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Anthropogenic Threats to Degraded Forest Land in the Savannahs’ Region of Togo from 1984 to 2020, West Africa

Journal of Geoscience and Environment Protection 2024年第1期12卷 164-179页

作者： Kossi Senyo Ehlui Wouyo Atakpama Henrik von Wehrden Alagie Bah Edinam Kola Christian Anthony-Krueger Hodabalo Egbelou Kokouvi Bruno Kokou Tchaa Boukpessi West Africa Science Service center on climate Change and Adapted Land Use (WASCAL) University of the Gambia Banjul Gambia Laboratoire de Recherche sur la Dynamique des Milieux et des Sociétés Université de Lomé Lomé Togo Laboratoire de Botanique et écologie Végétale Département Botanique Faculté des Sciences Université de Lomé Lomé Togo West Africa Plant Red List Authority (WAPRLA) IUCN Species Survival Commission Gland Switzerland Faculty of sustainability Center of Methods Leuphana University of Lüneburg Lüneburg Germany center for International Forestry Research and World Agroforestry (CIFOR-ICRAF) Nairobi Kenya Laboratoire de Recherche sur la Dynamique des Milieux et des Sociétés (LARDYMES) Department of Geography FSHS University of Lomé Lome Togo Department of Science Education University of Cape Coast Cape Coast Ghana Institut Togolais de Recherches Agronomiques (ITRA) Lomé Togo Laboratoire de Recherches Biogéographiques et d’Etudes Environnementales Department of Geography University of Lome Lome Togo

This study focuses on the landscape dynamics of the savannahs’ region in the far north of Togo. Based on a literature review and satellite images analysis using GIS and remote sensing, the study aims to ascertain the effects of anthropogenic threats on the forest coverage of the Savannahs’ Region between 1984 to 2020. The objective is to clarify the dynamics of land use in the region from 1984 to 2000 and from 2000 to 2020. The findings indicate a significant decline in forest coverage within the region from 1984 to 2020, a trend attributed to land use patterns. Dry forests in the Savannah region are largely converted to farmlands, housing, dry savannahs or agroforestry parks, leading to a steady reduction in forest areas.

关键词： Forest Degradation Land Use Land Cover Savannahs Region Togo

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Simulations of the Tropical Intraseasonal Oscillation by the Atmospheric General Circulation Model of the Beijing climate center

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Acta meteorologica Sinica 2010年第5期24卷 571-583页

作者：董敏吴统文王在志张芳 Laboratory for climate studies of CMA National Climate Center

The performance of BCC （Beijing climate center） AGCM 2.0.1 （Atmospheric General Circulation Model version 2.0.1） in simulating the tropical intraseasonal oscillation （TIO） is examined in this paper.The simulations are validated against observation and compared with the NCAR CAM3 （Community Atmosphere Model version 3） results.The BCC AGCM2.0.1 is developed based on the original BCC AGCM （version 1） and NCAR CAM3.New reference atmosphere and reference pressure are introduced into the model.Therefore,the original prognostic variables of temperature and surface pressure become their departures from the reference atmosphere.A new Zhang-McFarlane convective parameterization scheme is incorporated into the model with a few modifications.Other modifications include those in the boundary layer process and snow cover calculation.All simulations are run for 52 yr from 1949 to 2001 under the lower boundary conditions of observed monthly SST.The TIOs from the model are analyzed.The comparison shows that the NCAR CAM3 has a poor ability in simulating the TIO.The simulated strength of the TIO is very weak.The energy of the eastward moving waves is similar to that of the westward moving waves in CAM3.While in observation the former is much larger than the latter.The seasonal variation and spatial distribution of the TIO produced by CAM3 are also much different from the observation.The ability of the BCC AGCM2.0.1 in simulating the TIO is significantly better.The simulated TIO is evident.The strength of the TIO produced by the BCC AGCM2.0.1 is close to the observation.The energy of eastward moving.waves is much stronger than that of the westward moving waves,which is consistent with the observation.There is no significant difference in the seasonal variation and spatial distribution of the TIO between the BCC model simulation and the observation.In general,the BCC model performs better than CAM3 in simulating the TIO.

