advanced global imaging radiometer geophysical parameters pigment absorption phytoplankton carbon...

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Advanced Global Imaging Radiometer Geophysical Parameters Pigment absorption Phytoplankton carbon Net primary production Export production Dissolved Organic Carbon CDOM photochemistry Slope of CDOM absorption Particulate Organic Carbon Particle size spectrum Particulate beam attenuation Carbon loading & dispersal Solar radiation & K d Particulate inorganic carbon Functional groups HABs Eutrophication ….others…. Objectives Improved separation of in-water constituents through expanded spectral range and resolution Improved atmospheric correction – aerosols, bright targets, ozone nt Characteristics -day global coverage, noon/sun-synchronous polar orbit m 20 aggregated wavebands 350 – 1400 nm, +ozone band patial resolution 00:1 (UV) to ~ 500 NIR lt to minimize sun glint contamination zation scrambler to minimize polarization sensitivity (tenths of a percent) l & well-characterized spectral response (in-band & out-of-band) l & well-characterized focal plane electronic cross-talk l & well-characterized stray light haracterized response as a function of scan angle tial sampling to minimize image stripping d saturation over bright targets and lunar on-orbit calibration te sensor optical model ystem for near real-time processing, distribution, algorithm evaluations, & periodic re hensive calibration/validation program

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Advanced Global Imaging Radiometer

Geophysical ParametersPigment absorptionPhytoplankton carbonNet primary productionExport productionDissolved Organic CarbonCDOM photochemistrySlope of CDOM absorptionParticulate Organic CarbonParticle size spectrumParticulate beam attenuationCarbon loading & dispersalSolar radiation & KdParticulate inorganic carbonFunctional groupsHABsEutrophication….others….

Objectives• Improved separation of in-water constituents through expanded spectral range and resolution• Improved atmospheric correction – aerosols, bright targets, ozone

Measurement Characteristics• LEO, 2-day global coverage, noon/sun-synchronous polar orbit• Minimum 20 aggregated wavebands 350 – 1400 nm, +ozone band• 1 km spatial resolution• SNR 1500:1 (UV) to ~ 500 NIR• 200 tilt to minimize sun glint contamination• Polarization scrambler to minimize polarization sensitivity (tenths of a percent)• Minimal & well-characterized spectral response (in-band & out-of-band)• Minimal & well-characterized focal plane electronic cross-talk• Minimal & well-characterized stray light• Well-characterized response as a function of scan angle• Sequential sampling to minimize image stripping• No band saturation over bright targets• Solar and lunar on-orbit calibration• Complete sensor optical model• Data system for near real-time processing, distribution, algorithm evaluations, & periodic reprocessing.• Comprehensive calibration/validation program

Advanced Global Imaging Radiometer

SeaWiFS 20-band SeaWiFS

Simple E

xpansion

Advanced Global Imaging Radiometer

Hyperspectral

• Multiple grating spectrometer

• 5 nm resolution from 350 to 800 nm

• Discrete bands from 800 to 1400 nm (20 – 50 nm bandwidth)

• On-board or post-download binning

• Full spectral download = 1 Tb science data per day

• 300 Mbps X-band transfer to polar ground station

• On-ground 20 nm binned data for standard global products

• High resolution data for regional applications, events, science development

Primary telescope

Aft Optics

Aerosols

Objective• Global characterization of absorbing aerosol properties (height, column thickness, species) in support of ocean science missions (global LEO, regional GEO, … etc)

Equivalent Aerosol Optical Depths

Spring Fall

Issues • Aerosol characteristics are source dependent Urban particular problem (coastal challenge) Dust significant over vast ocean regions Non-absorbing not a problem

• Seasonally and spatially varying Monitoring required

• Current atmospheric correction model does not achieve required accuracy (+/-0.002 reflectance units) without correct vertical distribution (assuming correct aerosol type)

• Atmospheric correction errors increase at shorter wavelengths, thus critical for effectively utilizing UV wavelengths

• Aerosol loads also link to land-atmosphere-ocean feedbacks

Measurement Characteristics (minimum)• Aerosol Heights to 0.5 km• Aerosol optical thickness range 0.05 to 1• 10 km horizontal resolution• 10% accuracy• Extrapolation to global fields • Aerosol absorption column optical depth

Aerosols

Aerosol Lidar(a) Vertical aerosol backscatter & extinction profiles(b) Layer-wise optical, microphysical, & macrophysical properties

(#/surf./vol. concentrations, eff. radius, complex index of refr., SSA)(c) Aerosol particle shape and cloud liquid/ice phase

Multi-Angle or Scanning Aerosol Spectropolarimeter (a) Column-average optical, microphysical, & macrophysical aerosol properties (AOD, particle sizes & shape, SSA, size-resolved real RI…)

(b) Tropospheric ozone to determine short- & long-term changes (c) Aerosol heights for ocean color correction (d) NO2, HCHO, O3 and SO2

MISR (image from David Diner)

GLAS (image from Jim Spinhirne)

Particle Profiler

CA

LIP

SO

’s C

AL

IOP

lida

rSpec’s• 2-wavelength, 3-channel (532, 532, 1064)• 110 mJ Nd:Yg laser • Repetition rate = 20.25 Hz• 1 m telescope• Footprint/FOV = 100m/130rad• Mass = 300 kg• Variable vertical resolution• Aerosol height & thickness for AOD > 0.005• Altitude = 600 km

Photons per 1 m bin per shot

0

0

0

0

0

0

0

0

1

3

7

19

50

124

299

3

4

6

7

9

13

18

23

31

41

54

71

93

122

159

9

10

11

13

14

16

19

21

24

26

31

35

40

45

51

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

Depth Oligo Meso Maine

Similar to typical cirrus cloud

Objective• Active measurement of subsurface scattering as independent measure of particle abundance

