Comparisons between AIRS tropospheric water vapor and a trajectory - - PowerPoint PPT Presentation

Comparisons between AIRS tropospheric water vapor and a trajectory model

• A. E. Dessler

Department of Atmospheric Sciences

Texas A&M University

Water Vapor

• Abundance determined by mix of

– large-scale transport, – small-scale processes occurring around convection, – microphysical processes

Lots of water 100% RH Passively advected

What is a trajectory calculation?

✖

What is a trajectory calculation?

✖

What is a trajectory calculation?

✖ History of parcel’s lat, lon, T, p for the past 30 days

15 10 5 water vapor (ppmv) x 10^3 55 50 45 40 35 30 Day 325 320 315 310 Pot'l Temp (K) 55 50 45 40 35 30 Day

Parcel 2010 on 3/1/03: final location 24.5°S, 149.5°W

Lots of water 100% RH Passively advected

Lots of water 100% RH

• 1. Set RH = 100% whenever

“convection” is encountered

• 2. Water vapor is passively advected
• 3. Except when RH > 100%, in which

case condensation occurs Passively advected

Lots of water 100% RH Previous work: Sherwood, Pierrehumbert, Salathe, Dessler, Folkins, Minschwaner Passively advected

15 10 5 water vapor (ppmv) x 10^3 55 50 45 40 35 30 Day 325 320 315 310 Pot'l Temp (K) 55 50 45 40 35 30 Day

1863 ppmv

Parcel 2010 on 3/1/03: final location 24.5°S, 149.5°W

• Model “convection” comes from average

rising motion in NCEP reanalysis

• Model “microphysics” is simplest possible:

hard RH limit of 100%

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10 20 360 270 180 90

X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X Regular grid of parcels on a pressure surface, 1°x1° resolution Compare annual average with annual avg. V4 L3 AIRS

AIRS data: 3/1/2003 @ 600-500 hPa

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10 20 30 360 270 180 90 12 10 8 6 4 2 x10

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ppmv, thousands

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10 20 30 360 270 180 90 12 10 8 6 4 2 x10

3

Black contour = 4000 ppmv

AIRS data: 3/1/2003 @ 600-500 hPa Traj model: 547 hPa

223 hPa 346 hPa 547 hPa

Average: 3/1/03-2/28/04

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10 20 30 360 270 180 90 10000 8000 6000 4000 2000

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10 20 30 360 270 180 90 2000 1500 1000 500

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10 20 30 360 270 180 90 250 200 150 100 50

250-200 hPa 400-300 hPa 600-500 hPa

Average: 3/1/03-2/28/04

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10 20 30 360 270 180 90 10000 8000 6000 4000 2000

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10 20 30 360 270 180 90 2000 1500 1000 500

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10 20 30 360 270 180 90 250 200 150 100 50

250-200 hPa 400-300 hPa 600-500 hPa

Average: 3/1/03-2/28/04

1200 1000 800 600 400 200

• No. of Obs.

10000 8000 6000 4000 2000 H2O (ppmv) 1400 1200 1000 800 600 400 200

• No. of Obs.

2000 1500 1000 500 H2O (ppmv) 1400 1200 1000 800 600 400 200

• No. of Obs.

250 200 150 100 50 H2O (ppmv)

Trajectory AIRS

1200 1000 800 600 400 200

• No. of Obs.

10000 8000 6000 4000 2000 H2O (ppmv) 1200 800 400

• No. of Obs.

8000 6000 4000 2000 H2O (ppmv) 1200 800 400

• No. of Obs.

2000 1500 1000 500 H2O (ppmv) 1200 800 400

• No. of Obs.

2000 1500 1000 500 H2O (ppmv) 1200 800 400

• No. of Obs.

250 200 150 100 50 H2O (ppmv) 1200 800 400

• No. of Obs.

250 200 150 100 50 H2O (ppmv)

Maximum RH = 80% Maximum RH = 100%

1000 800 600 400 200 Pressure (hPa)

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20 40 60 Latitude 10000 8000 6000 4000 2000

Potential Temperature Surfaces Dehydration locations for parcels that end at 547 hPa

1000 800 600 400 200 Pressure (hPa)

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20 40 60 Latitude 10000 8000 6000 4000 2000

Potential Temperature Surfaces Dehydration locations for parcels that end at 547 hPa

1000 800 600 400 200 Pressure (hPa)

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20 40 60 Latitude

Potential Temperature Surfaces Zonally averaged NCEP data, 3/1/03-2/28/04 See Kelly, Pierrehumbert, Galewsky

1000 800 600 400 200 Pressure (hPa)

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20 40 60 Latitude

Potential Temperature Surfaces Zonally averaged NCEP data, 3/1/03-2/28/04 See Kelly, Pierrehumbert, Galewsky

1000 800 600 400 200 Pressure (hPa)

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20 40 60 Latitude

Potential Temperature Surfaces Zonally averaged NCEP data, 3/1/03-2/28/04 See Kelly, Pierrehumbert, Galewsky

1000 800 600 400 200 Pressure (hPa)

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20 40 60 Latitude

Potential Temperature Surfaces Zonally averaged NCEP data, 3/1/03-2/28/04 See Kelly, Galewsky

1000 800 600 400 200 Pressure (hPa)

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20 40 60 Latitude 10000 8000 6000 4000 2000

Potential Temperature Surfaces Dehydration locations for parcels that end at 547 hPa Zonally averaged NCEP data, 3/1/03-2/28/04

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20 40 60 Latitude 3/03 5/03 7/03 9/03 11/03 1/04 0.12 0.10 0.08 0.06 0.04 0.02 0.00

Time-Latitude cross section of dehydration frequency Includes parcels that saturate at altitudes above 400 hPa

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20 40 60 Latitude 3/03 5/03 7/03 9/03 11/03 1/04 0.12 0.10 0.08 0.06 0.04 0.02 0.00

Time-Latitude cross section of dehydration frequency Includes parcels that saturate at altitudes above 400 hPa

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20 40 60 270 180 90 20 15 10 5 x10

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20 40 60 270 180 90 20 15 10 5 x10

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Conclusions

• Simple trajectory model with fixed RH limit does a

good job of reproducing AIRS annual average water vapor

– Some differences exist, particularly at high MRs – We see no evidence that subgrid-scale or microphysical processes are critical for accurate simulations

• Model shows that dehydration of mid-troposphere

air occurs in three latitude bands

– Extratropical dehydration occurs during mixing up the isentropes

• Thanks to the AIRS team!!!!

Future work

• This work --- in preparation
• Minschwaner, Dessler, Sawaengphokhai, Multi-model

analysis of the water vapor feedback in the tropical upper troposphere, J. Clim., accepted

• Wong, S., P.R. Colarco, and A.E. Dessler, Principal

component analysis of the evolution of the Saharan Air Layer and dust transport: Comparisons between a model simulation and MODIS and AIRS retrievals, J. Geophys. Res., submitted

• Wu, W., A.E. Dessler, G.R. North, On the transport of

surface temperature variations into the free troposphere,

• Geophys. Res. Lett., in preparation.