STATISTIC CHARACTERISTICS OF MCSS OVER ASIA AND WESTERN PACIFIC REGION

SHU Yu; PAN Yi-nong; WANG Wei

Abstract:

Mesoscale convective systems (MCSs) are severe disaster-producing weather systems. Previous attempts of MCS census are made by examining infrared satellite imageries artificially, with subjectivity involved in the process unavoidably. This method is also inefficient and time-consuming. The disadvantages make it impossible to do MCS census over Asia and western Pacific region (AWPR) with an extended span of time, which is not favorable for gaining a deeper insight into these systems. In this paper, a fire-new automatic MCS identification (AMI) method is used to capture four categories of MCSs with different sizes and shapes from numerical satellite infrared data. 47,468 MCSs are identified over Asia and western Pacific region during the warm season (May to October) from 1995 to 2008. Based on this database, MCS characteristics such as shape, size, duration, velocity, geographical distribution, intermonthly variation, and lifecycle are studied. Results indicate that the number of linear MCSs is 2.5 times that of circular MCSs. The former is of a larger size while the latter is of a longer duration. The 500 hPa steering flow plays an important role in the MCS movement. MCSs tend to move faster after they reach the maximum extent. Four categories of MCS have similar characteristics of geographical distribution and intermonthly variation. Basically, MCSs are zonally distributed, with three zones weakening from south to north. The intermonthly variation of MCSs is related to the seasonal adjustment of the large-scale circulation. As to the MCSs over China, they have different lifecycle characteristics over different areas. MCSs over plateaus and hill areas, with only one peak in their lifecycle curves, tend to form in the afternoon, mature at nightfall, and dissipate at night. On the other hand, MCSs over plains, which have several peaks in their lifecycle curves, may form either in the afternoon or at night, whereas MCSs over the oceans tend to form at midnight. Affected by the sea-land breeze circulation, MCSs over coastal areas of Guangdong and Guangxi always come into being at about 1500 or 1600 (local time), while MCSs over the Sichuan Basin, affected by the mountain-valley breeze circulation, generally initiate nocturnally.

Get Citation+

SHU Yu, PAN Yi-nong, WANG Wei. STATISTIC CHARACTERISTICS OF MCSS OVER ASIA AND WESTERN PACIFIC REGION [J]. Journal of Tropical Meteorology, 2012, 18(4): 457-472.

Export:

Article Metrics

STATISTIC CHARACTERISTICS OF MCSS OVER ASIA AND WESTERN PACIFIC REGION

School of Atmospheric Sciences and Key Laboratory for Mesoscale of Severe Weather/Ministry of Education, Nanjing University, Nanjing 210093 China Nanjing Meteorology Bureau, Nanjing 210008 China

School of Atmospheric Sciences and Key Laboratory for Mesoscale of Severe Weather/Ministry of Education, Nanjing University, Nanjing 210093 China

Received Date: 2011-02-25

Rev Recd Date: 2012-08-21

Abstract: Mesoscale convective systems (MCSs) are severe disaster-producing weather systems. Previous attempts of MCS census are made by examining infrared satellite imageries artificially, with subjectivity involved in the process unavoidably. This method is also inefficient and time-consuming. The disadvantages make it impossible to do MCS census over Asia and western Pacific region (AWPR) with an extended span of time, which is not favorable for gaining a deeper insight into these systems. In this paper, a fire-new automatic MCS identification (AMI) method is used to capture four categories of MCSs with different sizes and shapes from numerical satellite infrared data. 47,468 MCSs are identified over Asia and western Pacific region during the warm season (May to October) from 1995 to 2008. Based on this database, MCS characteristics such as shape, size, duration, velocity, geographical distribution, intermonthly variation, and lifecycle are studied. Results indicate that the number of linear MCSs is 2.5 times that of circular MCSs. The former is of a larger size while the latter is of a longer duration. The 500 hPa steering flow plays an important role in the MCS movement. MCSs tend to move faster after they reach the maximum extent. Four categories of MCS have similar characteristics of geographical distribution and intermonthly variation. Basically, MCSs are zonally distributed, with three zones weakening from south to north. The intermonthly variation of MCSs is related to the seasonal adjustment of the large-scale circulation. As to the MCSs over China, they have different lifecycle characteristics over different areas. MCSs over plateaus and hill areas, with only one peak in their lifecycle curves, tend to form in the afternoon, mature at nightfall, and dissipate at night. On the other hand, MCSs over plains, which have several peaks in their lifecycle curves, may form either in the afternoon or at night, whereas MCSs over the oceans tend to form at midnight. Affected by the sea-land breeze circulation, MCSs over coastal areas of Guangdong and Guangxi always come into being at about 1500 or 1600 (local time), while MCSs over the Sichuan Basin, affected by the mountain-valley breeze circulation, generally initiate nocturnally.

