Sains Malaysiana 44(2)(2015): 167–173
Impacts of 2009 Typhoons on Seawater
Properties and Top Layer Ocean’s Structure
in the Northwest
Pacific Ocean
(Kesan Ribut Taufan pada Tahun 2009 kepada Sifat-Sifat Air Laut dan Struktur Permukaan
Laut di Barat Laut Lautan Pasifik)
DAYANG SITI MARYAM MOHD HANAN*, THAN AUNG
& EJRIA SALEH
Borneo Marine Research
Institute, Universiti Malaysia Sabah, Jalan UMS, 88400 Kota Kinabalu,
Sabah, Malaysia
Diserahkan: 26 Februari 2013/Diterima: 4 Ogos 2014
ABSTRACT
Passing over the ocean
surface, typhoon absorbs heat from the sea water as it needs the
heat as its 'fuel'. The process is via evaporation of water. Subsequently,
the sea surface temperature (SST)
in that area will significantly decrease. Due to strong typhoon
wind water is evaporated from the surface layer of the ocean, the
amount of water mass in that area is lost, but the same amount of
salt will remain, causing sea surface salinity (SSS) to increase.
Strong winds induced by typhoons will also cause turbulence in the
water, causing entrainment, where cold deeper water is brought up
to the surface layer of the ocean, which will consequently increase
its SSS
and change the isothermal layer and mixed layer depth
(MLD). Here, isothermal layer
means the ocean layer where temperature is almost constant and MLD is the depth where salinity
is almost constant. This paper focuses on the effect of typhoons
on SST, SSS,
isothermal layer and MLD by
taking 15 typhoons in the Northwest Pacific throughout 2009 typhoon
season (typhoons Lupit and Ketsana are used as examples
in results) into consideration. Temperature and salinity data from
selected Array of Regional Geostrophic Oceanography (ARGO)
floats close to the individual typhoon’s track are used in
this study. The results showed that SST decreased up to
2.97°C; SSS increased up
to 0.44 pss and majority of the typhoons
showed deepening of isothermal layer (between 39.8 m and 4.6 m)
and MLD
(between 69.6 and 4.6 m) after the passage of typhoons.
Passing of each individual typhoon also removed significant amount
of heat energy from the affected area. The highest amount of heat
of 841 MJ
m-2
to the lowest of 30 MJ m-2 was calculated during the
study period. For comparison purpose, an equivalent amount of electrical
energy in kWh is also calculated using the amount of heat removed
by the typhoons.
Keywords: Isothermal
layer; MLD; SSS; SST;
typhoon; western North Pacific Ocean
ABSTRAK
Semasa
merentasi permukaan lautan,
taufan menyerap
haba daripada air laut kerana ia perlu kepanasan sebagai bahan 'bakar'. Proses ini dilakukan melalui
penyejatan air. Oleh
itu, suhu permukaan
laut (SST)
di kawasan berkenaan
akan menurun.
Apabila air tersejat
daripada lapisan permukaan laut akibat daripada laluan taufan, jumlah jisim air di kawasan berkenaan akan berkurang,
tetapi jumlah
garam akan kekal
sama, menyebabkan
kemasinan permukaan laut (SSS)
meningkat. Angin
kencang dicetuskan oleh taufan juga
akan menyebabkan
pergolakan dalam air di kawasan itu yang menyebabkan percampuran dengan air sejuk dibawa dari kawasan
lebih dalam
ke lapisan permukaan
lautan yang meningkatkan
SSTnya dan juga mengubah
lapisan suhu
dan lapisan campur
kedalaman (MLD).
Kertas ini
memfokuskan kepada kesan taufan terhadap
SST, SSS,
lapisan suhu
dan MLD dengan mengambil 15 taufan di Barat Laut Lautan Pasifik sepanjang 2009 (taufan Lupit and Ketsana digunakan sebagai contoh dalam keputusan)
untuk kajian.
Data suhu dan
kemasinan daripada tatasusunan oseanografi geostropik serantau (ARGO) terapung
paling hampir dengan
trek taufan masing-masing digunakan dalam kajian ini. Keputusan menunjukkan bahawa SST menurun sehingga 2.97°C; SSS meningkat sehingga
0.44 pss dan
majoriti taufan
menunjukkan pendalaman lapisan suhu (antara 39.8 dan 4.6 m) dan MLD
(antara 69.6 dan
4.6 m) selepas laluan
taufan. Laluan setiap taufan
juga menyingkirkan jumlah kepanasan yang ketara dari kawasan
terlibat. Nilai kepanasan
tertinggi ialah
841 MJ m-2 dan
yang terendah ialah
30 MJ m-2 semasa
tempoh kajian.
