Tropospheric Emissions: Monitoring of Pollution Use or disclosure of this information may be subject to United States export control laws. For official

Tropospheric Emissions: Monitoring of Pollution

Use or disclosure of this informationmay be subject to United States exportcontrol laws. For official use only.

23 July 2013

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TEMPO Instrument Performance

TEMPO Science Team Meeting

July 23-24 2013


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23 July 2013

Outline

• Notional TEMPO instrument layout• Instrument parameter assumptions• Instrument EOL SNR performance• EOL SNR impacts of a colder detector• Closing remarks

Introduction


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Notional TEMPO Instrument LayoutNotionalLayout

• Instrument trades are on-going to minimize instrument packaging while maximizing instrument performance


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23 July 2013

Instrument Parameters

Parameter Value Comment

Frame Integration Time 160 ms Set by saturation requirement

Coadded Frames 16 Set by SNR and Coverage Time Requirement

Spectral Range 290-485nm, 535-750nm Utilizes two CCDs

Spectral Dispersion 0.21 nm/pixel Assumes 2048 pixels for spectral coverage – best case assumption

Spectral Sampling 2.84 samples / FWHM Dictated by slit width and pixel pitch (to first order)

Spectral Bandpass 0.596 nm Dictated by slit width, dispersion, and pixel pitch (to first order)

Detector Full Well 300 ke- CCD designers are indicating that 200 ke- is more realistic; reduction will have performance implications

Detector Operating Temperature

+5 deg C Dark current and Random Telegraph Noise levels do not drive SNR performance

N/S GSD 8 km Spatially binning four 2 km N/S pixels

E/W GSD 4.2 km Dictated by spectrometer slit width and N/S GSD

Coverage Time 60 minutes Meets requirement value of 60 minutes

Parameters


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EOL SNR Performance Snapshot

• Requirements shown are from Xiong Liu (July 18, 2013)

EOL SNR


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O3 Channels Have Insufficient Margin

AtmosphericConstituent

Wvl(nm)

SNR Reqmt

SNR Perf

+5° C

Margin+5° C

O3 290 27 30 11%

O3 300 59 66 11%

O3, SO2 305 204 224 10%

O3, SO2 310 480 526 10%

O3, SO2 320 1516 1654 9%

O3, H2CO, SO2 330 2369 2583 9%

O3, H2CO, Cloud 340 2354 2567 9%

H2CO, Cloud, AOD 350 1414 2405 70%

AOD 380 1414 2200 56%

NO2 420 769 2623 241%

NO2, C2H2O2 430 1830 2280 25%

C2H2O2 460 2123 2646 25%

Cloud 490 1700 2350 38%

O3 540 1754 1913 9%

O3 600 1574 1717 9%

O3 650 1464 1597 9%

Cloud, Aerosols 690 888 1308 47%

EOL SNR Performance

• BATC SE guidelines recommend at least 30% SNR margin at SRR

• Several channels do not meet the minimum SNR margin guideline of 30%


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23 July 2013

O3 Channels Have Insufficient Margin

AtmosphericConstituent

Wvl(nm)

SNR Reqmt

SNR Perf

+5° C

Margin+5° C

SNR Perf

-15° C

Margin -15° C

O3 290 27 30 11% 48 76%

O3 300 59 66 11% 100 68%

O3, SO2 305 204 224 10% 297 46%

O3, SO2 310 480 526 10% 612 27%

O3, SO2 320 1516 1654 9% 1708 13%

O3, H2CO, SO2 330 2369 2583 9% 2621 11%

O3, H2CO, Cloud 340 2354 2567 9% 2605 11%

H2CO, Cloud, AOD 350 1414 2405 70% 2446 73%

AOD 380 1414 2200 56% 2243 59%

NO2 420 769 2623 241% 2660 246%

NO2, C2H2O2 430 1830 2280 25% 2322 27%

C2H2O2 460 2123 2646 25% 2683 26%

Cloud 490 1700 2350 38% 2391 41%

O3 540 1754 1913 9% 1962 12%

O3 600 1574 1717 9% 1770 12%

O3 650 1464 1597 9% 1653 13%

Cloud, Aerosols 690 888 1308 47% 1372 54%

EOL SNR Performance

• Detector dark current at -15° C is reduced by a factor of approximately 10 compared to +5° C

• Cooling detectors to -15° C gives more margin, but only pushes three channels above the 30% margin guideline

• There are not many instrument parameters that can be adjusted to give the 30% SNR margin at the O3 channels– 30% margin may require

unrealistically high optical throughput, for example


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23 July 2013

Closing Remarks

• Design work for TEMPO is on-going• Finalization of spectral range, SNR, GSD and Field of Regard requirements will

facilitate design activities• Several channels drive the system in terms of SNR performance

– Colder detector temperatures give some relief in the UV, but signal shot noise and other noise terms dominate the SNR in the VIS» Artificially setting the dark current equal to zero does not result in significantly more SNR

margin for those driving channels• Updated instrument parameters will impact SNR performance

– Detector design indicates that the full well will decrease» This will require shorter integration times and more coadds

– Detector designers indicate the QE will increase» This will help in terms of signal collection in the UV, but may require further shortening of

the integration time and increase of coadds– Taking a closer look at optical throughputs, etc…

• BATC looks forward to contract award and continued fruitful discussions with the TEMPO science team

Summary

Documents

Tropospheric Emissions: Monitoring of Pollution Use or disclosure of this information may be subject to United States export control laws. For official