关键词： Beijing climate center （BCC） atmospheric general circulation model （AGCM） tropical intraseasonal oscillation （TIO） simulation study

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Representativeness of Four Precipitation Observational Networks of China

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Acta meteorologica Sinica 2012年第4期26卷 454-466页

作者：任玉玉任国土 Laboratory for climate studies National Climate CenterCMA

Four precipitation observational networks with varied station densities are maintained in China. They are： the Global climate Observation System （GCOS） Surface Network （GSN）, the national Reference climate Network （RCN）, the national-Basic Meteorological Network （BMN）, and the national Ordinary Meteorolog- ical Network （OMN）. The GSN, RCN, BMN, and the merged network of RCN and BMN （R＆B） have been widely used in climatology and climate change studies. In this paper, the impact of the usage of different networks on the precipitation climatology of China is evaluated by using the merged dataset of All Station Network （ASN） as a benchmark. The results show that all networks can capture the main features of the country average precipitation and its changing trends. The differences of average annual precipitation of the various networks from that of the ASN are less than 50 mm （≤ 10%）. All networks can successfully detect the rising trend of the average annual precipitation during 1961-2009, with the R＆B exhibiting the best representativeness （only 2.90% relative difference） and the GSN the poorest （39.77%）. As to the change trends of country average monthly precipitation, the networks can be ranked in descending order as R＆B （1.27%）, RCN （2.35%）, BMN （4.17%）, and GSN （7.46%）, and larger relative differences appear from August to November. The networks produce quite consistent spatial patterns of annual precipitation change trends, and all show an increasing trend of precipitation in Northwest and Southeast China, and a decreasing trend in North China, Northeast China, and parts of central China. However, the representativeness of the BMN and R＆B are better in annual and seasonal precipitation trends, in spite of the fact that they are still far from satisfactory. The relative differences of trends in some months and regions even reach more than 50%. The results also show that the representativeness of the RCN for country average precipitation is higher than that of the BMN because the RCN has a more homogeneous distr

关键词： climate stations observational network monitoring precipitation climatology precipitation change

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Analysis of Isentropic Potential Vorticity for a Strong Cold Wave During 2004/2005 Winter

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Acta meteorologica Sinica 2008年第2期22卷 129-142页

作者：丁一汇马晓青 Laboratory for climate studies of China Meteorological Administration National Climate Center National climate center

Using the NCAR/NCEP daily reanalysis data from 1 December 2004 to 28 February 2005, the isentropic potential vorticity （IPV） analysis of a strong cold wave from 22 December 2004 to 1 January 2005 was made. It is found that the strong cold air of the cold wave originated from the lower stratosphere and upper troposphere of the high latitude in the Eurasian continent and the Arctic area. Before the outbreak of the cold wave, the strong cold air of high PV propagated down to the south of Lake Baikal, and was cut off by a low PV air of low latitude origin, forming a dipole-type circulation pattern with the low PV center （blocking high） in the northern Eurasian continent and the high PV one （low vortex） in the southern part. Along with decaying of the low PV center, the high PV center （strong cold air） moved towards the southeast along the northern flank of the Tibetan Plateau. When it arrived in East China, the air column of high PV rapidly stretched downward, leading to increase in its cyclonic vorticity, which made the East Asian major trough to deepen rapidly, and finally induced the outbreak of the cold wave. Further analysis indicates that in the southward and downward propagation process of the high PV center, the air flow west and north of the high PV center on isentropic surface subsided along the isentropic surface, resulting in rapid development of Siberian high, finally leading to the southward outbreak of the strong cold wave.

关键词： cold wave potential vorticity isentropic surface Siberian high East Asian major trough

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Role of anthropogenic forcing and atmospheric circulation in a lowtemperature event in February 2022 in eastern China

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Advances in climate Change Research 2023年第6期14卷 921-929页

作者： Zhi-Fan CHEN Ying SUN Xuebin ZHANG Tim LI Jin-Hua YU Key Laboratory of Meteorological Disaster Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environment Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science and TechnologyNanjing 210044China climate studies Key Laboratory National Climate CenterChina Meteorological AdministrationBeijing 10008lChina climate Research Division Environment and Climate Change CanadaToronto M3H 5T4Canada Department of Atmospheric Sciences University of Hawai at ManoaHonolulu HI 96822USA

