1. Water in the Pacific TTL during ATTREX 2013 Troy Thornberry 1,2, Drew Rollins 1,2, Ru-Shan Gao 1, David Fahey 1,2 1 NOAA ESRL CSD and 2 CIRES, University of Colorado MMS, FCDP, and CPL teams ATTREX Science Team Meeting 24 October 2013

2. Average flight: 7790 nm 14300 km 24.4 hrs ATTREX Flights

3. TTL Profiles ±15° Latitude

4. Temperature and WV Structure of the TTL  CP Tropopause altitudes between 17 and 18 km on individual profiles  H 2 O MR < 5 ppm above 16.5 km and as low as 1.5 ppm

5. Saturation Potential Temperature  Saturated mixing ratios not observed above ~380 K potential temperature surface  Altitude of the 380 K surface typically ~17.5 km (87 hPa)  Cirrus clouds observed with both large supersaturations and subsaturations, although mean values close to 100%

6. RH i and Clouds

7. RH ice climatology From Krämer et al., ACP, 2009 Data from FISH + FLASH/OJSTER, 9 missions, 1999-2006

8. Where does the ATTREX data fall? From Krämer et al., ACP, 2009 Data from FISH + FLASH/OJSTER, 9 missions, 1999-2006 Within the envelope of previous measurements Temperatures reached not as cold as FISH has seen

9. ATTREX RF05 26-27 February

10. Cloud Physics Lidar Longitude

11. High water content cloud 7 – 15°N 26-27 February 2013 FCDP Data, SPEC Inc., P. Lawson PI

12. Contrasting cirrus clouds 7 – 15°N 26-27 February 2013

13. Dehydration by sedimentation The larger diameter particles will fall much faster, leading to faster downward transport of water Both types of cloud particles fall much faster than typical ascent rates so should provide dehydration - Effect of observed supersaturations?

14. Can we use trajectories to inform the data? In situ data provides a snapshot in time Tracer species can provide information on air parcel history Possible to get direct dynamic information? Trajectories from Tao Wang, Texas A&M ERA interim reanalysis isentropic coordinate model with diabatic heating vertical transport

15. Can we use trajectories to inform the data?  Add calculated saturation H 2 O MR to look at potential dehydration history

16. Summary  Dehydration was likely occurring just below 380 K (~ 17.5 km) in the central and eastern Pacific boreal winter  TTL cirrus clouds varied significantly in ice crystal number and size and in supersaturation, yielding a wide range of dehydration potentials  ATTREX RH ice observations fit within the envelope from previous studies (Krämer et al, 2009)  Trajectories provide a possibility to investigate the air parcel history and provide context to the snapshot of in situ measurements  Tantalizing, but fraught…