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Publications (7)0 Total impact

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    ABSTRACT: Based on 1979-2005 typhoon data and NCEP/DOE AMIP-II reanalysis, a study is performed of behaviors of tropical cyclones generated in the monsoon trough (MTTC hereinafter) in the western North Pacific as well as effects of the monsoon trough strength on their production. Evidence suggests that (1) during this period the MTTC yearly number experiences stages as follows: normal (1979~87), more MTTCs (1988~94), and fewer MTTCs (1995~2005); MTTC variation is marked by quasi-4 and -2 yearly periods, with 1994 as the change from more to fewer MTTCs in annual number; (2) in the years of anomalous MTTC number there are great difference in the onset/ending day and genesis position. In the years of fewer (more) MTTCs in comparison to mean, MTCC starts its activity later (earlier), terminating on an earlier (later) day, its genesis area is smaller (bigger), located south- (north-) and/or west- (eastward) of mean; 3) the ITCZ intensity affects the MTTC genesis position and yearly number. When the lower-level western North Pacific subtropical high is positioned south- (north-) of normal, cross-equatorial flows at Somali and 90~1600E are weaker (stronger), the monsoon trough is weaker (stronger) with its position south- and/or westward (north- and/or eastward) with respect to normal. At that time, in the tropopause, the south-Asian high is east- (westward) of mean and the oceanic upper-air trough is south- and/or westward (north- and/or eastward). And the distribution in the high and lower troposphere allows the small-value band of vertical wind shear to decrease (increase) for a smaller (bigger) domain for MTTC genesis, and convection is suppressed (intensified), leading to positive (negative) OLR anomalies over waters east of the Philippine so that MTTC is generated south- and/or westward (north- and/or eastward) relative to normal and MTTC annual number is anomalously smaller (greater).© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
    09/2007;
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    ABSTRACT: Based on 1979-2005 typhoon data and NCEP/DOE AMIP-II reanalysis, a study is performed of behaviors of tropical cyclones generated in the monsoon trough (MTTC hereinafter) in the western North Pacific as well as effects of the monsoon trough strength on their production. Evidence suggests that (1) during this period the MTTC yearly number experiences stages as follows: normal (1979~87), more MTTCs (1988~94), and fewer MTTCs (1995~2005); MTTC variation is marked by quasi-4 and -2 yearly periods, with 1994 as the change from more to fewer MTTCs in annual number; (2) in the years of anomalous MTTC number there are great difference in the onset/ending day and genesis position. In the years of fewer (more) MTTCs in comparison to mean, MTCC starts its activity later (earlier), terminating on an earlier (later) day, its genesis area is smaller (bigger), located south- (north-) and/or west- (eastward) of mean; 3) the ITCZ intensity affects the MTTC genesis position and yearly number. When the lower-level western North Pacific subtropical high is positioned south- (north-) of normal, cross-equatorial flows at Somali and 90~1600E are weaker (stronger), the monsoon trough is weaker (stronger) with its position south- and/or westward (north- and/or eastward) with respect to normal. At that time, in the tropopause, the south-Asian high is east- (westward) of mean and the oceanic upper-air trough is south- and/or westward (north- and/or eastward). And the distribution in the high and lower troposphere allows the small-value band of vertical wind shear to decrease (increase) for a smaller (bigger) domain for MTTC genesis, and convection is suppressed (intensified), leading to positive (negative) OLR anomalies over waters east of the Philippine so that MTTC is generated south- and/or westward (north- and/or eastward) relative to normal and MTTC annual number is anomalously smaller (greater).
    Proc SPIE 01/2007;
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    ABSTRACT: Using the 1961-2001 rainfall datasets from 25 typical stations in Fujian Province treated by means of Empirical Orthogonal Function (EOF), Fast Fourier Function (FFT), Continuous Wavelet Transform (CWT) and Orthogonal Wavelet Transform (OWT) study is made of sequences of flood/drought indices (Z index) in different seasons. Evidence suggests that 1) the regional flood/drought events have significant 2~3 year periods in 1965-1975 and the 1990s; 2) rainfall amount in the south opposite to that in the north shows pronounced 1- and 3~ 4-yearly periods after the mid 1980s; 3) quantitatively, precipitation occurs in the west to middle in an opposite way to the other parts of the province, with noticeable 1~2 yearly periods in 1985 - 1998, and more appreciable 9~13-yearly periods after the 1980s; 4) within the study period (1961-2001) the drought trend is more apparent in the south (east) than in the north (west), particularly in the 1990s; 5) the regional climate is relatively wetter (drier) in the 1960s and 1980s (1970s and 1990s).
