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Gao T.,Inner Mongolia Meteorological Institute | Xuebin Z.,Environment Canada | Wulan,Inner Mongolia Meteorological Institute
Meteorological Applications | Year: 2010

The theme discussed in the present study is that of spring dust storm seasonal forecasts in Northern China. A comprehensive investigation of observations collected from 65 stations in Northern China, which studied strong winds for 35 years (1971-2005) and dust storms for 48 years (1961-2008), concluded that strong winds, which are recognized as a crucially dynamic factor, have unsurprisingly proven to be strongly related to dust storm activity. Therefore, determining effective predictors for strong winds should be helpful in spring dust storm forecasts. By employing this idea, comprehensive correlation analyses among the strong winds, dust storms and other influential elements from the oceans and the atmospheric circulations can be seen. From the spatial correlation fields between prior sea surface temperatures and the strong winds, four regions with higher oceanic coefficiencies are confirmed. The method of EOF (Empirical Orthogonal Function) decomposition is adopted to extract forecast signals from prior precipitation in Northern China and sea surface temperatures of those regions. The multivariable step-regression model is employed to select efficient predictors and the multivariable regression model is used to create forecast equations. With the cross validation approach, six series of 48 year hindcasts with six different predictor sets are conducted. Furthermore, the three-classification forecast method is used to judge successful or failed dust storm forecasts. Together, forecast skills of probability of detection and skill score suggest that series forecasts are better than random forecasts. The best forecast skill is gained from using the predictor set selected by the multivariable step-regression model. Copyright © 2010 Royal Meteorological Society.

Gao T.,Inner Mongolia Agricultural University | Gao T.,Inner Mongolia Meteorological Institute | Si Y.,Inner Mongolia Meteorological Science and Technology Service Center | Yan W.,Inner Mongolia Agricultural University | And 3 more authors.
Meteorological Applications | Year: 2014

Spring (March to May) is a crucial season for crop seeding and grass growth in Inner Mongolia (IM), China. Yearly harvests of agriculture, and animal husbandry, are controlled partially by spring precipitation. Based on the observations at 104 stations in IM, the spring precipitation during 1961-2010 was investigated and analysed. The results show that the amount of spring precipitation displays a trend associated with an increasing frequency of effective spring precipitation events (ESPE, with more than 10 stations among all observatories with over 10 mm daily precipitation). In addition, the synoptic conditions of the 141 ESPEs were studied through analysis of the sea level pressure (SLP), and 850, 700 and 500 hPa charts. They were classified into five types and named for the source positions of the frontal cyclones over the Eurasian continent on the SLP chart. Most of the Hetao, Mongolian and Huanghe cyclones in spring time, in general, bring strong wind, decreasing temperature or dust storms to IM. Sometimes they may also cause effective precipitation when the moisture transportation is favourable along the cyclone paths. The Northeast China cyclone mainly influences Northeast China and can lead to rainfall with adequate moisture supplies. In most cases, cold air from Siberia forms a frontal cyclone or a trough around Lake Baikal, and then heads eastward or southeastward, producing precipitation over large areas in IM in spring. Typical features of the synoptic evolutions of those five types are summarized and presented through analysis of representative ESPEs. © 2012 Royal Meteorological Society.

Wang H.-M.,Inner Mongolia Meteorological Institute | Wang H.-M.,Dalian Nationalities University | Li Z.-H.,Dalian Nationalities University | Wang Z.,Inner Mongolia Agricultural University
Chinese Journal of Applied Ecology | Year: 2013

Based on the monthly temperature and precipitation data of 15 meteorological stations and the statistical data of livestock density in Xilinguole League in 1981-2007, and by using ArcGIS, this paper analyzed the spatial distribution of the climate aridity and livestock density in the League, and in combining with the ten-day data of the normalized difference vegetation index (NDVI) in 1981-2007, the driving factors of the vegetation cover change in the League were discussed. In the study period, there was a satisfactory linear regression relationship between the climate aridity and the vegetation coverage. The NDVI and the livestock density had a favorable binomial regression relationship. With the increase of NDVI, the livestock density increased first and decreased then. The vegetation coverage had a complex linear relationship with livestock density and climate aridity. The NDVI had a positive correlation with climate aridity, but a negative correlation with livestock density. Compared with livestock density, climate aridity had far greater effects on the NDVI.

Gao T.,Inner Mongolia Meteorological Institute | Gao T.,Inner Mongolia Agricultural University | Jiang X.,The Observatory of Inner Mongolia | Hu Y.,The Observatory of Inner Mongolia
Theoretical and Applied Climatology | Year: 2013

Compared to the 50-year mean climatological value (1961-2010), the precipitation of middle-eastern Inner Mongolia exhibited a significant decrease during the past 10 years (2001-2010). To identify the climatic causes, a comprehensive investigation was conducted by inspecting climatic factors from this 50-year period, which appear to work together in connecting closely to the precipitation. Significant positive correlations with precipitation were found in sea level pressure (SLP) difference between the area of (30° N-20° S; 50-160° E) and the northeastern Pacific Ocean, between the Northern Atlantic and the northeastern Pacific Oceans, and sea surface temperature difference between the northeastern and northwestern Pacific in the previous year, while negative connections were found in the 500-hPa temperature difference between the Antarctic and the belt region around 60° S. During the period of 2001-2010, East Asia was prevailingly controlled by a huge high, which was regarded as one of unfavorable factors for producing rain or snow. Other factors were the enlarged 500 hPa temperature differences between the Antarctic and the zones around 60° S and the Equator, the negative SLP difference between the East Asia, northern Atlantic, and Pacific Oceans. Finally, the unique wind flows and associated moisture transports also played a key role in the precipitation reduction for the first decade of the twenty-first century. © 2012 Springer-Verlag.

