Regions Of Northern Hemisphere Research Articles

Analysis of the global atmospheric background sulfur budget in a multi-model framework

Analysis of the global atmospheric background sulfur budget in a multi-model framework

Comparative genomics on chloroplasts of Rubus (Rosaceae)

Rubus, the largest genus in Rosaceae, contains over 1400 species that distributed in multiple habitats across the world, with high species diversity in the temperate regions of Northern Hemisphere. Multiple Rubus species are cultivated for their valuable fruits. However, the intrageneric classification and phylogenetic relationships are still poorly understood. In this study, we sequenced, assembled, and characterized 17 plastomes of Rubus, and conducted comparative genomics integrating with 47 previously issued plastomes of this genus. The 64 plastomes of Rubus exhibited typical quadripartite structure with sizes ranging from 155,144 to 156,700 bp, and contained 132 genes including 87 protein-coding genes, 37 tRNA genes and eight rRNA genes. All plastomes are conservative in the gene order, the frequency of different types of long repeats and simple sequence repeats (SSRs), the codon usage, and the selection pressure of protein-coding genes. However, there are also some differences in the Rubus plastomes, including slight contraction and expansion of the IRs, a variation in the numbers of SSRs and long repeats, and some genes in certain clades undergoing intensified or relaxed purifying selection. Phylogenetic analysis based on whole plastomes showed that the monophyly of Rubus was strongly supported and resolved it into six clades corresponding to six subgenera. Moreover, we identified 12 highly variable regions that could be potential molecular markers for phylogenetic, population genetic, and barcoding studies. Overall, our study provided insight into plastomic structure and sequence diversification of Rubus, which could be beneficial for future studies on identification, evolution, and phylogeny in this genus.

Longitudinal features of day- and night-time ionospheric annual variations during the solar cycles 23 and 24

We present a study concerning the ionospheric annual variations (IAV) using the global ionospheric maps (GIMs). In this regard, the corresponding regional electron content (REC) is computed in four longitudinal sectors, namely Asia, Africa, America and Pacific. The features of day- and night-time IAV are investigated using (i) band-pass filters and (ii) summer to winter (SW) ratio of REC. The results indicate that IAV are stronger in the southern hemisphere as compared to its northern counterpart. The asymmetry in the amplitude of IAV is maximum for the Pacific region, followed by America, Africa and Asia. The IAV in southern hemisphere are regular ionospheric variations (RIAV) with positive and negative peaks occurring in the months of December and June, respectively. The northern hemisphere and latitudinal regions exhibit a day-time anomalous ionospheric annual variations (AIAV), during the peak years of the considered solar cycles, in which maxima (minima) occurs in local winter (summer). In this regard, the phase of AIAV is found to vary with solar activity. The night-time IAV show anomalous behavior in the northern hemisphere during the solar minimum. The SW ratio of day-time REC is less than unity at northern hemisphere during the peak of a solar cycle. However, the said ratio is always greater than one in southern counterpart. The fitting curve for day-time SW ratio has a strong negative slope in the northern hemisphere. The threshold of SSN (sunspot number) indicating the presence of the daytime winter anomaly at low- latitudes is found to be 25, 80, and 115 in the Africa, Asia-Pacific, and American regions, respectively. Additionally, this anomaly becomes observable in the mid-latitudes region of America and the Pacific region for SSN values exceeding 100 and 150, respectively. On the other hand, the correlation and fitting analysis demonstrate that night-time SW ratio enhances with increase in the solar activity. This result predicts that night- time winter anomaly can only be present during the periods of minimum and low solar activity. However, our analysis revealed that the night-time winter anomaly is observable only in the African low-latitude region for SSN < 85.