In February 2022,eastern China experienced prolonged low temperatures,with significant impacts on agriculture,transportation,and power supply.The regional average temperature anomaly for February 2022 was-0.65℃,making it the third coldest February from 2000 to 2022.Understanding the influence of anthropogenic forcing and atmospheric circulation on low-temperature events is important for climate change adaptation and mitigation in the region.This study used observational and model data from the Coupled Model Intercomparison Project Phase 6 to conduct an extreme event attribution study.The results showed that anthropogenic forcing led to a 1.5-fold decrease in the probability of 2022-like events,with anthropogenic greenhouse gases being the primary contributors to this reduction.Conversely,aerosols slightly increased the likelihood of such events.To evaluate the role of atmospheric circulation in this event,we chose Siberian High as the key circulation system and employed circulation similarity,intensity classification,and regression methods to estimate the impacts of circulation patterns,circulation in-tensity,and human-induced circulation change.The results demonstrated that under the influence of the same anthropogenic forcing,the presence of an anomalous Siberian High and anomalously enhanced intensity of the Siberian High both increased the likelihood of such a cold event occurrence.However,anthropogenic forcing exerts a negligible effect on such cold events via anomalous circulation.

关键词： Low-temperature event Attribution Intensity of the Siberian high Anthropogenic forcing Atmospheric circulation

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Dynamic-statistics combined forecast scheme based on the abrupt decadal change component of summer precipitation in East Asia

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Science China Earth Sciences 2015年第3期58卷 404-419页

作者： GONG ZhiQiang ZHAO JunHu FENG GuoLin CHOU JiFan Laboratory for climate studies National Climate Research Center CMA College of Atmospheric Science Lanzhou University

基于 19832011 CMAP 数据，在东亚的降水异例和它的附近的海区域(此后叫的东亚为短) 在 1999 前表明 ++ 模式并且 + 模式以后；这个十的变化在相应 EOF3 部件主要被包含。然而， NCC_CGCM 预报结果是相当不同的，它在 1999 前揭示 ++ ... 详细信息

基于 19832011 CMAP 数据，在东亚的降水异例和它的附近的海区域(此后叫的东亚为短) 在 1999 前表明 ++ 模式并且 + 模式以后；这个十的变化在相应 EOF3 部件主要被包含。然而， NCC_CGCM 预报结果是相当不同的，它在 1999 前揭示 ++ 模式并且 ++ 模式以后。同时，基于这些关键 SST 区域改进 NCC_CGCMs 预报精确性的概率被讨论，并且动态统计的联合预报计划为增加在东亚在夏天降水包含的十的变化的信息被构造。独立样品预报结果显示这个预报计划罐头有效地修改十的变化信息在东亚在夏天降水包含了的 NCC_CGCMs (特别在 30 敢琠敨攠癮的区域吗？？

关键词：年代际变化东亚地区预测计划夏季降水动态统计组件系统误差修正预测准确率

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Conversion of Kinetic Energy from Synoptic Scale Disturbance to Low-Frequency Fluctuation over the Yangtze River Valley in the Summers of 1997 and 1999

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Advances in Atmospheric Sciences 2007年第4期24卷 591-598页

作者：李跃凤 Laboratory for climate studies National Climate CenterChina Meteorological AdministrationBeijing 100081

以便从摘要的规模骚乱调查动能的变换(SSD；时期≤ s 甚至天) 到一个低频率的变化(LFF；时期 < 七天) ， LFF 动能的预算方程被导出。精力变换当时为 1997 和 1999 的夏天计算、分析。结果证明到 LFF 的从 SSD 的精力变换显然在重降雨... 详细信息

以便从摘要的规模骚乱调查动能的变换(SSD；时期≤ s 甚至天) 到一个低频率的变化(LFF；时期 < 七天) ， LFF 动能的预算方程被导出。精力变换当时为 1997 和 1999 的夏天计算、分析。结果证明到 LFF 的从 SSD 的精力变换显然在重降雨期间在中间和更低的对流层被提高，建议这是导致重降雨的机制之一，尽管本地 LFF 动能不能被提高。

关键词：长江流域夏季天气变化低频波动动能变换

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ENSO Features, Dynamics, and Teleconnections to East Asian climate as Simulated in CAMS-CSM

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Journal of Meteorological Research 2019年第1期33卷 46-65页

作者： Bo LU Hong-Li REN Laboratory for climate studies & China Meteorological Administration–Nanjing University Joint Laboratory for climate Prediction studies National Climate Center China Meteorological Administration Xinjiang climate center Department of Atmospheric Science School of Environmental Studies China University of Geoscience

