Abstract:We review the recent progress in studies of air-land interaction over the arid area of Northwest China and its impact on climate. The paper examines the analyses of the data observed continuously during the Field Experiment on Air-Land Interaction in the Arid Area of Northwest China (NWC-ALIEX) for 12 years and during many Intense Observation Periods of this project. The analyses of the land-surface parameters and studies of the characteristics of the boundary layer and air-land interaction in the arid area from continuous observations were reviewed as well as applications of these parameters to optimize the parameterization scheme in land surface models and to improve related land surface models. Moreover, we examined the characteristics of sensible heat transfer in the arid area of Northwest China and the impact of the air-land interaction in this area on climate variability in eastern China and its physical mechanism. We found a feature of high sensible heat transfer in spring and summer in the arid area of Northwest China, which has a strong impact on climate variability in eastern China. Finally, the issues that need further study and evaluation are also pointed out in this paper.

Abstract:The surface wind can be a better indicator of the onset of the Asian Summer Monsoon (ASM) system than the 850-hPa wind. The use of the new ASM onset index and analysis of pentad-isochrones, based on both the seasonal reversal of surface wind and the evident enhancement of rainfall, demonstrated that the onset of the Tropical Asian Summer Monsoon (TASM) first occurs over the southeastern Bay of Bengal (BOB) in May. It then propagates eastward to the Indochina Peninsula and reaches the South China Sea (SCS) in mid-May and the tropical North West Pacific (NWP) in early June. The surface depression of the Indian summer monsoon originates near the equatorial Arabian Sea, and then propagates northward to South Kerala in southwestern India in early June, indicating the onset of the Indian Summer Monsoon (ISM). In addition, the Subtropical Asian Summer Monsoon (STASM) is first formed over the NWP southeast of Honshu, Japan, and then it expands westward and merges into the precipitation zone of the SCS monsoon in early June, forming a northeast-southwest rainy belt. Almost at the same time, the summer monsoon reaches southeastern China and the Baiu in Japan also starts. In mid-June, the rainfall belt shifts northward to the Yangtze River and the Korean peninsula corresponding to the start of the Meiyu and Changma.
This paper also reviews some recent progress in dynamics studies on the ASM onset. In spring, an evanescent but strong warm pool is formed in the central-eastern BOB due to the combined forcing of the Tibetan Plateau and the large-scale land-sea distribution in South Asia. Due to the coupling between this warm pool at the surface and the pumping effect of the South Asia High (SAH) in the upper troposphere, a Monsoon Onset Vortex (MOV) usually develops over the eastern BOB, breaking the ridgeline of the subtropical high that is continuous in winter, resulting in the first onset of TASM over the BOB. Furthermore, the vertical easterly/westerly shear over the eastern/western BOB prompts/inhibits the convection and increases/decreases the surface sensible heat transfer from ocean to atmosphere, resulting in a monsoon onset barrier over the west coast of the BOB that prevents the westward propagation of the monsoon onset. Hence, the monsoon onset can expand only eastward followed by the successive onset of the SCS and the tropical West Pacific summer monsoon. The strong latent heat released by the monsoon rainfall induces the westward development of the SAH and the conspicuous strengthening of zonal asymmetric potential vorticity (PV) forcing. Accompanied by the mid-troposphere anticyclone over the Arabian Peninsula stimulated by strong local surface sensible heating, the depression near the equatorial Arabian Sea moves northward and grows to a monsoon onset vortex, causing the ISM onset. Overall, the three phases (i.e., the BOB, the SCS, and the Indian summer monsoon onset) of the TASM onset that persist for about one month can be considered as a consequential process driven by certain dynamic-thermodynamic rules covering a specific geographic environment, including the Tibetan Plateau and the land-sea distribution in South Asia.