Gao T.,Inner Mongolia Meteorological Institute | Gao T.,Inner Mongolia Agricultural University | Han J.,Inner Mongolia Observatory | Gao L.,Inner Mongolia Agricultural University | Yan W.,Inner Mongolia Agricultural University
Theoretical and Applied Climatology | Year: 2014

The study of the winter temperatures, averaged from the records of 11 observatories in the Da Hinggan Mountains and its western areas in China (DHM-WA), identified 11 extremely cold (≤ - 1.5 °C) and 13 extremely warm winters (≥ + 1.5 °C) during the past 60 years (1951-2010). The winters of 2011 and 2012 are another two extremely cold events. Aimed at exploring the climate causes, a comprehensive investigation is carried out on variations of some major atmospheric circulation components. Additionally, opposite circulation regimes are verified by examining the mean 500-hPa circulation patterns and sea level pressure (SLP) corresponding to 14 warm and 18 cold sea surface temperature (SST) phases over the North India Ocean (NIO) during the period of 1951-2010. Composite of an extremely cold winter usually includes a large and strong Siberian High, a deep East Asian trough to the west, an small and weak western Pacific Subtropical High to the east, a large North Polar vortex and a weakened westerly stream over Eurasia continent accompanied by a strong meridional winds from the polar region to lower latitude. Moreover, it has been found that a favorable circulation condition associated with the extremely cold winters to DHM-WA is mainly controlled by the SST over NIO in the previous warm season (June-September); This is primarily related to changes in the intensity of the Walker and Anti-Walker circulations, which subsequently influence the major circulation components and result in an extremely cold winter in DHM-WA. © 2013 Springer-Verlag Wien.

Yongmei,Inner Mongolia Normal University | Bao Y.,Inner Mongolia Normal University | Bao Y.,Northeast Normal University | Bilige,Inner Mongolia Meteorological Institute
Intelligent Systems and Decision Making for Risk Analysis and Crisis Response - Proceedings of the 4th International Conference on Risk Analysis and Crisis Response, RACR 2013 | Year: 2013

The Normalized Difference Vegetation Index (NDVI) derived from long-term satellite datasets (AVHRR/GIMMS [1981-2006] and MODIS/TERRA [2000-2010]) was used to estimate changes in the amount of vegetation. To investigate the causes of the vegetation change, we analyzed the month temperature, precipitation data and calculated the relationship with NDVI. The results indicated that the average NDVI was not seen clear increase and decrease tendency during the study period of 30 years, and annual NDVI change in the central part of the grasslands was larger compared with forest, desert and arable land. The NDVI in the growing season showed a high correlation with precipitation one to two months prior, and it turned out that there was a positive high correlation between temperature and NDVI in the early stage of the growing season in eastern Inner Mongolia, a negative correlation between June and August temperatures and NDVI in central Inner Mongolia. © 2013 Taylor & Francis Group.

Gao T.,Inner Mongolia Meteorological Institute | Han J.,Inner Mongolia Observatory | Wang Y.,Xilinhot National Climatological Observatory | Pei H.,Inner Mongolia Meteorological Bureau | Lu S.,Inner Mongolia Meteorological Institute
Meteorological Applications | Year: 2012

From 1961 to 2008, the overall frequency of dust storms in northern China has shown an unquestionable reduction. However, the Hunshdak Sandy Lands of northern China display an increasing frequency in dust storm activities, especially during the period 2001 to 2008. In an attempt to explore the cause of this increase, a comprehensive investigation was conducted by examining the climate variables, the average normalized difference vegetation index (NDVI) and the local inhabitant migrations. The climate variables include local precipitation, temperature, aridity, evaporation, relative humidity, soil moisture and wind speed. Moreover, by analyzing the 2001-2008 average anomaly charts (relative to the 30 year climatology of 1971-2000) of the upper air and surface conditions, an advantageous atmospheric circulation background for drought development over the Hunshdak was confirmed. Meanwhile, a multivariable step-regression model was employed to distinguish the significant variables of the climate elements mentioned before. The model output suggests that aridity is the leading factor impacting the Hunshdak dust storm frequency. During 2001 to 2008, the lack of local precipitation, higher temperature and strong evaporation deteriorated the local surface condition to below that before 2000, which is verified by the reduction of vegetation cover (NDVI), soil moisture and relative humidity. Furthermore, compared to the 30 year climatology of the wind speed observed during dust storm occurrence time, the mean velocity of 2001-2008 was reduced by 3.0 m s -1, indicating that even with relatively weaker winds, dust storms still occurred primarily due to the degeneration of surface conditions around the Hunshdak. © 2011 Royal Meteorological Society.