This study evaluates the performance of CAMS-CSM(the climate system model of the Chinese Academy of Meteorological Sciences) in simulating the features, dynamics, and teleconnections to East Asian climate of the El Ni?o–Southern Oscillation(ENSO). In general, fundamental features of ENSO, such as its dominant patterns and phase-locking features, are reproduced well. The two types of El Ni?o are also represented, in terms of their spatial distributions and mutual independency. However, the skewed feature is missed in the model and the simulation of ENSO is extremely strong, which is found—based on Bjerknes index assessment—to be caused by underestimation of the shortwave damping effect. Besides, the modeled ENSO exhibits a regular oscillation with a period shorter than observed. By utilizing the Wyrtki index, it is suggested that this periodicity bias results from an overly quick phase transition induced by feedback from the thermocline and zonal advection. In addition to internal dynamics of ENSO,its external precursors—such as the North Pacific Oscillation with its accompanying seasonal footprinting mechanism, and the Indian Ocean Dipole with its 1-yr lead correlation with ENSO—are reproduced well by the model. Furthermore, with respect to the impacts of ENSO on the East Asian summer monsoon, although the anomalous Philippine anticyclone is reproduced in the post-El Ni?o summer, it exhibits an eastward shift compared with observation;and as a consequence, the observed flooding of the Yangtze River basin is poorly represented, with unrealistic air–sea interaction over the South China Sea being the likely physical origin of this bias. The response of wintertime lowertropospheric circulation to ENSO is simulated well, in spite of an underestimation of temperature anomalies in central China. This study highlights the dynamic processes that are key for the simulation of ENSO, which could shed some light on improving this model in the future.

关键词： model evaluation ENSO dynamics teleconnection CAMS-CSM

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Boreal Summer Intraseasonal Oscillation and Its Possible Impact on Precipitation over Southern China in 2019

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Journal of Meteorological Research 2021年第4期35卷 571-582页

作者： Jieli HONG Zongjian KE Yuan YUAN Xie SHAO Laboratory for climate studies National Climate CenterChina Meteorological AdministrationBeijing 100081

Based on daily precipitation observation data in China,the intraseasonal oscillation(ISO)features of summer precipitation over southern China in 2019 have been investigated by wavelet and band-pass filtering analyses.The results show that enhanced(suppressed)precipitation occurred over southern China during early(late)boreal summer2019.The signals of both 10-20-and 30-60-day ISO in southern China are remarkable,with the amplitude of the10-20-day ISO larger than the 30-60-day ISO in boreal summer 2019.The synergistic effect of the 10-20-and 30-60-day ISO wet phases was found to exert a tremendous influence on persistent heavy precipitation in July 2019,when the amount of precipitation reached its maximum in southern China since 1981.The atmospheric circulation and convection evolution characteristics of both 10-20-and 30-60-day ISO are further investigated.An anomalous low-level anticyclone over the South China Sea is prominently linked to the wet phase of the 10-20-day ISO,whereas an anomalous low-level cyclone over southern China is dominantly associated with the wet phase of the 30-60-day ISO.Both events enhance the water vapor convergence and ascending motion over southern China.Thus,the atmospheric circulation that accompanied the synergism of the wet phases of the 10-20-and 30-60-day ISO resulted in persistent heavy precipitation over southern China in July 2019.

关键词： heavy precipitation intraseasonal oscillation(ISO) southern China

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Analysis of stable components in the extended-range forecast for the coming 10-30 days in winter 2010 and 2011

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Chinese Physics B 2013年第12期22卷 570-577页

作者：王阔封国林曾宇星汪栩加 College of Atmospheric Sciences Lanzhou University Laboratory for climate studies National Climate Center China Meteorological Administration

In this paper we try to extract stable components in the extended-range forecast for the coming 10–30 days by using empirical orthogonal function （EOF） analysis, similarity coefficient, and some other methods based on the National center for Environmental Prediction （NCEP）/National center for Atmospheric Research （NCAR） reanalysis daily data. The comparisons of the coefficient of variance of climatological background field and truth data in winter between 2010 and 2011 are made. The method of extracting stable components and climatological background field can be helpful to increase forecasting skill. The forecasting skill improvement of air temperature is better than geopotential height at 500 hPa. Moreover, this method improves the predictability better in the Pacific Ocean. In China, the forecast in winter in Northeast China is more uncertain than in the other parts.

关键词： stable components climatological background coefficient of variance

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