Abstract:Recently, the relationship between the Madden-Julian Oscillation (MJO) and the El Niño-Southern Oscillation (ENSO), the numerical simulation (forecasting) of the MJO, and the influences of the MJO on weather and climate have become some of the major issues at the forefront of atmospheric science. Studies of the interaction between the MJO and ENSO and their results has been reviewed in previous papers; therefore, in this paper we present a comprehensive overview of recent research advances by Chinese scientists on the MJO’s influence on weather and climate, as well as numerical simulation (forecasting) of the MJO. The studies used the Australian Bureau of Meteorology Real-time Multivariate (RMM) MJO index to investigate the relationship between MJO and typhoon activity over the northwest Pacific. The results show that the MJO plays a significant role in modulating the genesis of the typhoon over the northwest Pacific. For the typhoon genesis number over the northwest Pacific, the ratio between the active and inactive periods of the MJO is 2:1. During the MJO active period, the ratio of the northwest Pacific typhoon genesis number between phases 2-3 of the MJO in which the convection center of the MJO is located in the tropical eastern Indian Ocean and MJO phases 5-6 where the convection center of the MJO is located in the western Pacific is also 2:1. Composite atmospheric circulations show that the distribution of the dynamic typhoon-influencing factors and heating sources of the western Pacific in the different MJO phases are very different. In phases 2-3 of the MJO, all the factors tend to suppress the development of convection and typhoons in the western Pacific. In MJO phases 5-6, however, these factors promote convection development and create a favorable large-scale background circulation for the generation and development of typhoons. The composites of the 30-60 day low-frequency kinetic energy at the 850 hPa level for the typhoon-rich years show positive low-frequency kinetic energy anomalies over the northwestern Pacific east of the Philippines and south of 15°N, indicating that the MJO activity is strong in that region. In contrast, on typhoon-poor years, negative low-frequency kinetic energy anomalies are found over the monsoon trough regions of the northwestern Pacific east of the Philippines suggesting that the MJO activity is weaker over that region. Generally speaking, there are more (less) typhoons over the northwestern Pacific in the years when the MJO activity over the northwestern tropical Pacific is strong (weak). Corresponding to the different MJO phases, the precipitation over eastern China is anomalous whether in winter or spring. In spring, during MJO phases 2-3, the middle and lower reaches of the Yangtze River are wetter, while South China is drier. During MJO phases 4-5, South China is wetter while the middle and lower reaches of the Yangtze River are drier. During the other phases of the MJO, the anomalous precipitation of eastern China is negative. In winter, during phases 1-3 (especially phases 2-3), South China is wetter; during phases 6-8 (especially phases 6-7) South China is drier. In summer, the MJO over the Indian Ocean (the western Pacific) can influence southeastern China through the wave-train effect of the westerly jet in the lower troposphere (the meridional circulation and subtropical high over the western Pacific) which results in a wetter (drier) season in southeastern China. Moreover, the continual anomaly of the MJO over the tropical middle-east Indian Ocean has a clear impact on summer rainfall in Yunnan on an interannual time-scale. The atmospheric circulation analysis and numerical simulations all show that strong convection for the different phases of the MJO will generate different teleconnection patterns (Rossby wave train). These will result in favorable (or unfavorable) circulation and conditions for rainfall in different regions of China, which is the primary mechanism responsible for the precipitation anomalies associated with the MJO. The simulation (prediction) of the MJO in the numerical model is far from success and still an open question. Our series of numerical simulations clearly indicates that the simulation of the MJO strongly depends on a convective parameterized scheme in the model; whether the model can reproduce a realistic diabatic heating profile of the tropical atmosphere is the key to a successful simulation of the MJO. The MJO activities in the model match those of the observations to a certain degree only when the maximum of the heating profile is located in the middle and lower troposphere. The results of these simulations are consistent with our previous theoretical studies.

