CREATE Summer School on Arctic Science, 2013

Beginning of atmospheric CO2 measurements

1957-58: Charles David Keeling began monitoring atmospheric CO2 at

Mauna Loa Hawaii and the South Pole

Global Greenhouse Gas Measurements

Red denotes “active”: data from the station has been updated in the last 365 days

Archived at the World Data Centre for Greenhouse Gases (WDCGG)

WMO Global Atmospheric Watch (GAW)

Canadian Greenhouse Gas Measurement Program

(80°N, 86°W) Northernmost Site in the World

Flasks since 1975 and continuous since 1978

Intercomparison site (EC, NOAA, CSIRO, …)

since

2012

since 2012

since

2010

Flask and continuous measurements

• 1s precision ~ 0.1 ppm, accuracy ~0.2 ppm relative to WMO standards

• Whole air flasks collected and

analyzed in a central lab, commonly

by Gas Chromatography (GC) with

various different detection systems

(Mass Spec, FID etc.)

• Continuous measurements can be

done in the field using Non-dispersive

Infrared (NDIR) or Cavity Ring Down

Spectroscopy (CRDS) aka ‘Picarro’

NDIR

CRDS

Downsview

Expansion of Surface Networks

http://www.earthnetworks.com/

Aircraft measurements

• CONTRAIL and CARIBIC have take-off / landing

but mostly cruising altitude of ~10.5 km

• HIPPO 5 campaigns (~ 1 month each) during

2009-2011, repeated ascents/descents

• Also limited aircraft vertical profiles (Park Falls,

Southern Great Plains, Rarotonga Cook Islands, …)

and many small campaigns over the years, as well

as balloon measurements, CO2-sondes, “AirCore”

CO2

CO2, CH4 …

CO2, CH4 …

CONTRAIL (Comprehensive Observation

Network for Trace Gases by Airliner)

CARIBIC (Civil Aircraft for the Regular

Investigation of the Atmosphere Based

on an Instrument Container)

HIPPO (Hiaper Pole-to-Pole Observations)

Point measurements - Representativeness

2°x2.5° gridbox = 222 x 261 km2 (at 20°N)

Nassar et al. (2010), Geoscientific

Model Development, 3, 689-716.

Mauna Loa

peak 4.17 km,

measurement

site 3.4 km

383.75 384.50

zoom

Major mismatch in scales between

measurement and model …

they are not representative of one

another

Desirable CO2 or CH4 Measurement Characteristics for Source/Sink Estimation

• Horizontal Coverage: Observations over land, water and ice, all latitudes

• Footprint or Pixel: Small is good for horizontal resolution and more cloud-free observations, but must be large enough for sufficient signal

• Vertical Sensitivity: Surface sensitivity and vertical information

• Temporal Sampling: Sampling of seasonal and diurnal cycles

• Precision: High precision is very important (especially for CO2), requires good SNR and spectral resolution

• Ancillary: Measurements of cloud/aerosol, O2 A-band, other species

No single satellite can meet all of these requirements

Committee on Earth Observation Satellites (CEOS) Carbon Task Force

The CEOS Strategy for Carbon Observations from Space

• Introduction

• Land Domain

• Ocean Domain

• Atmosphere Domain

• Integration and the Way Forward

Berrien Moore (University of Oklahoma)

John Burrows (University of Bremen)

David Crisp (NASA-JPL)

Martin Heimann (Max Planck Inst. Jena)

Michio Kawamiya (JAMSTEC)

Ray Nassar (Environment Canada)

Peter Rayner (LSCE) To be released in late 2013

First Generation of GHG Satellite Observations

AIRS

SCIAMACHY

IASI TES

March-April-May multi-year average

Crevoisier et al. (2009) Chahine et al. (2008)

Buchwitz et al. (2007)

Kulawik et al. (2010)

HIRS TOVS

Chédin et al. (2003) TIR

em

issio

n

NIR

so

lar

refl

ecta

nce

Limb TIR Solar Occultation Profiles

ACE-FTS (Foucher et al. 2011)

All of these

(except HIRS)

also provide

CH4

Crisp et al.

