Aerosol-Cloud Ocean Biology Aerosol-Cloud Ocean Biology Mission (ACOB)Mission (ACOB)

Aerosol-Cloud Ocean Biology Aerosol-Cloud Ocean Biology Mission (ACOB)Mission (ACOB)

M. Schoeberl NASA/GSFC

C. McClain NASA/GSFC

Contributions from D. Diner, L. Remer, J. V. Martins, P. Hildebrand, J. Welton, B. Blair, M. McGill, G. Jackson, M.

Mischenko, D. Starr, P. Colarco, and a bunch of other people.

M. Schoeberl NASA/GSFC

C. McClain NASA/GSFC

Contributions from D. Diner, L. Remer, J. V. Martins, P. Hildebrand, J. Welton, B. Blair, M. McGill, G. Jackson, M.

Mischenko, D. Starr, P. Colarco, and a bunch of other people.

GSFC

What is ACOB?What is ACOB?What is ACOB?What is ACOB?

• ACOB is a multi-user mission with two science goals– Quantifying Aerosol-cloud interaction– Determining Ocean Carbon Cycling and other biological

processes• Why two goals?

– Next generation ocean color measurements require precise estimation of the aerosol contribution to the backscatter radiation

– Precise aerosol measurements are of interest to the aerosol cloud community

– There are common science problems between the two communities

• Aeolian fertilization of the ocean• Aerosol formation by DMS

• ACOB is a multi-user mission with two science goals– Quantifying Aerosol-cloud interaction– Determining Ocean Carbon Cycling and other biological

processes• Why two goals?

– Next generation ocean color measurements require precise estimation of the aerosol contribution to the backscatter radiation

– Precise aerosol measurements are of interest to the aerosol cloud community

– There are common science problems between the two communities

• Aeolian fertilization of the ocean• Aerosol formation by DMS

ACOB will addresses the aerosol science drivers for the next decadeACOB will addresses the aerosol science drivers for the next decade

Climate forcing and hydrological cycle: Understanding the global significance and physical processes underlying aerosol-cloud interactions to reduce major climate uncertainty (2 W m-2 globally) associated with aerosol “indirect effects”

Human health and biological activity: Associating changes in boundary layer air quality with aerosol sources and particle types, and quantifying aerosol impacts on human and ecosystem health

Previous groundwork toward development of community consensus on a future aerosol mission strategy

October 2004Progressive Aerosol Retrieval and Assimilation Global Observing Network (PARAGON) initiativeObjective: To outline an integrated system for determining aerosol climate and environmental impacts

NASA-wide aerosol strategy workshop, Williamsburg, VA, 18-19 August 2005Objective: To identify NASA’s specific contributions to PARAGON

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NCAR Workshop on Air Quality Remote Sensing from Space, Boulder, CO, 21-23 February 2006Objective: To examine what observational characteristics are required for the successful use of satellite remote sensing to measure environmentally significant pollutant trace gases and aerosols.

• Recommendation for advanced satellite imagers and lidars to reduce indeterminacies in current aerosol microphysical property retrievals and adoption of a systems approach to the development of new satellite missions (PARAGON publications)

• Emphasis upon aerosol-cloud interactions in relationship to climate change and the hydrologic cycle, and the relative impacts of anthropogenic and natural aerosols on climate and air quality (Williamsburg and GSFC workshop)

• “Understanding of the composition and size characteristics of atmospheric aerosols by means of multi-angle, spectropolarimetric, and stereoscopic-imaging techniques in conjunction with active (high spectral resolution lidar) measurements.” (NCAR workshop)

More recently, GSFC Workshop Nov 2006, emphasized the role of aerosols in precipitation

• Recommendation for advanced satellite imagers and lidars to reduce indeterminacies in current aerosol microphysical property retrievals and adoption of a systems approach to the development of new satellite missions (PARAGON publications)

• Emphasis upon aerosol-cloud interactions in relationship to climate change and the hydrologic cycle, and the relative impacts of anthropogenic and natural aerosols on climate and air quality (Williamsburg and GSFC workshop)