Abstract:The present paper presents a concise summary of our studies on interdecadal and interannual variabilities of the Asian summer monsoon and its projection for recent five years, which can be summarized in the following three aspects:
1) A significant interdecadal weakening of the Asian summer monsoon was identified on the basis of our analysis of a 123-year precipitation dataset in China and studies made by Indian investigators. This variability has caused significant changes in summer precipitation patterns in both East and South Asia. In East Asia, the main monsoon precipitation belt has continuously retreated southward, leading to a precipitation pattern of droughts in North China and floods in South China. The interdecadal change in the preceding winter and spring over the Tibetan Plateau and the sea surface temperature anomaly (SSTA) of the tropical central and eastern Pacific, in addition to the resulting land-sea thermal contrast, are the main drivers for the weakening of the Asian summer monsoon. In the future, the responses of the South and East Asian summer monsoons to a warmer climate will differ, with a continuous weakening in the former and enhanced circulation and precipitation fields in the latter.
2) The interannual variability is mainly characterized by biennial and four-seven-year oscillations. The present paper focuses on formative processes, mechanisms and influences of tropospheric biennial oscillation (TBO) on precipitation in East Asia. The formation and cycle processes of two particular TBO modes, the Yangtze River Valley (YRV) and the Huaihe River Valley (HRV) modes, have been examined.
3) On the basis of previous studies of teleconnection modes in the Asian monsoon region, we suggest the occurrence of low-level teleconnection types propagating along a strong monsoonal airflow belt from South Asia or the western North Pacific to East Asia. Such teleconnection types can exert an important effect on the Meiyu/Baiu season and summer precipitation in North China and Northeast Asia.
Finally, it is indicated that global warming will have a more significant effect on the Asian summer monsoon in this century. Therefore, both anthropogenic and natural forcing are important factors in the long-term variation of the Asian summer monsoon.

Abstract:This paper summarizes the applications of conditional nonlinear optimal perturbation (CNOP) in recent predictability studies. These include four main contributions. First, the CNOP approach was extended to consider not only initial perturbations but also model parametric perturbations. The extended CNOP approach can study the predictability problems induced by either initial errors or model errors as well as those induced by both initial errors and model errors. Second, the extended CNOP approach was applied to the predictability studies of ENSO events and Kuroshio path anomalies. The effect of initial errors and model parametric errors on the predictability of these events was demonstrated and it was shown that the initial errors play a dominant role in the predictability of ENSO and the Kuroshio path anomalies. The CNOP approach was also applied to investigate the optimal precursors (OPRs) of the onset of blocking events and optimally growing initial errors (OGRs). The results demonstrated that OPRs and OGRs are often concentrated at a localized region; furthermore, their patterns are very similar. Finally, the CNOP approach was used to study adaptive observations of typhoons. With the CNOP, the sensitive areas of some typhoon cases were determined and with the data from the Observing-Systems Simulation Experiments (OSSEs) and/or Observing-Systems Experiments (OSEs) the validity of the sensitive area was demonstrated. Specifically, the OGRs of typhoon cases often concentrate in a particular region. Increasing the number of the observations in this region may significantly improve the forecasting skill for typhoons. The region identified by OGRs may represent the sensitive area of typhoon forecasting. The OGRs of El Niño events, Kuroshio path anomalies, and blocking events are also localized in a particular region. Based on the approach of the typhoon adaptive observation, the sensitive areas associated with these events may be identified as the localized regions of the OGRs.

Abstract:In this paper, research results on the mechanism and prediction of disastrous weathers, including heavy rainfall causing floods, severe strong rainfall by landfall typhoons, cold waves, heavy snowfall, strong dust storms, and extreme hot events, are briefly presented. Some of the main extreme weathers are mentioned and discussed. Recently, disastrous weathers have been occurring very frequently and causing significant damages. These weathers are associated with multiscale systems and the interactions between them, particularly due to climate changes, general circulation anomalies, and activities of mesoscale systems. Therefore, the mechanism and prediction of disastrous weathers have become more complicated. Nevertheless, the abovementioned related scientific problems are still reviewed in this paper. Moreover, some suggestions are proposed for the future research.

Abstract:Studies on the recent changes of the summer and winter monsoons, with priority on decadal-interdecadal scales, are reviewed briefly in this paper. The major changes in the East Asian summer monsoon (EASM) include a weakening of the EASM and a shift in precipitation patterns at the end of 1970s; an increase in South China precipitation after 1992-1993; a decrease in precipitation in the middle-and-lower reaches of the Yangtze River and an increase in precipitation in the Huaihe River valley after 1999; and instability in the relationship between the EASM and El Niño-Southern Oscillation (ENSO). The changes in the East Asian winter monsoon (EAWM) include a weakening of the EAWM and its interannual variability after the mid-1980s, an increase in winter snowfall in Northeast China after the mid-1980s, and a weakening of the EAWM-ENSO relationship after the mid-1970s. In addition, the impact of the autumn Arctic sea ice decline on the winter snow cover in the Northern Hemisphere is discussed. These changes in EASM and EAWM indicate that the extreme climate and phenology have been significantly altered.

