Study on short lived climate pollutants in hanoi in the context of climate change and sustainable development

VIETNAM NATIONAL UNIVERSITY, HANOIVIETNAM JAPAN UNIVERSITY DO DUY TUNG STUDY ON SHORT-LIVED CLIMATE POLLUTANTS IN HANOI IN THE CONTEXT OF CLIMATE CHANGE AND SUSTAINABLE DEVELOPMENT MASTE

VIETNAM NATIONAL UNIVERSITY, HANOI

VIETNAM JAPAN UNIVERSITY

DO DUY TUNG

STUDY ON SHORT-LIVED

CLIMATE POLLUTANTS IN HANOI

IN THE CONTEXT OF CLIMATE CHANGE AND SUSTAINABLE

DEVELOPMENT

MASTER’S THESIS

VIETNAM NATIONAL UNIVERSITY, HANOI

VIETNAM JAPAN UNIVERSITY

DO DUY TUNG

STUDY ON SHORT-LIVED

CLIMATE POLLUTANTS IN HANOI

IN THE CONTEXT OF CLIMATE CHANGE AND SUSTAINABLE

In writing Master’s thesis, I carefully read the thesis guidelines at Vietnam JapanUniversity, Vietnam National University and fully understand what is written thereand comply with all related rules and guidelines I ensure that this thesis is my ownresearch and has not been published The use of results of other research and

documents must comply with the regulations Citations and references fordocuments, books, research papers and web pages must be on the list of references

of the thesis

I pledge my honor that I comply with provisions give above

Author of the thesis

Do Duy Tung

TABLE OF CONTENTS

PLEDGE i

LIST OF TABLES iv

LIST OF FIGURES v

LIST OF ABBREVIATIONS vii

ACKNOWLEDGEMENT viii

ABSTRACT ix

CHAPTER 1 BACKGROUND AND OBJECTIVES 1

1.1 Definition of SLCPs and their significance 2

1.2 Definition of BC, TO3 and PM2.5 and their significance 8

1.2.1 BC 8

1.2.2 TO 3 10

1.2.3 PM 2.5 12

1.3 Preceding Studies: Status of SLCPs in Vietnam and Southeast Asia 13

1.4 Mitigation measures to reduce SLCPs in Vietnam and SE Asia 21

1.5 SLCPs’ sources in Vietnam 22

1.6 Objectives of this study 24

CHAPTER 2 METHODOLOGY AND STRATEGY IN THIS STUDY 25

2.1 Strategy to attain the objectives 26

2.2 Ground-based Observation 28

2.2.1 BC 29

2.2.2 Tropospheric Ozone 31

2.2.3 PM2.5 34

2.3 Signatures indicating contributions of local/regional/remote sources 36

2.3.1 Diurnal variation 36

2.3.2 Correlation of observed SLCP concentration levels with the trajectory and local meteorological parameters 37

2.4 Remote Observational Sites 41

2.4.1 Initial Data Processing 41

2.4.2 Observational Data Provided by Other Activities 41

2.5 Meteorological Data and Trajectory Analysis 42

2.5.1 HYSPLIT Trajectory Model 42

2.5.2 Local Meteorological Data 42

CHAPTER 3 RESULTS 43

3.1 Observed SLCPs’ Concentrations and Their Variation 43

3.1.1 Winter 45

3.1.2 Spring 47

3.1.3 Summer 48

3.1.4 Autumn 49

3.2 Seasonal Features of Trajectories 53

CHAPTER 4 ANALYSIS AND DISCUSSION 55

4.1 Correlation between SLCPs in each season 55

4.1.1 BC and PM2.5 55

4.1.2 PM2.5 and TO3 57

4.2 Comparison of Observed Enhances of SLCP with the Transport Areas in each season 59

4.2.1 Winter 60

4.2.2 Spring 62

4.2.3 Summer 62

4.2.4 Autumn 63

4.3 Comparison of Observed Enhances of SLCP with the local / regional transport features 64

4.4 Comparison of Multi-station Observational Data 65

4.5 Discussion on contribution of local/regional sources in Northern Vietnam and on the inference of SLCP Climate Effect in this region 67

4.5.1 Contribution of local/regional sources in Northern Vietnam 67

4.5.2 Climate Effects of BC 67

CHAPTER 5 CONCLUSION 66

REFERENCES 67

APPENDIX 70

LIST OF TABLES

Table 1.1 Key features of SLCPs compared with CO2 6

Table 2.1 Diurnal Analysis of BC, O3 and PM2.5 concentration in Hanoi 39

Table 2.2.2 Evidences for distinguishing local/remote source influences 40

LIST OF FIGURES

Figure 1.1 Critical air polluted condition in Hanoi by open biomass burning 1

Figure 1.2 Global annual mean distribution of BC direct radiative forcing at TOA 3