• “Understanding of the composition and size characteristics of atmospheric aerosols by means of multi-angle, spectropolarimetric, and stereoscopic-imaging techniques in conjunction with active (high spectral resolution lidar) measurements.” (NCAR workshop)

More recently, GSFC Workshop Nov 2006, emphasized the role of aerosols in precipitation

Aerosol measurement recommendationsAerosol measurement recommendations

Critical advances are needed in the areas of: aerosol and cloud vertical profiling, horizontal and vertical spatial resolution, global coverage, identification of precipitation processes, revisit time, and fusion of measurements to reduce uncertainties and indeterminacies

Evolution of aerosol/cloud researchEvolution of aerosol/cloud research

The current decade will demonstrate improvements in our ability to observe aerosols and their affects from space

• Terra Aqua: Significant improvements in quantifying direct radiative impacts; statistical inferences regarding aerosol effects on cloud properties; major improvements in determining near-surface air quality over land (MODIS, MISR)

• A-Train - Aqua, Aura, CALIPSO, CloudSat, Glory

• OMI: Best yet measurements of aerosols over bright surfaces ~ 20 km resolution

• CALIPSO: Measurements of aerosol backscatter very close to clouds - no swath

• Glory: Major advances in aerosol characterization but with sparse coverage and resolution too coarse for observing cloud boundaries or intra-urban pollution - no swath

• CloudSat: Impact of aerosols on cloud formation not aligned with CALIPSO - no swath

What is missing from already-manifested missions in the 2015 time frame?

• NPOESS: No vertical profiling information; no multi-angle or polarimetric imaging for reducing aerosol uncertainties to climate-quality requirements

• EarthCARE: Single-wavelength lidar limits aerosol microphysical characterization; single-frequency W band radar has limited sensitivity to precipitation; lacks comprehensive passive aerosol measurement

• No future missions have clear linkage to the hydrological cycle - especially impact on precipitation

The current decade will demonstrate improvements in our ability to observe aerosols and their affects from space

• Terra Aqua: Significant improvements in quantifying direct radiative impacts; statistical inferences regarding aerosol effects on cloud properties; major improvements in determining near-surface air quality over land (MODIS, MISR)

• A-Train - Aqua, Aura, CALIPSO, CloudSat, Glory

• OMI: Best yet measurements of aerosols over bright surfaces ~ 20 km resolution

• CALIPSO: Measurements of aerosol backscatter very close to clouds - no swath

• Glory: Major advances in aerosol characterization but with sparse coverage and resolution too coarse for observing cloud boundaries or intra-urban pollution - no swath

• CloudSat: Impact of aerosols on cloud formation not aligned with CALIPSO - no swath

What is missing from already-manifested missions in the 2015 time frame?

• NPOESS: No vertical profiling information; no multi-angle or polarimetric imaging for reducing aerosol uncertainties to climate-quality requirements

• EarthCARE: Single-wavelength lidar limits aerosol microphysical characterization; single-frequency W band radar has limited sensitivity to precipitation; lacks comprehensive passive aerosol measurement

• No future missions have clear linkage to the hydrological cycle - especially impact on precipitation

ACOB is the NAS ACE MissionACOB is the NAS ACE Mission“Science Objectives: The science goal of ACE is to reduce the uncertainty in

climate forcing through two distinct processes described above. The first goal is to better constrain aerosol-cloud interaction. This goal is achieved by simultaneous measurement of aerosol and cloud properties by radar, lidar, polarimeter, and a multi-wavelength imager.

Mission and Payload: … LEO, sun-synchronous early-afternoon orbit. The orbit altitude of 500-650 km. The notional mission consists of four instruments:

• A multi-beam cross-track dual wavelength lidar for measurement of cloud and aerosol heights and layer thickness;

• A cross-track scanning cloud radar with channels at 94 GHz and possibly 34 GHz for cloud droplet size, glaciation height, and cloud height;

• A highly accurate multiangle - multiwavelength polarimeter to measure cloud and aerosol properties (This instrument, would have a cross-track and along-track swath with ~1 km pixel size.)

