monsoon climate
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MAUSAM ◽  
2021 ◽  
Vol 52 (1) ◽  
pp. 229-244
Author(s):  
K. RUPA KUMAR ◽  
R. G. ASHRIT

The regional climatic impacts associated with global climatic change and their assessment are very important since agriculture, water resources, ecology etc., are all vulnerable to climatic changes on regional scale. Coupled Atmosphere-Ocean general circulation model (AOGCM) simulations provide a range of scenarios, which can be used, for the assessment of impacts and development of adaptive or mitigative strategies. Validation of the models against the observations and establishing the sensitivity to climate change forcing are essential before the model projections are used for assessment of possible impacts. Moreover model simulated climate projections are often of coarse resolution while the models used for impact assessment, (e.g. crop simulation models, or river runoff models etc.) operate on a higher spatial resolution. This spatial mismatch can be overcome by adopting an appropriate strategy of downscaling the GCM output.   This study examines two AOGCM (ECHAM4/OPYC3 and HadCM2) climate change simulations for their performance in the simulation of monsoon climate over India and the sensitivity of the simulated monsoon climate to transient changes in the atmospheric concentrations of greenhouse gases and sulfate aerosols. The results show that the two models simulate the gross features of climate over India reasonably well. However the inter-model differences in simulation of mean characteristics, sensitivity to forcing and in the simulation of climate change suggest need for caution. Further an empirical downscaling approach in used to assess the possibility of using GCM projections for preparation of regional climate change scenario for India.


Phytotaxa ◽  
2021 ◽  
Vol 527 (3) ◽  
pp. 221-233
Author(s):  
SHAMIL R. ABDULLIN ◽  
ARTHUR YU. NIKULIN ◽  
VERONIKA B. BAGMET ◽  
VYACHESLAV YU. NIKULIN ◽  
ANDREY A. GONTCHAROV

A new coccoid cyanobacterium Aliterella vladivostokensis sp. nov. was described from an urban aerophytic habitat in a temperate monsoon climate (Vladivostok, Russia) using a polyphasic approach. Phylogenetic analyses based on the 16S rRNA gene sequences confirmed that our isolate was a member of the Aliterella genus clade. Aliterella species are hardly distinguishable from each other morphologically and were described from highly contrasting natural and artificial environments with only a few records from several continents. Despite high similarity of morphometric data for A. vladivostokensis and A. antarctica cells and a compensatory base change in the D1–D1′ helix shared by these species; high percent of dissimilarity (11.6±1.3) between their 16S–23S internal transcribed spacer sequences with at least 5 autapomorphic mutations in the D1–D1′ and Box-B helices, and distinct folding patterns of the Box-B helix allowed us to erect a new species.


2021 ◽  
Author(s):  
Bolin Sun ◽  
Long Ma ◽  
Tingxi Liu ◽  
Xing Huang

Abstract The overlap region between the eastern fringe of the Asian westerly region and the temperate continental-monsoon climate transition zone is sensitive to climate changes and is characterized by fragile ecosystems. It is necessary to uncover the patterns of long-term historical climate variability there. A standardized tree-ring width chronology was constructed based on the tree-ring samples collected from four representative tree species in four typical areas in the overlap region, and the 203- to 343-year annual mean minimum temperature series in the overlap region were reconstructed. The reconstructed series overlapped well with extreme climate events and low-temperature periods recorded in historical data. Therefore, the reconstructed model is stable and reliable. As suggested by the reconstructed series, the variability of annual mean minimum temperature was increasingly drastic from east to west in the overlap region, with gradually shorter periodicities. In the 19th century, the high-latitude area was in the high-temperature period, and the entire overlap region experienced significant low-temperature periods lasting 20–45 years till the 1950s. The western part had an earlier start time of low-temperature periods, longer cooling duration, and slower cooling rate than the central part. The overlap region experienced a significant warming period in approximately the last half-century, with temperature increasing faster in the western and eastern parts than in the central part. The temperature variability in the overlap region was more intense in the last two centuries, with shorter periodicities and a larger proportion of cold periods. The central and western parts of the Asian westerly region, the mid- to high-latitude regions of the transition zone, and the overlap region saw significantly low-temperature periods or drastic cooling trends (the Little Ice Age) in the first half of the 19th century and significant warming trends under global warming afterwards. The influences of these changes might have been exacerbated by the westerly circulation. This study not only provides new insight into the use of dendroclimatology to extract temperature series in the Asian westerly region and the transition zone but also serves as a reference for research on global climate change.


MAUSAM ◽  
2021 ◽  
Vol 61 (1) ◽  
pp. 47-74 ◽  
Author(s):  
D. R. SIKKA ◽  
AJIT TYAGI ◽  
L. C. RAM

Summer monsoon season of the year 2009 resulted in a major drought on the scale of India with rainfall deficiency of 23% from the normal. This was the monsoon season when a pilot phase of the programme Continental Tropical Convergence Zone (CTCZ), a planned multiyear programme to understand the complex interactions among the land, ocean, atmosphere, biosphere components of the regional monsoon climate system, was undertaken. The paper attempts to document the major features in the evolution of monsoon 2009 and provides a preliminary diagnosis of the causes for monsoon drought.


