Ozone Layers, Northern Boundary Conditions, and Air-Ground

Comparisons During SCOS-97

Donald L. BlumenthalJerry A. Anderson

Sonoma Technology, Inc.Petaluma, CA

SCOS97-NARSTO DATA ANALYSIS CONFERENCE February 15, 2001

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

The STI Piper Aztec Used During the SCOS97 Sampling Program

Air access tubes

NO/NOy Inlet

Temperature Sensor Housing

Dew Point InletExhaust

Teflon sample inlet lines through the access tube

NO1/NOW Inlet

Total radiation sensor

Sensor Location and Sample Air Inlet Systems on the Aztec

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

M2M1

Gaviota

Montgomery

Gillespie

Ramona

Oceanside (OCN)Palomar

Fallbrook

TemeculaDana Point (DP)

Banning (BNG)Riverside(RAL)

YuccaValley(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

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

M2M1

Gaviota

Montgomery

Gillespie

Ramona

Oceanside (OCN)Palomar

Fallbrook

TemeculaDana Point (DP)

Banning (BNG)Riverside(RAL)

YuccaValley(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

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 9 10 11 12 13 14 15 16 17

Time (PST)

500

1000

1500

2000

2500

Altitude (m

agl)

10

20

30

40

50

60

70

80

90

100

110

120

130

140

8040 60

0

1600

Ozone (ppb)

Altitu

de (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

Figure 7-1. Morning spiral at El Monte airport on August 5, 1997.

Morning spiral at El Monte Airport on August 5, 1997

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

Location Average ozone at

spiral bottom* (ppb) Max ozone (ppb)

< 800 m agl

Average height ofmax ozone

< 800 m agl (m agl) # spirals in

average

Basin sites Camarillo 11 56 461 11

Offshore Malibu 25 62 511 7

Van Nuys 9 60 406 12

Santa Paula 24 78 350 1

Santa Barbara 38 128 497 1

El Monte 17 71 585 7

Ontario 3 71 588 6

Rialto 24 63 450 11

Riverside 19 61 536 10

Weighted average: 16 64 489 66

Desert sites Agua Dulce 44 63 324 5

Rosamond 37 59 214 5

Yucca Valley 40 55 337 5

Banning 41 60 409 5

Weighted average: 41 59 321 20

* When bottom of spiral was near the surface over the runway.

Detached Layers Observed During Spirals in the STI Aztec

Location

# of morningspirals with

detached layers

% of morningspirals with

detached layers

# of afternoonspirals with

detached layers

% of afternoonspirals with

detached layers

Basin sites Camarillo 2/13 15% 3/12 25%Offshore Malibu 1/7 14% 0/3 0%Simi Valley 1/1 100% 0/5 0%Santa Paula 1/1 100%Santa Barbara 0/1 0%Van Nuys 2/13 15% 2/12 17%El Monte 2/7 29% 1/8 13%Azusa 1/6 17% 1/2 50%San Gabriel Reservoir 3/6 50%Ontario 1/7 14% 1/8 13%Rialto 0/12 0% 2/12 17%Riverside 1/12 8% 3/11 27%

Total: 15/86 17% 13/73 18%

Desert sites Agua Dulce 0/5 0%Bohunk's 0/4 0%Rosamond 0/5 0%Hesperia 0/5 0% 0/4 0%Yucca Valley 0/5 0% 0/4 0%Banning 1/5 20% 0/4 0%

Total: 1/25 4% 0/16 0%

Figure 7-5. Afternoon spiral offshore of Malibu on September 28, 1997.

Afternoon Spiral Offshore of Malibu on September 28, 1997

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

Location & Date Spiral/Traverse Ozone* (ppb) NOy* (ppb) NOw* (ppb)

August 4 Agua Dulce spiral 50 1-3 0.5-2Rosamond spiral 70 2-3 1-2Rosamond-Hesperia traverse 50-70 2-4 1-2Hesperia spiral 60 2-3 0-1Cajon-Soggy Lake traverse 50-70 4 2Yucca Valley spiral 70 2-3 0.5-1Banning spiral 60-70 2 1

August 22 Agua Dulce spiral 50 1 0.5Rosamond spiral 50-60 0-1 0-0.5Rosamond-Hesperia traverse 55-65 2 1Hesperia spiral 35 3 2Cajon-Soggy Lake traverse 40 2 1Yucca Valley spiral 35 2 1Banning spiral 45 1-2 0.5-1

September 4 Agua Dulce spiral 50-70 4-5 2Rosamond spiral 50-60 2 1-2Rosamond-Hesperia traverse 50 1.5-4 0.5-1Hesperia spiral 50-65 2-4 0-.5Cajon-Soggy Lake traverse 50 4-2 1-0Yucca Valley spiral 50 1-2 0-1Banning spiral 50 1 0

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

Location & Date Spiral/Traverse Ozone* (ppb) NOy* (ppb) NOw* (ppb)

September 5 Agua Dulce spiral 80 6 2Rosamond spiral 70 4 1Rosamond-Hesperia traverse 70-60 4-5 1-2Hesperia spiral 55-60 4 1Cajon-Soggy Lake traverse 60-80 4-5 1-2Yucca Valley spiral 60 3 1Banning spiral 40-60 2 0

October 3 Agua Dulce spiral 30-50 2-7 1-4Rosamond spiral 44 2 0-0.5Rosamond-Hesperia traverse 45 3 1Hesperia spiral 45 1 0Cajon-Soggy Lake traverse 45 2 1Yucca Valley spiral 40-50 2-1 1-0Banning spiral 44 1-2 0-1

*Concentrations given are approximate numbers outside the influence of near surfaceemissions.NOw is a measurement of NOy with the nitric acid and particle nitrate filtered out.

Comparison of Aircraft to Surface Ozone Measurements

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.

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.

Summary (3 of 3)

• Morning boundary conditions for NOy 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 NOy was nitric acid or nitrate aerosol.

• Instantaneous aircraft ozone data agreed well with nearby surface hourly averages and should be useful for model evaluation.