1. Studies of Advanced Baseline Sounder (ABS) for Future GOES Jun Li + Timothy J. Schmit @ Allen Huang+ W. Paul Menzel @ @NOAA/NESDIS/ORA +CIMSS, UW-Madison ITSC-XII, Feb.27 - Mar.05, 2002, Lorne, Victoria, Australia UW-Madison

2. More than 5 years of high spectral measurements from polar orbits: - AIRS (Atmospheric InfraRed Sounder) - IASI (Infrared Atmospheric Sounding Interferometer) - CrIS (Crosstrack Infrared Sounder) Approximately 5 years of high spectral, spatial and temporal measurements from geostationary orbit: - GIFTS (Geostationary Imaging Fourier Transform Spectrometer) 30 years of filter wheel technology in geostationary orbit: - VAS and GOES Sounder 40 years since the first interferometer flown in space to study the weather: IRIS (Infrared Radiation Interferometer Spectrometer) ABS is scheduled to be on GOES-R in 2012 The time is right to update the GOES sounder! The technology is mature. The need is documented.

3. Limitations of Current GOES Sounders –scan conflicts between oceans vs CONUS (regional vs hemispheric) –low vertical resolution for moisture, temperature –eclipse and related outages

4. User Requirements Current (1999) NWS Thresholds Resolutions - Temporal: The ‘sounding disk’ in 1 hour - Spectral : from 3.7-15.4 µm at 0.6 to 2.5 cm -1 resolution (similar to spectral performance of polar interferometers - CrIS) - Spatial: 10 km horizontal resolution for independent observation Accuracies 1 degree K temperature; 10% relative humidity Applications - Nowcasting - Short-range weather forecasting - Longer-range numerical weather prediction

5. User Requirements

6. Sounder Comparison Coverage RateCONUS/hrSounding Disk/hr Horizontal Resolution - Sampling Distance10 km10 km Vertical resolution~3 km 1 km Accuracy Temperature2 deg. K 1 deg. K Humidity20%10% CurrentRequirement

7. Areas within 62 degrees local zenith angle from GOES-East and GOES-West sub- satellite points are indicated. Threshold coverage rate calls for the 62 arc region, excluding half of over-lap, to be scanned each hour. Current GOES -E and -W sounder hourly coverage is also shown. Spatial Coverage

8. GOES-12 Sounder -- Cloud Top Pressure

9. GOES-12 Imager -- Cloud Top Pressure

10. Geostationary Sounders (# of channels) VAS (experimental) GOES Sounder (operational) GIFTS (experimental) (12) (18) (~1600) Advanced Baseline Sounder (operational) time

11. Spectral coverage of the proposed ABS’, ABS, GIFTS and the current GOES radiometer sounder ABS:

12. Spectral widthsSpectral resolutions ABS 3-band: 650 -1200 cm -1 0.625 1210-1740 cm -1 1.25 2150-2720 cm -1 2.5 ABS’ 2-band: 650 -1200 cm -1 0.625 1650-2250 cm -1 0.625

13. Noise vectors used for the ABS simulations ABS’

14. Is a new 2-band ABS’ comparable to a traditional 3- band ABS for Temperature? UW/CIMSS

15. Is a new 2-band ABS’ comparable to a traditional 3- band ABS for Moisture? UW/CIMSS

17. ABS’ LW 650 - 1200 cm**-1

20. 00 and 12 UTC only. Land-based CONUS locations.

23. 12 UTC. Land-based CONUS location. 12 UTC Land-based CONUS location

24. Detection of Temperature Inversions Possible with Interferometer The detection of inversions is critical for severe weather forecasting. Combined with improved low-level moisture depiction, critical ingredients for night-time severe storm development over the Plains can be monitored. Knowing if there is an inversion can also help improve the profiles estimates. Spikes down - Cooling with height Spikes up - Heating with height Texas Ontario Brightness Temperature (K) (low-level inversion) (No inversion) GOES Wavenumber (cm -1 )

25. Cloud-Top Information Future GOES -- simulating the Advanced Baseline Sounder (ABS) performance

26. Summary The information from CrIS-like three spectral bands is close to that from GIFTS- like two spectral bands. The Advanced Baseline Sounder overcomes existing instrument limitations. Geostationary interferometer will resolve high temporal and vertical fluctuations of moisture that are not resolved by current in-situ or satellite measurements. Only geostationary interferometer observes critical meteorological parameters (temperature, moisture, clouds, winds) with necessary temporal, spatial and vertical resolutions to support future Nowcasting, Short-range weather forecasting, and Longer-range numerical weather prediction. Technology is mature and meteorological need is documented. Time is right to update geostationary sounding instruments. Advanced Sounder will provide required high spectral resolution measurements.