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

Passively advected 100% RH Lots of water

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

Parcel 2010 on 3/1/03: final location 24.5°S, 149.5°W Day 30 35 40 45 50 55 325 Pot'l Temp (K) 320 315 310 water vapor (ppmv) x 10^3 15 10 5 0 30 35 40 45 50 55 Day

Passively 100% RH advected Lots of water

Passively 100% RH advected 1. Set RH = 100% whenever “convection” is encountered 2. Water vapor is passively advected 3. Except when RH > 100%, in which case condensation occurs Lots of water

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

Parcel 2010 on 3/1/03: final location 24.5°S, 149.5°W Day 30 35 40 45 50 55 325 Pot'l Temp (K) 320 315 310 1863 ppmv water vapor (ppmv) x 10^3 15 10 5 0 30 35 40 45 50 55 Day

• Model “convection” comes from average rising motion in NCEP reanalysis • Model “microphysics” is simplest possible: hard RH limit of 100%

20 X X X X X X X X X X X X 10 X X X X X X X X X X X X 0 X X X X X X X X X X X X X X X X X X X X X X X X -10 X X X X X X X X X X X X -20 0 90 180 270 360 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 30 ppmv, thousands 20 12 10 10 8 x10 0 6 3 4 -10 2 -20 0 -30 0 90 180 270 360

AIRS data: 3/1/2003 @ 600-500 hPa Traj model: 547 hPa 30 20 12 10 10 8 x10 0 6 3 4 -10 2 -20 0 -30 0 90 180 270 360 Black contour = 4000 ppmv

30 Average: 20 250 3/1/03-2/28/04 10 200 0 150 100 -10 223 hPa 50 -20 -30 0 90 180 270 360 30 20 2000 10 1500 0 1000 -10 500 346 hPa -20 -30 0 90 180 270 360 30 20 10000 8000 10 6000 0 4000 -10 2000 547 hPa -20 0 -30 0 90 180 270 360

30 Average: 20 250 3/1/03-2/28/04 10 200 0 150 100 -10 250-200 hPa 50 -20 -30 0 90 180 270 360 30 20 2000 10 1500 0 1000 -10 500 400-300 hPa -20 -30 0 90 180 270 360 30 20 10000 8000 10 6000 0 4000 -10 2000 600-500 hPa -20 0 -30 0 90 180 270 360

Average: 1400 Trajectory 1200 3/1/03-2/28/04 1000 No. of Obs. 800 AIRS 600 250-200 hPa 400 200 0 0 50 100 150 200 250 H2O (ppmv) 1400 1200 1000 No. of Obs. 800 600 400-300 hPa 400 200 0 0 500 1000 1500 2000 H2O (ppmv) 1200 1000 No. of Obs. 800 600 600-500 hPa 400 200 0 0 2000 4000 6000 8000 10000 H2O (ppmv)

Maximum RH = 100% Maximum RH = 80% 1200 1200 No. of Obs. No. of Obs. 800 800 400 400 0 0 0 50 100 150 200 250 0 50 100 150 200 250 H2O (ppmv) H2O (ppmv) 1200 1200 No. of Obs. No. of Obs. 800 800 400 400 0 0 0 500 1000 1500 2000 0 500 1000 1500 2000 H2O (ppmv) H2O (ppmv) 1200 1000 1200 No. of Obs. No. of Obs. 800 800 600 400 400 200 0 0 0 2000 4000 6000 8000 10000 0 2000 4000 6000 8000 H2O (ppmv) H2O (ppmv)

Potential Temperature Surfaces Dehydration locations for parcels that end at 547 hPa 200 10000 8000 400 Pressure (hPa) 6000 600 4000 2000 800 0 1000 -60 -40 -20 0 20 40 60 Latitude

Potential Temperature Surfaces Dehydration locations for parcels that end at 547 hPa 200 10000 8000 400 Pressure (hPa) 6000 600 4000 2000 800 0 1000 -60 -40 -20 0 20 40 60 Latitude

Potential Temperature Surfaces 200 400 Pressure (hPa) 600 800 1000 -60 -40 -20 0 20 40 60 Latitude Zonally averaged NCEP data, 3/1/03-2/28/04 See Kelly, Pierrehumbert, Galewsky

Potential Temperature Surfaces 200 400 Pressure (hPa) 600 800 1000 -60 -40 -20 0 20 40 60 Latitude Zonally averaged NCEP data, 3/1/03-2/28/04 See Kelly, Pierrehumbert, Galewsky

Potential Temperature Surfaces 200 400 Pressure (hPa) 600 800 1000 -60 -40 -20 0 20 40 60 Latitude Zonally averaged NCEP data, 3/1/03-2/28/04 See Kelly, Pierrehumbert, Galewsky

Potential Temperature Surfaces 200 400 Pressure (hPa) 600 800 1000 -60 -40 -20 0 20 40 60 Latitude Zonally averaged NCEP data, 3/1/03-2/28/04 See Kelly, Galewsky

Potential Temperature Surfaces Dehydration locations for parcels that end at 547 hPa 200 10000 8000 400 6000 Pressure (hPa) 4000 600 2000 800 0 1000 -60 -40 -20 0 20 40 60 Latitude Zonally averaged NCEP data, 3/1/03-2/28/04

60 40 0.12 20 0.10 Latitude 0.08 0 0.06 0.04 -20 0.02 -40 0.00 -60 3/03 5/03 7/03 9/03 11/03 1/04 Time-Latitude cross section of dehydration frequency Includes parcels that saturate at altitudes above 400 hPa

60 40 0.12 20 0.10 Latitude 0.08 0 0.06 0.04 -20 0.02 -40 0.00 -60 3/03 5/03 7/03 9/03 11/03 1/04 Time-Latitude cross section of dehydration frequency Includes parcels that saturate at altitudes above 400 hPa

60 20 40 15 20 x10 0 10 3 -20 5 -40 -60 0 90 180 270

60 20 40 15 20 x10 0 10 3 -20 5 -40 -60 0 90 180 270

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.