Evaluation of EDAS winds used for backtrajectories

• EDAS winds used in HYSPLIT for backtrajectories – residence time worst days, worst sulfur, etc.

• Also used for trajectory regression attribution analysis

• But how good are the winds?• We compared EDAS winds to 0Z and 12Z

soundings for 500 m, 1500 m, and 3000 m heights at several locations

EDAS rotated CCW 45% at 500 m, misses strong SSW peak at 1500 m, good at 3000 m

Good comparison even at 500 m at Great Falls

Good comparison at all levels at Salem, Oregon

At San Diego EDAS overdoes SSE at 500 m summer, overdoes NW at 1500 m; good overall at 1500 m and 3000 m

Summary of EDAS wind evaluation

• EDAS performs very well at 3000 m• EDAS generally good performance at 1500 m.• EDAS marginal performance at 500 m except where

there is not much elevated terrain• Backtrajectories started from 500 m or below may start

out with a significantly biased wind direction • No systematic bias across different sites noted• We have not yet considered morning versus afternoon

performance- may be expected to perform better in afternoon

Generally poor performance by FNL at Fairbanks for all levels

Bandelier

Aqua Tibia

500m 1500m

500m 1500m

Wind Cave

Yellowstone

500m 1500m

500m1500m