In situ observations of water vapor and cirrus IWC in the Pacific TTL during ATTREX Troy Thornberry,...
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![Page 1: In situ observations of water vapor and cirrus IWC in the Pacific TTL during ATTREX Troy Thornberry, Drew Rollins, Ru-Shan Gao, David Fahey Paul Bui, Sarah.](https://reader035.fdocuments.in/reader035/viewer/2022081603/5697c0021a28abf838cc30d9/html5/thumbnails/1.jpg)
In situ observations of water vapor and cirrus IWC in the Pacific TTL during ATTREX
Troy Thornberry, Drew Rollins, Ru-Shan Gao, David FaheyPaul Bui, Sarah Woods
2014 Western Pacific Airborne Campaigns Science Team Meeting Boulder Colorado, October 21, 2014
![Page 2: In situ observations of water vapor and cirrus IWC in the Pacific TTL during ATTREX Troy Thornberry, Drew Rollins, Ru-Shan Gao, David Fahey Paul Bui, Sarah.](https://reader035.fdocuments.in/reader035/viewer/2022081603/5697c0021a28abf838cc30d9/html5/thumbnails/2.jpg)
ATTREX 2 & 3 Flights
Sampling of the TTL over the Pacific with the goal of improving understanding of the dynamical and microphysical processes related to the final dehydration of air entering the stratosphere.
![Page 3: In situ observations of water vapor and cirrus IWC in the Pacific TTL during ATTREX Troy Thornberry, Drew Rollins, Ru-Shan Gao, David Fahey Paul Bui, Sarah.](https://reader035.fdocuments.in/reader035/viewer/2022081603/5697c0021a28abf838cc30d9/html5/thumbnails/3.jpg)
ATTREX 2 & 3 Flights
Extensive in situ sampling of the Pacific TTL with measurements of water vapor andcirrus properties.
However, some sampling limitations…
![Page 4: In situ observations of water vapor and cirrus IWC in the Pacific TTL during ATTREX Troy Thornberry, Drew Rollins, Ru-Shan Gao, David Fahey Paul Bui, Sarah.](https://reader035.fdocuments.in/reader035/viewer/2022081603/5697c0021a28abf838cc30d9/html5/thumbnails/4.jpg)
Latitude and Longitude
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Sampling Histograms
Comparison of 2013 and 2014 from GH sampling perspective
2013: > 74 hours in the TTL2014: > 108 hours in the TTL
Limited sampling in either year at temperatures < 186 K
![Page 6: In situ observations of water vapor and cirrus IWC in the Pacific TTL during ATTREX Troy Thornberry, Drew Rollins, Ru-Shan Gao, David Fahey Paul Bui, Sarah.](https://reader035.fdocuments.in/reader035/viewer/2022081603/5697c0021a28abf838cc30d9/html5/thumbnails/6.jpg)
TTL temperature profiles
Higher CP tropopause observed in 2013
More consistent T structure above the CPT in 2013
Similar lower T values in both years determined by GH sampling limits
![Page 7: In situ observations of water vapor and cirrus IWC in the Pacific TTL during ATTREX Troy Thornberry, Drew Rollins, Ru-Shan Gao, David Fahey Paul Bui, Sarah.](https://reader035.fdocuments.in/reader035/viewer/2022081603/5697c0021a28abf838cc30d9/html5/thumbnails/7.jpg)
Combined Temperature profile
Combined profile looks reasonable
During both 2013 and 2014 a number of warm profiles were measured
![Page 8: In situ observations of water vapor and cirrus IWC in the Pacific TTL during ATTREX Troy Thornberry, Drew Rollins, Ru-Shan Gao, David Fahey Paul Bui, Sarah.](https://reader035.fdocuments.in/reader035/viewer/2022081603/5697c0021a28abf838cc30d9/html5/thumbnails/8.jpg)
Temperature vs Theta profile
Coldest temperatures sampled between 365 and 380 K potential temperature
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Water vapor profiles
2013
2014Typical WV values above CP lower by ~ 05 ppm in 2013 than 2014
Consistent with zonal mean value difference
![Page 10: In situ observations of water vapor and cirrus IWC in the Pacific TTL during ATTREX Troy Thornberry, Drew Rollins, Ru-Shan Gao, David Fahey Paul Bui, Sarah.](https://reader035.fdocuments.in/reader035/viewer/2022081603/5697c0021a28abf838cc30d9/html5/thumbnails/10.jpg)
Combined WV profile
Apparent discontinuity above 410K due to difference in profile top between ATTREX-2 and ATTREX-3
![Page 11: In situ observations of water vapor and cirrus IWC in the Pacific TTL during ATTREX Troy Thornberry, Drew Rollins, Ru-Shan Gao, David Fahey Paul Bui, Sarah.](https://reader035.fdocuments.in/reader035/viewer/2022081603/5697c0021a28abf838cc30d9/html5/thumbnails/11.jpg)
In-cloud vs Clear-sky
![Page 12: In situ observations of water vapor and cirrus IWC in the Pacific TTL during ATTREX Troy Thornberry, Drew Rollins, Ru-Shan Gao, David Fahey Paul Bui, Sarah.](https://reader035.fdocuments.in/reader035/viewer/2022081603/5697c0021a28abf838cc30d9/html5/thumbnails/12.jpg)
ATTREX cloud fraction
Define cloud using FCDP and NW IWC measures
Sampled cloud fractions similar to satellite climatology
Particularly high cloud fraction observed at lowest sampled temperatures
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Clear-sky RHice profile
Broad range of RHice observed in clear air from very dry to supersaturated
Frequent dry values observed near 360K
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In-cloud RHice profile
Distribution of RHice within cirrus centered near 100% throughout profile
Values range from ~50% to above homogeneous freezing threshold
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Clear-sky RHice vs T
Koop et al. (Nature 2000)Homogeneous freezing threshold
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In-cloud RH vs T
![Page 17: In situ observations of water vapor and cirrus IWC in the Pacific TTL during ATTREX Troy Thornberry, Drew Rollins, Ru-Shan Gao, David Fahey Paul Bui, Sarah.](https://reader035.fdocuments.in/reader035/viewer/2022081603/5697c0021a28abf838cc30d9/html5/thumbnails/17.jpg)
IWC vs T
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STW vs Temperature
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Summary
• GH observations of temperature and water vapor profiles are consistent with the zonal mean differences between 2013 and 2014
• Sampled cloud fractions higher than satellite climatology• RHice below homogeneous freezing threshold in clear air
• Distribution of RHice in cirrus peaks near 100% but has a broad range and potentially some very high values
• Significant cirrus IWC measurements along with cirrus properties measurements
• Distribution of TW (vapor + IWC) includes a number of values significantly exceeding homogeneous freezing threshold
![Page 20: In situ observations of water vapor and cirrus IWC in the Pacific TTL during ATTREX Troy Thornberry, Drew Rollins, Ru-Shan Gao, David Fahey Paul Bui, Sarah.](https://reader035.fdocuments.in/reader035/viewer/2022081603/5697c0021a28abf838cc30d9/html5/thumbnails/20.jpg)
Directions
• NW and FCDP/Hawkeye IWC closure
• Investigation of in situ cirrus nucleation mechanisms
• Dehydration efficiency…
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Non-water containing particles in the LS?
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END
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WV profile
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IWC/TW ratio vs T
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Hawkeye FCDP vs FCDP