Status of GEMS (Geostationary Envi-ronment Monitoring Spectrometer)

Mission

Jhoon Kim

P.I., GEMS Program

Director, Global Environment Satellite Research Center (GESC)

Professor, Department of Atmospheric Sciences,

Yonsei University, Seoul, Korea

(jkim2@yonsei.ac.kr)

GEOCAPE Community Workshop,

May 11th, 2011, Boulder, CO

ContributorsGEMS Science Team - KARI, Yonsei Univ., GIST, Pusan Nat’l Univ., SNU, Konkuk Univ., Ewha Women’s Univ.

H. Lee (Yonsei University)

Kelly Chance, Xiong Liu (Harvard Smithonian Center for Astro-physics)

GEMS SAG(Science Advisory Group) - NASA, GSFC, JPL, ESA, JAXA, NCAR, NRL, MPI, NOAA, KNMI, Harvard Univ., UCLA, Univ of Alabama, Dalhousie Univ., Univ of Iowa, Univ of Bremen, Univ of Heidelberg, Univ of Tokyo, …)

Ministry of Environment, Rep. of Korea

NIER(National Institute of Environmental Research)

1995~2006KOREASAT 1-5

National Space Program of Korea

1992-1999KITSAT-1~3

2003STSAT- 1

2006KOMPSAT-2

2011KOMPSAT-3

(EO)

1999KOMPSAT-1

2017KOMPSAT-7

(EO)

2011KOMPSAT-5

(SAR)

2010COMS

2015KOMPSAT-6

(SAR)

2009STSAT-2

2011STSAT-3

2012KOMPSAT-3A

(EO)

2009 KSLV-1

2008Astronaut

2017KSLV-II

2020Lunar Orbiter

2025Lunar Mission

2017

2010 KSLV-1

GEO

GEO

GEO

2011

2018 GEO KOMPSAT

2014CAS-12020

CAS-2

Restriction on Use, Publication, or Disclosure of Proprietary/Controlled Information – KARI proprietary

Political Support

GOCI-2Met.Payload

GEMS System/BusAIT

ME MEST

MLTMKMA

National Committee of Space Development

ME : Ministry of EnvironmentKMA : Korea Meteorological Administration

MEST : Ministry of Education, Science & TechnologyMLTM : Ministry of Land, Transport & Maritime Affairs

Collaborative Support from Govern-ment

GEO KOMPSAT

Spatial Coverage of GEMS

(Richter, 2005)

NS: 5 S ~ 55 N, EW: 75 E~145 E

GEOCAPE

Sentinel-4

GMAP-AsiaGEMS

POGEQA

Science Questions & Objectives of GEMSScience Questions Objectives

1. What are the temporal and spatial varia-tions of concentrations and emissions of gases and aerosols that are important for

air quality?

1. To provide measurements of atmospheric chemistry, precursors of aerosols and ozone in particular, in high temporal and spatial resolution over Asia

2. How do regional and intercontinental transport affect local and regional air quality?

2. To monitor regional transport events: transboundary pollution and Asian dust

3. How does air pollution drive climate forcing and how does climate change affect air quality?

3. To quantify radiative forcing of aerosol and ozone and to monitor air quality for long term

4. How does meteorology affect the air quality ?

4. To improve our understanding on interactions between atmospheric chemistry and

meteorology

5. Can we quantify the outflow from Asia to cross Pacific ?

5. To better understand the globalization of tropospheric pollution

6. How can we improve the accuracy of air quality forecast using satellite measurements?

6. To improve air quality forecast by constraining emission rates and assimilating chemical

observation data

Measurement of air quality in high temporal and spatial resolution

Credit: CCSP Strategic Plan (illustrated by P. Rekacewicz).

EMISSION(local and urban scale)

AIR QUALITY(local and regional)

LONG-RANGE TRANSPORT

METEOROLOGY

CLIMATE FORCING

Meteorology

Source Sink

FEEDBACK AtmosphericCorrection forOcean color

Information Service to Public

Air quality forecast with weather observation

PMAir quality

O3Air quality

Satellites

Surface monitors

CTM

Aircraft, lidar

NEW KNOWLEDGE

Air quality monitoring& forecasting

Source quantification,policing of environ-mental agreements

Long-range transport

Climate forcing

Biogeochemical cycling

Weather forecasting

NO2SO2O3

HCHOAerosolCloud

Data Assimilation

Integrated Simulation

Emission DB

CTM

Concentration, Ni (t, x,y,z)

RTM

GEMS Instrument

Function

GEMSRadiance SpectrumL (l; t, x,y)

Retrieval Algorithm

GEMS-retrieved

Concentration

N’i (t, x,y)

Surface Reflectance

a ( , , l q f; t, x,y)

Si (l; t, x,y)

Intercomparison

Ri ( )l

Met Field

Cloud, Wind, Vi (t, x,y,z)Temperature, T(t,x,y,z)…

Constrain / consistency?