(2004, ASR)

Greenhouse Gases Observing Satellite (GOSAT)

Thermal And Near-infrared Sensor for carbon Observation (TANSO)

TANSO-FTS is main instrument with interferometer from ABB (Canada)

Band 1) 0.758-0.775 μm Band 2) 1.56-1.72 μm

Band 3) 1.92-2.08 μm Band 4) 5.56-14.3 μm (TIR)

TANSO-CAI for cloud aerosol imaging

Glint ocean observation

Japan (JAXA / NIES / MOE) launched in 2009

Greenhouse Gases Observing Satellite (GOSAT)

v1.2 averaged at 2°x2.5°

350 400

Mean XCO2 2009-09

Cloud OD < 0.20

Miller et al. (2007, JGR)

based on Breon et al. (2005, GRL)

GOSAT

d = 10.5 km Only ~7% of GOSAT CO2 and CH4

observations pass cloud filter (Yoshida et al. 2011, Retrieval algorithm for CO2

and CH4 column abundances from short-

wavelength infrared spectral observations by the

Greenhouse gases observing satellite, AMT, 4,

717–734, 2011)

][

][2095.0

2

22

O

COXCO

High latitude retrievals are limited by

Solar Zenith Angle, Surface Albedo

Total Carbon Column Observing Network (TCCON)

Record direct solar spectra in the NIR (resolution 0.02 cm-1) to

retrieve column-averaged mole fractions: XCO2, XCH4, etc. Wunch et al. (2011), The Total Carbon Column Observing Network, Phil. Trans. R.

Soc. A, 369, 2087-2112

October 2011 but new ones and more to come

TCCON uses only Bruker 125HR Fourier Transform Spectrometers. Other FTS

measurements exist such as in the Canadian FTIR Observing Network (CAFTON)

Atmospheric Carbon Observations from Space

(ACOS) Retrievals from GOSAT

GOSAT XCO2 Bias Correction

Butz et al. (2011, GRL) “Toward Accurate

CO2 and CH4 Observations from GOSAT”

“Column-averaged dry air

CO2 mole fraction”

XCO2 = 0.2095*[CO2] / [O2]

Depends on surface

pressure derived using the

O2 A-band

Retrieval precision

continues to improve

Orbiting Carbon Observatory 2

OCO launch

photo by Matt Rogers,

Colorado State University

• OCO-2 is a rebuild of OCO which failed to reach orbit due to a launch mishap

• 3 grating spectrometers (narrow 2.0, 1.6, 0.76 mm bands)

• High precision (~1 ppm), nadir and glint, small footprint (1.25 x 2.26 km2) XCO2 using O2 A-band, front of the A-Train

• Million Observations per month (GOSAT ~14,000)

OCO

Key Future GHG Missions with Surface Sensitivity

• OCO-2 (NASA, 2014) - XCO2 goal of 1.0 ppm precision, O2 A-band, 1.29 x

2.26 km2 footprint, A-train, NIR nadir and glint at high latitudes

• TanSat (China, 2015) - Same CO2 and O2 bands as OCO-2 but also a

Cloud and Aerosol Imager (CAI)

• MERLIN (DLR-CNES, 2016) - CH4 Lidar (night and day measurements)

• OCO-3 (NASA, 2017) - OCO-2 spare parts on International Space Station

• GOSAT-2 (Japan, 2018) - CO2, CH4, and O2 A-band with smaller footprint,

expanded glint range for ocean observations (perhaps also CO)

• MicroCarb (CNES, 2019) - XCO2 from satellite ~30-50% the size and cost

of OCO-2 with similar sensitivity, step toward low-cost constellation

• PCW-PHEOS-FTS (CSA, 2020) - CO2, CH4, O2 A-band and other gases,

under consideration for mission with focus on northern high latitudes

• CarbonSat (ESA, 2020) - CO2, CH4 and O2 A-band, 2 x 2 km2 pixels and

broad swath, high precision, 1 of 2 competing Earth Explorer 8 missions

• ASCENDS (NASA, 2021) - CO2 Lidar (night and day measurements)

Apologies for the Acronyms!

Comparison of Footprints and Swaths

1.29 x 2.26 km2 10.5 km

diameter

Figure provided by Heinrich Bovensmann

(University of Bremen)

0.1

0.1

CarbonSat – Point Sources

CO2, CH4, O2 A-band

AMT, 2010

Space-based Lidars

• Lidars are ‘active’, do not need solar reflectance, measure during the night / polar night, and potentially better SNR over snow/ice, but only measure along satellite ground-track

• Methane Remote Lidar Mission (MERLIN)

~100 kg platform to launch around 2016

CH4 DIAL, pressurized Nd:YAG laser

• Active Sensing of CO2 over Nights, Days and Seasons (ASCENDS)

CO2 and O2 Lidars, currently 3 competing instrument designs from different NASA centers

Launch is no earlier than 2023

GHGSat

• Demonstration nanosatellite to launch

in 2015 from a Montreal company

• Commercial satellite (not research) to

measure emissions from Oil &Gas

industry, Power Generation, Landfills,

Mining and other

• Will utilize a Fabry-Perot spectrometer

which evolved from the Miniature

Earth Observing Satellite (MEOS)

concept once proposed to CSA by

Prof. Jim Sloan

ACE CH4 and CO2

• ACE-FTS uses CO2 spectral lines to retrieve temperature and altitude (related to pressure) based on assumed values of CO2

