Diurnal Wind Variations in TexAQS-2

John W. Nielsen-Gammon and Andrew McNeel

Texas A&M University

Diurnal (24-hour) Winds

• Sea Breeze Cycle strongly affects ozone concentrations and locations in Houston

• Nighttime transport strongly affects ventilation and intrastate-interstate pollution dispersion

• Objective: use TexAQS-2 profiler network to characterize diurnal winds

Technical Issues

• Profiler winds are– Contaminated by other sources– Contaminated by migrating birds– Noisy

• Approach:– Use QC’d winds (Sonoma Technology)– Use mostly complete days– Interpolate using linear and EOF methods

TexAQS-2 Profiler Network

Ledbetter

Palestine

Jayton

La Porte (diurnal wind fraction)

La Porte (Average W-E & N-S winds)

La Porte u/v, Aug/Sep 2006 episode

Huntsville u/v, Aug/Sep 2006 episode

Longview u/v, Aug/Sep 2006 episode

New Braunfels u/v, Aug-Sep 2006 episode

Ledbetter u/v, Aug-Sep 2006 episode

Brazos A-19 u/v, Aug-Sep 2006 episode

Southerly Wind Maxima

• Longview: 00-01 CDT, 300 m, 7 m/s

• Huntsville: 22-00 CDT, 300 m, 6.5 m/s

• La Porte: 19-22 CDT, 250 m, 3 m/s

• Brazos A19: 00 CDT, <400 m, > 4 m/s

La Porte u/v, Aug/Sep 2006 episode

La Porte u/v, June 2006

Longview u/v, June 2006

Jayton u/v, June 2006

Conclusions

• Diurnal winds are caused by:– Sea breeze– Frictional decoupling– and enhanced by adverse shear

• At night, they are almost invisible to the conventional observing network

• Important in regional transport• Challenging to model

La Porte (onshore & alongshore diurnal wind)