2021 ◽  
Author(s):  
Jianbo Jia ◽  
Wende Yan ◽  
Jia Lu ◽  
Wenping Deng

Abstract Variations in precipitation pattern under climate changes influence water availability that have important implications for plants water use and vegetation sustainability. However, the water use characteristic of the main tree species under different temporal-spatial of water availability remain poorly understood, especially in high temporal-spatial heterogeneity area, such as subtropical monsoon climate region of China. We investigated water use characteristics of the most widely and common natural trees, Mallotus philippensis and Celtis biondii , in edaphic and rocky habitats. We measured the δD and δ 18 O values of xylem and soil water and water potential of plant leaves during the wet season in 2020. The results showed that the two species mainly absorbed soil water from shallow layers and switched for deeper layers during the late of the wet season in both habitats. But the plant water sources were different in edaphic and rocky habitats when the antecedent precipitation was much high, deep layers soil water in the former and still shallow layers in the latter. The two species had no significant differences in water uptake depth, but notably distinction in the diurnal water potential ranges. M. philippensis maintained less negative predawn and midday water potential, whereas C. biondii showed higher diurnal water potential ranges. Besides, the water potential of C. biondii were negatively associated with antecedent precipitation amount. These results indicate that there is significant eco-physiological niche segregation but no ecohydrological segregation co-existing species in communities. Besides, antecedent precipitation amount and habitat differences were the main factors influencing the plant water uptake depth. While the relationship between leaf physiological traits and water availability was affected by the species types, rather than the habitats. Furthermore, during the long drought in growing season, there are probable divergent responses of M. philippensis and C. biondii , such as growth restriction and hydraulic failure. But when the precipitation is heavy and long, these natural species could increase the ecohydrological linkages between ecosystem and the deep-layer system in edaphic habitat.


Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2560
Author(s):  
Andrey A. Gontcharov ◽  
Arthur Yu. Nikulin ◽  
Vyacheslav Yu. Nikulin ◽  
Veronika B. Bagmet ◽  
Rezeda Z. Allaguvatova ◽  
...  

Chlorella-like green algae that reproduce only asexually by immotile autospores or motile zoospores are the most typical inhabitants of non-aquatic environments. They have a simple morphology that hampers their differentiation, but algae of such habit represent a diverse array of lineages, which are mostly in the classes Chlorophyceae and Trebouxiophyceae. One of these lineages is the order Watanabeales (Watanabea clade; Trebouxiophyceae), which comprises 10 genera that share a distinct mode of reproduction through unequally sized autospores. Most of these genera account for a few species that are rarely recorded in nature. In contrast, the genus Chloroidium is one of the most species-rich and widely distributed members of the order. Three strains of coccoid green alga were isolated during a study of soil algae in the temperate monsoon climate zone of Asia. These strains are described here as a new species, Chloroidium orientalis. SSU and ITS rDNA sequence data, morphological characteristics, and life cycle features differentiate these strains from known members of the genus.


2021 ◽  
Vol 13 (22) ◽  
pp. 4552
Author(s):  
Yanhong Dou ◽  
Lei Ye ◽  
Jiayan Zhang ◽  
Chi Zhang ◽  
Huicheng Zhou

This study evaluated and intercompared seven near-real-time (NRT) versions of satellite-based precipitation products (SPPs) with latencies of less than one day, including GSMaP-NRT, GSMaP-Gauge-NRT, GSMaP-NOW, IMERG-Early, IMERG-Late, TMPA 3B42RT, and PERSIANN-CCS for wet seasons from 2008 to 2019 in a typical middle–high latitude temperate monsoon climate basin, namely, the Nierji Basin in China, in four aspects: flood sub-seasons, rainfall intensities, precipitation events, and hydrological utility. Our evaluation shows that the cell-scale and area-scale intercomparison ranks of NRT SPPs are similar in these four aspects. The performances of SPPs at the areal scale, at the event scale, and with light magnitude are better than those at the cell scale, at the daily scale, and with heavy magnitude, respectively. Most SPPs are similar in terms of their Pearson Correlation Coefficient (CC). The main difference between SPPs is in terms of their root-mean-square error (RMSE). The worse performances of TMPA 3B42RT are mainly caused by the poor performances during main flood seasons. The worst performances of PERSIANN-CCS are primarily reflected by the lowest CC and the underestimation of precipitation. Though GSMaP-NOW has the highest RMSE and overestimates precipitation, it can reflect the precipitation variation, as indicated by the relatively high CC. The differences among SPPs are more significant in pre-flood seasons and less significant in post-flood seasons. These results can provide valuable guidelines for the selection, correction, and application of NRT SPPs and contribute to improved insight into NRT-SPP retrieval algorithms.


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