The Tibetan long-term monthly mean rainfall exhibits a SE to NW decrease, showing strong regionality. The summertime vigorous rainfall centers are roughly coincident with those of heat sources <Q1> averaged throughout the atmospheric extent, with latent heating making the greatest contribution to <Q1>. In the heat source stronger (weaker) year than normal, the western Pacific subtropical high amplifies (falls off), making westward extension (eastward withdrawal); the South-Asian high intensifies (weakening), eastward expanding (westward extending); summer monsoon becomes intense (enfeebled). In that case, the precipitation is more (less) in the Jiang-Huai valley compared to normal in relation to the rainfall lower (higher) than mean over the littoral provinces of South China, and two parallel anomalously deep wavetrains (just one wavetrain) of cyclones alternate with anti-cyclones over the Pacific.
The analysis of photochemical theory and HALOE, SAGE II, ECMWF/ERA-40 data indicate that ozone variations are
inversely correlated with temperature in the upper stratosphere, while ozone variations are positively correlated with
temperature in the middle stratosphere. Ozone layer mainly locates at middle stratosphere, where solar UV radiation is
largely absorbt. The radiation is main action in middle stratosphere, so temperature variation depends on ozone variation.
In the upper stratosphere, the ozone concentrations decrease rapidly, the photochemical actions instead of radiation
actions play a principal role. The ozone-depleting reaction rates depend on temperature, so the coefficient correlation of
Ozone and temperature is reverse.
ECMWF daily reanalysis is applied to investigate 1961-2001 heat source/sink and the climate features in relation to the
atmospheric heat distribution over the QTP (Qinghai-Tibetan Plateau) by means of the "inverse algorithm". Results
suggest that 1) in March - September (October - February), the QTP acts as a heat (cold) source, the strongest being in
June (December). For the region as a whole, the heat source feature lasts longer, with its intensity much higher compared
to the cold source; 2) as shown in the heating vertical profile, the maximum heat source layer occurs dominantly between
500-600 hPa, but with the season-dependent heating strength and depth, and, in contrast, the cold source has its
maximum layer and intensity varying as a function of time; 3) the horizontal distribution of the heat sources throughout
the troposphere 1> (from surface to 100 hPa) is complicated, displaying noticeable regionality, i.e., the heat source
changes faster in the western than in the eastern QTP, with the western source considerably stronger in April - August,
and intensified quickly enough to show a 200 W/m2 center in May, one month ahead of the eastern source. When July
comes the regional heat source begins to weaken towards the south, during which the western source weakens faster,
changing to a cold source in October, again one month earlier compared to the eastern counterpart; 4) since 1979 the
seasonal variability of the heat source has shown climate transition signals, as clearly seen in 1990/91.
Utilizing the NECP/NCAR reanalysis data, the annual atmospheric circulation over East Asia from 1981 to 2000 is
investigated. It is discovered that a zonal positive vorticity belt maintains to the south of Tibetan Plateau, due to the
interaction of the plateau boundary layer and its neighboring free atmosphere. Particularly, there is an obvious
topographic trough related to the positive vorticity near 90°E. According to this phenomenon, a Tibetan Plateau
Topographic Trough Index (TPTTI) is defined in the paper over the key areas (80-90°E, 25°N). The index is proved to be
effective in distinguishing between the characteristic of the Tibetan Plateau topographic trough (TPTT) and that of the
Bay of Bengal Trough (BOBT). The annual variation of the TPTT is closely related to the plateau heating source, and the
former's significant abrupt changes during April and June might be primarily induced by the seasonal sudden jump of the
latter. In winter, the low-level anticyclone caused by the Tibetan plateau cooling is strengthened and superimposes the
westerly wind that should have been strengthened by dynamic effect, which weakens the TPTT. However, in summer, the
low-level cyclone resulting from the Tibetan plateau heating strengthens the circumferential westerly and deepens the
TPTT. Further investigations indicate that there is a considerable relationship between the South China Sea summer
monsoon onset and the evolution of the TPTT and the BOBT. The TPTT propagates southward and the vortex near Sir
Lanka moves northward continuously, till they meet and interact over the Bay of Bengal. This is the direct process of the
subtropical high belt splitting initially over Bay of Bengal and the establishment of the BOBT. Subsequently, the
southwesterly wind becomes stronger and promotes the eastward retreat of subtropical high, causing the South China Sea
summer monsoon bursts over the whole South China Sea.
The trends of water vapor and methane in the stratosphere have been analyzed by using the HALOE data from 1992 to
2005. The variations of water vapor and methane averaged along latitude circle are analyzed in the levels 2hPa, 10hPa,
30hPa and 80hPa, which are taken as the upper, middle and lower stratosphere. Besides the seasonal and inter-annual
variations, The trends of water vapor and methane in various levels are not the same. The variations of water vapor and
methane generally are contrary. In the years when the water vapor increases, the methane decreases, and when the water
vapor decreases, the methane increases.
Based on the TRMM (Tropical Rainfall Measuring Missio) remote sensing data, the relationship between the daily
precipitation and the SST (Sea Surface Temperature) in the low latitude ocean area were analyzed during the Asia
monsoon season in this paper. By calculated the corresponding and lag correlation coefficient of the precipitation and the
SST in the low latitude ocean area in different domain, the paper discussed the relationship between the daily
precipitation and the SST in these areas during the onset, the middle and the terminative period of Asia monsoon season.
The results shown that the relationship was differently in dissimilitude ocean area and period.
EOF analysis has been conducted of the interdecadal variability of sea temperature anomaly fields at standard levels in the subsurface, and the abrupt change feature of sea temperature has been tested by use of movable t-test technique. A possible mechanism of the ocean-air system in the tropical Pacific is investigated by using the subsurface temperature, heat storage and wind stress data, leading to the main results as follows.
The analysis indicates that around 1980 there occurs a significant interdecadal abrupt change of temperature from sea surface to different depths, of which 4 modes show the accident and their formation is closely related to the southwestward subduction route of North Pacific sea temperature anomalies. The interdecadal signal of subduction in the window region of the North Pacific propagates southwestward to the subtropics, meeting the anomalous signal which propagates northeastward from the western Pacific at ~ 160-meter level in the thermocline. Therefore, the influence of the former on ENSO interdecadal variability might be indirect while the latter plays a more important role.
The western tropical South Pacific, which displays evident interdecadal variability, is the key region of the ENSO interdecadal variability. The positive temperature anomaly will move to the mid-tropical Pacific and the atmospheric response will excite an anticyclonic wind stress to the east of Australia, which will lead to the generation of a negative temperature anomaly in the tropical southwest Pacific. A similar evolution with an opposite sign will follow subsequently. The whole cycle takes about 13 years to complete.
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