• A multi-band cross-track visible/UV spectrometer with ~1 km pixel size, including Aqua MODIS, NPP VIIRS, and Aura OMI aerosol retrieval bands and additional bands for ocean color and dissolved organic matter.”

ACOB Measurement Strategy

Particle Ranges

In order to understand the interaction between pollution, clouds and precipitation we need measurements that are sensitive to the particle distribution, cloud height and particle composition. Following the measurement suite pioneered by the A-Train, a combination of active and remote multi-wavelength sensors is needed.

Candidate Sensor System

Next generation aerosol lidar: Vertical profiles of aerosol abundances and microphysical properties with across-swath capability and/or direct extinction-backscatter separability

Multiangle imaging spectropolarimeter (UV-SWIR): Global column-averaged aerosol amount, size distribution, absorption, particle shape, refractive index; some height sensitivity

Cloud profiling radar: Vertical profiles of droplet effective radius and vertical profile of water phase, cloud base and top height, precipitation rates

Optical spectrometer (ORCA): Measurements of biomass growth rates, organic and non-organic suspended matter assessments, aerosol absorption and size sensitivity

Active sensors

Low frequency µ- wave radiometer (W - Ku band) : Cloud precipitation

Passive sensors

Particle Ranges

High frequency µ- wave radiometer (800 GHz - W band): Cloud ice water content

GSFC

ACOB Candidate Payload ACOB Candidate Payload ACOB Candidate Payload ACOB Candidate Payload

Instrument Purpose Sources

Ocean Color Radiometer Ocean biosphere measurements, aerosols

ORCA (GSFC)

Polarimeter Aerosol properties, removal of aerosol effects for ocean biosphere

APS + Polder A (GSFC, CNES)

PACS (GSFC)

MSPI (JPL)

Multi-beam lidar* Aerosol heights, properties

MBL (GSFC)

HSR lidar (nadir only)* Aerosol heights, properties, microphysics

LaRC

Cloud Radar Cloud properties JPL, GSFC

Cloud Radiometer (HF) Cloud IWC, ice, particles SIRICE (joint with JPL)

Cloud Radiometer (LF) Precipitation GMI (Ball)

*It is unlikely we can fly both of theseHQ has asked GSFC and LaRC leads to discuss hybrid option

GSFC

Multi-beam LidarMulti-beam LidarMulti-beam LidarMulti-beam LidarUses wider swath cross-track observations to improve aerosol and cloud parameterization in mesoscale and global transport models by providing multi-grid vertical profile data. Provides increased swath coverage for formation flight missions relying on combined lidar and imager observations (e.g. ocean color).

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Cross-trackTotal Swath

Forest fires in Quebec generate thick smoke plumes transported to NE United States

MODIS AOD MODIS AOD

Nadir-only lidar does not provide enough spatial coverage for most aerosol plumes

Cross-track lidar example:500 km Sun Synch Orbit7 Fixed Lidar beams0°, ±5°, ±10°, ±15° angles

Coherent aerosol time and space scales:Average: ~5 hrs, ~100 km Plumes: ~1 hrs, ~30 km

Nadir vs. Cross-track Lidar Example:

Improved spatial coverage through complicated aerosol plumes

Cross-track spacing on the order of

aerosol plume scales & model grid sizes

nadir

Wider swath profiling over difficult ocean color regions

PolarimetersPolarimetersPolarimetersPolarimeters

Three concepts

1) MSPI JPL

2) POLDER-A +EOSP

3) PACS

The POLDER-A is a multi-channel multi-angle imaging photopolarimeter which will provide

• detailed and accurate aerosol and cloud retrievals with a 2-day global coverage;• Channels 443, 490, 670, 865 1370, 1650, 2130 nm

The APS is a high-precision multi-channel multi-angle photopolarimeter which will provide

• continuation of the Glory APS climate record;• in-flight calibration of POLDER-A polarimetry and photometry; • improved and updated look-up tables for the POLDER-A retrievals. • Channels 412, 443, 555, 672, 865, 910, 1378, 1610, 2250 nm

