1. Monica Harkey, UW-Madison Matthew Hitchman, Marcus Buker
An Evaluation of the UWNMS Treatment of Water Vapor Transport and Cirrus Formation in the UT/LS
Monica Harkey, UW-Madison
Matthew Hitchman, Marcus Buker

2. Hypothesis and method
Changes in tropical cirrus microphysics caused by emissions from biomass burning may (partly) explain moistening of the lower stratosphere
UWNMS model runs with control and perturbed ice microphysics will show first-order effects on the distribution of water vapor in the UT/LS

3. The volumes of interest …
… in the vertical
The tropical tropopause environment is high and cold, it’s affected by convection and often contains extensive cirrus layers. The TTL exists between about 14 and 18 km.

4. The volumes of interest …
… in the horizontal
Microwave limb sounder data showing seasonal means of RH with respect to ice at ~150 hPa
Two regions which show seasonal variation in water vapor in the TTL are shown here (boxed). The study I’ll describe here has a focus over northern South America.
Jensen et al., 2001

5. Where the cirrus are—SAGE
Not only do the regions of interest (boxes) have seasonal variation in water vapor, but a corresponding seasonal variation of cirrus, as viewed by SAGE (less in JJA when ITCZ moves north of regions)
Wang et al., 1996

6. Where the cirrus are—LITE
Explain what LITE is
… just showing the extent of cirrus in the tropical tropopause environment/TTL. Cirrus occur frequently and can extend 2700 km horizontally.
Winker and Trepte, 1998

7. How tropical cirrus form
wave motions
from convective influences (anvils, pileus)
large-scale, slow uplifting
Here bring up Jensen, Brewer, Holton and Potter, etc.

8. How clouds affect water vapor in the UT/LS
Jensen, Sherwood, Rosenlof bring up their contributions
Rosenfield et al. (1998)

9. The “knowns:” ?
Water vapor in the lower stratosphere is increasing (Rosenlof et al., 2001)
Cirrus near the tropopause affect water vapor transport into the lower stratosphere
Cirrus occur near tropical tropopause frequently
Bring up Sherwood again for transition to idea to biomass burning output affecting cirrus

10. Tropical biomass burning—Africa
Image taken by Bob Yokelson during SAFARI campaign, southern Africa in 2000

11. Tropical biomass burning—South America
MODIS image from 22 July 2003,
showing fires surrounding Xingu National Park (and indigenous peoples reserve),
Brazil

12. Where biomass burning products were measured:
TRACE A August and September 1992
PEM Tropics A August through October 1996
PEM Tropics B February through April 1999
pink shows flights which sampled that stuff at altitudes of 10 km or higher (up to 12)
Biomass burning stuff =

13. How do we know biomass burning was really the source?
TRACE-A flight #6 took place on 27 Sept (point to study volume)
Fire counts, satellite image shows cold front and storms popping up in front of it.
My thought is that buoyant plumes + frontal lifting + convective lifting = combustion materials have a good chance of being lofted up to affect clouds.

14. Where did the material go?

15. What are some properties of biomass-burning plumes?
PEM Tropics B flight number 5 measured enhanced levels of biomass burning “stuff” above 10 km, also aerosol size, en route to Hawaii from California.
Size of aerosol during portions of flight where enhanced biomass burning stuff detected is plotted here—peak around 0.45 microns.

16. What are some properties of biomass-burning plumes?
Noted that many of the organics contained potassium, so was probably from biomass burning sources
Kojima et al., 2004

17. How can combustion materials affect ice clouds?
Kojima et al. (2004) found organics abundant in upper troposphere, many sulfate aerosols embedded with organics
Measurement techniques can destroy molecules (Cziczo et al., 2004)
Cziczo et al. also noted organics appear to be inefficient IN
Kojima et al. (2004) found organics abundant in upper troposphere, many sulfate aerosols embedded with organics
Define organics:
Cziczo et al wouldn’t go so far as to say that organics act to suppress ice nucleation (too much uncertainty with speciation) but it appears they need higher humidities/sat. vapor pressure to nucleate

18. The “knowns:”
biomass burning emissions?
Water vapor in the lower stratosphere seems to be increasing
Cirrus near the tropopause affect water vapor transport into the lower stratosphere
Cirrus occur near tropical tropopause frequently

19. the UWNMS …
Arbitrary resolution—used 400 m in the vertical, 30 km in the horizontal
Non-hydrostatic model especially needed in region of study
For more information on this model,
written by Prof.Greg Tripoli, visit:

20. … the UWNMS …
ECMWF 12-hour, 2.5 x 2.5 degree winds, temperature, and moisture up to 200 hPa
HALOE latitude-binned and pressure-averaged water vapor at and above 200 hPa
Explicit microphysics predict concentration of pristine crystals, aggregates
convective parameterization using Kuo scheme

21. … the UWNMS and idealized IN …
Control run:
pristine crystals initialized at 1 μm (6.4 x grams for hexagonal plate)
Perturbed run:
crystals initialized at 0.45 μm (9.1 x grams)
Explain what we expect to see

22. Pristine crystal concentration at 13.5 km 24 hours into run
Control run
Perturbed run

23. Pristine crystal concentration at 13.5 km 30 hours into run
Control run
Perturbed run

24. Pristine crystal concentration at 13.5 km 36 hours into run
Control run
Perturbed run

25. Pristine crystal concentration at 13.5 km 42 hours into run
Control run
Perturbed run

26. Pristine crystal concentration at 13.5 km 48 hours into run
Control run
Perturbed run

27. Pristine crystal concentration at 14.5 km 24 hours into run
Control run
Perturbed run

28. Pristine crystal concentration at 14.5 km 30 hours into run
Control run
Perturbed run

29. Pristine crystal concentration at 14.5 km 36 hours into run
Control run
Perturbed run

30. Pristine crystal concentration at 14.5 km 42 hours into run
Control run
Perturbed run

31. Pristine crystal concentration at 14.5 km 48 hours into run
Control run
Perturbed run

32. Pristine crystal concentration at 15.5 km 24 hours into run
Control run
Perturbed run

33. Pristine crystal concentration at 15.5 km 30 hours into run
Control run
Perturbed run

34. Pristine crystal concentration at 15.5 km 36 hours into run
Control run
Perturbed run

35. Pristine crystal concentration at 15.5 km 42 hours into run
Control run
Perturbed run

36. Pristine crystal concentration at 15.5 km 48 hours into run
Control run
Perturbed run

37. What does this mean, in bulk?
White—isosurface of 0.1 mixing ratio of pristine crystals in control run, blue—same value, but for perturbed run. Note “cloud” extent is larger in perturbed run than in control run, as expected

38. Water vapor difference at 13.5 km

39. Water vapor difference at 14.5 km

40. Water vapor difference at 15.5 km

41. The difference in water vapor between control and perturbed runs

42. Summary
As expected,
crystal mixing ratios higher in perturbed run, with smaller (0.45 micron) initial size
“cloud” extent between control, perturbed runs varies
ice initialized with a smaller crystal size results in an increase of water vapor mixing ratio within and above clouds
Therefore UWNMS seems suitable for studying these volumes

43. Direction for the future
Fashion idealized “gunk”—biomass burning derived IN—to be activated at a specific T, q and interact with water vapor in the UWNMS
Conduct sensitivity studies with varying concentrations—how do cloud properties, water vapor distribution change?