AIRS and IASI Consistency Assessment for Future JPSS/ CrIS

1. AIRS and IASI Consistency Assessment for Future JPSS/CrIS Likun Wang Mitch Goldberg, XiangqianWu, ChangyongCao, Robert A. Iacovazzi Jr., FangfangYu, Yapping Li

2. Outlines • Background • Methodology • Results • Conclusion 2010 CalPOP Meeting

3. Motivation Decades of hyperspectral measurements for long-term CDRs • Question1: Do we understand the radiometric differences among them, especially between AIRS and IASI? • Question 2:How do these differences changes with different climate regions and time? CLARREO CrIS on NPP and JPSS IASI on METOP: 8461 AIRS on NASA AQUA: 2378 channels 2002 2006 2011(?) 2017(?) 2007 AMS Meeting, San Antonio

4. Inter-Comparison Method • SNO versus Double Differences • Simultaneous Nadir Overpass • Direct comparison at the Polar Regions • Double Differences • Using a transfer target • e.g., Radiometer, SST, Radiative calculations • Differences of AIRS and IASI relative to a transfer target • Spectral versus Integration Method • Spectral method: the finest spectral scale • Integration method: relatively large wavelength intervals 2010 CalPOP Meeting

5. Double Difference versus SNOs SNOs Polar Regions In the Tropics 1) Indirect vs. Direct comparison 2) Tropics vs. Polar Regions Four channels 2010 CalPOP Meeting

6. GEOS Decontamination GEOS Decontamination Double difference Method (Wang et al. 2010, JAMC) The bias between AIRS and GOES is relative But IASI agrees with AIRS results, therefore the bias is likely in GOES! Double difference can assess the consistency between IASI and AIRS. 2009 EUMETSAT Conference

7. SNO Method Step 2: Averaging AIRS and IASI Spectra AIRS Step 1: Pairing the SNO pixels between AIRS and IASI based on collocation criteria IASI Step 3: Convolved with GOES imager SRFs Wang et al. manuscript for GRL

8. Scene temperature: Double differences versus SNOs Double Differences IASI-GOES AIRS-GOES SNOs North South 2010 CalPOP Meeting

9. Water vapor channel (6.7µm)(IASI-AIRS BT Difference) SNO method has relatively large uncertainties. SNO method Green line is zero line Double differences GOES patch temperature change The stability of transfer target is important for double differences 2010 CalPOP Meeting

10. Window channel I (10.7µm) Green line is zero line 2010 CalPOP Meeting

11. Window channel II (12.0 µm) 2010 CalPOP Meeting

12. Sounding channel (13.3 µm) GOES decontamination 2010 CalPOP Meeting

13. Final results 2010 CalPOP Meeting

14. Mean Spectral Residuals Tobin’s SNO Results(AIRS-IASI BT difference) North SNOs AIRS - IASI (K) wavenumber (cm-1) South SNOs AIRS - IASI (K) wavenumber (cm-1)

15. Summary • Focusing on different climate regions, the double difference and SNO methods allow assessing the IASI-AIRS radiance differences globally. • Both methods reveal the good agreement between AIRS and IASI either in the Tropics or in the Polar regions, while their differences are less than 0.1 K and AIRS is slightly warmer than IASI. • Future study will include the CrIS/NPP to link AIRS, IASI, and CrIS. 2010 CalPOP Meeting