GEMSInstrument Re-

quirements

Dynamic rangeSpectral rangeSpectral resolutionSNR, MTF …

Spectral coverage of GEMS

GEMS

AOD

0.1 1 10

Fre

qu

en

cy (

%)

01020304050

SO2 (1E+14 #/cm2)

0.1 1 10 100 1000

Fre

qu

en

cy (

%)

02468

101214

NO2 (1E+14 #/cm2)

0.1 1 10 100 1000

Fre

qu

en

cy (

%)

02468

101214

HCHO (1E+14 #/cm2)

0.1 1 10 100 1000

Fre

qu

en

cy (

%)

02468

101214

O3 (1E+16 #/cm2)

0.1 1 10 100 1000

Fre

qu

en

cy (

%)

02468

101214

Average probability distribution function (PDF)

Baseline products

Product Importance Min(cm-2)

Max(cm-2)

Nominal(cm-2)

Accuracy Spectral window

(nm)

Spatial Resolution

(km2)

SZA(deg)

NO2Ozone

precursor3x1013 1x1017 1x1014 1x1015 425 - 450 5 x 5 < 70

SO2Aerosol

precursor6x108 1x1017 6x1014 1x1016 310 – 330 5 x 5 < 60

HCHOProxy for

VOCs1x1015 3x1016 3x1015 1.0x1016 327 – 357 5 x 5 < 70

O3Oxidant, pollutant

4x1017 2x1018 1x1018 2% or 6 DU

300-340Chappuis

band ?5 x 5 < 70

AOD PM, type, 0 4 0.220% or 0.1@

400nm300-500 2.5 x 5 < 70

CHOCHO : Feasibility not confirmed yet

Radiance at GEMS

• Radiance for GEMS: libRadtran SZA:0-70o

Surface albedo 0.03 (Lambertian Surface) Gases: O3, SO2, HCHO, NO2 + Aerosol

• Min. Clear sky condition based on CMAQ v4.5.1 • GEMS’s solid angle: 5×5 km 1.9×10-8 sr • 0.2 nm sample, 0.6 nm resolution (FWHM) for

GEMS

Radiance at GEMS

Maximum gas column densities and AOD (BC) with the highest PDF value

Minimum gas column densities and AOD (Sulfate) with the highest PDF value

Nominal gas column densities and minimum AOD (Sulfate)

Min. Radiance

Max. Radiance

70605040302010

0

Molecules Wave-length window

(nm)

Radiance Time # of pho-tons cm-2

px-1

SO2 & O3 315-335 1.25×1012 6 2.91×104

HCHO 327-356 3.23×1012 6 7.49×104

NO2 423-451 5.42×1012 2 4.18×104

Min. & Max. radiance at GEMSA. Minimum radiance obtained frommaximum gas column densities and AOD (BC) with the highest PDF value

B. Maximum radiance obtained from minimum gas column densities and AOD (Sulfate) with the highest PDF value

Molecules Wave-length window

(nm)

Radiance Time # of pho-tons cm-2

px-1

SO2 & O3 315-335 2.17×1013 6 5.03×105

HCHO 327-356 2.19×1013 6 5.09×105

NO2 423-451 3.02×1013 2 2.33×105

Mole-cules

Wave-length window

(nm)

RadianceRange

Time # of photon cm-2 px-1

SO2 & O3 315-335 2.41×1012 - 1.98×1013 6 5.58×104 –

4.59×105

HCHO 327-356 6.11×1012 - 2.08×1013 6 1.41×105 –

4.83×105

NO2 423-451 9.09×1012 - 2.74×1013 2

7.02×104 – 2.11×105

C. Radiance obtained from nominal gas column densities and minimum AOD (Sulfate)

Cloud

17

Radiance simulation for GEMS

(K.M. Lee)

The percentage of clear sky region

Resolution March June September December

4kmⅹ4km 38.15 30.82 33.80 37.68

8kmⅹ8km 24.05(33.17)

19.25(26.62)

21.86(29.57)

23.06(32.36)

16kmⅹ16km 13.66(27.13)

10.80(21.70)

12.81(24.54)

12.90(25.96)

1 In terms of area at a given time2 The ratios in parentheses are the value when allowing 25% cloud fraction for clear sky region.