Observationally Constrained Projections of Twenty-First-Century Regional Warming in the Extratropical Northern Hemisphere

Abstract Physically based observational constraint methods can effectively reduce uncertainty in global warming projections but have not been widely applied at regional scales. We first develop and apply multivariate linear regression models for constraining projections of surface air temperature averaged over subcontinental regions in the extratropical Northern Hemisphere, based on a set of potential constraints including climatological metrics derived from tropical and subtropical low-level cloud and global average past warming trend, as well as a set of regional climate metrics previously used in the literature. We evaluate the performance of the multivariate linear regression models based on cross-validated tests using output from phases 5 and 6 of the Coupled Model Intercomparison Projects (CMIP). We find that linear regression models using global-scale low-cloud metrics alone perform more robustly than linear regression models using the past global mean warming trend or regional climate metrics as constraints. These results, while favoring global constraints over the set of regional constraints considered, do not preclude the existence of even better regional constraints for particular regions. Through model-based cross-validation, the projections constrained using low-level cloud metrics exhibit more accurate best estimate projections, narrower uncertainty ranges, and more reliable uncertainty estimates in most Northern Hemisphere regions when compared with unconstrained projections. Application of the approach to climate projections based on both Shared Socioeconomic Pathway (SSP) 1-2.6 and SSP5-8.5 using observed low-cloud metrics results in considerably narrower 5%–95% uncertainty ranges of twenty-first-century warming over subcontinental Northern Hemisphere land regions compared to unconstrained projections.

Upper Cretaceous dinoflagellate cysts events from the sub-tropical northern hemisphere

Recognizing the ranking optime sequence of fossil dinoflagellate cysts can be a challenge for qualitative biostratigraphy. For this reason, we present the result of a quantitative stratigraphic study through probabilistic analysis of six wells from Baja California (Mexico) and six from the Gulf of Suez and the Mediterranean Sea (Egypt), which allows us to recognize 22 species of dinoflagellate cysts in an optimal sequence with 95% probability for the Upper Cretaceous in subtropical areas of the Northern Hemisphere. Photoautotrophic species represent the largest number in the database (159 species), indicating that they are the main producers, while heterotrophic species are in the minority (74 species). Spiniferites and Florentinia are the most abundant and diverse taxa, which, together with the absence of the genus Impagidinium, indicates a shallow marine depositional environment. The quantitative analysis estimates an optimal classified succession that allows the Upper Cretaceous to be divided into five groups (G1 to G5) of species communities with similar ages. The greatest species diversity is found in group G4, associated with the Maastrichtian, and the least in group G1, associated with the early Cenomanian to early Turonian. These results and comparison with previous studies using the same method of quantitative biostratigraphy suggest a similarity of paleoenvironmental conditions in subtropical regions of the Northern Hemisphere and tropical regions during the Upper Cretaceous.

The core bacteriobiome of Côte d'Ivoire soils across three vegetation zones.

The growing understanding that soil bacteria play a critical role in ecosystem servicing has led to a number of large-scale biogeographical surveys of soil microbial diversity. However, most of such studies have focused on northern hemisphere regions and little is known of either the detailed structure or function of soil microbiomes of sub-Saharan African countries. In this paper, we report the use of high-throughput amplicon sequencing analyses to investigate the biogeography of soil bacteria in soils of Côte d'Ivoire. 45 surface soil samples were collected from Côte d'Ivoire, representing all major biomes, and bacterial community composition was assessed by targeting the V4-V5 hypervariable region of the 16S ribosomal RNA gene. Causative relationships of both soil physicochemical properties and climatic data on bacterial community structure were infered. 48 phyla, 92 classes, 152 orders, 356 families, and 1,234 genera of bacteria were identified. The core bacteriobiome consisted of 10 genera ranked in the following order of total abundance: Gp6, Gaiella, Spartobacteria_genera_incertae_sedis, WPS-1_genera_incertae_sedis, Gp4, Rhodoplanes, Pseudorhodoplanes, Bradyrhizobium, Subdivision3_genera_incertae_sedis, and Gp3. Some of these genera, including Gp4 and WPS-1_genera_incertae_sedis, were unequally distributed between forest and savannah areas while other taxa (Bradyrhizobium and Rhodoplanes) were consistently found in all biomes. The distribution of the core genera, together with the 10 major phyla, was influenced by several environmental factors, including latitude, pH, Al and K. The main pattern of distribution that was observed for the core bacteriobiome was the vegetation-independent distribution scheme. In terms of predicted functions, all core bacterial taxa were involved in assimilatory sulfate reduction, while atmospheric dinitrogen (N2) reduction was only associated with the genus Bradyrhizobium. This work, which is one of the first such study to be undertaken at this scale in Côte d'Ivoire, provides insights into the distribution of bacterial taxa in Côte d'Ivoire soils, and the findings may serve as biological indicator for land management in Côte d'Ivoire.

