Advanced Sounder Capabilities- Airborne Demonstration with NAST-I W.L. Smith, D.K. Zhou, and A.M. Larar NASA Langley Research Center, Hampton, Virginia Twelfth International TOVS Study Conference (Lorne Australia, 27 Feb-5 Mar, 2002) NAST on Proteus Performance: Ceiling kft Airspeed 300 ktas Endurance hrs Operating Altitude: 100 to 60,000 ft ER-2

NPOESS Airborne Sounder Testbed (NAST) IR interferometer ( NAST-I ) Spectral Range:3.5 – 16microns Spectral Resolution:>2000 (0.25cm -1 )

NAST-I Spectral Coverage Encompasses all future satellite sounders CrIS CO 2 O3O3 H2OH2O N 2 O CO 2 CO N 2 O CH 4 H2OH2O GIFTS-SWGIFTS-LW H2OH2O CO 2 O3O3 N2ON2O CH 4 CO N2ON2O CO 2 H2OH2O H2OH2O AIRS/CrIS GIFTS NAST-I /IASI Spectral Coverage Comparison

p NAST-I Observes 3-Dimensional Structure With High Spatial Resolution and Radiometric Accuracy

Optimal Regression Retrieval Approach for NAST-I Application R = radiance  = surface emissivity B s = surface Planck radiance  = transmittance  s = surface transmittance  * = (  s ) 2 /  P s = surface pressure P ac = aircraft pressure S = number of sample profiles  = radiance deviation from the mean M = covariance matrix of  E = eigenvectors of M – EOFs C = radiance EOF amplitudes A = {T s, , T, q,...} parameters K and k = regression coefficients  = emissivity EOF amplitudes

NAST-I Spectrum and Retrieval Channels NAST-I Spm RTVL Chnls

Retrieval Accuracy Vs EOF Number Full Noise 1/2 Noise

Observed Vs Calculated from Retrieval

Retrievals for Two Different EOF #s 48 EOFs Radiosonde 23 EOFs

Radiosonde Validation Altitude (km) Relative Humidity (%) Distance (75 km) 3km Andros Is. Bahamas, Sept 12, 1998 NAST Raob

Spectral H 2 O Sensitivity H 2 O Sensitivity [dT B (,p)/dlnq(p)]

Water Vapor Retrieval Sensitivity 75 km LW-side of H 2 O Band SW-side of H 2 O Band

ARM CART-Site Sounding Validation C D A B Space & Time Variability Spatial (~22km) & Temporal (~2-3hr) Temperature Variation Over Purcell Sfc Temp (21Z) Sfc Temp (19Z) P P

PROTEUS NAST-I Flight Over CART Site Loop 1 [18:06 – 19:50 UT, March 19, 2000]

PROTEUS/NAST-I Flight Over CART Site Loop 2 [19:50 – 21:24 UT, March 19, 2000]

VERTICAL PROFILE COMPARISONS NOV 30 DEC 05

COMPARISON WITH GSFC-SRL (DEC. 5, 2000) NAST-I cross section is produced by profiles from 7 high altitude passes over Lamont OK. GSFC-SRL Ground-based Scanning Raman LIDAR produced from 10 min averages at Lamont OK Time Average Loss of Sensitivity

Wallops Island Va. to Dryden Ca. (8/27/99)

Proteus NAST-I Vertical Cross-section (CLAMS 7/12/01) This flight demonstrates the ability to observe the spatial moisture structure below a scattered and semi-transparent Cirrus cloud cover UTC

Effective Surface Temperature (July 26, 2001) GOES image High dense convective clouds over North Carolina and low cumulus clouds over the Delmarva peninsula

Effective Cloud Properties (July 26, 2001)

Vertical Cross-section (July 26, 2001) CLOUDS Clouds IR Window Image Along Track

Surface Skin Temperature (July 14, 2001) º K (  = 0.54º K)  NAST-I retrieved (within  0.1  Lat. and Lon.) º K  NOAA buoy site CHLV2 measured (i.e., the bulk SST). The cool “skin”, observed by NAST-I, relative to the sub-surface water, observed by the buoy, is expected as a result of evaporative cooling.

Surface Emissivity (July 14, 2001) Seawater Emissivity Lab. measured (solid) NAST-I retrieved (dashed) NAST-I validation (dots)

March 20, 2001March 21, 2001 NPOESS Aircraft Sounding Testbed (NAST) soundings over Alaska from the ~15km flight altitude of the Proteus (March 20-21, 2001). Upper panels show flight track and cross-section. (Note the updrafts and downdrafts seen in the water vapor at 7-9 km.) Bottom panels show comparisons with North Slope CART-site radiosondes. IR Image along track Surface Skin Temperature Along Track

Can CAT Be Measured ? Strong Turbulence Signatures at 300 mb Weak Turbulence Signatures at 150 mb No Turbulence Signatures at 500 mb Downdrafts:Warm & Dry Updrafts:Cold & Moist Temp Moisture NAST Near Fairbanks AK (3/21/01; 1-2 GMT) Moisture 200 km

Summary The NAST provides high spatial resolution radiance measurements which can be used to validate the radiometric accuracy and retrieval products of advanced IR sounding systems High spatial resolution features of atmospheric temperature, moisture, and clouds can be retrieved from NAST radiances Lower tropospheric water vapor profiles depend on measurements along the shortwave side of the 6.3  m H 2 O band High spectral/spatial resolution sounders can profile above an opaque overcast cloud cover and above and below thin and/or broken clouds Surface skin temperature and emissivity can be retrieved simultaneously from the spectral radiance measurements and this is important for the retrieval of accurate lower tropospheric moisture profiles Atmospheric turbulence might be observed with very high spatial resolution advanced sounders