Holiday effect of the Taipei Metropolitan area 台北都會區的假期效應

Holiday effect of the Taipei Metropolitan area台北都會區的假期效應

報告人：談珮華博士國立嘉義大學史地學系副教授

日期： 2009 年 10 月 7 日

Goal

• Study the holiday effect over the Taipei Metropolitan area.

• Holiday effect

• The statistically significant differences of variables between holiday and non-holiday periods.

The weekend effect 週末效應• Stock market

• Disease, syndrome

Introduction (1)• Weekend effect of air pollutants

• Gaseous pollutants such as NOx, CO, VOCs 揮發性有機物 or NMHC 非甲烷碳氫化合物 , and SO2 higher on weekdays than on weekends

(e.g., Bronnimann and Neu 1997; Beirle et al. 2003; Qin et al. 2004; Riga-Karandinos and Saitanis 2005; Steinbacher et al. 2005; Riga-Karandinos et al. 2006)

• Particulate pollutants such as PM10, PM2.5, PM1, and black carbon higher on weekdays than on weekends

(Morawska et al. 2002; Madhavi Latha and Badarinath 2003) .

污染來源• 氣狀污染物• 粒狀污染物• NOx, CO, NMHC, O3, SO2, PM10

Introduction (2)• O3: major secondary air pollutant a more complex distribution• Lower on weekdays than weekends

(e.g., Cleveland et al. 1974; Lebron 1975; Bronnimann and Neu 1997; Diem 2000; Qin et al. 2004; Riga-Karandinos and Saitanis 2005; Tsai 2005; Riga-Karandinos et al. 2006)

• Higher on weekdays than weekends (Bronnimann and Neu 1997; Diem 2000)

• ?? O3 precursor substances, such as NOx and NMHC, are decreased on weekends, while O3 is simultaneously increased.

Introduction (3)• Several hypotheses for O3 weekend effect (California Air R

esources Board, 2003). (1) nonlinear relation between O3 and its precursors: lower N

Ox on weekends a faster ozone production rate in NOx-saturated (VOC-limited) areas

(2) NO titration effect (NO 滴定效應 ): lower NOx less ozone destruction on weekends, ozone↑, O3 + NO NO2+O2

(3) aerosol and UV radiation: on weekends, aerosol ↓ sunshine↑ ozone↑(4) NOx timing: delayed weekend traffic patterns and stronger sunshine ozone↑(5) carry-over emissions: higher traffic volumes on Friday evenings than on weekends more O3 precursors on weekends

Introduction (4)• Weekend effect of meteorological parameters• Diurnal temperature range, DTR (Forster and Solomon

2003; Gong et al. 2006a)日溫差• dayily minimum temperature, Tmin (Forster and Solom

on 2003)最高溫• dayily maximum temperature, Tmax (Gong et al., 2006

a)最低溫• daily precipitation frequency (Gong et al., 2006b)• annual precipitation and tropical cyclonic mean maximu

m wind speed (Cerveny and Balling 1998)• seasonal rainfall, seasonal maximum and minimum tem

perature (Simmonds and Keay 1997)• visibility (Tsai 2005)能見度

• Most weekend-weekday differences are statistically significant, but their sign might be opposite for different regions or seasons (Forster and Solomon 2003, Gong et al. 2006a), and are attributed to anthropogenic influences (Cerveny and Balling 1998; Forster and Solomon 2003).

avg (Sat-Mon) – avg (Wed-Fri) DTR avg (Sat-Mon) – avg (Wed-Fri) Tmin

Forster and Solomon (2003)

Introduction (5)

• Weekend effect: a useful tool to detect the influence of human-related activities on the environment and climate system.

• Other similar effects, such as “holiday effect”, provide a possibility to study such phenomena for regions not showing a clear weekend effect.