    Proc SPIE 09/2006;
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    ABSTRACT: In studying on the components of surface radiation balance and heat balance over inhomogeneous landscape, the utilization of satellite remote sensing is indispensable. In this paper, a parameterization method based on the data of Landsat-7 ETM+ and 22 weather stations is proposed for deriving the regional distributions of the components of radiation and heat balance on surface over the South Ningxia area. The South Ningxia area is classified into five surface types, regional distributions of components for both balance are calculated for each type. Further more, distribution maps and frequency distribution of the parameters and components is given out. The results indicate: All regional distributions are obvious and regular and characterized by their terrain nature. The figures of the mountains and rivers are very clear for flourish vegetation growing there. It can be seen that the derived regional distributions of surface radiation balance and surface heat balance components for the whole mesoscale area are in good accordance with the land surface status.
    IEEE International Geoscience & Remote Sensing Symposium, IGARSS 2006, July 31 - August 4, 2006, Denver, Colorado, USA, Proceedings; 01/2006
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    ABSTRACT: Based on 1961-2003 NCEP/NCAR reanalysis treated with EOF, wavelet and cross wavelet techniques we investigate different space patterns of July-September precipitation over Fujian in relation to summer monsoon over the NW Pacific and Indian Ocean at a range of time scales. Results show that 1) the uniform rainfall all over the province and opposite distribution of precipitation in the SE to the NW part are the dominant modes, 2) the NW Pacific summer monsoon exerts steadier impacts on rainfall in the former case, manifested dominantly in the interannual variation especially after the mid 1980s, depending on the strong (weak) monsoon for excessive (insufficient) precipitation, with the response center in the eastern seaboard of the province whereas the Indian Ocean monsoon has rather stable influence on rainfall differing in amount between SE and NW Fujian, mainly in the interdecadal variation, and it also exerts remarkable effects on the interannual variation subsequent to the mid 1980s, relying on the intense (weak) monsoon for more (less) precipitation in the SE and less (more) in the NW part in this season. It follows that the NW Pacific (Indian) monsoon has its effect on the rainfall amount (space distribution) during July to September, and 3) with the strong monsoons over the two oceans the difference in rainfall between SE and NW Fujian is increased and in the opposite case precipitation is lower over much of the province, and when the monsoons are contrary in intensity the departure field shows a complicated pattern, manifesting pronounced locality.
    IEEE International Geoscience & Remote Sensing Symposium, IGARSS 2006, July 31 - August 4, 2006, Denver, Colorado, USA, Proceedings; 01/2006
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    ABSTRACT: The paper investigates the multiple time scale features of the annual frequency of tropical cyclones (TC) affecting Fujian and the air - sea background in abnormal TC frequency years in 1884~2003, leading to the conclusions as follows: (1) The province experiences two (three) stages of more (fewer) TC hitting, with the turning years being 1902,1931, 1955 and 1971, and the last in particular serves as the strong turning point for the frequency change on a yearly basis. The frequency experiences oscillations in quasi-13, -4 and -2.5 years, and especially the quasi-4 year oscillations are the most significant;(2) examining the summertime 500hPa height field in the years of more (fewer) TC striking the province, we find the geopotential heights over the Okhotsk Sea to be lower (higher) than in normal years, and the anomaly to be characterized by a "- + -" ("+ - +") pattern from high to lower latitudes, the zonal (meridional) circulations to prevail, the westerly trough, the northern limit of the subtropical high (sub-high) and its ridge line to be northward (southward) of average; (3) a noticeable negative (positive) SSTA band is found over the eastern equatorial Pacific as well as a swathed positive (negative) SSTA in the western Pacific dominant source region of TC and also the NW Pacific, indicating that the frequency of TC affecting Fujian depends not only on SST in the TC genesis area but the position and intensity of atmospheric circulations that play a crucial role in the TC track, which thus affects the yearly frequency of TC influencing Fujian.
    IEEE International Geoscience & Remote Sensing Symposium, IGARSS 2006, July 31 - August 4, 2006, Denver, Colorado, USA, Proceedings; 01/2006
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    ABSTRACT: Analyses and assessment on the influence of sanddust activities in the Hexi Corridor on the PM10 concentration in Lanzhou city from 2001 to 2005 lead to the following conclusions of this paper. Lanzhou PM10 concentrations (LPC) possess a double-peak annual distributive character with one peak in December and the other in next March both in the same winter half-year, however, the number of the sanddust activities in the corridor shows a single-peak annual variation with the peak in April (9.8 times/month). It is known from comparing the distributions of the both that the peak value of the number of Hexi sanddust activities (HSA) corresponds to the sub-peak of LPCs in spring, and it is held that the winter particular boundary layer condition is mainly responsible for the peak of LPC in December. The number of spring HSA is positively/significantly correlated with the LPC in the same time period, i.e. the frequent period of HSA corresponds to the sub-peak period of LPCs. The quantitative analyses of sanddust indices indicate that 15.7 %, 37.8%, and 49.5% of the annual, march, April LPCs are associated with the impact of HSAs, respectively, and 8%, 12.7%, 19.8% of the annual, march, April LPCs arise from the PM10 particles transfer of HSAs. The HSAs lead to the multiplication of the LPC in successive impacting day, but the impacting extent is different in different time periods.
    Proc SPIE 01/2006;