18

(Y.S. Choi and J. Kim)

19

0.2 nm: original model spectra resolution0.4, 0.6, and 0.8 nm: Virtual instrumental spectra resolution

Solar ZA:60Solar AA:300Satellite ZA:30Satellite AA:300

Case 1: spectrum for analysis (NO2) _ (420-450nm)

(Y.J. Kim)

Case 1: Result of NO2 SCD

20

Instrument spec-tral

resolution(nm)

NO2 SCD(molecules/

cm2)

Rela-tive Er-ror(%)

NO2 SCD Fitting error(molecules/

cm2)

Relative fit-ting

error (%)

Minimum detectable

SCD (2σ)(molecules/

cm2)

Usefulness

0.2 2.86E+17　 1.06E+16 3.7% 2.11E+16 o

0.4 2.82E+17 -2% 1.53E+16 5.4% 3.06E+16 o

0.6 2.74E+17 -4% 1.22E+16 4.4% 2.44E+16 o

0.8 2.65E+17 -7% 1.23E+16 4.6% 2.46E+16 o

(Y.J. Kim)

21

± 3.7%± 5.4% ± 4.4% ± 4.6%

Case 1: NO2 slant column density and Uncertainty

(fitting interval: 430-450 nm)

± 10.0% rela-tive error

(Y.J. Kim)

Case 2: Result of SO2 SCD

22

Instrumentspectral

Resolution (nm)

SO2 SCD(molecules/

cm2)

RelativeError (%)

SO2 SCDfitting error(molecules/

cm2)

Relative fitting Error (%)

Minimumdetectable

SCD(2σ)

Useful-ness

0.2 (310-330 nm) 3.99E+16　 1.37E+15 3.4% 4.10E+15 O

0.4 (310-330 nm) 3.55E+16 -11% 1.82E+15 5.1% 5.47E+15 Δ

0.6 (310-330 nm) 1.96E+16 -51% 2.54E+15 12.9% 7.61E+15 ?

0.8 (310-330 nm) 1.25E+16 -69% 3.19E+15 25.6% 9.58E+15 X

(Y.J. Kim)

23

Case 2: SO2 slant column density and Uncertainty

(fitting interval: 310-330 nm)

± 3.4%

± 5.1%

± 12.9%

± 25.6%

± 20.0% relative error

(Y.J. Kim)

24

Retrieved O3 and its % errors

(%

)

(#

/cm

2)

Retrieved O3 Column concentration

Relative Error

Spectral resolution (nm)(R. Park)

25

Retrieved HCHO and its % errors

(#

/cm

2)

(%

)

Retrieved HCHO Column concentration

Relative Error

Spectral resolution (nm) (R. Park)

(K. Chance)

(K. Chance)

(K. Chance)

(K. Chance)

SNR Requirements

Wavelengths (nm)

SNR Related gas

Remark

315-325 1225 SO2

327-356 1394 HCHO

423-451 1800 NO2

433-465 1931 CHOCHO

• For 8x8 km2 footprints• May consider spatial coadding

GEMS Requirements

System Attributes Requirements

Lifetime> 7 years

[option : >10 years]

Reliability > 0.85 @EOL

Field of regard5000 km (N/S) 5000 km (E/W)

[Region of interest : 55N~5S, 75E~145E]

Duty cycle / Imaging time8 images during daytime

(30 min imaging + 30 min rest) 8 times / day

Ground sampling distance

< 5 km (N/S) 5 km (E/W) for gases at Seoul

[option : < 2.5 km (N/S) 7.5 km (E/W)]

2.5 km (N/S) x 5 km (E/W) for aerosol

Spectral range 300 nm to 500 nm [Option: 300 to 650 nm]

Spectral resolution < 0.6 nm

Spectral sampling < 0.2 nm (3 samples)

Signal-to-noise ratio> 720 @nominal radiance of 320nm (TBC)

> 1500 @nominal radiance of 430nm (TBC)

Data quantization 12 bits

31

GEMS Requirements

System Attributes Requirements

MTF> 0.3 in N/S direction @Nyquist frequency

> 0.3 in E/W direction @Nyquist frequency

Radiometric calibration accu-

racy< 4%

Spectral calibration accuracy < 0.02 nm

Polarization factor < 4% (TBC)

Polarization factor variance < 1%

Data rate < 10 Mbps (Option: 40 Mbps)

Mass < 110 Kg

Volume < 800 mm x 1200 mm x 700 mm

32

Heavy shielding could effectively protect the primary particles at the expense of mass and volumeAs the incident energy increases, more thicker shielding is required.

