Distinct Regional Features Research Articles

Role of atmospheric heating over the South China Sea and western Pacific regions in modulating Asian summer climate under the global warming background

The response of monsoon precipitation to global warming, which is one of the most significant climate change signals at the earth’s surface, exhibits very distinct regional features, especially over the South China Sea (SCS) and adjacent regions in boreal summer. To understand the possible atmospheric dynamics in these specific regions under the global warming background, changes in atmospheric heating and their possible influences on Asian summer climate are investigated by both observational diagnosis and numerical simulations. Results indicate that heating in the middle troposphere has intensified in the SCS and western Pacific regions in boreal summer, accompanied by increased precipitation, cloud cover, and lower-tropospheric convergence and decreased sea level pressure. Sensitivity experiments show that middle and upper tropospheric heating causes an east–west feedback pattern between SCS and western Pacific and continental South Asia, which strengthens the South Asian High in the upper troposphere and moist convergence in the lower troposphere, consequently forcing a descending motion and adiabatic warming over continental South Asia. When air–sea interaction is considered, the simulation results are overall more similar to observations, and in particular the bias of precipitation over the Indian Ocean simulated by AGCMs has been reduced. The result highlights the important role of air–sea interaction in understanding the changes in Asian climate.

Progress in studies of the precipitation diurnal variation over contiguous China

This paper summarizes the recent progress in studies of the diurnal variation of precipitation over contiguous China. The main results are as follows. (1) The rainfall diurnal variation over contiguous China presents distinct regional features. In summer, precipitation peaks in the late afternoon over the southern inland China and northeastern China, while it peaks around midnight over southwestern China. In the upper and middle reaches of Yangtze River valley, precipitation occurs mostly in the early morning. Summer precipitation over the central eastern China (most regions of the Tibetan Plateau) has two diurnal peaks, i.e., one in the early morning (midnight) and the other in the late afternoon. (2) The rainfall diurnal variation experiences obvious seasonal and sub-seasonal evolutions. In cold seasons, the regional contrast of rainfall diurnal peaks decreases, with an early morning maximum over most of the southern China. Over the central eastern China, diurnal monsoon rainfall shows sub-seasonal variations with the movement of summer monsoon systems. The rainfall peak mainly occurs in the early morning (late afternoon) during the active (break) monsoon period. (3) Cloud properties and occurrence time of rainfall diurnal peaks are different for long- and short-duration rainfall events. Long-duration rainfall events are dominated by stratiform precipitation, with the maximum surface rain rate and the highest profile occurring in the late night to early morning, while short-duration rainfall events are more related to convective precipitation, with the maximum surface rain rate and the highest profile occurring between the late afternoon and early night. (4) The rainfall diurnal variation is influenced by multi-scale mountain-valley and land-sea breezes as well as large-scale atmospheric circulation, and involves complicated formation and evolution of cloud and rainfall systems. The diurnal cycle of winds in the lower troposphere also contributes to the regional differences in the rainfall diurnal variation. (5) Evaluation of the model performance shows that the present numerical models are weak in simulating the rainfall diurnal variation over contiguous China. The simulations are not significantly improved by increasing the model horizontal resolution alone. The key is to reduce the uncertainty in physical parameterizations related to the rainfall processes.

Study of distinctive regional features of surface solar radiation in North and East China

Solar radiation is an important energy source for plants on the earth and also a major component of the global energy balance. Variations in solar radiation incident at the earth’s surface profoundly affect the human and terrestrial environment, including the climate change. To provide useful information for predicting the future climate change in China, distinctive regional features in spatial and temporal variations of the surface solar radiation (SSR) and corresponding attributions (such as cloud and aerosol) are analyzed based on SSR observations and other meteorological measurements in North and East China from 1961 to 2007. Multiple models, such as the plane-parallel radiative transfer model, empirical and statistical models, and correlation and regression analysis methods are used in the study. The results are given as follows. (1) During 1961–2007, the total SSR in North China went through a process from quickly “dimming” to slowly “dimming”, while in East China, a significant transition from “dimming” to “brightening” occurred. Although there are some differences between the two regional variation trends, long-term variations in SSR in the two regions are basically consistent with the observation worldwide. (2) Between the 1960s and 1980s, in both North and East China, aerosols played a critical role in the radiation dimming. However, after 1989, different variation trends of SSR occurred in North and East China, indicating that aerosols were not the dominant factor. (3) Cloud cover contributed less to the variation of SSR in North China, but was the major attribution in East China and played a promoting role in the reversal of SSR from dimming to brightening, especially in the “remarkable brightening” period, with its contribution as high as 70%.