Long-term spatiotemporal analysis of the climate related impact on the transmission rate of COVID-19.

BackgroundThe association between weather conditions and the spread of COVID-19 was demonstrated by previous studies but focused on specific countries or investigated shorter periods of duration limiting the interpretation of the results. AimTo make an international comprehensive insight into the association between the weather conditions and the spread of COVID-19 by spanning many regions in the Northern and Southern hemispheres over a period of two years for the COVID-19 Outbreak. MethodsThe data were analyzed by using statistical description, linear and multiple regressions, and the Spearman rank correlation test. Daily and weekly COVID-19 cases, the average temperatures, Wind Speed, the amount of precipitation as well as the relative humidity rates were collected from Irbid, Jordan as the main location of analyses, as well as comparison cities and countries in both hemispheres. Resultswe found that certain climate variables are significant factors in determining the transmission rate of COVID-19 worldwide. Where, The temperature in the northern hemisphere regions was the most important climate factor that affects the increase in the transmission rate of COVID-19 (Northern Hemisphere rs = −0.65; Irbid rs = −0.74995; P < 0.001), While in southern hemisphere, the climate factor that affects the increase in the transmission rate of COVID-19 was the humidity (rs = 0.55; P < 0.01), In addition, we found the negligible and oscillated effect of wind speed on the transmission rate of COVID-19 worldwide. Moreover, we found that in Irbid 82% of COVID-19 cases were in the fall and winter seasons, while in summer the percentage of COVID-19 cases didn't exceed 3% during the total study period. ConclusionThis study can help develop international strategies and policies against COVID-19-related pandemic peaks, especially during the colder seasons in the Northern Hemisphere regions from the first month of fall to the last month of winter.

Woznikella triradiata n. gen., n. sp. – a new kannemeyeriiform dicynodont from the Late Triassic of northern Pangea and the global distribution of Triassic dicynodonts

Despite nearly two centuries of intensive research of dicynodont diversity and distribution, the progress of the last two decades makes the early 21st century a dicynodont renaissance. Here we introduce Woznikella triradiata n. gen., n. sp., a Late Triassic European kannemeyeriiform with stahleckeriid affinities that may represent an early diverging lineage of that family, preceding its split into Placeriinae King, 1988 and Stahleckeriinae Lehman, 1961. Woznikella triradiata n. gen., n. sp. is distinguished from other dicynodonts by its autapomorphic, slender scapula with distinctly expanded dorsal and ventral parts, acromion directed anterodorsally, and inconspicuous scapular spine. Furthermore, we review reported global occurrences of Triassic dicynodonts, including fragmentary, indeterminate finds that may capture cryptic diversity, and analyze the biogeography of the Permian and Triassic Dicynodontia. According to our results, the region of southeastern Africa (Malawi, Mozambique, Namibia, South Africa, Tanzania, Zambia) throughout the Permian and Triassic served as a hotspot of dicynodont diversity and origin point for lineages migrating north and west. Multiple taxa independently migrated to the Americas and Eurasia, indicating open passages between the regions of Southern and Northern Hemisphere. Southern migrations from the Northern Hemisphere appear to be very rare, however.

