GOES-N Science Test

Timothy J. Schmit

NOAA/NESDIS/STAR

Advanced Satellite Products Branch (ASPB)

and many others

UW-MadisonMay 2005

GOES-N- GOES-N science post-launch check-out is upcoming

- Details (schedule) still vague. - These tests are an essential step for the system to ultimately become operational.

- better calibration- longer imager BlackBody looks- colder detectors

- no spring and fall outages due to eclipse- reduced Keep Out Zone outages- better navigation (earth sensor -> star tracker)- GOES-N VISITview (beta version) developed

GOES-8/12 GOES-N/P

GOES-8/12

GOES-N/PPosition of the boom allows for colder detectors and hence less instrument noise

GOES-N/O/P will have similar instruments to GOES-8-12, but will be on a different spacecraft bus. The new bus will allow improvements both to the navigation and registration, as well as the radiometrics.

GOES-N Post-Launch (Science) Test

Milestones/Goals:– Acquire and Save GOES-N PLT radiance data– Check-out GOES-N radiance quality (noise, etc.)– Produce and validate GOES-N products (For example, generation

of temperature and moisture retrievals, cloud top information, DPI, Winds, etc. )

– NOAA NESDIS Tech Memo– Test instruments during eclipse periods– Verify improved navigation and registration– Don Hillger, RAMMT is slated to coordinate the schedules, etc

during the science test. ASPT/CIMSS will produce and verify several products. Other groups (FPDT, etc) will also be involved.

Hillger, D. W., T. J. Schmit, and J. M. Daniels, 2003: Imager and sounder radiance and product validations for the GOES-12 science test, NOAA Technical Report 115, U.S. Department of Commerce, Washington, DC.

GOES-12 Sounder noise values (in radiance units) compared to those from GOES-8. The specification noise values for the GOES Sounder bands are also included for comparison purposes.

Radiance example from GOES-12 PLT

Derived Product example from GOES-12 PLT

GOES-8 (left) and GOES-12 (right) retrieved total precipitable water (TPW) from the Sounder displayed as an image. The data are from 19 UTC on 20 October 2001.

Limitations of Current GOES Imagers

– Regional/Hemispheric scan conflicts

– Low spatial resolution

– Missing spectral bands

– Eclipse and related outages

GOES-N/O/P will supply data through the eclipse periods.The spacecraft batteries are specified to be large enough to run through eclipse.

Shields have been added to the secondary mirror spiders. Outages due to Keep Out Zones (KOZ) will be minimized.

Outages due to Eclipse

and the Keep-Out-Zone

GOES-8 (~3 hours of data outage)

No data!

GOES-N+

(<<1 hour of data outage)

0100 UTC0100 UTC 0200 UTC0200 UTC 0300 UTC0300 UTC

0400 UTC0400 UTC 0500 UTC0500 UTC 0600 UTC0600 UTC

0700 UTC0700 UTC 0800 UTC0800 UTC 0900 UTC0900 UTC

The Onset Of Hurricane Ivan: 16 September 2004

GOES-10 & -12 Sounder Cloud Top Pressure Coverage

Outage during landfall

Improved radiometrics on GOES-N+

The GOES-N+ instruments will be less noisy. 

Lower (colder) patch (detector) temperature is the main driver.

Other modifications have been made to improve the noise performance on both instruments.

Improved GOES-N (Sounder) noise compared to GOES-12

longwave shortwave

Improved calibration on GOES-N+

Reduction in striping to be achieved through increasing the Imager's scan-mirror's dwell time on the blackbody from 0.2 sec to 2 sec. 

The more accurate blackbody characterization improves the calibration of the infrared detectors.

Example infrared image with striping:

Improved calibration on GOES-N+

Analysis shows that the blackbody noise will be reduced by about 13% in Imager channels 3-5, which should improve the precision of their calibration by approximately that amount and also reduce the striping by an unknown amount (since there are a lot of other factors besides uncorrelated blackbody errors that cause the striping).

This improvement begins with GOES-N ” 

Improved navigation on GOES-N+• The GOES-N navigation will be improved

• New spacecraft bus • Use of star trackers

• GOES-N performance will be verified on-orbit

GOES-I/M Performance & GOES-N Expected Performance

85 urad

(~3 km)

168 urad

= 6 km

Nighttime

(IR)

53 urad

(<2 km)

112 urad

= 4 km

Daytime

(Visible)

GOES-N+GOES-I/MNavigation

at Nadir

GOES-N Imager and Sounder spectral response functions.

Note the imager band selection is similar to GOES-12.

GOES-N Imager Weighting Functions

CIMSS

Pre

ssur

e

GOES-N Sounder Weighting FunctionsP

ress

ure