Bagi tujuan perbandingan, nilai setara tenaga
elektrik dalam
kWh juga dikira menggunakan
amaun kepanasan
yang disingkirkan oleh taufan.
Kata kunci: Barat Laut
Lautan Pasifik;
lapisan suhu; MLD; SSS; SST; taufan
RUJUKAN
ARGO - Part of the integrated
global observation strategy. 2010. http://www.argo.ucsd.edu.
Accessed on 29 September 2010.
Babin,
S.M., Carton, J.A., Dickey, T.D. & Wiggert, J.D.
2004. Satellite evidence of hurricane induced phytoplankton blooms in an oceanic
desert. Journal of Geophysical Research 109: C03043.
Chen,
C.T.A., Liu, C.T., Chuang, W.S., Yang, Y.J., Shiah,
F.K., Tang, T.Y. & Chung, S.W. 2003. Enhanced buoyancy and hence
upwelling of subsurface Kuroshio waters after a typhoon in the southern East
China Sea. Journal of Marine Systems 42: 65-79.
Dickey,
T., Frye, D., McNeil, J., Manov, D., Nelson, N., Sigurdson, D., Jannasch, H.,
Siegel, D., Michaels, T. & Johnson, R. 1998. Upper-ocean
temperature response to hurricane Felix as measured by the Bermuda testbed mooring. American Meteorological Society 126:
1195-1201.
Emanuel, K.A. 1986. An
air-sea interaction theory for tropical cyclones, Part I: Steady state
maintenance. Journal of the Atmospheric Sciences 43(6): 585-604.
Garrison, T. 2005. Oceanography:
An Invitation to Marine Science. 6th ed. Belmont, CA: Thomson Brooks/Cole.
Gierach,
M.M., Subrahmanyam, B. & Thoppil,
P.G. 2009. Physical and biological responses to hurricane Katrina (2005) in a 1/25° nested
Gulf of Mexico HYCOM. Journal of Marine Systems 78: 168-179.
Hidore,
J.J. & Oliver, J.E. 1993. Climatology: An Atmospheric Science. NY:
Macmillan Publishing Company.
JTWC (Joint Typhoon
Warning Center). 2009. Annual Tropical Cyclone Report.
http://www.usno.navy.mil. Accessed on 15 May 2010.
Lin,
I., Liu, W.T., Wu, C.C., Wong, G.T.F., Hu, C., Chen, Z., Liang, W.D., Yang, Y.
& Liu, K.K. 2003. New evidence for enhanced ocean primary production triggered
by tropical cyclone. Geophysical Research Letters 30(13): 1718.
MODIS. 2012.
http://modis.gsfc.nasa.gov. Accessed on 16 April 2012.
Moran,
J.M., Morgan, M.D. & Pauley, P.M. 1994. Meteorology: The Atmosphere
and the Science of Weather. NJ: Macmillan College Publishing Company, Inc.
Muller-Karger, F.E., Vukovich, F., Leben, R., Nababan, B., Hu, C.
& Myhre, D. 2000. Remote Sensing Study of
Upwelling in the Northeastern Gulf of Mexico and the Effects of Hurricanes Earl
and Georges, Annual Report: Year 2. U.S. Department of the Interior Minerals
management Service. Gulf of Mexico OCS Region, New Orleans.
Price, J.F. 1981. Upper Ocean Response to a Hurricane. American
Meteorological Society 11: 153-175.
Robertson,
E.J. & Ginis, I. 1998. The
upper ocean salinity response to tropical cyclones. Graduate
School of Oceanography, University of Rhode Island.
Son,
S., Platt, T., Fuentes-Yaco, C., Bouman,
H., Devred, E., Wu, Y. & Sathyendranath,
S. 2007. Possible biogeochemical response to the passage of hurricane Fabian observed by
satellites. Journal of Plankton Research 29(8): 687-697.
Sorokin, Y.I. 1995. Coral Reef Ecology. Germany: Springer- Verlag Berlin Heidelberg.
Walker, N.D., Leben, R.R. & Balasubramanian, S. 2005. Hurricane-forced
upwelling and chlorophyll a enhancement within
cold-core cyclones in the Gulf of Mexico. Geophysical Research
Letters (32): L18610.
Wang,
X.D., Han, G.J., Qi, Y.Q. & Li, W. 2011. Impact of
barrier layer on typhoon-induced sea surface cooling. Dynamics of
Atmosphere and Oceans 52(3): 367-385.
Xiaoping,
J., Zhong, Z. & Jing, J. 2008. Upper
ocean response of the South China Sea to Typhoon Krovanh (2003). Dynamics of Atmospheres and Oceans 47: 165-175.
*Pengarang untuk surat-menyurat; email: dayang.siti.maryam@gmail.com
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