Macro-analysis of climatic factors for COVID-19 pandemic based on Köppen–Geiger climate classification

This study integrated dynamic models and statistical methods to design a novel macroanalysis approach to judge the climate impacts. First, the incidence difference across Köppen-Geiger climate regions was used to determine the four risk areas. Then, the effective influence of climate factors was proved according to the non-climate factors' non-difference among the risk areas, multi-source non-major component data assisting the proof. It is found that cold steppe arid climates and wet temperate climates are more likely to transmit SARS-CoV-2 among human beings. Although the results verified that the global optimum temperature was around 10 °C, and the average humidity was 71%, there was evident heterogeneity among different climate risk areas. The first-grade and fourth-grade risk regions in the Northern Hemisphere and fourth-grade risk regions in the Southern Hemisphere are more sensitive to temperature. However, the third-grade risk region in the Southern Hemisphere is more sensitive to relative humidity. The Southern Hemisphere's third-grade and fourth-grade risk regions are more sensitive to precipitation.

Comparative study on the effects of CME and CIR-induced geomagnetic storms on the ionosphere of northern and southern hemispheric regions during the different phases of solar cycle 24

The ionospheric response to CME and CIR-induced geomagnetic storms has been studied using TEC data from northern and southern hemispheric low-latitude stations. During the main phase of geomagnetic storm, opposite effects are observed for almost all the CME and CIR-driven storms at the two stations. During the recovery phase, alternately positive and negative storm effects are observed for almost all CIR-driven storms, while no such fluctuations are observed for CME-driven storms. Recovery periods of CIR-driven storms are longer than that of CME-driven storms. Storm effects are larger at the southern hemispheric station compared to the northern hemispheric station. The observations are explained by the contribution of storm-time prompt penetration electric fields (PPEFs), disturbed dynamo electric fields (DDEFs), and disturbed meridional (equatorward) winds, as well as the neutral compositional changes over low latitudes.

Investigation of the planar midlatitude ionospheric trend under different levels of solar activity

A better understanding of the ionosphere through accurate mathematical models is no doubt a crucial element. This study focuses on the challenging problem of building a model representing the complex structure of the midlatitude ionosphere. Previous studies have shown that a regional planar model is suitable in representing the total electron content (TEC) trend in the midlatitude ionosphere in both hemispheres. In this study, the planar trend model for 12 non-overlapping northern hemisphere regions in three groups of geographically near 4 regions is further investigated under different levels of solar activity; low, moderate and high. To that end, the coefficients of the model are estimated in the least squares sense using total electron content values from global ionospheric maps (GIMs) for the years 2009, 2012 and 2014. Subsequently, these coefficients are used to reconstruct estimated TEC maps which are then compared with actual GIM-TEC by investigating their difference in normalized L2 norm squared sense. The regional planar trend model provides a particularly successful representation in the years 2012 and 2014 for which the solar activity level is the dominant factor determining the TEC trend. Under low solar activity conditions of 2009, other factors such as ocean currents, temperature variations and meteorological phenomena are suspected to have a considerable effect in some regions depending on their geographic location and on seasonal trends in those regions. As an example, studies show that under the influence of the Pacific Decadal Oscillation (PDO) and Siberian High (SH), a significant cooling trend between 2004 and 2018 in autumn is observed in Eurasia, which, in conjunction with the low solar activity levels, may be related to the deviations from the actual GIM-TEC in 2009 in these regions. As solar radiation increases, however, such bottom-side forcings are masked in 2012 and 2014 and these deviations are no longer observed.