The idea behind the combination is that APS would make measurements along the track and those would be extended across the track by POLDER-A

APS and POLDER-A Combination

APS angular scanning

APS

Polder A

Multiple cameras with extended spectral range, polarimetry, and wider swath

Synergistic use of multiple techniques reduces retrieval indeterminacies– multiangle: particle size, shape, retrievals over bright regions (deserts, cities)

– multispectral: particle size (visible and SWIR), absorption and height (near-UV)• nominal bands: 380, 412, 446, 558, 650, 865, 1375, 1610, 2130 nm

– polarimetric: size-resolved refractive index and size distribution width• nominal bands: 650, 1610 nm

MSPI - Advanced MISR Instrument

0.5% polarimetric uncertainty is a challenging requirement for a wide field-of-view imager

Intensity only

2% polarimetry

0.5% polarimetry

NPOESS reqmt

UV-VIS NIR

Cloud-Aerosol PolarimeterCloud-Aerosol Polarimeter

TIRTIR

ThermalThermal

TIRVIS/NIR

Cloud Scanner

PACS - Passive Aerosol Cloud SuitePACS - Passive Aerosol Cloud Suite

Specs for coarse resolution component:• s: (360?), 380, 410, 440, 550, 660, 870, 910, 1230, 1380, 1550, 1640, 2100nm• Polarization: selected channels X all channels• Along track MultiAngle views: 9-20 angles all wavelengths + 150 angles rainbow (660nm)• Wide Swath: along and cross track

Specs for coarse resolution component:• s: (360?), 380, 410, 440, 550, 660, 870, 910, 1230, 1380, 1550, 1640, 2100nm• Polarization: selected channels X all channels• Along track MultiAngle views: 9-20 angles all wavelengths + 150 angles rainbow (660nm)• Wide Swath: along and cross track

Rainbow AnglesRainbow Angles

Thermal Imager• s: 8550, 11030,12020nm• X-track Swath: 90dg (single imager)• 2 Angles: Nadir and Fwd 15dg apart• Spatial resolution 1.2km at nadir

Multi-Angle Views along trackMulti-Angle Views along track

UV-VIS NIR

Cloud-Aerosol Polarimeter

TIR

Thermal

TIRVIS/NIR

Detailed/High Resolution Cloud Microphysics

Detailed/High Resolution Cloud Microphysics

Cloud ScannerCloud Scanner

PACS - Passive Aerosol Cloud SuitePACS - Passive Aerosol Cloud Suite

PointingSystem

•VIS-NIR: 660, 870, 940, 1230, 1380, 1550,1640, 2100 • TIR: 8550, 11030,12020nm• Nadir Resolution: VIS=110m, TIR=340m (less for larger array)• Pointing Capability +/- 60dg• X-track FOV options: 20dg• Must be small size/mass for pointing

Specs for high resolution componentSpecs for high resolution component

GSFC

OCEAN Color Radiometer (ORCA)OCEAN Color Radiometer (ORCA)OCEAN Color Radiometer (ORCA)OCEAN Color Radiometer (ORCA)o(nm) SNR(req'd) SNR @ Ltyp Well_Vol @ (Lmax) Attenuator (Lmax) OptTx / QE Lwell_cap Lmax (req)