• Part 1. air pollutant concentrations

• Part 2. meteorological parameters

Part 1. air pollutant concentrations

• The method

– the Chinese New Year holiday– the most important holiday for the Chinese people.– The Chinese New Year (CNY) and non-Chinese Ne

w Year (NCNY) periods.– 春節及非春節期間

• The CNY and NCNY periods

Year Before the CNY period The CNY period After the CNY period

2006 Jan. 18 - Jan. 27 Jan. 28 - Feb. 2 Feb. 3 - Feb. 12

2005 Jan. 27 - Feb. 5 Feb. 6 - Feb. 13 Feb. 14 - Feb. 23

2004 Jan. 11 - Jan. 20 Jan. 21 - Jan. 26 Jan. 27 - Feb. 5



2001 Jan. 11 - Jan. 20 Jan. 21 - Jan. 28 Jan. 29 - Feb. 7


1999 Feb. 3 - Feb. 12 Feb. 13 - Feb. 18 Feb. 19 - Feb. 28



1996 Feb. 8 - Feb. 17 Feb. 18 - Feb. 22 Feb. 23 - Mar. 3


1994 Jan. 30 - Feb. 8 Feb. 9 - Feb. 13 Feb. 14 - Feb. 23Sources: Taiwan Central Personnel Administration (1994-2006)

Part 1. air pollutant concentrations

• The methodWeather effect a longer record in time filter out the random change of weather climatic feature

The study area

6.39 million inhabitants

Population density

2750 /km2

The data

• NOx, CO, NMHC, O3, SO2, PM10

• Hourly and daily surface measurements of six major air pollutants from thirteen (four for NMHC) air quality monitoring stations of the Taiwan Environment Administration during the holiday and non-holiday periods in 1994-2006.

Air pollutants CNY NCNY C C /NCNY

NOX (ppb) 26.8 44.8 –18.0* – 40%

CO (ppm) 0.66 0.91 – 0.25* – 27%

NMHC (ppm) 0.27 0.52 – 0.25* – 48%

O3 (ppb) 25.1 21.1 + 4.0* +19%

SO2 (ppb) 2.3 4.4 – 2.1* – 48%

PM10 (μg/m3) 42.1 51.3 – 9.3* – 18%

*significance with p level < 0.05

Results13-station daily mean air pollutant concentrations in 1994-2006

<<<<

<

>

(a) NOX

0

10

20

30

40

50

60

70

1 3 5 7 9 11 13 15 17 19 21 23hour

con

cen

trat

ion

(p

pb

)(b) CO

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1 3 5 7 9 11 13 15 17 19 21 23hour

con

cen

trat

ion

(p

pm

)

(c) NMHC

0.00.10.20.30.40.50.60.70.8

1 3 5 7 9 11 13 15 17 19 21 23hour

con

cen

trat

ion

(p

pm

)

(d) O3

0

5

10

15

20

25

30

35

1 3 5 7 9 11 13 15 17 19 21 23hour

con

cen

trat

ion

(p

pb

)

(e) SO2

0

1

2

3

4

5

6

1 3 5 7 9 11 13 15 17 19 21 23hour

con

cen

tra

tio

n (

pp

b) (f) PM10

0

10

20

3040

50

60

70

1 3 5 7 9 11 13 15 17 19 21 23hour

con

cen

tra

tio

n (

μg

/m3

)

CNYNCNY

(a) NO

010203040506070

1 3 5 7 9 11 13 15 17 19 21 23

hour

con

cen

tra

tio

n (

pp

b) (b) NO2

0

10

20

30

40

50

60

70

1 3 5 7 9 11 13 15 17 19 21 23

hour

con

cen

tra

tio

n (

pp

b)

(c) NO2+O3

0

10

20

30

40

50

60

70

1 3 5 7 9 11 13 15 17 19 21 23

hour

con

cen

tra

tio

n (

pp

b) (d) UV-A

0

5

10

15

20

1 3 5 7 9 11 13 15 17 19 21 23hour

rad

iati

on

(μ

m/m2 )