HTML

Reference (26)

[1]	MADDOX R A, ROGERS D M, HOWARD K W.Mesoscale convective complexes over the United States during1981－An annual summary [J]. Mon. Wea. Rev., 1982, 110:1501-1514.
[2]	HOUZE R A, SMULL B F, DODGE P. Mesoscaleorganization of springtime rainstorm in Oklahoma [J]. Mon.Wea. Rev., 1990, 118: 613-654.
[3]	FRITSCH J M, KANE R J, CHELIUS C R. Thecontribution of mesoscale convective weather systems to thewarm-season precipitation in the Unites States [J]. J. ClimateAppl. Meteor., 1986, 25: 1333-1345.
[4]	JIRAK I L, COTTON W R, MCANELLY R L. Satellite andradar survey of mesoscale convective system development [J].Mon. Wea. Rev., 2003, 131(10): 2428-2449.
[5]	MADDOX R A. Mesoscale convective complexes [J]. Bull.Amer. Meteor. Soc., 1980, 61(11): 1374-1387.
[6]	MADDOX R A. Large-scale meteorological conditionsassociated with midlatitude mesoscale convective complexes[J]. Mon. Wea. Rev., 1983, 111: 126-140.
[7]	MCANELLY R L, COTTON W R. Meso-β scalecharacteristics of an episode of meso-α scale convectivecomplexes [J]. Mon. Wea. Rev., 1986, 114: 1740-1770.
[8]	COTTON W R, LIN M S, MCANELLY R L, et al. Acomposite model of mesoscale convective complexes [J]. Mon.Wea. Rev., 1989, 117: 765-783.
[9]	BLUESTEIN H B, JAIN M H. Formation of mesoscalelines of precipitation: Severe squall lines in Oklahoma duringthe spring [J]. J. Atmos. Sci., 1985, 42: 1711-1732.
[10]	BLUESTEIN H B, MARX G T, JAIN M H. Formation ofmesoscale lines of precipitation: Nonsevere squall lines inOklahoma during the spring [J]. Mon. Wea. Rev., 1987, 115:2719-2727.
[11]	PARKER M D, JOHNSON R H. Organizational modes ofmidlatitude mesoscale convective systems [J]. Mon. Wea. Rev.,2000, 128: 3413-3436.
[12]	SHU Yu, PAN Yi-nong. Self-identification of mesoscaleconvective system from satellite infrared imagery [J]. J.Nanjing Univ. (Nat. Sci.), 2010, 46(3): 337-348.
[13]	ORLANSKI L A. A rational subdivision of scales foratmospheric processes [J]. Bull. Amer. Meteor. Soc., 1975,56(5): 527-530.
[14]	AUGUSTINE J A, HOWARD K W. Mesoscale convectivecomplexes over United States during 1985 [J]. Mon. Wea. Rev.,1988, 116: 686-701.
[15]	AUGUSTINE J A, HOWARD K W. Mesoscale convectivecomplexes over United States during 1986 and 1987 [J]. Mon.Wea. Rev., 1991, 119: 1575-1589.
[16]	VELASCO L, FRITSCH J M. Mesoscale convectivecomplexes in Americas [J]. J. Geophy. Res., 1987, 192:9591-9613.
[17]	MILLER D, FRITSCH J M. Mesoscale convectivecomplexes in the western Pacific region [J]. Mon. Wea. Rev.,1991, 119: 2978-2992.
[18]	LAING A, FRITSCH J M. Mesoscale convectivecomplexes over the India monsoon region [J]. J. Climate, 1993,6: 911-919.
[19]	LAING A, FRITSCH J M. Mesoscale convectivecomplexes in Africa [J]. Mon. Wea. Rev., 1993, 121:2254-2263.
[20]	ANDERSON C J, ARRITT R W. Mesoscale convectivecomplexes and persistent elongated convective systems overthe United States during 1992 and 1993 [J]. Mon. Wea. Rev.,1998, 126: 578-599.
[21]	MA Yu, WANG Xu, TAO Zu-yu. Geographic distributionand life cycle of mesoscale convective system in China and itsvicinity [J]. Prog. Nat. Sci., 1997, 7 (6): 701-706.
[22]	ROMATSCHKE U, HOUZE R A. Characteristics ofprecipitating convective systems in the premonsoon season ofSouth Asia [J]. J. Hydrometeor., (in press).
[23]	ZHENG Yong-guang, CHEN Jiong, ZHU Pei-jun.Distribution and diurnal variation of MCS over China and itsvicinity in summer [J]. Chin. Sci. Bull., 2008, 53(4): 471-481.
[24]	YU Fan, CHEN Wei-ming. Research on the cloudclassification for the bi-spectrum cloud picture [J]. J. NanjingInst. Meteor., 1994, 17(1): 117-124.
[25]	COTTON W R, ALEXANDER G D, HERTENSTEIN R,et al. Cloud venting－A review and some new global annualestimates [J]. Earth-Sci. Rev., 1995, 39: 169-206.
[26]	CORFIDI S F, MERRITT J H, FRITSCH J M. Predictingthe movement of mesoscale convective complexes [J]. Wea.Forecast., 1996, 11, 41-46.

STATISTIC CHARACTERISTICS OF MCSS OVER ASIA AND WESTERN PACIFIC REGION

Abstract:

References

Get Citation+

Share Article

Article Metrics

Proportional views

Manuscript History

Online:

通讯作者: 陈斌, bchen63@163.com