Building a small fire database for Sub-Saharan Africa from Sentinel-2 high-resolution images

Coarse resolution sensors are not very sensitive at detecting small fire patches, making current estimations of global burned areas (BA) very conservative. Using medium or high-resolution sensors to generate BA products becomes then a priority, particularly in areas where fires tend to be small and frequent.Building on previous work that developed a small fire dataset (SFD) for Sub-Saharan Africa for 2016, this paper presents a new version of the dataset for 2019 using the two Sentinel-2 satellites (A and B) and VIIRS active fires. Total estimated BA was 4.8 Mkm2. This value was much higher than estimations from two global, coarser-spatial resolution BA products based on MODIS data for the same area and period: 80 % greater than estimates from FireCCI51 (based on MODIS 250 m bands) and 120 % larger than MCD64A1 (based on MODIS 500 m bands). The main differences were observed in those months with higher fire occurrence (November to January for the Northern Hemisphere regions and June to September for the Southern Hemisphere ones).Accuracy assessment of the SFD product was based on a novel sampling strategy designed to obtain independent fire reference perimeters. Validation results showed remarkable high accuracy values comparing to existing global BA products. Overall omission errors (OE) were estimated as 8.5 %, commission errors (CE) as 15.0 %, with a Dice Coefficient of 87.7 %. All of these estimations implied significant improvements over the global, coarser spatial resolution BA products (OE > 50 % and CE > 20 % for the same area and period), as well as over the previous SFD product for 2016 of the same area, generated from a single Sentinel-2 satellite and MODIS active fires (OE = 26.5 % and CE = 19.3 %). Temporal accuracies greatly increased as well with the new product, with 92.5 % of fires detected within the first 10 days of occurrence.

Effects of urbanization on woody plant phylogenetic diversity and its associations with landscape features in the high latitude northern hemisphere region, Northeast China

Urbanization is one of the primary drivers of terrestrial modification, with marked biological homogenization worldwide but relatively poor knowledge of woody phylogenetic diversity. Here, we investigated 943 plots, about 93,000 woody plants from 130 species in Northeast China, and calculated six phylogenetic diversity indexes, and urbanization landscape metrics; the responses of phylogenetic diversity to urbanization and its coupling relationship with landscape features were explored at 25 km × 25 km, 50 km × 50 km and 75 km × 75 km grid scales. We found that urbanization had enhanced the evolutionary distinctiveness of woody plants, characterizing as increasing Faith phylogenetic diversity (FPD) and their mean pairwise distance (MPD) while decreasing the mean nearest taxon distance (MNTD); these trends were independent of landscape scales and gymnosperm inclusion or not. As indicated by increasing SesMPD (Standardized MPD), the dominant role of community assemblage changed from environmental filtering in low urbanization intensity (UI) to competitive exclusion in high UI regions. Artificial surface area (ASA) and its percentage, SHAPE_F (Shape index of forest), and PD_F (Patch density of forest) had a threshold effect on phylogenetic diversity. ASA%, GDP (gross domestic product), and population density were the most potent predictors for the variations of phylogenetic diversity, and GDP contributed the most (42.9%). A higher GDP accompanied a higher FPD, SesPD (Standardized FPD), and SesMNTD (Standardized MNTD); higher PD_F and lower SHAPE_F were associated with higher MNTD, MPD, and SesMPD. In conclusion, urbanization strongly modifies woody plant phylogenetic diversity. Identifying the threshold effects and significant factors for phylogenetic variations allows biodiversity assessment and conservation through proper landscape configuration under the urbanization context.

Chemical Composition, Antioxidant, and Antimicrobial Activity of Dracocephalum moldavica L. Essential Oil and Hydrolate.

Steam distillation was used for the isolation of Dracocephalum moldavica L. (Moldavian dragonhead) essential oil (DMEO). This aromatic herbaceous plant is widespread across the Northern Hemisphere regions and has been utilized in health-improving studies and applications. In addition to the DMEO, the hydrolate (DMH), a byproduct of the distillation process, was also collected. The DMEO and DMH were analyzed and compared in terms of their chemical composition, as well as their in vitro biological activities. The main component in DMEO was geranyl acetate, while geranial was dominant in DMH. The DMEO demonstrated better antioxidant and antimicrobial activities compared with the DMH against Staphylococcus aureus, Escherichia coli, Salmonella Typhimurium, and Listeria monocytogenes, which represent sources of food-borne illness at the global level. The DMEO and DMH show promise as antioxidant and antimicrobial additives to various products.

