Comparison of Lidar Derived and Aircraft Measured Air ...

Comparison of Ozone DIAL and in situ Aircraft Measurements Honey L. Walters Thesis Advisor: Dr. John J. Carroll Special Thanks: Alan Dixon and Dave Salardino Objective Compare NOAA DIAL and UCD aircraft ozone measurements Overall performance Altitude or time of day dependence Data SCOS97-NARSTO (Southern CA Ozone Study-North American Research Strategy for Tropospheric Ozone) El Monte, CA NOAA Lidar (National Oceanic and Atmospheric Administration)

DIAL (Differential Absorption Lidar) UCD instrumented aircraft U.V. Photometric Ozone Analyzer Procedures Match up corresponding data (i.e. same day, time, and altitude)-39 total matching profiles Average UCD O3 in 15 m layers to match up with NOAA altitude Determine mean bias between UCD O3 and NOAA O3 and RMS difference for each flight Look at data in 100 m altitude bins (i.e. 200-300 m, 300-400 m) to determine bias for time of day and altitude range

Data-Difficulties NOAA determines O3 at all altitudes at the same time UCD aircraft cannot obviously be at all altitudes at the same time UCD is 10 s averaged and NOAA is averaged on the order of 6+ minutes Unsteady [O3] as indicated by sequential NOAA O3 profiles Results Time Mean Bias Mean RMS # of Profiles Predawn Up

3.24 13.2 5 Morning Down 8.77 20.24 6 Early Afternoon Up 3.14 15.86 10 Late Afternoon 3.6 Down 20.66 10

Early Evening Up 4.33 20 4 Late Evening Down -3.3 23.64 4 Results NOAA [Ozone] vs Altitude Morning on Sept. 29, 1997 1600 1400 6.64 6.77 6.81 6.89

A ltitu d e m (M S L ) 1200 PST PST PST PST 1000 800 600 400 200 0 0 20 40 60 [Ozone] (ppb) 80 100 120

Results NOAA [Ozone] vs Altitude Afternoon on Sept. 28, 1997 1600 1400 A ltitu d e m (M S L ) 1200 14.29 PST 14.36 PST 14.48 PST 1000 800 600 400 200 0 5 30 55 80 [Ozone] (ppb) 105

130 155 Results UCD [Ozone], NOAA [Ozone], and Bias vs Altitude Early Afternoon Upward Spiral on August 22, 1997 1600 1400 A ltitu d e m (M S L ) 1200 1000 800 600 UCD Ozone NOAA Ozone (9.93 PST) NOAA Ozone (10.47 PST) NOAA Ozone Average Bias 400 200 0 -30 -10

10 30 50 [Ozone] (ppb) 70 90 110 Results UCD [Ozone], NOAA [Ozone], and Bias vs Altitude Late Afternoon Downward Spiral on Sept. 27, 1997 1600 1400 A ltitu d e m (M S L ) 1200 1000 800 600 UCD Ozone NOAA Ozone (14.42 PST)

NOAA Ozone (14.62 PST) NOAA Ozone (14.71 PST) NOAA Mean Ozone Bias 400 200 0 -50 0 50 [Ozone] (ppb) 100 150 Results Ozone Mean Bias vs Altitude Layer 1400 1300 1200 A ltitu d e m (M S L ) 1100 1000 900

Early Afternoon Upward Spiral Late Afternoon Downward Spiral 800 700 600 500 400 300 200 100 0 -15 -10 -5 0 5 Ozone Mean Bias (ppb) 10 15 Results

Altitude Layer vs Ozone Mean Bias for all flights except late evening O z o n e M e a n B ia s (p p b ) 30 Maximum Mean Bias Minimum Mean Bias Mean Bias 20 10 0 -10 100 200 300 400 500 600 700

800 900 Altitude m (MSL) 1000 1100 1200 1300 1400 Conclusion UCD and NOAA O3 compare well at most times and locations Evening flights compare poorly due to lack of matching data, poor time matches, and unsteady O3 conditions There are poor comparisons near ground and at higher altitudes (800m +) When the NOAA O3 profile shows conditions to be unsteady, there s a larger bias and an increase in noise (RMS) There is no significant difference between upward aircraft spirals and downward aircraft spirals