Figure 1.3 Radiative Forcing Caused by Human Activities Since 1750 3

Figure 1.4 Model of CO2 and SLCP cuts compared with other pathways until 2100

4

Figure 1.5 Dominant sources of BC from human activities 9

Figure 1.6 Schematic Display of Photochemical Ozone Formation in the

Troposphere 10

Figure 1.7 Diagram shows PM2.5 particles size 12

Figure 1.8 Planetary boundary layer (PBL) heating by surface emission of BC 15

Figure 1.9 Monthly mean BC mass concentration (left) and heating rate (right)

over Ahmedabad in 2008 16

Figure 1.10 Vertical profiles of heating rate due to aerosol black carbon calculated

from FBC profiles 17

Figure 1.11 Annual mean model median change in near-surface temperature (top

left), zonally averaged temperature change for the model median (black line) andindividual models (top right). 18

Figure 2.1 Initial strategy of research activities in this study 26

Figure 2.2 Updated strategy to attain objectives of this study 28

Figure 2.3 Schematic diagram of Particle Soot Absorption Photometer (PSAP) 30

Figure 2.4 Flowrate calibration in PSAP 30

Figure 2.5 Schematic diagram of dual-beam UV-absorption ozone photometer 32

Figure 2.6 Schematic diagrams of the newly developed PM2.5 sensor: 34

Figure 2.7 PM2.5 optical sensor calibration 35

Figure 2.8 Three typical patterns of BC, O3 and PM2.5 concentration in Hanoi 36

Figure 2.9 Local, regional and remote sources to Hanoi 39

Figure 2.10 Screenshot of monitoring portal of CEM website

http://enviinfo.cem.gov.vn/ 41

Figure 2.11 Screenshot of monitoring portal of AQICN website http://aqicn.org/ 42

Figure 3.1 Monthly average of BC, PM2.5 and TO3 in Hanoi in 2019 44

Figure 3.2 Timeseries of BC, TO3 and PM2.5 in Hanoi associated with

meteorological data in winter 2019 47

Figure 3.3 Timeseries of BC, TO3 and PM2.5 in Hanoi associated with

meteorological data in spring 2019 48

Figure 3.4 Timeseries of BC, TO3 and PM2.5 in Hanoi associated with

meteorological data in summer 2019 49

Figure 3.5 Timeseries of BC, TO3 and PM2.5 in Hanoi associated with

meteorological data in autumn 2019 49

Figure 3.6 Hourly concentration of PM2.5, BC and O3 in Hanoi 51

Figure 3.7 PM2.5 concentration in Hanoi during Tet 2020 compared with 2019 52

Figure 3.8 SLCPs in Hanoi during lockdown as coronavirus widespread 53

Figure 3.9 PM2.5 of Hanoi in April 2020 compared with April 2019 53

Figure 3.10 Trajectories of SLCPs in Hanoi associated with meteorological data in wintertime 2019 54

Figure 3.11 Time series of BC, TO3 and PM2.5 in Hanoi associated with meteorological data in 2019 55

Figure 4.1 Correlation of BC and PM2.5 in each season 56

Figure 4.2 Correlation of TO3 and PM2.5 in each season 57

Figure 4.3 Photochemical smog in Hanoi 58

Figure 4.4 SLCP Transport Areas in each season 60

Figure 4.5 Winter variation of SLCP Transport Areas 61

Figure 4.6 Spring variation of SLCP Transport Areas 62

Figure 4.7 Summer variation of SLCP Transport Areas 63

Figure 4.8 Autumn variation of SLCP Transport Areas 64

Figure 4.9 Comparison of transport features and observed enhances of BC and PM2.5 65

Figure 4.10 Diurnal variation of BC and TO3 in Hanoi 65

Figure 4.11 PM2.5 in Hanoi compared with coastal cities in Northern Vietnam .66

Figure 4.12 Atmospheric heating rate of BC 68

(Source: Ramachandran and Kedia, 2009) 68

Figure 4.13 BC concentration in Tokyo have decreased 3 time by stringent regulations for PM emissions 69

Figure 4.14 The differences between the prior and posterior anthropogenic BC emissions for April and October 2006, using OMI_GC AAOD_BC as the observation. 69

Top of the AtmosphereUltra-Fine ParticleUltra-Violet

I would like to express my gratitude to Professor Kazuyuki Kita for his tirelessguidance and training It’s barely impossible to conduct this research without hislead

I thank VJU staff and lecturers, Dr Akihiko Kotera, Dr Hoang Thi Thu Duyen, Ms.Bui Thi Hoa for their great help in doing this project, especially in the hard time ofcoronavirus pandemic, so that this study can continue to moving forward

My appreciation and gratefulness go to JICA, Vietnam - Japan University, IbarakiUniversity and Vietnam National University of Forestry for their support to set upinstruments and implement SLCP monitoring systems in Hanoi

The results showed monthly average of BC, daytime TO3 and PM2.5 as 1-3μg/mg/m3,21-55ppbv, 18-65μg/mg/m3, accordingly Both BC and PM2.5 were remarkablyincreased during rush hours or night-time in diurnal variation In contrast, TO3 wasoften high at noon and depleted to zero at night These diurnal variations can beattributed to their local/regional emissions and production of them near Hanoi Theclimax episodes of BC and PM2.5 were observed in wintertime, especially inJanuary with periods lasting from 1 day to 1 week These high rises were mostlyassociated with winter monsoon trajectories from South China Sea, which actuallytransported emissions from North East region of Northern Vietnam These resultsfirstly show a large contribution of Northern Vietnam sources of SLCP to theirconcentrations.