(e) UV-B

0

0.5

1

1.5

2

2.5

3

1 3 5 7 9 11 13 15 17 19 21 23hour

rad

iati

on

(μm

/m2 )

hour

hour

CNY NCNY

In CNY, at noon, UVA & UVB , if nonlinear, NOx↓, O3↑, But O3

(d) O3

0

5

10

15

20

25

30

35

1 3 5 7 9 11 13 15 17 19 21 23hour

con

cen

trat

ion

(p

pb

)

Total oxidants

O(1) nonlinear relation between O3 and its precursors: lower NOx on weekends a faster ozone production rate in NOx-saturated (VOC-limited) areas

OO (2) NO titration effect: lower NOx, lower NO less ozone destruction on weekendsX(3) aerosol and UV radiation: on weekends, aerosol ↓ su

nshine↑ ozone↑; in CNY, aerosol ↓ ozone ↑ but sunshine X(4) NOx timing: delayed weekend traffic patterns and str

onger sunshine, ozone↑; in CNY, no such patternX(5) carry-over emissions: higher traffic volumes on Frida

y evenings than on weekends more O3 precursors on weekends; 4-8 days in CNY

Ozone holiday effect

(b) CO

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1994 1996 1998 2000 2002 2004 2006

con

cen

trat

ion

(p

pm

)

(d) O3

0

5

10

15

20

25

30

35

1994 1996 1998 2000 2002 2004 2006

con

cen

trat

ion

(p

pb

)(b) PM10-normal

01020

30405060

708090

1994 1996 1998 2000 2002 2004 2006

(a) NOX

0

10

20

30

40

50

60

70

1994 1996 1998 2000 2002 2004 2006

con

cen

trat

ion

(p

pb

)

(c) NMHC

0.0

0.2

0.4

0.6

0.8

1.0

1994 1996 1998 2000 2002 2004 2006

conc

entr

atio

n (p

pm)

(a) SO2-normal

0

1

23

4

5

67

8

9

1994 1996 1998 2000 2002 2004 2006

Con

cen

trat

ion

(p

pb

)

Concentration (g/m3)CNYNCNY

NCNY

CNY

NCNY

CNY

The effect of dust• The influence levels of dust storms on Taiwan• Daily maximum PM10 concentrations for any of the

three air quality monitoring stations in northern Taiwan

• 0 < 150 g/m3

• 1 150-200 g/m3

• 2 200-300 g/m3

• 3 300-400 g/m3

CNY: dust & no-dust casesNCNY: dust & no-dust cases

P=(No-dust minus dust)/dust NOx CO NMHC O3 SO2 PM10

Year Date P (%) P (%) P (%) P (%) P (%) P (%)

CNY

2004Jan.21(0), Jan.22(0), Jan.24(0), Jan.25(0) 88* 38* 21# -32* -56* -45*

2002Feb.9(1), Feb.10(0), Feb.11(3), Feb.12(2) 19 1 12 -19* -52* -65*

1994 Feb.9(2), Feb.10(1) 13 13 0 -20* -31# -48*

NCNY

2006 Feb.12(0) 8 -10 69 -31* -20* -55*

2005 Feb.1(0) 93* 43* 93 -37* -29* -39*

2004 Jan.13(0), Feb.5(0) 73* 30* 17 -29* -17* -35*

2001 Jan.14(2), Feb.1(1) 108* 35* 150* -26* 23* -54*

1999 Feb.19(1) 204* 102* 193 -27* 207* -38*

1994Feb.8(0), Feb.20(0), Feb.21(0), Feb.22(1), Feb.23(1)

8 -1 -2 -26* 1 -29*

Conclusions (1)• Holiday effect of air pollutant concentrations was fo

und over the Taipei Metropolitan area.– Daily (24-h)mean, diurnal cycle and interannual variation

• NOx, CO, NMHC, SO2 and PM10: CNY< NCNY

• O3: CNY > NCNY

• The diurnal cycles of the differences of O3, total oxidants and NOx between the CNY and NCNY periods NO titration effect is more important

Conclusions (2)• 1994-2006

• NOx and CO: negative trends in NCNY

• SO2 and PM10: positive trends in CNY

Holiday effect is weakening.

