430 likes | 447 Views
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. Hypothesis and method.
E N D
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
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
The volumes of interest … … in the vertical
The volumes of interest … … in the horizontal Jensen et al., 2001
Where the cirrus are—SAGE Wang et al., 1996
Where the cirrus are—LITE Winker and Trepte, 1998
How tropical cirrus form • wave motions • from convective influences (anvils, pileus) • large-scale, slow uplifting
How clouds affect water vapor in the UT/LS Rosenfield et al. (1998)
? 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
Tropical biomass burning—Africa Image taken by Bob Yokelson during SAFARI campaign, southern Africa in 2000
Tropical biomass burning—South America MODIS image from 22 July 2003, showing fires surrounding Xingu National Park (and indigenous peoples reserve), Brazil
What are some properties of biomass-burning plumes? Kojima et al., 2004
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
biomass burning emissions? The “knowns:” • 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
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: http://mocha.meteor.wisc.edu/
… 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
… the UWNMS and idealized IN … • Control run: pristine crystals initialized at 1 μm (6.4 x 10-12 grams for hexagonal plate) • Perturbed run: crystals initialized at 0.45 μm (9.1 x 10-13 grams)
Pristine crystal concentration at 13.5 km 24 hours into run Control run Perturbed run
Pristine crystal concentration at 13.5 km 30 hours into run Control run Perturbed run
Pristine crystal concentration at 13.5 km 36 hours into run Control run Perturbed run
Pristine crystal concentration at 13.5 km 42 hours into run Control run Perturbed run
Pristine crystal concentration at 13.5 km 48 hours into run Control run Perturbed run
Pristine crystal concentration at 14.5 km24 hours into run Control run Perturbed run
Pristine crystal concentration at 14.5 km30 hours into run Control run Perturbed run
Pristine crystal concentration at 14.5 km36 hours into run Control run Perturbed run
Pristine crystal concentration at 14.5 km42 hours into run Control run Perturbed run
Pristine crystal concentration at 14.5 km48 hours into run Control run Perturbed run
Pristine crystal concentration at 15.5 km24 hours into run Control run Perturbed run
Pristine crystal concentration at 15.5 km30 hours into run Control run Perturbed run
Pristine crystal concentration at 15.5 km36 hours into run Control run Perturbed run
Pristine crystal concentration at 15.5 km42 hours into run Control run Perturbed run
Pristine crystal concentration at 15.5 km48 hours into run Control run Perturbed run
The difference in water vapor between control and perturbed runs
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
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?