318 (2) 300 347 367,328 1 / 1 0.4 / 0.55 3,131 230

345 (20) 750 995 309,614 1 / 0.32 0.26 / 0.7 4,360 270

360 (20) 1,125 1,348 695,263 1 / 0.32 0.47 / 0.75 2,157 300

380 (20) 1,500 1,504 966,442 1 / 0.32 0.5 / 0.844 1,707 330

412 (20) 1,500 2,034 2,145,314 1 / 0.32 0.66 / 0.9 1,119 480

443 (20) 1,500 2,019 2,629,799 1 / 0.32 0.65 / 0.893 1,065 560

460 (20) 1,500 1,908 2,774,139 1 / 0.32 0.64 / 0.882 1,054 585

490 (20) 1,500 1,807 2,721,315 1 / 0.32 0.61 / 0.867 1,056 575

510 (20) 1,500 1,549 2,537,161 1 / 0.32 0.59 / 0.855 1,064 540

532 (20) 1,500 2062 4,981,300 1 / 0.94 0.57 / 0.55 551 549

555 (20) 1,500 1,687 4,019,205 1 / 0.6 0.54 / 0.83 672 540

595 (20) 1,500 1,574 4,296,620 1 / 0.6 0.59 / 0.81 588 505

620 (20) 1,500 1,508 - 368,881 0.931 / 0.68 0.56 / 0.95 447 480

667 (10) 1,000 1,008 - 502,618 0.909 / 0.75 0.56 / 0.916 391 430

678 (10) 1,000 1,006 - 819,163 0.859 / 0.81 0.55 / 0.909 365 425

748 (10) 750 751 4,604,343 1 / 0.83 0.51 / 0.81 391 360

765 (40) 750 1,227 3,662,376 1 / 1 0.3 / 0.8 546 400

865 (40) 750 827 2,329,505 1 / 1 0.44 / 0.5 580 270

1025 (50) 400 672 2,146,975 1 / 1 0.55 / 0.4 489 210

1240 (30) 375 388 4,250,933 0.24 pF 0.54 / 0.75 127 125

4,304,449

1375 (30) 500 1,327 3,456,740 0.2 pF 0.45 / 0.75 114 110

3,587,040

Summing Capacitor Volume 3,945,744 0.22 pF 22

Type: Passive radiometerFore-optic: Rotating telescopeAft-optic: Grating and filter-based spectrometer Cross-track swath: ±60°Approx. dimension: 1 m3

Measurement range: 317–1375 nmMeasurement specifics: 2 nm bandwidth ozone channel centered at 317 nm; 4–5 nm spectral resolution 345 nm – 800 nm (w/ 700 – 800 nm included for terrestrial applications); four 30 to 50 nm wide bands between 865 – 1375 nm; CCD arrays in 3 focal planes Ground resolution at nadir: 1.1 kmSNR requirements (based on 20 nm integrated bandwidths for 345 to 800 nm & 30-50 nm bands @845-1400 nm: >1000 for 345 – 400 nm; >1500 for 400 – 720 nm; >750 for 720 – 900 nm; > 400 for 1000 – 1400 nmGlobal coverage: 2 daysMODIS OMI

MODIS/OMI

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GSFC

High Frequency µ-wave RadiometerHigh Frequency µ-wave Radiometer High Frequency µ-wave RadiometerHigh Frequency µ-wave Radiometer

Submillimeter/Millimeter (SM4) Radiometer

• Conical Scanning Imager with 1600 km swath

• 10-km spatial resolution => 0.36 pencil beam

• 6 Receivers > 12 Channels

Vertical + Dual Polarization at 643 GHz

{183V, 325V, 448V, 643 V&H, and 874V GHz}

• Three-point calibration (hot, cold, space cold)

• Heritage: MLS, CoSSIR, HERSHEL, MIRO

Earth

GSFC

Cloud RadarCloud RadarCloud RadarCloud RadarProducts:• Cloud top height• Microphysical profile information• Particle phase/Glaciation height• IWC and CWC• Precipitation detection

What we would like:• Swath as well as dual frequencies (W and

Ka) – Even a narrow swath will be hard

due to narrow back scattering phase function

– Lower frequencies mean larger antenna

• More sensitivity to precipitation • Sensitivity to low clouds (aerosols

probably have more effect on them) • (-30dBz)

It is unlikely that the cloud radar can point more than 10º off nadir

Products:• Cloud top height• Microphysical profile information• Particle phase/Glaciation height• IWC and CWC• Precipitation detection

What we would like:• Swath as well as dual frequencies (W and

Ka) – Even a narrow swath will be hard

due to narrow back scattering phase function

– Lower frequencies mean larger antenna

• More sensitivity to precipitation • Sensitivity to low clouds (aerosols

probably have more effect on them) • (-30dBz)

