This study analyzed energy fluxes and the surface energy budget in the surface layer of a tropical coastal ocean in Malaysia over a two-year period. Key findings include: - Solar radiation and net radiation decreased annually by 3-4% while latent heat flux decreased 13% and sensible heat increased 7%. - The largest energy deficit occurred in April and lowest in November, following cycles of solar radiation and net radiation. - Evaporation was strongest in the Northeast Monsoon and weakest in the Southwest Monsoon. - Variations between the two monsoon seasons were larger (18-30%) than annual variations (7-13%).

1. Energy Fluxes in the Surface
Layer of a Tropical Coastal Ocean
Yusri Yusup, PhD
(Universiti Sains
Malaysia)
John Stephen
Kayode, PhD
(Universiti Sains
Malaysia)
Abbas F.M.
Alkarkhi, PhD
(Universiti Kuala
Lumpur)
International Conference on Atmospheric Chemistry and Climate Change in Asia 2018
27-28 March 2018
Universiti Kebangsaan Malaysia

2. Why the tropical coast?
Energy Fluxes in the surface layer of a tropical coastal ocean
Source: http://carboncycle.aos.wisc.edu/ocean-update/
• A dynamic and heterogeneous
location that is under-examined.
• The response of the surface energy
budget to climate change is less
understood.
• The response of low-latitude water
bodies are different than their high-
latitude counterparts.
• Sesonal effects are local but important.
• Energy fluxes correlate with mass flux (e.g.
carbon flux).
Problem statement:
The purpose of this study is to determine the
variations of the energy fluxes and the surface
energy budget in the surface layer of a tropical
coastal ocean.

3. Location: The Muka Head Research
Station
07/02/18 Energy Fluxes in the surface layer of a tropical coastal ocean 3
• At the Centre for Marine and Coastal Studies (CEMACS),
Universiti Sains Malaysia.
• Intertidal zone of the tropical coastal ocean in southern
South China Sea and Straits of Malacca in the Eastern
Boundary Current (EBC).(5°28’6’’N, 100°12’1’’E)

4. 07/02/18
Energy Fluxes in the surface layer of a tropical
coastal ocean 4
The Muka Head
Research Station
National Forest Reserve

5. Dataset and Data Processing
• Frequency: Half-hourly
(33,452 data points)
• Period: 2 years from 12
November 2015 to 8 October
2017
• 20-Hz data processed by
EddyPro®.
• Data analyses and processing
by R and Rstudio®.
• Removed fluxes data that failed
QC.
• Removed energy fluxes not
from the coastal ocean.
07/02/18 Energy Fluxes in the surface layer of a tropical coastal ocean 5
Instruments Measured Variables
Open path CO2/H2O gas
analyzer (LICOR, LI-7500A)
at 4 m
CO2 and water vapor flux
Ultrasonic anemometer
(YOUNG,81000) at 4 m
Three-component wind
velocities (u, v, w)
Two temperature
thermistors (LICOR) at
depths of 0.5 m and 2.5 m
Sea surface and beneath the
sea surface temperatures
Temperature and relative
humidity sensor (HMP155,
Vaisala)
Temperature and relative
humidity
Pyranometer (LICOR, LI-
200SL)
Global radiation
Net radiometer (NR LITE 2,
Kipp & Zonen)
Net radiation

6. Instrumentation
07/02/18 Energy Fluxes in the surface layer of a tropical coastal ocean 6

7. Energy Budget: Tropical Coast
07/02/18 Energy Fluxes in the surface layer of a tropical coastal ocean 7
Rn
Energy residual

8. Daily-averaged Solar Radiation
[W m–2
]
07/02/18 Energy Fluxes in the surface layer of a tropical coastal ocean 8
• One cycle from November to
October; max in April and min in
November.
• RG decreased 3%.
• RN decreased 4%.
• Average albedo = 0.28-0.29
2016 2017
RG 189.7 W m–2
184.6 W m–2
RN 137.0 W m–2
131.5 W m–2

9. Daily-averaged Energy Fluxes
[W m–2
]
07/02/18 Energy Fluxes in the surface layer of a tropical coastal ocean 9
• No apparent cycle for H.
• One cycle for LE from August to
July; max in February and min in
August.
• Strongest evaporation in the
Northeast Monsoon, weakest in
Southwest Monsoon.
• Bowen ratio = H / LE, averaged at
0.11 (typical ocean value); more
evaporation than heat (dry)
released.
• LE decreased 13%, increased 7%.
2016 2017
LE 9.72 W m–2
8.62 W m–2
H 1.70 W m–2
1.82 W m–2

10. Energy Residual [W m–2
]
07/02/18 Energy Fluxes in the surface layer of a tropical coastal ocean 10
Daily-averaged Energy Residual
[W m–2
]
• Largest energy deficit in April (end of Northeast Monsoon) and lowest in November
(Fall Transitional Monsoon)
• G, energy storage by the water, is at its highest at the same time as the largest
deficit.
• Followed the cycles of RG and Rn.
• Decreased 2%.
137.1 W m–2
134.1 W m–2

11. 07/02/18
Energy Fluxes in the surface layer of a tropical coastal ocean
11
Temperature
[°C] and Vapor
Pressure [kPa]
• Max T in April and min in
January.
• Water and air T follow the
same trend.
• Highest Δe in April and min
in January.
• Large energy residual
increase the heat stored in
the ocean and vice versa.
• Persistent unstable
atmosphere, ΔT = -2°C.
• Persistent pressure
gradient, Δe = -1.09 kPa.
29.6°C
27.7°C
4.16 kPa
3.07 kPa

12. Daily-averaged Wind Speed [m s–2
]
07/02/18 Energy Fluxes in the surface layer of a tropical coastal ocean 12
• One cycle from August to July.
• Largest U in February (Northeast Monsoon) and lowest in August (Southwest
Monsoon).

13. 07/02/18 Energy Fluxes in the surface layer of a tropical coastal ocean 13
Annually-averaged Monthly
Variation of Energy Flux [W m–2
]
• The ocean heats up
in the beginning of
the year and cools
as the year
progress.
• Evaporation
intensifies with
energy stored.
• Sensible heat
increases with the
cooling of the
ocean.
• Between Monsoons:
• ΔLE = -30%
• ΔH = +18%

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Conclusions
• From January to December that covers 2 Monsoons.
• Inter-seasonal variations are larger (18-30%) than annual variations (7-13%).

15. What’s Next?
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Energy Fluxes in the surface layer of a tropical
coastal ocean 15
• To collect more data that spans multiple
years.
• To close the energy budget by accounting
for tides, storage, and input mass.
• To collaborate with other researchers to
get a better understanding of the
exchanges of the tropical coastal ocean.
• To identify strong but specific events that
enhance energy exchanges.
• Data-sharing policy: available by request
and welcomed; e-mail me at
yusriy@usm.my or yusriyp@gmail.com.

16. Please visit
http://atmosfera.usm.my
or contact
Yusri at yusriy@usm.my or
+6012 388 7413