• CH4 profiles can be retrieved using T,P from CO2 but CO2 retrieval requires altitude (pressure) derivation in some other way

• Foucher et al. (2011) use N2 continuum

• Similar work being carried out by Chris Sioris

• 30 profiles per day (maximum) but continuum retrieval is very sensitive to cloud and only ~7% pass cloud filtering

ACE CO2 (ppm) May 2007

Foucher, Chedin, Armante, Boone, Crevoisier, Bernath

(2011), CO2 atmospheric vertical profiles retrieved from

space observation using ACE-FTS solar occultation

instrument, Atmos. Chem. Phys., 9, 2873-2890.

Chemical and Aerosol Sounding Satellite

• CASS satellite have FTS along with solar

imagers

• Proven FTS technology from ACE applied to a

‘climate’ focus, with increased low latitude

coverage

• CH4 profiles: upper troposphere and above

• Pointing information from solar imagers instead

of spectra

• CO2 profiles: upper troposphere and above

without reliance on N2 continuum

• Unique for the high vertical resolution

capability

PI: K.A. Walker (University of Toronto)

Satellite Orbits and Coverage

• Low Earth Orbit (LEO)

• Near-polar plane

• If sun-synchronous,

Earth’s rotation gives

global sampling but only

at a fixed overpass time

• Geostationary Orbit (GEO)

• Near-equatorial plane ~35,800 km altitude

• Synchronized with Earth rotation to give

continuous sampling over selected area

(<60°N/S)

• TEMPO / GEO-CAPE, Sentinel-4, GEMS

for Tropospheric Chemistry

GOSAT (NIES v2.00 2009-08 averaged at 0.9° x 0.9°)

Satellite Orbits and Coverage

• Low Earth Orbit (LEO)

• Near-polar plane

• If sun-synchronous,

Earth’s rotation gives

global sampling but only

at a fixed overpass time

• Geostationary Orbit (GEO)

• Near-equatorial plane ~35,800 km altitude

• Synchronized with Earth rotation to give

continuous sampling over selected area

(<60°N/S)

• TEMPO / GEO-CAPE, Sentinel-4, GEMS

for Tropospheric Chemistry

Highly Elliptical Orbit (HEO)

• WMO Vision for the Global Observing System (GOS) in 2025

• Conservation of angular momentum requires faster motion when

close to Earth (perigee), slower motion when far from Earth (apogee)

• 12-24 hour orbit with apogees

slightly higher than GEO

Apogee

Perigee

Three Apogee Orbit (16-hr)

Trishchenko et al. (2011), J. Atmos. Ocean. Tech.

Polar Communications and Weather (PCW)

• Canadian Space Agency led mission with 2 satellites in Highly Elliptical Orbit (HEO) under consideration for launch ~ 2020

• Weather - Environment Canada

– Operational meteorological imaging instruments for northern latitudes

• Communications - Department of National Defence

– Increase northern communications capability

• CSA is also considering additional science instruments

• Weather, Climate and Air quality (WCA) mission concept (PI: Jack McConnell, York U) is an atmospheric research option that completed Phase A last year, under the Polar Highly Elliptical Orbit Science (PHEOS) program

PHEOS-WCA Instrument Configurations

• Fourier Transform Spectrometer (FTS)

• UV-Visible Spectrometer (UVS)

CSA

Allocations

Size:

30 x 30 x 30 cm3

(27 000 cm3)

Mass: 50 kg

Power: 100 W

All Bands Configuration

Optimal Configuration

Compliant Configuration

FTS (aperture 15 cm)

with UVS, 85 kg

~103 800* cm3 FTS (aperture 10 cm)

with UVS, 45 kg

~35 128* cm3 FTS (aperture 10 cm)

No O2 A band or SWIR CO2

No UVS, 37 kg

~25 184* cm3

*volumes shown with 20% contingency

O2 A band and SWIR CO2

PHEOS-FTS observation locations

Checkerboard pattern of data-thinning to meet downlink requirement, and

observations every other repeat cycle to accommodate other observing priorities

Three-APogee (TAP) orbit

2 satellites, 8h apart in co-planar 16h orbit

Apogee ~43,500 km, Perigee ~8100 km

3 Apogees/day (8:00 and 16:00 local time)

observing ±4 h from apogee giving up to 16 h

of data per 48 h per region/apogee. Each

region: 48 scans for 100 sec each, consisting

of 56x56 array of 10x10 km2 pixels.

Nassar et al, Satellite observations of CO2 from a Highly Elliptical Orbit (HEO) for

studies of the northern high latitude carbon cycle, submitted to JGR