Abstract:Mesoscale meteorology has been a subject of intense research activities in recent years because of its important role in daily weather forecasting and significant contribution to the predictions of meteorological disasters. Mesoscale meteorology explores the occurrence, development, and forecasting of mesoscale weather systems and the accompanying severe weather such as heavy rainfall, hail, and tornado wind. Recent observational, theoretical, and numerical studies have advanced our understanding of mesoscale weather dynamics. The present review mainly focuses on achievements since 2007, which consist of waves, vortices, fronts, stability, Q-vectors, and conservative quantities. In the field of waves, progress includes the study of formation and propagation of gravity waves; research of typhoon waves including vortex Rossby waves, mixed low-frequency vortex Rossby waves, and high-frequency inertial gravity waves; and the study of the wave-activity relationships that consider the water vapor effect. Recent studies have also expanded our understanding of the vortex, particularly the Tibetan Plateau Vortex (TPV), and tropical cyclones, which is of great importance in weather forecasting. The front is another key weather system in China. Advances in front research include an experimental study of the generation and maintenance mechanism of the β mesoscale double rainbands in the Meiyu front and a proposal of the scalar frontogenesis function based on the generalized potential temperature, which makes the description of the front genesis process more closely related to the actual atmosphere. To address instability, we introduce a pseudo-momentum function based on the Energy-Casimir method and instability of transverse waves when the basic flow has linear or nonlinear shear. Moreover, the development of the Q-vector—from the geostrophic Q-vector to the ageostrophic moist Q-vector—and a new divergence function deduced by coupling of the geostrophic moist Q-vector and the vertical wind shear are introduced. Finally, we discuss the latest advances in two conservative quantities: potential temperature and potential vorticity.

Abstract:The East Asian upper-tropospheric jet is an important component of the East Asian summer monsoon and severely affects weather and climate in East Asia. During the past decade, various observational and numerical studies were conducted on variability in this jet and its effects on the East Asian climate. This paper reviews these studies mainly from the aspects of the features of the East Asian upper-tropospheric jet variability, the relationship between the jet and the East Asian climate, the possible mechanisms for jet variability, the evaluation of current climate models’ ability in simulating the jet, and projections of future changes in the jet.

Abstract:Because the dynamical climate prediction model is ineffective for skillful forecasting on a weekly to intra-annual scale in the East Asia region, the combination of a dynamical and statistical prediction method has been suggested as an optimal strategy. To realize the technique, a forecasting error correction method by utilizing historical analogue information was developed in China. The current applications show that this new method can significantly improve prediction skill in extended range, monthly, seasonal, and El Niño-Southern Oscillation (ENSO) prediction and hence have encouraged us to further explore operational applications for this method in the future.

Abstract:In this paper, major progresses in the studies of cloud physics and precipitation as well as weather modification during 2008-2012 have been reviewed and summarized; the important scientific issues that need to be solved urgently in the future have also been discussed. This paper reviews the current status of the advances in cloud-resolving models and simulation studies, observational studies on remote retrieval of cloud and precipitation, influences of aerosol on cloud and precipitation, and modeling and measurement of weather modification processes. Cloud and precipitation play critical roles in the atmospheric water cycle, climate change, weather forecasting, and reduction of atmospheric water resource exploitation and meteorological disasters. Therefore, it is important to improve our understanding of the formation, temporal and spatial structure, and evolution of cloud and precipitation.

Abstract:In this paper, the progress of recent climatological research on tropical cyclone (TC) activity over the western North Pacific conducted by the Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP/CAS), and associated domestic and international studies are synthesized and reviewed. In addition to recent climatological studies on the large-scale circulation patterns favorable to TC genesis and their barotropic energy conversions to eddies in summer and autumn, interannual, interdecadal, and intraseasonal variabilities of TC activity over the western North Pacific and their future changing trends attributed to global warming are reviewed. Moreover, recent research on the dynamical effects of the monsoon trough and convectively coupled tropical waves on tropical cyclogenesis over the western North Pacific are discussed. In addition, many important domestic and international studies associated with the abovementioned investigations are also systematically reviewed. Climatological problems of TC activity over the western North Pacific, which are urgently needed to be studied further in the future, are also pointed out in this paper.

