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

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.

Limitations of Current GOES Sounders

– scan conflicts between oceans vs CONUS (regional vs hemispheric)

– low vertical resolution for moisture, temperature

– eclipse and related outages

User RequirementsCurrent (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

Table 3: Sounder Band Descriptions

Waveband (cm-1) Unapodizedspectral

resolution (cm-1)650 - 1200 0.6251210 - 1740 1.252150 - 2720 2.5

Sounder Comparison

Coverage Rate CONUS/hr Sounding Disk/hr

Horizontal Resolution

- Sampling Distance 10 km 10 km

Vertical resolution ~3 km 1 km

Accuracy

Temperature 2 deg. K 1 deg. K

Humidity 20% 10%

Current Requirement

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.

SpatialCoverage

Geostationary Sounders

(# of channels)

VAS (experimental)

GOES Sounder(operational)

GIFTS(experimental)

(12)

(18)

(~1600)

(~1600)

Advanced BaselineSounder (operational)

time

Spectral coverage of the proposed ABS’, ABS, GIFTS and the current

GOES radiometer sounder

ABS:

Spectral widths Spectral 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

Noise vectors used for the ABS simulations

ABS’

Is a new 2-band ABS’ comparable to a traditional 3-band ABS for Temperature?

UW/CIMSS

Is a new 2-band ABS’ comparable to a traditional 3-band ABS for Moisture?

UW/CIMSS

ABS’ LW 650 - 1200 cm**-1

ABS’ LW 650 - 1200 cm**-1

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

12 UTC. Land-based CONUS location.

12 UTC Land-basedCONUS location

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

Bri

ghtn

ess

Tem

pera

ture

(K

)

(low-level inversion)

(No inversion)

GOESGOES

Wavenumber (cm-1)

Cloud-Top Information

Future GOES -- simulating the Advanced Baseline

Sounder (ABS) performance

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.