Measurement Characteristics• Global survey coupled with passive ocean color measurements

• ‘Sampling’ of the mixed layer

• Dark- and Light-side measurements

• Eyesafe lidar with surface penetrating (e.g. 532 nm) and non-penetrating wavelengths (e.g., 1064 nm)

• > 15o tilt to avoid surface flash

• < 20 km resolution

• 1 – 2 m vertical resolution

• Minimum 2 vertical depth bins

• Can be same instrument as aerosol profiler

Particle Profiler

Lidar In-space Technology Experiment (LITE)

• 3-wavelength Nd-Yg lidar • Space Shuttle in 1994• Multi-angle (+/-300) maneuvers • Increased gain at higher angles

532 nm

High Gain HG

150 150

1064 nm

150 150

Low Gain

Off

-Nad

ir A

ngl

e

0

30

15

Time Time

Variable Fluorescence

Objective• Mapping & Monitoring Nutrient Regimes• Physiological Indices• Functional Groups

Measurement Characteristics• Midnight vs Dawn differences in Variable Fluorescence (Fv/Fm)

(two platforms)

• Distinguish Fv/Fm values between 0.05 and 0.65 to 0.05 units

• 10 – 30 km spatial resolution

• Water-penetrating stimulation (e.g., 532 nm), detection at 680 nm

• Spectral fluorescence detection (?)

• Eyesafe

Options• Lidar• Solar Power• Clouds• Fv/Fm or simply Fo?• Suborbital or Space?• ‘Pump-n-Probe’ or ‘Painting the Surface’ (LIFT)?

LIFT (image from Zbignew Kolber)

Mixed Layer Depth and Illumination

Objective• Time-resolved global mixed layer depths• Quantification of ocean net primary production• Characterization of photochemical reactions (CO, DMS, CO2, COS, CS2, …etc)• Surface heat budget

Measurement Strategies• Assimilation of field observations into physical ocean models

• Application of remotely sensed geophysical parameters (e.g., winds, heat flux, E-P, currents, SSH, SST,…etc)

• Empirical retrievals from remote sensing biological or chemical stocks and transformations

• Application of passive remote sensing data and optical models to calculate illumination

Mission Phasing

Backup Slides

Timeline

MissionThemes

Immediate(1 – 5 Years)

Long-Term(10 - 25 Years)

Near-Term(5 - 10 Years)

Global ImagingRadiometer

Aerosols &Particle Abund.

Physiology, Functional Groups, &Fluorescence

Mixed LayerDepth

MissionTheme

Technology Development

Launch/Mission

Ultraviolet

Issues & Approaches

Geophysical Parameters

Near Ultraviolet • Information Rich• High Energy• High Transparency

Ocean Carbon, Ecosystems and Near-Shore

Unexplored Territory

Mid

-UV

Nea

r-U

V

Visible Near InfraRed

* Remote Sensing Reflectance = water leaving / incident

*

Santa Barbara Channel

South Pacific photo (Andre Morel)

• Accurate separation and characterization of CDOM & Pigment Absorption

Ocean Carbon, Ecosystems and Near-Shore

Issues & Approaches

• Spectral Matching more sensitive to radiance reflectance errors than empirical ratio algorithms

• ‘Black water’ assumption invalid in coastal zones for historical wavebands

• Optical distinctions are subtle b/w ecosystem components (functional groups, HABS)

• Particulate scattering is key attribute for addressing many Carbon, Ecosystem, and Near -shore issues

• Coastal waters are optically complex, with particularly problematic atmospheres

• Relating particulate scattering to biomass requires description of particle size spectrum

• Fluorescence measurements

• Independent, active scattering measurements

• Expansion to near UV

• Enhanced Spectral Resolution UV

• Enhanced Spectral Resolution Visible

• Advanced Atmospheric Correction OzoneAbsorbing aerosol heightsUV band near 350 nmExpanded NIR

• Rigorous prelaunch characterization, regular lunar and solar calibration, field validation

Ocean Carbon, Ecosystems and Near-Shore

Passive Geophysical Parameters

GLAS profile data Geophysical Parameter

• Pigment absorption

• Phytoplankton carbon

• Net primary production

• Export production

• Dissolved Organic Carbon

• CDOM photochemistry

• Slope of CDOM absorption

• Particulate Organic Carbon

• Particle size spectrum (pss)

• Particulate beam attenuation

• Carbon loading & dispersal

• Solar radiation & Kd

• Particulate inorganic carbon

• Functional groups

• HABs

• Eutrophication

bbp (spectral matching, lidar)

aph (spectral matching)

Phyto C, C:Chl, PAR, MLD, Kd, part. size spec., fluor.

Algorthm Product

(Phyto C, NPP, MLD)t, Ecosystem Model

CDOM (spectral matching), empirical algorithms

CDOMt, PAR, MLD, Kd, Degredation model

CDOM (enhanced spectral UV/VIS resolution)

bbp, pss (spectral matching, lidar)

Spectral matching with enhanced VIS resolution

High VIS spectral resolution, Lidar

Near-shore particulate and dissolved carbont

UV/VIS radiances, modeling

High VIS (UV?) spectral resolution

High VIS (UV?) spectral resolution

Near-shore Phyto C & NPP, fluorescence

bbp (spectral matching), empirical algorithm

0 0.5 1.0 1.5 2.0Growth Rate (div d-1)

Growth Rate (day-1)

Los

s R

ate

(day

-1)

Johannessen et al. 2003

Spectral beam attenuation coefficient retrieved from ocean color inversionCollin S. Roesler, Emmanuel Boss (2003)

W.Balch, Bigelow LaboratoryAlvain et al. 2005