The sensitivity of cloud dynamics andboundary layer structure to 3-D

radiative heating effects*

I3RC WorkshopWorkshop

William O’Hirok

University of California, Santa Barbara

*a radiative narrative

Water vapor

0

Z

Surf ↓ 3D > ICATOA ↑ 3D < ICAABS 3D > ICA

SZA = 0

3D ICA(horizontal transport)

Water vapor

0

Z

Surf ↓ 3D < ICATOA ↑ 3D > ICAABS 3D > ICA

SZA = 45

3D ICA

ICA3D

SZA = 60°

0 0.1 0.2K/hour

12

km

0

Shortwave heating rate profile0 km 100

12

km

0

MMCR derived cloud field

3D shortwave radiative effectstend to cancel on the scale ofGCMs

ICA

3D

3D-ICA

MMCR

Shortwave heating rate (K/hour)

0 km 100

12

km

0

model resolution (km)

Heating Rate (3D –ICA)

+ 20 %

60 %

- 20 %

0°

60°

Is 3D radiation relevant to climate modeling?(superparameterization)

All 3D shortwave radiation studies have been static

What is the impact on cloud structure and the resultingradiative field?

3DRT CloudResolving Model (WRF-3DRT)

Weather and Forecasting Model

(WRF)

RRTM_SW16 Band

k-distribution

Monte Carlo5 % column accuracy

moisture, temperature,

pressure, and aerosol fields

Toa upwelling, surface downwelling

irradiances, atmospheric heating rates

WRF 3DRT

non-hydrostatic 2D – 400/512 columns x 80 layers 250 m layer and column resolution

240 minute simulation 3 second time step

5 minute radiation time step shortwave - 3D*

longwave -1D RRTM microphysics - water, ice, graupel, snow, rain (Lin et

al.) surface layer physics - Monin-Obukov

turbulence – TKE scheme*ocean/soil surface layers - thermal diffusion

open/periodic boundaries initial temperature perturbation

* modified for air-surface exchange

MONTECARLO

TAUOPT. PROP

COLUMNSTORAGE

band loop

READ ATM,CLOUD, AER

PROFILES&COMPUTE

COLUMN OPTICS.

DISORT

RRTM

ICA out* 3D out

cloud field

RRTM MCWRAPPER

column loop

ERRORyes*For experiments ICAperformed by Monte Carlo

Case 2 Case 3 Case 4

F↑ F↓

MC – DISORT MC – DISORT MC – DISORT

Wm-2 Wm-2 Wm-2

Laye

r #La

yer #

Two not so well thought out experiments comparing generated cloud fields using *3D and ICA radiation schemes

A. Deep convection over water - periodic boundary conditions fordynamics and radiation.

B Deep convection over land - open x boundary for dynamics, periodicboundary for radiation.

*3D radiation on 2D field

periodic boundary 35 min

periodic boundary 55 min

periodic boundary 110 min

periodic boundary 195 min

periodic boundary 220 min

.25 .40

15

0

0 - 80 min 0 - 240 min3DICA

3DICA

domain average condensate(liquid, ice, snow, graupel,rain)

cloud fraction (liquid, ice)

heig

ht (k

m)

15

0

heig

ht (k

m)

.0 .0

Periodic boundary

g kg-1 fraction

Albedo (3D/ICA)

Transmission (3D/ICA)

Atm. Heating (3D/ICA)

Time 13:00 17:00 13:00 17:00

Domain Average

0.8

1.2

0.4

1.6

0.4

1.6

1.01.0 1.0

13:00 17:00

accumulated precipitation

latent Heat

atmospheric absorption

vertical wind variance

2.0

0.0

5.0

0.01.0

0.0

2.0

1.0

1.0

1.2

0.0

0.8

Domain average ratios (3D/ICA)

simulation time (m) 0 24060 120

ICA ICA

3D 3D

13:402.4

2.0

0.0

0.8

0.4

1.6

1.2

0.2

0.1

2.4

2.0

0.0

0.8

0.4

1.6

1.2

0.2

0.1

8.0

2.0

0.5

4.0

1.0

0.

8.0

2.0

0.5

4.0

1.0

0.

cloud condensate (g/kg) SW heating rate (K/hour)

return time window for water vapor

simulation time (m) 0 24060

20

0120

heig

ht (k

m) qv(t) - qv(0) at 0 km

0 km 100 0 km 100

cloud condensate cloud condensate

SW heating rate SW heating rate

vertical velocity vertical velocity

2.4 K/hour1.2 K/hour

-20 m/s

+20 m/s

+11 m/s

-19 m/s

6 g/kg4.1 g/kg

ICA 3D14:40

open boundary 120 min

open boundary 240 min

domain average accumulated precipitation

simulation time (m) 0 24060 120 0 128

12050

6025

0 0

km

mm

mm

open boundary

0 - 240 min3DICANR

1.0 .80

15

0

0 - 240 min3DICA

domain average condensate(liquid, ice, snow, graupel,rain)

cloud fraction (liquid, ice)

heig

ht (k

m)

15

0

heig

ht (k

m)

.0 .0

open boundary

g kg-1 fraction

NR

0 - 240 min3DICANR

0 - 240 min3DICANR

domain average precipitation

50

0250 500 1000 2000 4000

model resolution (m)

5 2 RT min timestep – little difference

open boundary

mm

2d underestimates 3D radiative effects

2d overestimates turbulence

Periodic boundary conditions may enhance modeled chaotic process

Open boundary conditions lose energy

What to do?

x

y

compute-0-1

RRTMMCWRAP

compute-0-2

RRTMMCWRAP

compute-0-3

RRTMMCWRAP

compute-0-4

RRTMMCWRAP

compute-0-5

RRTMMCWRAP

compute-0-…

RRTMMCWRAP

MC

compute-0-1

RRTMMCWRAP

compute-0-2

RRTMMCWRAP

compute-0-3

RRTMMCWRAP

compute-0-4

RRTMMCWRAP

compute-0-5

RRTMMCWRAP

compute-0-…

RRTMMCWRAP

WRF in

WRFHeating rates

multiband optical properties

column group atmospheric properties

all column single band optical properties

all column single band fluxes

Multi-spatial/spectral cluster computing (ROCKS based, psuedo MPI)

Spatial integrator

Errorcheck

Spectralintegrator

photon count message

LITERAL MELT DOWN

Hence, a two field(!) conclusion 3D radiation …