Water Vapor during ICARTT 2004: Comparison of AATS-14, J31 in situ, Ron Brown sonde measurements

1. Water Vapor during ICARTT 2004: Comparison of AATS-14, J31 in situ, Ron Brown sonde measurements NASA Ames Airborne Sunphotometer Team SSFR Team Presented by John Livingston SRI International/NASA Ames J31 Data Workshop 9-10Mar05

2. JETSTREAM-31 during ICARTT 2004 Vaisala HMP243 AATS-14 SSFR

3. Calculation of columnar water vapor from AATS-14 For the AATS-14 channel centered at 940.6 nm, V Vo exp [-mother] TH2O. LBLRTM V9.2 was used to calculate water vapor transmittance, TH2O, as a function of water vapor slant path, U, by varying the solar zenith angle. Calculations were performed for a variety of model atmospheres and a range of aircraft altitudes. The water vapor transmittance was modeled as TH2O = c exp [-a U b] , where U is the slant path water vapor in [atm-cm].

6. Calculation of water vapor density from AATS-14 • The columnar water vapor derived from AATS-14 measurements obtained during aircraft vertical profiles is smoothed with a spline fit and then differentiated to yield a corresponding profile of water vapor density. • This profile can be compared with coincident in-situ or remote measurements.

8. Calculation of relative humidity by the Vaisala HMP243 • HMP243 consists of a heated composite humidity sensor head and an optional sensor head to measure ambient temperature • Both probes mounted on the J31 during the ICARTT study • Primary output is dewpoint, which is calculated within HMP243 from humidity and temperature readings of composite sensor • Separate temp probe permits calculation of ambient relative humidity • HMP243 outputs of ambient temperature, Ttotal, and relative humidity, RHVaisala, were recorded by SSFR data system • Because the separate temperature probe is subject to dynamic heating effects, both Ttotal and RHVaisala must be corrected to account for these effects

9. Calculation of water vapor density from J31 in-situ measurements • Measured quantities: Pwing, Pnose, TVaisala probe2, RHVaisala

11. Table of AATS-14 H2O profiles and Ron Brown radiosonde measurements

12. 16 Jul F9

15. 22.2 km Mean separation: 26.0 km

16. 29 Jul F16

18. Mean separation: 7.2 km

19. Mean separation: 7.2 km

20. 15 Jul F8

22. Mean separation: 4.0 km

23. Mean separation: 4.0 km

24. 31 Jul F18

26. Mean separation: 14.9 km

27. Mean separation: 14.9 km

28. 7 Aug F23

29. Mean separation: 42.9 km

30. Mean separation: 42.9 km

31. Mean separation: 39.9 km

32. 22 Jul F13 • DC-8 coordination

33. Mean separation: 3.6 km

34. 3 Aug F21

35. Mean separation: 15.9 km