Biogeographic and evolutionary history of Crotonoideae based on pollen evidence from Indian Late Cretaceous and Paleogene sediments

AbstractEuphorbiaceae Juss. is a globally distributed angiosperm family with considerable diversity. It is divided into five subfamilies, each of which possesses pollen of distinct morphology. The subfamily Crotonoideae, occurring in evergreen, moist deciduous as well as dry deciduous forests of the world, shows a disjunct distribution pattern in Gondwana and Southeast Asia. This subfamily underwent multiple speciation and extinction events during the northward voyage of the Indian Plate during the Late Cretaceous‐early Paleogene. We studied Crotonoideae fossil pollen from the Late Cretaceous Deccan Intertrappeans (Central India) and early Paleogene sediments from the western Indian lignite mines, and as a result, report 10 pollen fossils showing similarity with the extant genera Blachia, Croton, Endospermum, Jatropha, Klaineanthus, and Tetrorchidium, representing 4 tribes of Crotonoideae viz. Adenoclineae, Codiaeae, Crotoneae, and Jatropheae. Fossil evidences from the present study suggest a Gondwanan origin for Crotonoideae. Based on the extant and fossil species, Africa could be the place of origin for most of the Crotonoideae lineages that later dispersed to India via the Kohistan‐Ladakh Island Arc during the late Maastrichtian‐Paleocene time. The former distribution of Crotonoideae in mid‐high latitudinal regions is due to the dispersal of the subfamily from Africa to mid latitudinal regions of northern hemisphere during the early Paleogene via the boreotropical dispersal route. This study also corroborates the “Out of India” hypothesis for the dispersal of Crotonoideae from India to Southeast Asia. The present deep‐time fossil records from India discussed in this study substantiate the evolutionary and biogeographic history of subfamily Crotonoideae.

Sixfold Increase in Historical Northern Hemisphere Concurrent Large Heatwaves Driven by Warming and Changing Atmospheric Circulations

Abstract Simultaneous heatwaves affecting multiple regions (referred to as concurrent heatwaves) pose compounding threats to various natural and societal systems, including global food chains, emergency response systems, and reinsurance industries. While anthropogenic climate change is increasing heatwave risks across most regions, the interactions between warming and circulation changes that yield concurrent heatwaves remain understudied. Here, we quantify historical (1979–2019) trends in concurrent heatwaves during the warm season [May–September (MJJAS)] across the Northern Hemisphere mid- to high latitudes. We find a significant increase of ∼46% in the mean spatial extent of concurrent heatwaves and ∼17% increase in their maximum intensity, and an approximately sixfold increase in their frequency. Using self-organizing maps, we identify large-scale circulation patterns (300 hPa) associated with specific concurrent heatwave configurations across Northern Hemisphere regions. We show that observed changes in the frequency of specific circulation patterns preferentially increase the risk of concurrent heatwaves across particular regions. Patterns linking concurrent heatwaves across eastern North America, eastern and northern Europe, parts of Asia, and the Barents and Kara Seas show the largest increases in frequency (∼5.9 additional days per decade). We also quantify the relative contributions of circulation pattern changes and warming to overall observed concurrent heatwave day frequency trends. While warming has a predominant and positive influence on increasing concurrent heatwave frequency, circulation pattern changes have a varying influence and account for up to 0.8 additional concurrent heatwave days per decade. Identifying regions with an elevated risk of concurrent heatwaves and understanding their drivers is indispensable for evaluating projected climate risks on interconnected societal systems and fostering regional preparedness in a changing climate. Significance Statement Heatwaves pose a major threat to human health, ecosystems, and human systems. Simultaneous heatwaves affecting multiple regions can exacerbate such threats. For example, multiple food-producing regions simultaneously undergoing heat-related crop damage could drive global food shortages. We assess recent changes in the occurrence of simultaneous large heatwaves. Such simultaneous heatwaves are 7 times more likely now than 40 years ago. They are also hotter and affect a larger area. Their increasing occurrence is mainly driven by warming baseline temperatures due to global heating, but changes in weather patterns contribute to disproportionate increases over parts of Europe, the eastern United States, and Asia. Better understanding the drivers of weather pattern changes is therefore important for understanding future concurrent heatwave characteristics and their impacts.