Abstract:Two patterns of winter temperature variability over East Asia and their association with the atmospheric circulation patterns for the last 100 years are documented based on the 20th century reanalysis datasets. In one pattern, the changes in temperature over the southwest of East Asia (south of 40°N and west of 105°E) are opposite to those over northeastern East Asia (north of 40°N and east of 105°E). The other pattern is characterized by consistent changes in temperature over East Asia south of 40°N. The Eurasian atmospheric circulation teleconnection pattern, the North Atlantic Oscillation (NAO), and the Siberian high are associated with the first type of East Asian temperature variability. The Eurasian pattern in a negative phase at 500 hPa, the NAO in a positive phase, and a weaker Siberian high are favorable for an increase in winter temperature over Mongolia and east of 105°E in China (Southwest China and the Tibetan Plateau), and vice versa. The western Pacific pattern (WP) at 500 hPa and the North Pacific Oscillation (NPO) correspond to the second type of East Asian temperature variability pattern. When WP and NPO were in a positive phase (negative values in the north and positive values in the south of the Pacific Ocean), the winter temperatures over the area south of 40°N in East Asia increased (decreased). The differences in the spatial pattern of the atmospheric modes can impact on the winter East Asian temperature interannual variability. During the last 100 years, the Eurasian pattern and the NAO were most notable during 1984-2010, contributing to the rapid warming over East Asia after the 1980s. We also found that the correlation between the East Asian winter temperature variability and polar circulation has increased since the middle of the 20th century and that the eastward extending Siberian high has a strong link to the polar circulation, which could also be responsible for the warming over East Asia during the last 100 years.

Abstract:Along with the long-term global warming trend since the industrial revolution, observations of global averaged surface air temperature have also shown a decadal variability. Superimposing the climate variations with two time scales above can result in reduced or no warming in some decades such as 1999-2008 and increased warming in other decades such as 1980-1998. The main goal of this study was to explore the reasons that may cause the warming hiatus or accelerated warming periods by using a coupled global climate model (GCM) FGOALS-s2, developed at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics (IAP), Beijing, China. The model reproduces not only the long-term warming trend, but also significant decadal variability. The global mean energy budget analysis indicates that the decadal variability of the global mean surface temperature is independent of the net top-of-atmosphere (TOA) radiation flux, implying that it may be associated with the re-distribution of heat in the climate system. Using composite analysis and regression analysis, the decadal characteristics of the global surface temperature and sea surface temperature (SST) were very similar in most regions: during the hiatus period, the SST decreased, and more heat flux penetrated into the subsurface or deep ocean; during the acceleration period, more heat was trapped in the upper ocean and the SST increased. Furthermore, on a decadal timescale, the climate variability of the Subtropical-Tropical meridional Cells (STC) played a crucial role in modulating the SST and the subsurface temperature in the Pacific Ocean. Remote responses of the anomaly wind stress and the net surface heat flux to the SST anomalies in the tropical Pacific can induce the decadal changes of sea temperature in the Indian Ocean and the Atlantic Ocean. In the processes associated with decadal variability, ocean circulations also play important roles, e.g., the Indonesian Throughflow (ITF) has a great impact on the changes of the subsurface sea temperature in the South Indian Ocean at decadal time scales, and the deep-ocean temperature in the Atlantic can be directly affected by the Atlantic Meridional Overturning Current (AMOC).

Abstract:The implementation of the international Array for Real-time Geostrophic Oceanography (Argo) Project facilitates unprecedented global ocean observations of sea-water temperature and salinity from the sea surface to a depth of 2000 m. Application of these new oceanic data in atmospheric and oceanic research and operation is essential for understanding the atmospheric and oceanic variability and increasing the accuracy of climate prediction and oceanic monitoring and analysis. The global ocean data assimilation systems are set up by developing a nonlinear temperature- salinity coordinated assimilation scheme and adjusting the temperature and salinity on the basis of altimetry data, which enhances the monitoring and analyzing capability for the global ocean. The global ocean data assimilation systems are integrated with coupled atmosphere-ocean models, which increases the forecast skills for short-term climate prediction. Argo data are applied for improving physical parameterization schemes in oceanic models, and the model capability of describing the real oceans and forecasting El Niño/Southern Oscillation is increased. A novel method has been developed for estimating surface and mid-layer ocean currents on the basis of the trajectories of Argo float drifting, which improves the accuracy of estimation of global surface and mid-layer ocean currents and makes up the insufficiency in observed ocean currents.