Relation between the incident energy and shielding thickness is not linear for aluminum shielding.

10 kg of Al shield was adopted in OMI whose total mass is 65 kg.

33

Space radiation

Proton propagation in Al Al Shield Thickness vs. Proton Energy

De-polarizer : use to minimize polarization effect

Major source of polarization : grating or prism

De-polarization methodSpatial averaging – employing birefringent crystal wedge devices (OMI case)– Usually used in LEO or in case of low spatial resolution (induce image degradation)

Spectral averaging – the basis of the Lyot depolarizer– In case of low spectral resolution (induce spectral degradation)

Temporal averaging – Time-Domain Polarization Scrambler (TDPS)– Use the photo-elastic modulator, now under development, No spatial/spectral degradation

SolutionFirst of all, the polarization sensitivity of optical system shall be minimized.

TDPS is best if possible, Lyot depolarizer is also suitable for GEO.

34

Polarization

Double Wedge Scrambler Lyot Polarization Scrambler TDPS test setup

GEMS Interface RequirementInterface Requirements - Volume < 800mm(XSAT) 1200mm(YSAT)

700mm(ZSAT)

- Mass < 110 kg

GEO KOMPSAT Configuration

GEMS and GOCI-2 may have more volume and mass budget

- Can increase capability in spatial resolutionor spectral coverage

Mission : Air Pollution Monitoring Meteorological observation Ocean Color monitoring

Mass : Dry mass 1280.9 kg Launch mass 2640 kg

Power : In-orbit 1500 W, Transfer orbit 1100 WMission Life : 10 years

2A Sat. : Met Sensor 2B Sat. : GEMS,

GOCI-2

(Twin Satellites)

2A 2B

Satellite configuratio

n w/payloads

Resolution• 16 ch, Full size image < 15 min• 0.5, 1 km (Vis), 2 km (IR)

• GOCI-2 : 250 m• GEMS : 5 km x 5 km

Life time 10 years 10 years

Launch Mass

2849 kg 2550 kg

Power 2903 W 2903 W

Orbit GEO @ 128.2±0.05 E GEO @ 128.2±0.05 E

Solar Panel

ABI

GOCI-2

Solar Panel

GEMS

Status of GEO KOMPSAT Mission• GEMS Program Office

– Established GEMS Program Office inside ME and GEMS Research Center at Yonsei Univer-sity in 2009

– Started preliminary study in 2009 to setup requirements and instrument concept design by ME

• Budget– Following the successful launch of COMS in June, 2010, the budget request proposal was approved on Dec. 2010 by the Government Budget Review Committee led by the Ministry of Planning and Finance.

• RFP– Response to RFI received in Dec. 2010– RFP planned to be issued in the fall, 2011 – Selection of main contractor by the end of 2011

• International Collaboration– Recognized as a part of ACC by CEOS– Established Technical Group on Atmospheric Composition Measurements from Geostationary

Satellites with NASA– ToR for NASA-NIER/ME collaboration endorsed by NASA HQ and NIER/ME– MOU with NCAR(2010) and Harvard CfA (2011, ongoing)– Collaboration under discussion with Netherland and Japan

Master Schedule of MP-GEO SAT

Global Environmental Monitoring

Constellation of GEO Mission to study Air QualityConstellation of GEO Mission to study Air Quality

GEO-CAPE(America)

GMES S4MTG (Europe)

GEMSGEO KOMPSAT(Asia)

Constellation synergy- Improving spatial and temporal coverage to monitor globalized pollutants- Sharing basic requirements on data products and instrument to maintain data quality- Consolidating socio-economic benefit analysis- Supporting QA and CAL/VAL

GMAP Asia(Asia Pacific)

POGEQA(Europe)

ChineseGEO AQ Mission(Asia)

THANK YOU FOR YOUR ATTENTION !

40

Status of GEMS (Geostationary Environment Monitoring Spec-

trometer)

Jhoon Kim

P.I., GEMS Program

Director, Global Environment Satellite Research Center (GESC)

Professor, Department of Atmospheric Sciences,

Yonsei University, Seoul, Korea (jkim2@yonsei.ac.kr)

GEOCAPE Community Workshop, May 11th, 2011, Boulder, CO