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Temporal and Spatial Distribution of the Interannual Variability of the Global Precipitation in the Tropical Region

Author: ZhaoJingHua
Tutor: HuangFei
School: Ocean University of China
Course: Meteorology
Keywords: Tropical Rainfall S-EOF Spatial and temporal characteristics El Nino Modoki
CLC: P426.613
Type: Master's thesis
Year: 2008
Downloads: 39
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Abstract

In this paper, the use of the National Center for Environmental Prediction / National Center of Atmospheric Research (NCEP / NCAR) reanalysis data and the Climate Prediction Center Merged Analysis of Precipitation (CMAP) precipitation data, Season-reliant Empirical Orthogonal Function (S-EOF) analysis continuous power spectral analysis method, regression analysis and correlation analysis method, the space evolution of the global tropical precipitation with seasonal distribution and its interannual decadal changes, mainly the first two can be distinguished from each other and with the remaining modes distinguish primary modes were discussed in detail, and to explore the sea surface temperature corresponding to each of the main modes, abnormal atmospheric circulation and other factors affect the distribution of tropical precipitation space. Articles used in the S-EOF analysis method to extract the main modes of tropical precipitation According to the main modal eigenvalue, the first two modes, respectively, 23.7% and 12.2% of the total variance, statistical test results show that this The two modes can be distinguished and accounted for the variance, while the remaining modes are not independent, so we focus on these two modes. The first principal modal space distribution characteristics of tropical marine mainland equator perennial Americas and equatorial Atlantic region are a negative area, the central and western equatorial Pacific are a positive area, while the eastern equatorial Pacific Ocean Pacific, especially in the southern hemisphere was The seasonal variation of the small value of the area, the positive area and the negative area showed enhanced quarterly basis starting from the northern hemisphere summer, to the strongest winter, began to weaken after summer reached the weakest; variance largest regional tropical marine mainland area and in the equatorial Pacific, the seasonal variation is mainly reflected in the spring and summer smaller variance, autumn and winter. The second main modal space is characterized by northern and western equatorial Pacific and 200S areas near perennial are a positive area along the equatorial region of the strip of the southern hemisphere equatorial central and eastern Pacific as a strip of negative area along the equatorial regions, while the southern hemisphere Pacific southeast compared to the small value of the area in the South Atlantic region, the ocean continent and the Indian Ocean region affected by the seasons; biggest regional variance contribution mainly in the equatorial Pacific, also ITCZ ??region, seasonal changes mainly in summer, autumn variance contribution, winter and spring. The power spectrum analysis, PC1 exists a prospective 4.5-year cycle changes PC2 quasi fluctuations period of six years and nine years. Dominant tropical precipitation modal space distribution factors for the evolution of the El Nino season. By regression analysis shows that, the Pacific, the SST distribution to the western Pacific cold anomaly and the central and eastern Pacific warm anomaly, tropospheric Lower West Pacific region appear abnormal high pressure while the eastern Pacific appear abnormal low pressure, resulting in abnormal westerly in the equatorial regions, thus the tropical Central and Western Pacific's moisture transport to the tropical eastern Pacific, according to the principle of conservation of mass, the Western Pacific Region inevitable closing movement spoke to the equator, and strengthen the region Hadley circulation, while the equator asymmetric anomalous cyclonic circulation lead by the wind in Western Pacific ITCZ ??divergence from the equator in the eastern Pacific, because of this dual role led to the modal abnormal precipitation is concentrated in just a single narrow zone along the equatorial regions, with the development of the El Nino, the equatorial westerly continuously enhance the abnormal precipitation band can reach the shores of America across the Pacific; in the upper troposphere, the equatorial eastern Pacific abnormal Dongfeng throughout the tropical eastern Pacific are abnormally high pressure, due to the divergence of the high pressure, the rise in the region The movement is further enhanced; vertical velocity field 1400W east of the Pacific are abnormal upward motion, the upward motion is also exacerbated by the region's precipitation abnormal ones. The the dominant tropical precipitation second modal spatial distribution factors for the seasonal evolution of El Nino Modoki modal. By regression analysis that, in the Pacific, SST distribution presented the Pacific unusually warm, the abnormally cold zone in the eastern tropical Pacific and Western Pacific El Nino Modoki modal, the lower troposphere South Pacific latitudes there is a huge low-pressure, and southeast of Pacific enhanced subtropical high and Australian high in the spring, leading to the Western Pacific abnormal westerly East Pacific abnormal Dongfeng westerly and easterly in the central and western Pacific convergence to rise, resulting in exceptionally wet the area, from the tropical western Pacific westerly anomalies in 1800E nearby area is divided into two, turning into the northwest and southwest, respectively, in the North and South Pacific, the western tropical Pacific water vapor anomalies eastward, corresponding in the Pacific there are two rainy belt, one in the north of the equator ITCZ northward stretch south of the equator, a SPCZ strengthen; the divergence role of abnormally high pressure of the troposphere near the dateline, strengthen the upward motion of the Pacific region, and the vertical velocity field also show that the region as strong The upward motion, the Western Pacific Maritime Continent region and the East Pacific abnormal sinking motion, leading to the Western and Central Pacific Ocean wet precipitation abnormal distribution of the eastern Pacific and western arid.

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CLC: > Astronomy,Earth Sciences > Atmospheric science (meteorology ) > Meteorological elements,atmospheric phenomenon > Water vapor,condensation,and precipitation > Precipitation > Ordinary precipitation > Surface distribution
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