Given the significant climate forcing of BC, this study strongly suggests thatmitigation measures to reduce BC in Vietnam can considerably improve bothregional climate change and air quality in the Northern Vietnam region

CHAPTER 1 BACKGROUND AND OBJECTIVES

“Science is where revolutions happen.”

~Carlo Rovelli

As a physicist and bestselling author, Carlo Rovelli, a professor at Aix-MarseilleUniversity has guided thousands of readers through a marvelous adventure ofphysical world in his wonderful book named ―Seven Brief Lessons on Physics‖ In

this book, he also wrote: “Ever since we discovered that Earth is round and turns like a mad spinning-top, we have understood that reality is not as it appears to us”.

Overall, the Earth and the Universe still conceal many uncertainties and mysteriesfrom us Our mission is to find them out This will not only help us to survive fromcurrent threats and moving on but also enable us to tackle the incoming challenges

in the future

In this chapter, we will review the decadal efforts of scientists and researchers toimprove our understandings on black carbon, tropospheric ozone, and their impacts

on our climate system by comparing observations and simulations

However, before coming to basic definitions of SLCPs’ species and updatedmechanisms of their climate impact, we can have a look through a story behind apicture, which was taken nearby my place in Hanoi, evidently showed the

threatening existence of black carbon in everyday life of local residents

Figure 1.1 Critical air polluted condition in Hanoi by open biomass burning

In this above picture, local people were still doing exercises in a really badcondition of air quality of black and thick smoke from biomass burning nearby thestadium After two rounds, a middle-aged runner started coughing and walkingslowly to the source of the smoke There he met the burner burning leaves and trashbehind his house The conversation between them shifted from a low tone request to

a furious quarrel The thing that stopped them from diving into each other withkicks and punches was just a fence Suddenly, the fire became so much bigger andcaught into the house of the burner Someone started screaming The burner stoppedhis ―loud conversation‖ with the middle-aged man and urged people around to helphim extinguish the fire

It’s clear that no one could force the burner to stop burning leaves in the backyardbehind his house, but his own threat Every action has a motive

Whenever I crossed by the burnt house outside the stadium, I thought that if thosetwo men observed the small flame calmly and consciously, they would have soonrealized that it could turn into a really big fire in that dry and windy day Then, thetragedy could have been avoided

1.1 Definition of SLCPs and their significance

Several air pollutants, which have significant warming effects and short lifetime inatmosphere, are called Short-lived Climate Pollutants (SLCPs) Significant SLCPsare black carbon (BC) and tropospheric ozone (TO3) Besides, SLCPs also includenon-pollutants such as methane and hydrofluorocarbons (HFCs), which are alsoreferred as Short-lived Climate Forcers (SLCFs)

Until today, SLCP is still an unfamiliar topic and remains underrated in SoutheastAsia, and in particular Vietnam Recently, PM2.5 from biomass burning,transportation and thermal power plants have been taken into serious consideration

by localities due to its direct impacts to human health However, the link betweenSLCPs, especially black carbon and tropospheric ozone, with climate change issues

and sustainable development has not received enough concern from Vietnam

academia and policy makers

Figure 1.2 Global annual mean distribution of BC direct radiative forcing at TOA

(Source: Wang et al., 2014)

Recent studies have shown that radiative forcing by SLCP increase is evaluated to

be comparable with that by CO2 Sum of radiative forcing by SLCPs is estimated to

be 1.75W/m2, larger than 1.66W/m2 of CO2

Although the lifespan of SLCPs in the atmosphere is much shorter than carbondioxide (SLCPs’ is hours to years, while CO2 is a decade to century), SLCPs’radiative forcing is significant compared with CO2 According to a research of EPA

in 2016, the positive warming effect of BC, TO3 and methane in total is comparablewith that of CO2 and accounts for around half of total radiative forcing caused byhuman activities

Because of long lifetime of CO2, only mitigation actions on CO2 are insufficient,but cutting down SLCPs is necessary to achieve 1.5 C target by 2030 according to

SR 1.5 ̊C IPCC 2018

Figure 1.4 Model of CO2 and SLCP cuts compared with other pathways until 2100

(Source: Allen, 2015)

The short atmospheric lifetime of SLCPs means that their concentrations can bereduced in a matter of weeks to years after emissions are cut, with a noticeableeffect on global temperature within the following decades In contrast, CO2 has along lifetime, so the majority of the climate benefits will take many decades toaccrue after the reductions Long-term warming, however, will be essentiallydetermined by total cumulative CO2 emissions – assuming SLCPs are eventuallyreduced – and will be effectively irreversible on human timescales without carbonremoval Thus SLCPs and CO2 both have important effects on climate, but theseoccur on very different timescales (CCAC, 2014).

