<GIFTS_Cal_Req.ppt>9 March 2004

GIFTS System Calibration Requirements Flowdown

Hank Revercomb

9 March 2004

<GIFTS_Cal_Req.ppt>9 March 2004

Slide 2

GIFTS Overall Absolute Calibration Budget

Subject of BB CDR

<GIFTS_Cal_Req.ppt>9 March 2004

Slide 3

GIFTS Top-level Absolute Calibration Budget

<GIFTS_Cal_Req.ppt>9 March 2004

Slide 4

GIFTS Spectral Calibration Budget

**3-sigma for single sample is 3 ppm-100 sample average assumed

**

Standard Atmosphereused for conversion tobrightness temperature

<GIFTS_Cal_Req.ppt>9 March 2004

Slide 5

GIFTS Radiometric Calibration Budget (Absolute)

<GIFTS_Cal_Req.ppt>9 March 2004

Slide 6

GIFTS Radiometric Calibration Equation:Basis for Uncertainty Modeling

• Radiance N derived from raw spectra of Earth (CE), Space (CS), and the internal Hot (CH) and Cold (CC) Blackbodies

t is the signal transmission of the telescope mirrors &m is the transmission of the Blackbody pick-off mirror

• Bi is the Radiance from the Hot, Cold, and Space References [eg. BH=H B(TH) + (1- H) B(Tstr), where B(T) is the Planck function and Tstr is the effective structure temperature for reflection]

( ) SCH

SECH

t

m BCC

CCReBBN +⎟⎟

⎠

⎞⎜⎜⎝

⎛

−

−−⎟⎟

⎠

⎞⎜⎜⎝

⎛=τ

τ

<GIFTS_Cal_Req.ppt>9 March 2004

Slide 7

GIFTS Absolute Calibration-Longwave

Longwave Band (800 cm-1)Tc=255, Th=290, Ts=240, Tt=280, Tm=250

0.00

0.20

0.40

0.60

0.80

1.00

1.20

190 210 230 250 270 290 310

Scene Temperature [K]

GIFTS

External BB

Requirement

(excluding uncertainty in correction forNon-linearity & Polarization)

Longwave Band (800 cm-1)Tc=255, Th=290, Ts=240, Tt=280

<GIFTS_Cal_Req.ppt>9 March 2004

Slide 8

GIFTS Absolute Calibration-Shortwave

Shortwave Band (1800 cm-1)Tc=255, Th=290, Ts=240, Tt=280, Tm=250

0.00

0.20

0.40

0.60

0.80

1.00

190 210 230 250 270 290 310

Scene Temperature [K]

GIFTS

External BB

Requirement

(excluding uncertainty in correction forNon-linearity & Polarization)

Shortwave Band (1800 cm-1)Tc=255, Th=290, Ts=240, Tt=280

<GIFTS_Cal_Req.ppt>9 March 2004

Slide 9

GIFTS Calibration Error Sources-LW

NEN/4=0.050.3% 0.3 K

Longwave Band (800 cm-1)Tc=255, Th=290, Ts=240, Tt=280, Tm=250

0.00

0.10

0.20

0.30

0.40

0.50

190 210 230 250 270 290 310

Scene Temperature [K]

GIFTS Nominal BB Tau Ratio Noise Residual Ttel changes

Longwave Band (800 cm-1)Tc=255, Th=290, Ts=240, Tt=280

<GIFTS_Cal_Req.ppt>9 March 2004

Slide 10

GIFTS Calibration Error Sources-SW

0.5% NEN/4=0.0025 0.3 K

0.00

0.10

0.20

0.30

0.40

0.50

190 210 230 250 270 290 310

Scene Temperature [K]

GIFTS Nominal BB Tau Ratio Noise Residual Ttel changes

Shortwave Band (1800 cm-1)Tc=255, Th=290, Ts=240, Tt=280

<GIFTS_Cal_Req.ppt>9 March 2004

Slide 11

GIFTS Blackbody Budget

Subject of this BB Subsystem CDR:Budget is 0.5 K 3-sigma Absolute &

0.1 K 3-sigma Reproducibility, by analogy