Estimating Vertical Motion Profile Shape within Tropical

Weather States

Zachary Handlos and Larissa Back

University of Wisconsin – MadisonDepartment of Atmospheric and Oceanic

Sciences

Convection/Large Scale Circulation Vertical Structure

http://rsd.gsfc.nasa.gov/rsd/images/goes8_lg.jpg

http://www.physicalgeography.net/fundamentals/images/thunderstorm.jpg

http://cdn.physorg.com/newman/gfx/news/hires/2009/6-tropicalstor.jpg

Hypothesis

Vertical motion profile shape varies (in space and time) in association with weather states.

We explore this hypothesis by estimating vertical motion profile shape using observed precipitation and surface convergence data.

CTP-TAU Histogram Rossow et al (2005)

Adapted from Rossow et al (2005)

Weather States

Stratiform Rain Fraction and Vertical Motion Profiles

Houze (2004)

Vertical Motion (Heating) Profiles in West, East Pacific

Western Pacific

53.56%

East-Central Pacific

58.73%

Percent Stratiform Rain Fraction:

Surface Convergence, Precipitation and ω Profiles

Where to go from here:

Going to construct Vertical Motion Profiles Use relationship between precipitation, surface

convergence, basis functions

Basis Functions

PCA: vertical motion data

http://www.med.govt.nz/upload/2778/angel-investment-9.gif

Estimating ω Profiles

ω ( x,y,t,p )=o1

( x,y,t )Ω1

( p )+o2

(x,y,t )Ω2

( p )

Solve for vertical motion:

Solve for amplitudes o1, o

2:

Basis Functions Ω

1, Ω

2

LP=M s1 o1 (x,y,t )+M s2 o2 ( x,y,t )− ΔF rad

Ms1

, Ms2

= adiabatic cooling per unit amplitude (balanced by latent heating)

−∇⃗⋅u⃗ =o 1 ( x,y,t ) c1+o 2 ( x,y,t )c 2

c1, c

2 surface convergence of each basis function

Input observational data

Dry Static Energy Budget:

Mass Continuity:

Weather State ω-profiles

Weather State ω-profiles

Conclusions

Stratiform rain fraction does not explain geographic variability in vertical motion “bottom-heaviness”

Vertical motion profile “bottom-heaviness” associated with precipitation, surface convergence variability

ISCCP weather states associated with unique profile shapes