Gao T.,Inner Mongolia Meteorological Institute | Han J.,Inner Mongolia Observatory
Meteorological Applications | Year: 2010

The evolutionary characteristics of dust storms in spring in northern China springs are determined by synthesizing the previous patterns and analyzing the geopotential height at 500 hPa. Some potential seasonal predictors are found through detecting the atmospheric circulation factors in both qualitative and quantitative analyses. Based on the frequency series obtained through comprehensive investigations of dust storm events which occurred from 1970 to 2005, two sample sets, each containing 6 years, are selected to represent the most frequent and infrequent occurrences of spring dust storms. For the first set, most of the West Pacific subtropical highs in the previous summer are relatively small and weak compared to those in normal years. In the previous winter, the mid-latitude region of the Eurasian continent is strongly controlled by a large and active low system, simultaneously with a strong and westerly positioned trough over East Asia. The northern hemisphere polar vortex, in general, changes from weak to strong with a large area from the previous winter to the current spring. The geopotential height over the Tibetan Plateau keeps a lower than normal value with a relatively strong India-Burma trough from the preceding summer in to the spring. For the second set, the evolution displays opposite features. Furthermore, by using a bootstrapping technique, indices of the atmospheric circulation elements are detected quantitatively. The forecast skill score of the 36 year hindcast (1970-2005) indicates that those indices can provide forecast signals in certain situations for spring dust storm seasonal predictions in northern China. © 2009 Royal Meteorological Society.

Paek H.,University of California at Irvine | Yu J.-Y.,University of California at Irvine | Hwu J.-W.,Center for Research and Development | Lu M.-M.,Center for Research and Development | And 2 more authors.
Monthly Weather Review | Year: 2015

This study reveals a possible cause of model bias in simulating the western Pacific subtropical high (WPSH) variability via an examination of an Atmospheric Model Intercomparison Project (AMIP) simulation produced by the atmospheric general circulation model (AGCM) developed at Taiwan's Central Weather Bureau (CWB). During boreal summer, the model overestimates the quasi-biennial (2-3 yr) band of WPSH variability but underestimates the low-frequency (3-5 yr) band of variability. The overestimation of the quasi-biennial WPSH sensitivity is found to be due to the model's stronger sensitivity to the central Pacific El Niño-Southern Oscillation (CP ENSO) that has a leading periodicity in the quasi-biennial band. The model underestimates the low-frequency WPSH variability because of its weaker sensitivity to the eastern Pacific (EP) ENSO that has a leading periodicity in the 3-5-yr band. These different model sensitivities are shown to be related to the relative strengths of the mean Hadley and Walker circulations simulated in the model. An overly strong Hadley circulation causes the CWB AGCM to be overly sensitive to the CP ENSO, while an overly weak Walker circulation results in a weak sensitivity to the EP ENSO. The relative strengths of the simulated mean Hadley and Walker circulations are critical to a realistic simulation of the summer WPSH variability in AGCMs. This conclusion is further supported using AMIP simulations produced by three other AGCMs, including the CanAM4, GISS-E2-R, and IPSL-CM5A-MR models. © 2015 American Meteorological Society.

Gao T.,Inner Mongolia Meteorological Institute | Gao T.,University of California at Irvine | Yu J.-Y.,University of California at Irvine | Paek H.,University of California at Irvine
Theoretical and Applied Climatology | Year: 2016

The impacts of four teleconnection patterns on atmospheric circulation components over Eurasia and the Pacific region, from low to high latitudes in the Northern Hemisphere (NH), were investigated comprehensively in this study. The patterns, as identified by the Climate Prediction Center (USA), were the East Atlantic (EA), East Atlantic/Western Russia (EAWR), Polar/Eurasia (POLEUR), and Scandinavian (SCAND) teleconnections. Results indicate that the EA pattern is closely related to the intensity of the subtropical high over different sectors of the NH in all seasons, especially boreal winter. The wave train associated with this pattern serves as an atmospheric bridge that transfers Atlantic influence into the low-latitude region of the Pacific. In addition, the amplitudes of the EAWR, SCAND, and POLEUR patterns were found to have considerable control on the “Vangengeim–Girs” circulation that forms over the Atlantic–Eurasian region in winter or spring. The EA and EAWR mainly affect the westerlies in winter and spring and the POLEUR and SCAND, respectively, in summer and winter. Strong westerlies confine the extension of the North Polar vortex, which generally results in a small weak vortex and a shallow East Asian trough located in a position further east than normal. Furthermore, the North Polar vortex presents significant connections with the patterns during winter and summer. Analyses in this work suggest that the teleconnection patterns in summer could be driven, at least partly, by the Atlantic Multidecadal Oscillation, which to some degree might transmit the influence of the Atlantic Ocean to Eurasia and the Pacific region. © 2016 Springer-Verlag Wien

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