Optical and physical characteristics of Bay of Bengal aerosols during W‐ICARB: Spatial and vertical heterogeneities in the marine atmospheric boundary layer and in the vertical column

Analysis of the continuous and collocated measurements of columnar spectral aerosol optical depths (AODs) and mass size distributions in the marine atmospheric boundary layer (MABL) over the Bay of Bengal (BoB), carried out from 27 December 2008 to 29 January 2009 during the Winter Integrated Campaign for Aerosols, Gases and Radiation Budget (W‐ICARB), revealed distinct regional features in the spatial variations of the aerosol properties in the MABL and column. In general, AODs were high over the northern and northwestern parts of the BoB, with pockets of very high values, within which the AODs were as high as ∼0.8 while the smallest values (∼0.1) were observed over the northeastern BoB, off the Myanmar and Bangladesh coasts. Interestingly, though, this region had the highest Angstrom wavelength exponent α (∼1.5), notwithstanding the generally high values that prevailed over the eastern as well as northern coastal regions of India. Back trajectory analyses revealed the significant role of the advected aerosols in the observed spatial pattern. Within the MABL, high accumulation mode mass concentrations (MA) prevailed over the entire BoB with the accumulation fraction ranging from 0.6 to 0.95, whereas very high fine‐mode (r < 0.1 μm) aerosol mass fractions (∼0.8) were observed over the northeastern and western coastal BoB adjoining the Indian mainland (where α was high to very high). The vertical distributions, inferred from the columnar and MABL properties as well as from the Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations data, revealed better homogeneity in the northeastern and eastern BoB, whereas significant heterogeneity was seen over other regions.

Kvaderstenskirker mellem Viborg og Randers – Et bygningsarkæologisk studie

The medieval churches of Sønderlyng and Middelsom districtsIn 12th century Jutland, a tradition developed of building churches of granite ashlars. In the northern part of the peninsula, the main inspiration for this came from the cathedral in Viborg, construction of which began just prior to AD 1150 and continued until completion during the first decades of the 13th century. In this article, the author attempts to identify similarities and differences in this building method by way of a buildings archaeological survey of 29 churches within a restricted geographical area comprising Sønderlyng and Middelsom districts, which are located just east of Viborg (fig. 1). An assessment has also been undertaken of the originality of the individual standing monuments. This is also based on the above-mentioned observations, together with information from the relevant archives. The methods applied have been developed with the aim of describing and comparing the basic features of Romanesque ashlar churches, such as their ground plans, plinths, dimensions, course heights, windows and portals (figs. 2-7, 9, 15). The most recent account of a group of Romanesque ashlar churches from 1942 deals with the churches in Thisted county and has, to some extent, been compared with the results of the present study.These results show that considerable parts of the masonry have been re-laid as a consequence of the extensive repairs and restoration work carried out across the country during the late 19th century. These were executed mainly on south-facing walls, leaving the majority of the original church wall sections to be found on their northern sides. The results also demonstrate that certain norms and regulations prevailed in early church building within the study area. The ground plans were laid out according to certain proportional principles, and the heights of the ashlar courses heights decreased upwards. A church with an apse would be provided with richer decoration in the form of, for example, profiled plinths and cornices and columned portals of various types. One of these types, with six free-standing columns, a particular elaborate architectonic characteristic of the area, is found only on apsed churches. Conversely, apses which were added subsequently can be identified partly through their plainer decorative expression and, in a few instances, by their divergent ground plan.The artistic details of Romanesque church building in the area show great variation, and it is argued that the finer stonework, such as the Ørum portal (fig. 16), could have been produced in central workshops in the market towns. Furthermore, based on the work of Elna Møller and Jens Vellev, it is pointed out that the original apsed churches and six free-standing columned portals date from the last quarter of the 12th century. However, the distinct portal in Vorning (fig. 14) is probably slightly older.When compared, a certain pairing tendency can be observed in some of the churches, for example those in Ålum and Tånum. This provides a hint concerning the organisation of early ashlar church building. Compared to the much larger group of ashlar churches in Thisted County, the ground plans of the churches in these two districts are slightly wider, and they are more elaborate architectonically, at least with respect to the portals. Several distinct regional features are thereby recognisable, but it is apparent that there was also a certain degree of cultural exchange between the various parts of Jutland.Anders Christian ChristensenHorsens Museum

Poverty and the Distribution of Land

Redistributive land reforms have begun to attract the attention of scholars and policy makers once again. In this paper, we review old arguments and bring them up‐to‐date in the light of recent research. We begin with the case in favour of redistributive reforms focusing on fragmented factor markets and systems of labour control, of which concentration of land ownership is but one aspect. We then examine land reform in practice, focusing on distinct regional features and outcomes in sub‐Saharan Africa, Latin America, the transition economies of the former Soviet bloc and, as examples of success, East Asia (including China and Vietnam). Next we discuss the macroeconomic context and the two‐way direction of causality between a redistribution of productive assets and the overall performance of the economy. We underline the importance of weakening the system of labour control, eliminating landlord bias and correcting urban bias. Finally, we argue that a prominent feature of all successful land reforms has been a high degree of land confiscation; full compensation and various types of ‘market friendly’ land reform are unlikely to be successful.