1. Ozone Layers, Northern Boundary Conditions, and Air-Ground Comparisons During SCOS-97 Donald L. Blumenthal Jerry A. Anderson Sonoma Technology, Inc. Petaluma, CA SCOS97-NARSTO DATA ANALYSIS CONFERENCE February 15, 2001

2. Measurement Objectives Investigate formation of aloft ozone layers Assess importance of aloft layers to surface concentrations Provide episode boundary conditions in the desert Provide data for model input and evaluation

3. The STI Piper Aztec Used During the SCOS97 Sampling Program

4. Air access tubes NO/NO y Inlet Temperature Sensor Housing Dew Point Inlet Exhaust Teflon sample inlet lines through the access tube NO 1 /NO W Inlet Total radiation sensor Sensor Location and Sample Air Inlet Systems on the Aztec

5. The Flight Routes Flown on the First Day of an IOP Lompoc Rosamond (L00) Santa Barbara (SBA) M9 M10 M8 M7 M6 M5 M4 M3 M2 M1 Gaviota Montgomery Gillespie Ramona Oceanside (OCN) Palomar Fallbrook Temecula Dana Point (DP) Banning (BNG)Riverside (RAL) Yucca Valley (L22) Soggy Lake (SL) San Pedro Point (SPP) Rialto (L67) Ontario (ONT) Hesperia Profiler Site (HES) MAL Santa Monica (SMO) El Monte (EMT) Azusa (AZU) San Gabriel Res. (SGR) R1 R2 Bohunk’s (OCL6) R3 Agua Dulce (L70) Van Nuys (VNY) Camarillo (CMA) Santa Paula (SZP) Simi Valley (SIM) San Clemente I. Catalina I. San Miguel I. Santa Rosa I. Anacapa I. Santa Barbara I. San Nicolas I. N PM AM Spiral points End points Traverses

6. Flight Routes for the Second and Following Days of an IOP and for Santa Barbara Lompoc Rosamond (L00) Santa Barbara (SBA) M9 M10 M8 M7 M6 M5 M4 M3 M2 M1 Gaviota Montgomery Gillespie Ramona Oceanside (OCN) Palomar Fallbrook Temecula Dana Point (DP) Banning (BNG) Riverside (RAL) Yucca Valley (L22) Soggy Lake (SL) San Pedro Point (SPP) Rialto (L67) Ontario (ONT) Hesperia Profiler Site (HES) MAL Santa Monica (SMO) El Monte (EMT) Azusa (AZU) San Gabriel Res. (SGR) R1 R2 Bohunk’s (OCL6) R3 Agua Dulce (L70) Van Nuys (VNY) Camarillo (CMA) Santa Paula (SZP) Simi Valley (SIM) San Clemente I. Catalina I. San Miguel I. Santa Rosa I. Anacapa I. Santa Barbara I. San Nicolas I. N PM AM Spiral points End points Traverses

7. Flight Pattern Frequencies Northern Boundary (Desert) - Morning Northern Boundary (Desert) - Afternoon Northern Basin - Morning Northern Basin - Afternoon Ventura-Santa Barbara - Morning Western Boundary offshore 5 flights 4 flights 7 flights 8 flights 1 flights 2 flights Total: 27 flights 8/4, 8/22, 9/4, 9/5, 10/3 8/5, 8/6, 8/23, 9/6 8/5, 8/6, 8/23, 9/6, 9/28, 9/29, 10/4 8/4, 8/22, 9/4, 9/5, 9/28, 9/29, 10/3, 10/4 8/7 7/14, 9/3

8. 8040 60 0 1600 Ozone (ppb ) Altitude (m agl) Surface-Based Mixing Depth Ozone (ppb) LIDAR ozone and the surface-based mixing depth (left) and ozone concentrations at 1500 PST (right) at El Monte (EMT) on August 4, 1997. Ozone and Mixing Depth at El Monte

9. Morning spiral at El Monte Airport on August 5, 1997

10. Early-Morning Spiral Boundary-Layer Ozone Peaks and Surface Concentrations

11. Detached Layers Observed During Spirals in the STI Aztec

12. Afternoon Spiral Offshore of Malibu on September 28, 1997

13. Boundary Conditions in Boundary Layer Above Surface Emissions During Morning Desert Flights (1 of 2)

14. Boundary Conditions in Boundary Layer Above Surface Emissions During Morning Desert Flights (2 of 2)

15. Comparison of Aircraft to Surface Ozone Measurements

16. Summary (1 of 3) Ozone carryover aloft was seen below the subsidence inversion on all mornings in spirals in the Basin Peak carryover in the Basin in the boundary layer averaged 64 ppb and ranged up to 120 ppb. Morning Basin surface concentrations in spirals averaged 16 ppb. Surface concentrations will clearly be increased by mixing down of aloft ozone as the mixing layer deepens.

17. Summary (2 of 3) Detached layers were seen above the boundary layer on less than 20% of morning and afternoon spirals. Detached layers are not likely to be important contributors to surface concentrations in the Basin, but may impact mountain slopes. High afternoon ozone concentrations occur in low- elevation layers offshore which may impact coastal slopes. Morning boundary conditions in the desert on the first days of episodes ranged from 40 to 70 ppb for ozone, with typical variations of 20 to 30 ppb from place to place on any day.

18. Summary (3 of 3) Morning boundary conditions for NO y were typically 2 to 4 ppb with variations of 1 to 2 ppb from place to place. Typically about half or more of the boundary NO y was nitric acid or nitrate aerosol. Instantaneous aircraft ozone data agreed well with nearby surface hourly averages and should be useful for model evaluation.