It is unlikely that the cloud radar can point more than 10º off nadir

New Strategy: as with GPM and TRMM use a low frequency radiometer to increase the precipitation measurement

swath

New Strategy: as with GPM and TRMM use a low frequency radiometer to increase the precipitation measurement

swath

GSFC

Low Frequency µ-wave Radiometer (GMI)Low Frequency µ-wave Radiometer (GMI)Low Frequency µ-wave Radiometer (GMI)Low Frequency µ-wave Radiometer (GMI)

GMI Key ParametersGMI Key Parameters

Mass (with margin):~150 kgPower:~125 WData Rate:~30 kbpsAntenna Diameter:~1.2 m Channel Set:10.65 GHz, H & V Pol18.7 GHz, H & V Pol23.8 GHz, V Pol36.5 GHz, H & V Pol89.0 GHz, H & V Pol166 GHz, H & V Pol, 183±3 GHz, V (or H) Pol183±8 GHz, V (or H)(166 and 183 GHz to have same resolution as 89

GHz)

GMI Key ParametersGMI Key Parameters

Mass (with margin):~150 kgPower:~125 WData Rate:~30 kbpsAntenna Diameter:~1.2 m Channel Set:10.65 GHz, H & V Pol18.7 GHz, H & V Pol23.8 GHz, V Pol36.5 GHz, H & V Pol89.0 GHz, H & V Pol166 GHz, H & V Pol, 183±3 GHz, V (or H) Pol183±8 GHz, V (or H)(166 and 183 GHz to have same resolution as 89

GHz)

GMI Key ProductsGMI Key Products

• Rain rates from ~0.3 to 110 mm/hr• Increased sensitivity to light rain over land and falling snow

CM1 would be a GPM daughter satelliteCM1 would be a GPM daughter satellite

Ball Aerospace and Technology Corporation (BATC) is developing GMI

Same as HF radiometerSame as HF radiometer

GSFC

ACOB: Two Spacecraft Observing GeometryACOB: Two Spacecraft Observing GeometryACOB: Two Spacecraft Observing GeometryACOB: Two Spacecraft Observing Geometry

ORCAORCA

Cloud RadarCloud Radar

Multi-beam LidarMulti-beam Lidar

Multi-anglemulti-wavelength

polarimeter

Multi-anglemulti-wavelength

polarimeter

RadiometersHF (Orange)LF (Purple)

RadiometersHF (Orange)LF (Purple)

Polarimeter & Radiometers (90º)

90º

30º

Radar (20º)

Lidar (30º)

20º

Orbit: 650 km SSOrbit: 650 km SS

ORCA (120º)

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GSFC

Next StepsNext StepsNext StepsNext Steps

• Community driven STM and white paper

• IMDC studies of payload

• Cost estimates

– cheaper than the space station

– more near term than the human settlement of Mars

• HQ buy in

• Community driven STM and white paper

• IMDC studies of payload

• Cost estimates

– cheaper than the space station

– more near term than the human settlement of Mars

• HQ buy in

Synergies between aerosol and ocean ecosystem/biomass measurements

Ocean measurement requirement

Novel use of near-UV wavelengths to separate non-living organic material from phytoplankton

Biomass assessment in coastal and turbid waters

Suspended matter concentrations

Aerosol payload benefit

Accurate characterization of aerosol properties is essential because optical depths are high in this spectral region; passive and active combination provides sensitivity to aerosol absorption and height

Multiangle observations at shortwave-IR wavelengths permit atmospheric correction over bright waters. Observations within and outside of glint pattern constrain surface wind speed, aerosol optical depth, and particle size distribution

Independent assessment using lidar observations

Aerosol measurement requirement

Stratospheric ozone correction

Aerosol absorption, height, and chemical environment

Ocean color payload benefit

Simultaneous measurement of ozone concentration

UV spectrometery to 345 nm provides associated trace gas sensitivity and potential simplification of aerosol radiometer design

ACOB and Climate

• ACOB will link the whole spectrum of particles from aerosols-clouds-precipitation to untangle the climate/aerosol impacts

• ACOB will provide simultaneous measurements of these key parameters within the same footprint.

• ACOB will quantify the ocean carbon cycling and the biological pump component