Abstract:Recent advances in studies on the characteristics and mechanisms of the East Asian winter monsoon (EAWM) variability are reviewed in the paper. In particular, the possible effect of the stratospheric process on the EAWM and the climate anomalies are documented and investigated. It was found that the path of the EAWM, as well as the variation in its intensity, is important. The EAWM intensity is usually associated with uniform changes in wintertime temperature throughout China, whereas the EAWM path tends to induce a north-south temperature dipole pattern which is associated with two sub-systems that develop in the north and the south of China. Moreover, since the beginning of this century the forming of the EAWM was delayed while its intensity tended to decrease during the mature phase of the monsoon and intensify in early spring compared to earlier records. All these variations are shown to be closely related to the north-south temperature dipole pattern. Further analysis indicates that the north-south dipole pattern is one of the major modes of the EAWM variability and is closely associated with the intensity of the stratospheric Polar Vortex. When an anomalous polar vortex propagates downward, this may induce anomalous Arctic Oscillation (AO) and Siberian High in the lower troposphere, leading to the emergence of a north-south temperature dipole pattern in East Asia. Studies on the causes of EAWM variability suggest that the impact of the El Niño-Southern Oscillation (ENSO) has weakened since the mid-late 1970s. In contrast, the impacts from the circulation anomalies in the mid-high latitudes such as the North Pacific Oscillation (NPO) and the Ural blocking have increased significantly. The mechanisms involved have also been investigated. In addition, the persistent weakening of the EAWM since 1987 may be related to the interdecadal change of the quasi-stationary planetary wave activity. Through wave-flow interaction the planetary wave activity may induce variations in the AO, the Siberian High, and the Aleutian Low, and result in anomalous EAWM. Finally, the possible effects of the 11-year solar cycle on the East Asian climate anomalies during the boreal winter and the associated processes are also discussed.

Abstract:The rainfall pattern and circulation features associated with the Meiyu flooding of the Huaihe River valley, China in June are investigated by data analyses. The Meiyu flooding of the Huaihe River valley in June is associated with the second joint Singular Value Decomposition (SVD) mode of the Asia-Pacific circulation and rainfall. It is characterized as a ‘Meiyu dipole mode’ in eastern China with more rainfall to the north of the Yangtze River and less to the south. An anomaly anticyclonic circulation lies to the north of Taiwan and an anomaly cyclonic circulation lies to the south over the western Pacific in the lower troposphere. Moreover, an anticyclone is located over the Arabian Sea and the westerly winds and rainfall are strengthened over India. The above anomalies represent the lead variation in the seasonal evolution over the eastern Asia-Pacific area, and are related to the triple pattern in the oceanic heat content in the Pacific Ocean in spring. The ‘triple pattern’ heat anomaly stimulates the anomalies of the sea surface sensible heating and the associated subtropical anticyclone in the western Pacific. As a result, the ‘Meiyu dipole mode’ is induced. A heat content index can be defined and can be considered as one prediction index for Meiyu flooding events of the Huaihe River valley.

Abstract:More than 800 extra-solar planets (exoplanets) have been identified since 1995. Exoplanetary atmosphere and climate are two of the newest areas in exoplanetary science research. The purpose of the present paper is to review the most recent progresses in these areas. Because Earth’s atmosphere and climate are always used as a reference for studies in solar planetary atmospheres and climates, we first briefly introduce basic knowledge of these areas for comparison. We next introduce concepts of habitable zone of stars and habitability of exoplanets. We mainly focus on recent observational, simulation, and theoretical results of physical, chemical, and dynamical properties of exoplanetary atmospheres. Moreover, we introduce possible climate environments of habitable exoplanets around M-type dwarfs.

Abstract:This paper presents an overview of the recent important developments in the field of atmospheric boundary layer physics at the State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC) of the Institute of Atmospheric Physics of the Chinese Academy of Sciences over the last 4 years (2009-2012). It focuses on theoretical, experimental, and numerical studies of the atmospheric boundary layer, as well as the development of an ultrasonic anemometer/thermometer (UAT-2). Some future research prospects are also presented in this paper.