According to Special Report 1.5°C of IPCC, Human-induced warming has reachedapproximately 1°C above pre-industrial levels since 2017 At the present rate, theglobal temperature would reach 1.5°C around 2040 Pledges contained withincurrent NDCs are insufficient to put the world on a course to 1.5 ̊C, even with themaximum rates of change post-2030 available in the models (IPCC, 2018)

It should be taken into consideration that global temperatures could pass 1.5 Csooner if emissions do not decrease For example, the 1.5 ̊C guardrail could becrossed as early as 2030 if emissions follow the high emissions RCP8.5 scenariofrom IPCC’s 5th Assessment Report Following that scenario, even for a shortperiod, would make achieving a 1.5 ̊C virtually impossible (IPCC, 2013)

Therefore, it will be too late if mitigation is delayed An integrated multiple-benefitsapproach enables ambitious action by maximizing multiple-benefits and avoidingnegative trade-offs since climate change, air pollution, and sustainable developmentare inter-linked (CCAC, 2014)

Table 1.1 Key features of SLCPs compared with CO2

the Main Sources

atmosphere

(40%), biomass toxic chemicals to

BC (best 4-12 days burning (40%), biofuels the human body as

estimated)

Health:Cardiovascular,Precursor pollutants Respiratorydiseases

TO 3 +0.35 Hours - (CO, CH4, NMVOC, NOx)

Agriculture:

Weeks after photochemical

reaction reduction of crop

yield by damagingability to absorbCO2

Co-benefits of SLCPs’ cut will avoid negative trade-offs, since climate change, air

assessments coordinated by the UN Environment Programme (UNEP) haveidentified several “win-win‖ or synergy measures for near term climate protection

6

and clean air benefits (UNEP & WMO 2011; UNEP 2011a, UNEP 2011b) Fastuptake of these cost-effective and readily available measures, which targetemissions of short-lived climate pollutants (SLCPs) in key sectors, could bringrapid and multiple benefits for human well-being These measures are spread across

a variety of sectors, from waste management, where CH4 emissions can beharnessed as a source of energy, to transport, where high-emitting vehicles can beeliminated to reduce BC emissions, to industry where new technologies can bephased in to avoid use of HFCs with a high global warming potential (GWP) “Ifsomeone proposed that you could save close to 2.5 million lives annually, cut globalcrop losses by around 30 million tonnes a year and curb climate change by aroundhalf a degree Celsius, what would you do? Act, of course‖ UNEP’s ExecutiveDirector, Achim Steiner, has written “More than a decade of painstaking sciencehas built a case that cannot be ignored, namely, that swift action on the multiplesources of black carbon, HFCs, and methane can deliver extraordinary benefits interms of public health, food security and near term climate protection‖ (CCAC,2014)

Based on scientific evidence, Climate and Clean Air Coalition in 2014 stated thatthe rapid and large-scale implementation of SLCP control measures could delivernear term multiple benefits for climate change and sustainable development Recentreports have identified 16 BC and methane measures that can deliver significantbenefits to human well-being by protecting the environment and public health,promoting food and energy security, and addressing near term climate change.These measures involve technologies and practices that already exist and in mostcases are cost effective (CCAC, 2014)

If fully implemented by 2030, these measures could reduce global methaneemissions by about 40% and BC emissions by about 80% relative to a “reference‖scenario (UNEP & WMO 2011)

In short, SLCPs are responsible for a substantial fraction of near-term climatechange, with a particularly large impact in sensitive regions of the world, and canhave significant, detrimental health, agricultural and environmental impacts.However, the challenge is yet to be fully recognized by the international community(CCAC, 2014).

1.2 Definition of BC, TO 3 and PM 2.5 and their significance

As BC is a product of the incomplete combustion of fossil fuels, biofuels, andbiomass, the main sources of black carbon are open burning of biomass, dieselengines, and the residential burning of solid fuels such as coal, wood, dung, andagricultural residues (U.S EPA, 2012) When suspended in the atmosphere ordeposited on ice or snow, BC contributes to global warming by heating surrounding

areas, reducing albedo effect and causes human health problems as well

Figure 1.5 Dominant sources of BC from human activities

(Source: CCAC, nd.)

In terms of climate effect, BC heats surrounding atmosphere by absorbing incomingsolar radiation, leading to regional and global warming BC also contributes towarming in polar region and to melting Antarctic ice by depositing on cryosphere

BC is always emitted with co-pollutants, such as organic carbons and sulphates,which can have neutral or even cooling effect by dimming the sunlight and increasethe reflection ability of local or regional atmosphere Therefore, BC and co-pollutant particles may disturb the rainfall patterns by modifying atmosphericcirculation (semi-direct effect) and may affect Indian monsoon These effects wouldcreate impact on agriculture production, food security and sustainable development

of vulnerable countries, especially the ones in Asia and Africa

In terms of health effect, BC may cause cancer and has effects on cardiovascularsystem (WHO, 2013) BC and co-pollutants make up for most of the particulatematter 2.5 air pollution, one of the leading environmental causes of ill health andpremature death 3.5 and 3.2 million people die prematurely each year fromexposure to indoor and outdoor PM2.5 pollution, respectively (Lim S et al 2012)

1.2.2 TO 3

Ozone is a highly reactive gas composed of three oxygen atoms It is producednaturally in the stratosphere and is majorly produced from air pollutants in thetroposphere Depending on where it is in the atmosphere, ozone affects life on Earth

in either good or bad ways (EPA, 2012)

Figure 1.6 Schematic Display of Photochemical Ozone Formation in the

Troposphere(Source: CCAC, 2014)TO3 is the product of the chemical reactions involving a number of precursorpollutants as well as volatile natural organics precursor pollutants created by humanactivities include carbon monoxide (CO), non-methane hydrocarbons (NMHC) andnitrogen oxides (NOx), which are largely emitted by cars and other vehicles, fossil

fuel power plants, oil refineries, the agriculture sector and a number of otherindustries (UNEP, 2011).

Although the lifetime of TO3 is just a few hours in the atmosphere, its impact to ourclimate system and social system is significant TO3, of which CO, NMHC, NOx arethe main precursors, is also a major air pollutant, which damages ecosystemstructure and functions and the health and productivity of crops, thus threateningfood security O3 also reduces the ability of plants to absorb CO2, altering theirgrowth and variety

TO3 has strong greenhouse effect because it absorbs infrared radiation from theearth surface in the atmospheric window at around wavelength of 9.6μg/mm

To the matter of human health, TO3 makes it more difficult to breathe deeply andvigorously, shortness of breath and pain when taking deep breaths, or coughing andsore throats It can cause respiratory diseases such as asthma, emphysema, lungcancer, chronic bronchitis, etc., TO3 is dangerous to children, old people, andsensitive patients (EPA, 2019)

To agriculture and forestry, TO3 causes lower crop yield by reducingphotosynthesis activity and by damaging leaves and roots It also has warmingeffect by reducing absorption of CO2 by vegetation

1.2.3 PM 2.5

are tiny particles whose diameter is smaller than 2.5 micrometer (30 timessmaller than human hair), and their major components are sulfate aerosol,

secondary organic aerosol and BC

Figure 1.7 Diagram shows PM2.5 particles size

(EPA, nd.)PM2.5 contains BC which accounts for up to 10% as a key warming effectcomponent However, BC is often emitted along with its co-pollutants Therefore,PM2.5 also includes other cooling effect component such as sulfate and organicparticles which stem from vegetation and incomplete combustion of coal and oil.Major sources of PM2.5 are incomplete combustion of coal, oil and biomass frommotor vehicles, thermal power plants, residential burning, burning of (agriculture)

PM2.5

waste and wildfires It is also produced from vegetation, construction sites, metaland chemical industry, etc.

PM2.5 except for BC has cooling effect by scattering solar radiation (parasol effect).Some PM2.5 components such as sulfate aerosol are significant as condensationnuclei to producing clouds and rain

Because PM2.5 particles are small enough to be breathed into deep lung and they cancause premature deaths According to WHO, the global deaths every year on PM2.5

is about 7 million people and it is increasing fast in developing countries, especiallySoutheast Asia Recently, the number of researches on PM2.5 has been increasinglyconducted in many countries due to its critical impacts on human health

In this study, PM2.5 is used as a proxy of BC, because their concentrations generallyshow a tight positive correlation and because PM2.5 concentration can becontinuously measured much easier than BC concentration

1.3 Preceding Studies: Status of SLCPs in Vietnam and Southeast Asia

SLCPs observation in Vietnam

Several studies have shown concentrations of BC and TO3 based on in situobservations in Vietnam However, they were mostly focused on air pollution Nosimultaneous observation of BC and TO3 have been conducted so far

Gatari et al (2006) sampled and analyzed atmospheric aerosols from seven ruralsites in North of Vietnam, east of Hanoi and stated that coal and heavy fuel oilcombustion were major sources of atmospheric pollutants in the area and thatbiomass burning and road transport had a marked influence on regional air quality

It was also concluded that Pha Lai thermal power plant was the dominant emitter ofcoal combustion emission and PM2.5 concentrations were strongly influenced byseasonal variations

Concerning the air pollution and photochemical smog in Hanoi, D.D An et al.(2008) stated that photochemical smog potential in Hanoi at that time was still low.Analyzing hourly ozone concentrations in 2 year data (2002-2003), the result of thisstudy indicated that the high episode of TO3 was in March with ozone concentrationlarger than 46ppb and the emission sources were VOC and NOx emissions fromindustrialization and transportation in the city.

Sakamoto et al (2017) observed TO3 and its precursor pollutants CO, VOC andNOx in Hanoi, inner city area from 2015-2016 (1-year observation) The resultsfrom this research stated that the daily mean value of TO3 was 19.3 ± 15.3 ppb andthe correlation among CO, VOC and NOx indicated that the emission mainlyoriginated from vehicles including motorcycles, as well as buses, trucks and carswere the main sources of ozone precursors throughout the year

Investigating the seasonal and sub seasonal variation of ozone mixing ratio (OMR)

in Hanoi, Ogino et al (2013) mentioned that the minimum OMR shown in winterand maximum OMR found in spring and summer By analyzing 7-year ozonesondedata from Hanoi, the authors of this study concluded that low OMR air masses weretransported from the equatorial troposphere in winter, and high OMR air masses aretransported from the midlatitude stratosphere in summer

In general, there has been up to now few studies on SLCPs in Hanoi and Vietnam,and there are still uncertainties about BC and TO3 especially in the context ofclimate change

Climate influence of SLCPs in SE Asia

Figure 1.8 Planetary boundary layer (PBL) heating by surface emission of BC

BC particles absorb solar radiation and heat surrounding air, known as their directeffect Ramachandran and Kedia (2010) calculated the atmospheric heating ratesbased on the observed BC concentration and showed that heating rates including

BC aerosols are at least a factor of 3 higher than when BC aerosols are absent.However, the heating effect of BC is not very significant at the ground surface,because the atmospheric heating by BC is smaller than that by absorption of solarradiation by the ground In contrast, Tripathi et al (2007) and Wang et al (2018)calculated altitude profiles of the heating rate by BC was high throughout thesurface boundary layer although BC concentration gradually decreased withaltitudes Wang et al (2018) indicated that BC increased atmospheric temperature ataltitudes around the top of the surface boundary layer and that BC did not changethe surface temperature directly

Absorption of solar radiation by BC often enhances the temperature at abovealtitudes but does not change or decrease the temperature at the surface, and thisperturbation of the atmospheric temperature profile may change the atmospheric

circulation and distribution of precipitation, so-called semi-direct effect (e.g Kochand Del Genio, 2010) Lee and Kim (2010) suggested that BC radiative forcingcould change the circulation pattern to reduce precipitation especially in SoutheastAsia.

Although the climate influence by BC is difficult to quantitatively understandbecause it depends on various parameters: particle size, mixing state, altitudedistribution, atmospheric adjustment and so on (Matsui et al., 2018; Takemura andSuzuki, 2019), many model studies predicted that increase of BC emission causesignificant temperature increase near surface (Stjern et al., 2017; Sand et al., 2020)

Figure 1.9 Monthly mean BC mass concentration (left) and heating rate (right)

over Ahmedabad in 2008(Source: Ramachandrand and Kedia 2010)

Figure 1.10 Vertical profiles of heating rate due to aerosol black carbon calculated

from FBC profiles(Source: Tripathi et al., 2007; Wang et al., 2018)

Figure 1.11 Annual mean model median change in near-surface temperature (top

left), zonally averaged temperature change for the model median (black line) and

individual models (top right)

(Source: Stjern et al., 2017)The remaining panels in Figure 1.3.4 show individual model results Data are based

on the last 50 years of the coupled runs, and hatched areas in the model median mapindicate grid cells for which values are more than one multi-model standarddeviation away from zero

Although few studies have been focused on climate change by SLCPs in SoutheastAsia so far, it was studied as a part of Asian climate change especially in China andIndia The understanding about BC aerosols, ozone and their effects on regional andglobal climate has been improved through time.

Meehl et al (2008) mentioned possible effects of BC aerosols on Indian Monsoon

By simulating six-member ensemble of twentieth century with only BC varyingwhereas, natural and human-induced forcing fixed with their pre-industrial values,the researchers experimented the effects of BC over South and Southeast Asia.Differences of BC simulations showed that the radiative effects of BC aerosols weremost dramatic during the dry season over South Asia, and changes in thetemperature of air masses over India and Tibetan Plateau due to absorption andreflection solar radiation of BC aerosols would lead to anomalous inflow fromIndian Ocean to the south and increased precipitation over most of India in the pre-monsoon period (March, April, May) In summer, BC also weakened China rainfallwhile enhanced precipitation in Southeast Asia and Japan This study pointed thesignificance of BC aerosols for rainfall pattern over most of Asia and IndianMonsoon in particular

Lee and Kim (2010) discussed the effects of BC radiative forcing on decrease ofspring rainfall over Southeast Asia The results from this study showed that atypicalprecipitation patterns and associated large-scale circulation induced by BC radiativeforcing can explain observed rainfall reductions Therefore, BC was considered asone of the most important factors impacting precipitation trend in Southeast Asia.Although both Meehl et al (2008) and Lee & Kim (2010) agreed on possible effects

of BC on rainfall patterns in Southeast Asia, there were still many biases anduncertainties of BC radiative forcing due to underestimation of global models at thattime on solar radiation absorption of BC aerosols That was when Wang et al.(2016) estimated BC direct RF based on a model constrained by observations andindicated BC DRF in South and Southeast Asia This study reduced uncertainty in

BC RF from -101%/+152% to -70%/+71% over Asia and constrained BC RF of0.61 W/m2 This is the best estimate until now This implied that reduction in BCemissions would contribute to decrease the rate of global warming, but thecontribution could be less than previous thought.

In general, researchers in nearly a decade have found evidence linked SLCPs toclimate change, especially regional climate in Southeast Asia Chen et al (2017)also confirmed direct radiative forcing of anthropogenic aerosols, TO3 andgreenhouse gases and indicated that aerosol influence may change wind flow andprecipitation in East, Southeast, South Asia in winter This one more time rang thebell for policy makers, entrepreneurs and stakeholders to take SLCP’s cut intoserious consideration

Hang (2014) evaluated the impact of BC aerosols to temperature and precipitation

of Vietnam and surrounding regions from 1991 to 2000 by using RegCM 4.2 andmodule Chem_aerosol through 3 experimental simulation: no aerosols; BC fromhuman and biomass burning; and dust The results showed the average BC as 0.92 –1.17 mg/m2 The high rises of BC lasted from Nov to Mar, while low BC was fromJun to Sep due to wet deposition in rainfall season BC caused temperature decrease

in almost region, significant decrease in winter in India, Southeast China, Myanmar,Lao, N Vietnam from -0.3 to -0.8 Celsius degree Less decrease of T in summerand autumn (-0.1 to -0.3) in Lao and N Vietnam BC impact and dust impact onprecipitation was not clear however dust impact on rainfall was in larger than that of

BC In July, dust caused -8mm/month decreased precipitation in Myanmar and N.Vietnam

Van (2013) studied the ability to apply WRF-CHEM to Vietnam region by 2experiments of WRF_DUST and WRF_NOCHEM using meteorological data fromNCEP FNL in 2006 and emission inventories from RETRO and EDGAR Theresults showed the practical and meaningful application of WRF-CHEM toVietnam This was the first time 0.3 resolution simulated in Vietnam region with

2006 data file The simulation of emissions (PM10, PM2.5, SO2, dust) showedapplicability and could be applied in many other projects.

Beside reducing warming effect, SLCP’s cut could also reduce the rate of sea-levelrise ~20% in the first half of the century according to recent studies By 2100, thecombined mitigation of CO2 and SLCPs could reduce the rate of sea-level rise by

up to 50%, and cumulative sea-level rise by about 30% as compared to the samescenario (Hu A et al 2013)

1.4 Mitigation measures to reduce SLCPs in Vietnam and SE Asia

A number of countries participated in the Climate and Clean Air Coalition (CCAC),

a voluntary partnership of governments, intergovernmental organizations,businesses, scientific institutions and civil society organizations, for improving airquality and protecting the climate through actions to reduce short-lived climatepollutants (CCAC, nd)

Vietnam has become a partner of CCAC since 2017 to cooperate in implementingmeasures to mitigate methane in agriculture sector, especially in rice cultivation InVietnam, agriculture sector is responsible for 33% of total greenhouse gasemissions with livestock and rice production as primary sources Therefore, it isunderstandable and efficient to start cutting down methane as the first commitment

of reducing short-lived climate pollutants This is not only an ensured feasibleapproach but also a foreseeable efficient plan as Vietnam’s economy istransforming from agriculture sector to industry and service sector In addition,Vietnam starts contribution to cut down other SLCPs; requesting funding from

(https://www.ccacoalition.org/en/activity/vietnam-hfc-inventory), and Vietnamfreight assessment report (2017) which proposed actions for the development ofgreen freight program in Viet Nam, helping to reduce BC emission in Vietnam

In Southeast Asia, other countries have been actively contributed to SLCPs’reduction Thailand is developing their understandings on emissions of BC andprecursor pollutants of TO3 from biomass burning, vehicles and industrialproduction Lao is focusing on HFCs, municipal solid waste and agriculture.

1.5 SLCPs’ sources in Vietnam

Kurokawa and Ohara (2019) estimated air pollutants emissions including BCemission in Asia to make the Regional Emission inventory in ASia (REAS) version3.1, and showed NOx, most significant ozone precursor, and BC emission fromVietnam was 568 and 64 Gt/year in 2015 These values are larger than those fromLaos, Myanmar and Cambodia, similar to those from Thailand and Philippines, andmuch less than those from China and India

- Remote sources: long-range transport of air masses by human and industrialactivities in China, South Thailand and India; biomass burning in South China, India,Thailand, Myanmar and Lao

1.6 Objectives of this study

- To make clear the concentrations of BC, TO3 and PM2.5 in Hanoi and the

features of their variations based on in situ observations

- To identify source regions affecting the increase of these SLCPs in Hanoi for each season on the basis of the observed features and the trajectory analysis

The scope of this research mainly focuses on variations and sources of BC and TO3

as two species of short-lived climate pollutants in Hanoi The climate effects of BCand TO3 will be discussed in Chapter 4 based on results in Chapter 3 Quantitativeevaluation of warming effect by SLCP needs comprehensive climate model and isbeyond this study

CHAPTER 2 METHODOLOGY AND STRATEGY IN THIS STUDY

“In the real life, I was told, one had to abandon the impossible and embrace the practical.” “Give the

Constructing particle accelerator to create antimatter in a high school science fairwas the first ambitious project of young Michio, which earned him a ride toHarvard Today, Michio is known as the co-founder of string theory, finishing whatEinstein started, combining the theory of general relativity and quantum mechanics.More evidence and better understanding on string theory may one day allow us totravel between universes, into new dimensions, or even time travel

That is what people talked about Michio, actually I was more impressed with what

he described about Michael Faraday, the ―father‖ of force fields, which werepreviously thought to be useless Today, the light that we are using, and all theelectricity, computers and internet are driven by force fields of Faraday He hascreated forces to build our modern civilization However, not so many people knowthat the poor young Faraday was illiterate in mathematics Consequently, his

notebooks are full of hand-drawn diagrams, not of equations “Ironically, his lack

of mathematical training led him to create the beautiful diagrams of lines of forces that can be found in any physics textbooks nowadays”, Michio wrote in his recent

renowned book, Physics of the Impossible

Inspired by Michio and Faraday, I struggled to embrace this research without a solidbackground in natural science.

2.1 Strategy to attain the objectives

In order to achieve two objectives of this study, I apply the combination of theobservation of SLCPs, their source information, and the meteorological analysis Ihave observed data of black carbon, tropospheric ozone and particulate matter 2.5 inHanoi since December 2018, while I was in second semester of Master Program ofClimate Change and Sustainable Development in Vietnam - Japan University

Although these atmospheric compounds have been observed separately in Vietnam,

it is probably the first time to observe them simultaneously and compared Thissimultaneous observation will enable us to discuss their correlation to examine localsource contribution This is a significant advantage of this study

Figure 2.1 Initial strategy of research activities in this study

Figure 2.1.1 illustrates the original strategy of this study to attain our objectives Toanswer the questions (i) what is the concentration of SLCPs in Hanoi and how theyvary, we started and based on observational data as the primary data, becausereliable observations can directly provide these information To get the answer forthe question (ii) where do they come from and what source contribute to increaseSLCPs in Hanoi, we planned the correlation analyses of source distribution data andmeteorological data with the observational data After the data processing of blackcarbon, tropospheric ozone and particulate matter 2.5 to see the correlation, wefirstly examine their correlation and their diurnal variations Secondly, comparingthe observed variation of SLCP concentrations with the transport routes estimated

by the trajectory analysis, contributions of local/regional emission and that of thetransport from remote sources can be examined

In this study, a large contribution of remote sources was projected Contributions ofvarious remote source would be estimated from the integration of emission amountbased on the inventory data along air mass trajectories Because biomass burningemission has large variability, its contribution would be estimated using openburning signature derived from the remote sensing data along the air masstrajectory Comparing correlations of the observed variation with these estimation

of various sources, we can estimate that relative significance of them

However, in the process of this study, finding that local source more significantlycontributed to the increase of SLCPs than the projection, the focus of this study hasbeen changed to the local/regional source in the northern Vietnam The strategy ofthis study has been changed as to the following as illustrated in Figure2.1.2 Tomake clear the influence of local/regional sources, various features of the variation

of the observed SLCP concentrations with meteorological conditions includingtrajectories are examined as shown in the next section As one of key evidences, BCconcentrations observed at multiple sites surrounding Hanoi were compared Inorder to carry out this comparison, we use PM2.5 concentration data as a proxy or indicator of the BC concentration

Figure 2.2 Updated strategy to attain objectives of this study

2.2 Ground-based Observation

The primary data of this research are collected from our ground-based observationsystem which is provided by Professor Kazuyuki Kita with the support from JICA,Ibaraki University and Vietnam Japan University The instruments to measure BCand PM2.5 have been calibrated before shipping, the instrument to monitor TO3requires no calibration The detailed description, data processing and calibrationwill be described specifically each by each in below sections The incoming air flow

to BC and TO3 was pumped to one inlet, then it was separated to each BC and TO3instrument with different specialized tubes to ensure the same air sample andaccuracy for measurement All three instruments have been observed in VJU -MCCD office since December 2018

Picture: Simultaneous monitoring system of BC, TO3 and PM2.5 at VJU Hanoi