1. TAbMEP Assessment: POLARCAT H 2 O Measurements

2. Assessment Summary Table 1. Recommended POLARCAT H 2 O measurement treatment AircraftInstrument Reported 2σ Uncertainty Recommended Bias Correction Recommended 2σ Uncertainty NASA DC-8DLH5%-0.0562 - 0.00082 H 2 O DC8 {(-0.0562 - 0.00082 H 2 O) 2 + (.07) 2 } 1/2 NOAA WP-3DAOC5%- 0.0491 - 0.0950 H 2 O WP3D {(- 0.0491 - 0.0950 H 2 O) 2 + (0.308) 2 } 1/2 NASA P-3B 10%- 0.0903 + 0.0275 H 2 O P3B {(- 0.0903 + 0.0275 H 2 O) 2 + (.834) 2 } 1/2 DLR FALCON 10%- 0.0724 + 0.0673 H 2 O DLR {(- 0.0724 + 0.0673 H 2 O) 2 + (0.166) 2 } 1/2 ATR-42 FALCON 10%0.275 - 0.0130 H 2 O ATR42 10% a a The PI reported uncertainty was recommended because no IEIP precision value could be calculated for the ATR-42 Falcon data

3. Assessment Summary Cont. Intercomparison Data Within the Recommended Uncertainty DC-8 vs. WP-3D45% DC-8 vs. P-3D62% DC-8 vs. DLR94% DLR vs. ATR-4276% Only the DC-8 vs. DLR Falcon intercomparison meets the condition that 90% of data fall within the 2σ uncertainty bounds, making it a TAbMEP unified data set Remaining intercomparisons contain systematic error that cannot be fully accounted for in uncertainty calculations, causing the recommended uncertainties to be insufficient for TAbMEP unified data set requirements Table 2. TAbMEP unified data sets

4. Assessment Summary Cont. Table 3. POLARCAT H 2 O bias estimates AircraftInstrument Apparent Bias (a g/kg + b H 2 O) Best Estimate Bias (a g/kg + b H 2 O) NASA DC-8DLH0-0.0562 - 0.00082 H 2 O DC8 NOAA WP-3DAOC0.00649 - 0.0861 H 2 O DC8 - 0.0491 - 0.0950 H 2 O WP3D NASA P-3B - 0.0351+ 0.0291 H 2 O DC8 - 0.0903 + 0.0275 H 2 O P3B DLR FALCON - 0.0174 + 0.0731 H 2 O DC8 - 0.0724 + 0.0673 H 2 O DLR ATR-42 FALCON 0.327 - 0.0118 H 2 O DC8 0.275 - 0.0130 H 2 O ATR42

5. Assessment Summary Cont. FlightPlatform IEIP Precision Expected VariabilityObserved Variability Adjusted Precision 4/12 DC-82.2% 15.6% 2.2% WP-3D 15.4% 4/8 DC-81.5% 12.5% 1.5% P-3B 12.4% 4/19 DC-83.5% 41.8% 3.5% P-3B 41.7% 7/10 DC-82.5% 7.85% 2.5% P-3B 7.4% 7/9 DC-82.5% 8.66% 2.5% DLR Falcon 8.3% 4/15 P-3B 9.63% WP-3D 7/14 DLR Falcon 20.5% ATR-42 Falcon Table 4. POLARCAT H 2 O precision (1σ) comparisons

6. P-3B vs. DC-8

7. P-3B vs. DC-8 04/08/2008

8. DC-8 04/08/2008 IEIP = 1.5%

9. DC-8 04/08/2008 STD = 0.0022 g/kg

10. P-3B vs. DC-8 04/08/2008

13. P-3B vs. DC-8 04/19/2008

14. DC-8 04/19/2008 IEIP = 3.5%

15. DC-8 04/19/2008 STD = 0.0045 g/kg

16. P-3B vs. DC-8 04/19/2008

19. P-3B vs. DC-8 07/10/2008

21. DC-8 07/10/2008 IEIP = 2.5%

22. DC-8 07/10/2008 STD = 0.0050 g/kg

23. P-3B vs. DC-8 07/10/2008

26. P-3B vs. DC-8 All Flights

29. WP-3D vs. DC-8 04/12/2008

31. DC-8 04/12/2008 IEIP = 2.2%

32. DC-8 04/12/2008 STD = 0.0030 g/kg

33. WP-3D vs. DC-8 04/12/2008

36. P-3B vs. WP-3D 04/15/2008

41. DLR Falcon vs. DC-8 07/09/2008

43. DC-8 07/09/2008 IEIP = 2.5%

44. DC-8 07/09/2008 STD = 0.0050 g/kg

45. DLR Falcon vs. DC-8 07/09/2008

48. DLR Falcon vs. ATR-42 Falcon 07/14/2008