• The long-range transport of dust

SO2 and PM10 in CNY and NCNY

stronger impact in CNY due to cleaner air in CNY.

Conclusions (3)• It involved a great movement of people and

motor vehicles before and after the CNY period, the observed holiday effect provided evidence of the impact of human activity on ambient air quality.

• Holiday effect in other countries with similar national or cultural holidays.

Part 2. meteorological parameters• The goal

– the holiday effect

– The relation between air pollutants (PM10) and meteorological parameters

– Radiation effects of aerosol

–懸浮微粒的輻射效應• Direct effect 直接輻射效應• Indirect effect 間接輻射效應• Semi-direct effect 半直接輻射效應

• IPCC AR4 (2007)

Part 2. meteorological parameters• The method

• The study area

• The data: • 13 EPA stations(1994-2006, 13 years)

• 2 CWB stations(1986-2006, 21 years)

– surface measurement of Taipei weather station

– Radiosonde measurement of Banqiao station (00Z, 12Z)

• Tmax, Tmin, Tavg, DTR

• cloud cover, sunshine hour, sunshine rate,

• global solar radiation, rainfall, visibility

• Vertical profile of temperature

ResultsCNY NCNY Data source

PM10 < EPA* (13-average)

DTR < EPA* (13-average), CWB#

Tmax < EPA* (13-average), CWB

Tavg < EPA* (13-average), CWB

Cloud cover > CWB*

Sunshine hour < CWB*

Sunshine rate < CWB*

not statistically significant Tmin, global solar radiation, rainfall, visibility

CWB radiosonde measurement

• In average, warmer atmosphere in the NCNY than CNY period.

• atmospheric stability dT/dz

• 1000-500mb

• NCNY: -4.73 /km℃• CNY : -4.89 /km (C℃

NY more unstable)

-20 -10 0 10 20

1000

960

920

880

840

800

760

720

680

640

600

560

520

℃

CNY NCNY

(a) CNY and NCNY (00Z)

Conclusions (1)

Holiday effects:

DTR, Tmax, Tavg, cloud cover,

sunshine hour, sunshine rate

Conclusions (2)• Compared to CNY, in the NCNY• Semi-direct effect

– aerosol (PM10)↑, absorbed solar radiation ↑, warmer atmosphere, stability ↑, convection↓, cloud cover↓, sunshine hour ↑, sunshine rate ↑, Tmax ↑, DTR ↑

– aerosol in Taipei, SSA 0.76-0.79, many light-absorbed aerosols, ≒Shiu (2008)

• Direct effect: aerosol (PM10)↑, absorbed solar radiation↑, surface radi

ation↓ sunshine hour↓ but sunshine hour ↑ • Indirect effect:

aerosol (PM10)↑, CCN ↑, cloud cover ↑ but cloud cover↓

Conclusions

• Semi-direct radiation effect– Sounding data– ……..

CWB radiosonde measurement

• In average, warmer atmosphere in the NCNY period.

• But, the standard deviation is large if viewed year by year.

• Not a strong evidence.

• ………..

-5 -4 -3 -2 -1 0 1 2 3 4 5

1000

960

920

880

840

800

760

720

680

640

600

560

520

℃(b) CNY - NCNY (00Z)

參考資料

• Tan, P.-H., C. Chou, J.-Y. Liang, C. C.-K. Chou, C.J. Shiu, 2009: Air pollution “holiday effect” resulting from the Chinese New Year, Atmos. Environ., 43 (13), 2114-2124.

• 談珮華、周佳、梁靜宜、吳柏霖， 2008 ：台北都會區的假期效應，大氣科學， 36 (3) ， 197-215 。

• Thank you for your attention!!

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NOx-saturated area

NO + O3 -> NO2 + O2 (1)

NO2 + hυ -> NO + O (2)

O + O2 + M -> O3 + M (3)

O3 cycle

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Holiday effect of the Taipei Metropolitan area 台北都會區的假期效應