Abstract:Long-term and systemetic observation data of aerosol radiative properties creates an important foundation for the quantitative study of aerosol radiative and climatic effects. This paper introduces progress in observation studies of atmospheric aerosol radiative properties in China, emphasizing the following five aspects: (1) observations of Aerosol Optical Thickness (AOT), Single Scattering Albedo (SSA), and volume size distribution by using the ground-based sunphotometer network; (2) retrieval of AOT and SSA from whole-spectral solar direct radiation; (3) ground-based measurements of aerosol scattering and absorption coefficients by the nephelometer and the aethalometer; (4) ground-based and spaceborne lidar measurements of aerosol (backscattering coefficients) vertical distribution; and (5) remote sensing of aerosol optical properties from polar-orbiting and geostationary satellites.

Abstract:The performance of IAP/LASG climate system model FGOALS-s2 in the simulation of present-day climate in the Southern Hemisphere is assessed. The future changes in the southern hemispheric climate are projected for four Representation Concentration Pathways (RCPs). The results show that the major features of climate mean states of the Southern Hemisphere are well simulated, including the double jet phenomenon in June-July-August (JJA), although the north (south) branch is weaker (stronger) than the reanalysis. Under the four RCPs scenarios, the surface air temperature will become warmer, except in the south Atlantic-Indian ocean basin, and the warming amplitude over land is greater than that over the sea. Meanwhile, precipitation will increase in the entire hemisphere, except in the South Indian Ocean and in the center of the South Pacific Ocean. Under all RCP scenarios, the subtropical high in the Southern Hemisphere tends to be enhanced, while the circumpolar low tends to become deeper. The precipitation changes in December-January-February (DJF) and over sea are more obvious than those in JJA and over land. Under the four RCPs scenarios, the intensity of the Mascarene High (MH) will be weakened in the beginning but will be enhanced from the 2030s, while the Australain High (AH) will intensify in the beginning of the 21th century but will become weaker from the 2030s. The future evolution of Antarctic Oscillation (AAO) is scenario dependent but clearly tends to be intensified under RCP6.0 and RCP8.5 scenarios. The changes in AAO under the different RCPs scenarios are dominated by different temperature changes in the vertical direction. For example, both RCP6.0 and RCP8.5 emission scenarios lead to an enhanced meridional temperature gradient and thus to an enhanced mid-latitude westerly jet that is in favor of a stronger AAO.

Abstract:The National Key Research Program on Global Change Study, “Air-Land-Sea (ALS) interactions in Asia and their role in the global climate change” was implemented in 2010. The ALS project team has achieved many of the program’s scientific objectives in various fields. In the field of climatic dynamics, we found that the variations of sea surface temperature (SST) over the Indo-western Pacific warm pool are a vital driver for the interdecadal variability of the global tropical climate and an important modulator of global-scale subtropical droughts. We found an air-sea coupled cold-tongue SST mode in the eastern tropical Pacific and demonstrated the important role of this mode in the formation of different types of El Niño-Southern Oscillation (ENSO) patterns. Furthermore, we illustrated the mechanisms involved in these patterns and their different influences on the East Asian climate. The characteristics of the thermal forcing anomalies over the Tibetan Plateau and their possible climatic effects are explored. In addition, we proposed a new theory of planetary waves in non-uniform basic flow, and performed preliminarily analysis of its features under different conditions of the East Asian summer monsoon. In the field of climate prediction methods, we developed several physically-based statistical prediction techniques or models, such as the new approach of time-scale decomposition downscaling, an empirical North Atlantic Oscillation-ENSO-based seasonal prediction model of the East Asian summer monsoon, and an empirical Southern Hemisphere Annular Mode-based East Asian climate prediction model. The good performances of these prediction models provide important references for the relevant project operational divisions. From the observational and data assimilation aspect, our achievements include the integrated ocean observation along the 18°N cross-section in the South China Sea, which laid the foundation for the formation of China’s first long-term cross-section observation in the South China Sea. As for relevant international cooperation, the ALS project also continues to promote the leadership of the international programs of “Asian Monsoon Years (AMY 2007-2012)” and “East Asian Climate Modeling,” which would enhance the international status of China in related fields.

Abstract: