THE MONITORING ACTIVITIES
AT GAW STATIONS IN MALAYSIA
Maznorizan Mohamad, Toh Ying Ying, Mohd Firdaus Jahaya, Nur Aleesha Abdullah, Norazura Zakaria, Ng Chee Wah & Leong Kok Peng
Environmental Studies Division, Malaysian Meteorological Department, Ministry of Science, Technology and Innovation, MALAYSIA
PRECIPITATION CHEMISTRY MEASUREMENTS
INTRODUCTION
Rain acidity is commonly reported in pH. pH is a
measure of the hydrogen ion concentration in a
liquid and has a scale ranging from 0 to 14. Rain
from even very clean, remote sites is slightly acidic
with pH varying between 5.2 to 6.0 due to the
presence of dissolved natural acids, therefore rain is
only considered acidic if the pH is less than 5.2.
Since rainfall amount varies all the time, average
values of pH are volume weighted before
comparisons between sites are made. MMD uses
either the Acid Precipitation Sampler or the WetOnly Sampler to collect rainwater in its network. The
rainwater samples are accumulated weekly and a
biocide, thymol is used to prevent biological
degradation of the samples. The samples are then
sent to the Department of Chemistry’s laboratory for
chemical analysis.

The air quality monitoring network presently comprises of 23 stations, which 17 are located in Peninsular Malaysia, 4 in Sabah
and 2 in Sarawak.

3 Global Atmosphere Watch (GAW) stations:
 Regional (Developing Rural Site) - Cameron Highlands, Pahang
 Regional (Urban Site) - Petaling Jaya, Selangor
 Global (Forest Site) - Danum Valley, Sabah
REACTIVE GASES MEASUREMENTS
Currently, the Malaysian Meteorological Department continues to monitor gases such as sulphur dioxide (SO2) and nitrogen dioxide
(NO2) at the Petaling Jaya and Cameron Highlands site using the passive samplers. In addition to passive samplers, the Malaysian
Meteorological Department also monitors other gases and ions in the atmosphere at 3 GAW stations by using filter pack samplers.
The 2011 average percentage of gases and ions of atmospheric dry deposition for the 3 stations using filter pack samplers is shown
in Figure 6, whereby gases is the main contributor to the dry deposition compared to particulate ions.
The main gas found in the atmospheric dry deposition was ammonia (NH3) and Petaling Jaya has the highest concentration of NH3
followed by Danum Valley and Cameron Highlands. Meanwhile, ammonium (NH4+) is the main particulate ion found in the
atmosphere with the highest concentration of NH4+ was recorded in Cameron Highlands followed by Petaling Jaya and Danum
Valley.
EANET Participating Countries
The annual rainwater pH distribution map for the year 2000 to 2011 is shown in Figure 1, where
in the 2011, the state of Sabah and Sarawak received rainfall with pH between 5.2 and 5.6. In
Peninsular, Perlis state recorded the least acidic rainfall with the pH values > 5.6 followed by
Kedah with pH values between 5.2 and 5.6. The most acidic rainfall has been recorded in
Selangor with the pH values < 4.4 whereas other states of Peninsular received rainfall with pH
between 4.4 and 5.2. The areas that experienced high levels of acidity are categorized as rapid
growth centres, heavily industrialized with high population density.
PETALING JAYA
Figure 1
AEROSOLS MEASUREMENTS
THE GAW STATIONS IN MALAYSIA
Aerosols are made up of a composite group of matter which could be liquids or solids suspended in the atmosphere ranging in size from less than one
micron to almost a hundred microns. The major part of the mass of aerosols is contributed by the larger particles. Measurement of atmospheric aerosols
have consistently shown that 90% of the particles by numbers are less than 0.1 micron in diameter while more than 90% of the mass is associated with
particles of diameters larger than 1 micron. Particles in the 0.1 to 5-10 micron range are very significant to the human health because they are of
respirable size. Besides this effect, particles of these sizes can affect meteorological parameters such as visibility and solar radiation, and can be involved
in chemical reactions in the atmosphere producing secondary pollutants.
Global GAW Station Danum Valley
 Location: Lembah Danum, Lahad Datu, Sabah
 Forest site (Global/Baseline GAW)
 Latitude: 04° 58‘ 53" North
 Longitude: 117° 50‘ 37" East
 Altitude: 426 m above Mean Sea Level (MSL) - Atur Hill
 Within the 973 km2 forest reserve (managed by the Sabah
Foundation)
 Construction work began in 2002 under the 8th Malaysian
Development Plan
 Started operating in November 2003
Particulate Matter of less than 10 micron (PM10) concentration was measured at 16 stations in the monitoring network using the High-Volume PM-10
Sampler. The daily mean PM10 concentration in 2011 for Petaling Jaya and Cameron Highlands stations is shown in Figure 2 and Figure 3 respectively.
At an elevation of about 1500 m above sea level in fairly clean environment, Cameron Highlands showed lower PM10 concentration as compared to
Petaling Jaya station which is located in the urban area. Generally, the daily mean concentration of PM10 for Petaling Jaya and Cameron Highlands
stations was very much below 150.0 µg/m3 which is the recommended Malaysian Ambient Air Quality Guidelines.
Regional GAW Station Cameron Highlands
 Location: Tanah Rata, Cameron Highlands, Pahang
 Developing rural site (mountainous region)
 Latitude: 04° 28’ North
 Longitude: 101° 23’ East
 Altitude: 1545 m above Mean Sea Level (MSL)
CAMERON HIGHLANDS
DANUM VALLEY
Figure 6
OZONE MEASUREMENTS
Surface ozone in Danum Valley is measured using the THERMO 49i UV Ozone Analyzer. Surface ozone plays an
important role in physical, chemical and radiative process in the troposphere and also contributes to the
greenhouse effect. As shown in Figure 7, the daily average of ozone concentration recorded from July 2011 - June
2012 are ranged from 2.8 - 20.1 ppb.
Daily total column ozone is monitored in Petaling Jaya using the Brewer Spectrophotometer. The measured
amount of total column ozone varied between 232 and 283 Dobson Unit (DU) in 2011 (Figure 8). There is a
seasonal variation in ozone concentration but it is not as evident as those sites in the middle latitudes.
The vertical ozone profile is measured at Kuala Lumpur International Airport (KLIA), Sepang using ozonesonde
released at the beginning and middle of the month. The annual mean vertical ozone profile for 2011 is shown in
Figure 9. The profile shows a minimum at about 14 kilometers (km) above mean sea level (MSL) corresponding to
the top of the tropical tropopause layer. Above 15 km, ozone level increase rapidly to a maximum at about 27.5km
above MSL.
Figure 9
Regional GAW Station Petaling Jaya
 Location: Petaling Jaya, Selangor
 Urban site
 Latitude: 03° 6’ North
 Longitude: 101° 39’ East
 Altitude: 87 m above Mean Sea Level (MSL)
Figure 2
Figure 3
GREENHOUSE GASES MEASUREMENTS
MONITORING PROGRAMMES IN GAW STATIONS
It is known that one of the main contributors to the climate change are the long-lived GHG namely CO2, CH4, N2O and other lesser gases. MMD are
aware of the importance in keeping the status of GHG concentration updated, such that an environmental sustainability development could be properly
planned and structured. Among activities that MMD prioritized are the GHG monitoring and since 2004, MMD has collaborated with Commonwealth
Scientific and Industrial Research Organisation (CSIRO) in installing a LoFlo Mark II CO2 Analyzer at Danum Valley GAW station. At the same time MMD
is also collaborated with NIES since 2010 to install the Flask Sampling system in Danum Valley.
Figure 7
Figure 8
COLLABORATION AND COOPERATION WITH INTERNATIONAL
SCIENTIFIC COMMUNITY
 Twinning Programme with World Calibration Center for Physical Aerosol Properties (WCCPAP) Institute for Tropospheric Research, Germany
 National Institute of Environmental Studies (NIES), Japan - flask sampling
Wet Only Sampler
Brewer
APS
Filter Pack
XAD
Passive Sampler
TEOM
The LoFlo Analyzer measure carbon dioxide (CO2) continuously, while flask air samples are collected once a week. In order to maintain the accuracy of
the instrument, the LoFlo Analyzer is calibrated every 4 to 6 weeks. Figure 4 showed the hourly CO2 concentrations measured using LoFlo Analyzer and
weekly average CO2 concentrations measured using Flask Sampling at Danum Valley GAW Station from June 2009 to June 2012. The hourly CO2
concentrations ranged from 385 to 400 ppm while the weekly concentrations ranged from 380 to 400 ppm. Figure 5 showed the trend of annual average
CO2 concentration for both Danum Valley and Mauna Loa are quite similar with both are showing an increasing trend of 1.86 ppm/year for Danum Valley
and 1.98 ppm/year for Mauna Loa.
CSIRO - LoFlo Calibration
 Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia - LoFlo Mark II
CO2
 Collaboration with the Environment Canada on the Global Atmosphere Passive Sampling (GAPS)
programme - Persistent Organic Pollutants (POPs)
IFT Germany Nephelometer Calibration
 Acid Deposition Monitoring Network in East Asia (EANET) - Acid deposition
 Collaboration with World Radiation Centre, Davos, Switzerland - Aerosol Optical Depth monitoring
using Precision Filter Radiometer (PFR)
O3 Analyzer
PUF Disk
NIES - Flask Sampling
 Southern Hemisphere Additional Ozonesondes (SHADOZ) Programme - Ozonesonde
Flask Sampling
 European research project “SHIVA” (Stratospheric ozone: Halogen Impacts in a Varying Atmosphere)
HVAS PM-10
HVAS TSP
PFR
Multigas Analyzer
AWS
Ozonesonde
Nephelometer
MAAP
LoFlo Mark II CO2
Figure 4
Figure 5
 Yayasan Sabah, University Malaysia Sabah, Lancaster University, University of Leicester, University
of Cambridge, University of York, Leeds University, University of Manchester, University of East
Anglia, Centre for Ecology and Hydrology Edinburgh, Facility for Airborne Atmospheric Measurement
& National Center for Atmospheric Research and Environmental Protection Agency - Oxidant and
Particle Photochemical Processes Above a South-East Asian Tropical Rain Forest (OP3)
SHADOZ - Ozonesonde
EANET - Acid Deposition