Temperature sensitivity of vegetation phenology in spring in mid- to high-latitude regions of Northern Hemisphere during the recent three decades

Temperature sensitivity of vegetation phenology in spring in mid- to high-latitude regions of Northern Hemisphere during the recent three decades

Hydrodynamics of regional and seasonal variations in Congo Basin precipitation

The processes that determine the seasonality of precipitation in the Congo Basin are examined using the atmospheric column moisture budget. Studying the fundamental determinants of Congo Basin precipitation seasonality supports process-based studies of variations on all time scales, including those associated with greenhouse gas-induced global warming. Precipitation distributions produced by the ERA5 reanalysis provide sufficient accuracy for this analysis, which requires a consistent dataset to relate the atmospheric dynamics and moisture distribution to the precipitation field. The Northern and Southern Hemisphere regions of the Congo Basin are examined separately to avoid the misconception that Congo Basin rainfall is primarily bimodal. While evapotranspiration is indispensable for providing moisture to the atmospheric column to support precipitation in the Congo Basin, its seasonal variations are small and it does not drive precipitation seasonality. During the equinoctial seasons, precipitation is primarily supported by meridional wind convergence in the moist environment in the 800–500 hPa layer where moist air flows into the equatorial trough. Boreal fall rains are stronger than boreal spring rains in both hemispheres because low-level moisture divergence develops in boreal spring in association with the developing Saharan thermal low. The moisture convergence term also dominates the moisture budget during the summer season in both hemispheres, with meridional convergence in the 850–500 hPa layer as cross-equatorial flow interacts with the cyclonic flow about the Angola and Sahara thermal lows. Winter precipitation is low because of dry air advection from the winter hemisphere subtropical highs over the continent.

Explaining Globally Inhomogeneous Future Changes in Monsoons Using Simple Moist Energy Diagnostics

AbstractThis study examines the annual cycle of monsoon precipitation simulated by models from phase 6 of the Coupled Model Intercomparison Project (CMIP6), then uses moist energy diagnostics to explain globally inhomogeneous projected future changes. Rainy season characteristics are quantified using a consistent method across the globe. Model bias is shown to include rainy season onsets tens of days later than observed in some monsoon regions (India, Australia, and North America) and overly large summer precipitation in others (North America, South America, and southern Africa). Projected next-century changes include rainy season lengthening in the two largest Northern Hemisphere monsoon regions (South Asia and central Sahel) and shortening in the two largest Southern Hemisphere regions (South America and southern Africa). Changes in the North American and Australian monsoons are less coherent across models. To understand these changes, relative moist static energy (MSE) is defined as the difference between local and tropical-mean surface air MSE. Future changes in relative MSE in each region correlate well with onset and demise date changes. Furthermore, Southern Hemisphere regions projected to undergo rainy season shortening are spanned by an increasing equator-to-pole MSE gradient, suggesting their rainfall will be increasingly inhibited by fluxes of dry extratropical air; Northern Hemisphere regions with projected lengthening of rainy seasons undergo little change in equator-to-pole MSE gradient. Thus, although model biases raise questions as to the reliability of some projections, these results suggest that globally inhomogeneous future changes in monsoon timing may be understood through simple measures of surface air MSE.

Influence of Indian Summer Monsoon on Tropopause, Trace Gases and Aerosols in Asian Summer Monsoon Anticyclone Observed by COSMIC, MLS and CALIPSO

The existence of the Asian Summer Monsoon Anticyclone (ASMA) during the summer in the northern hemisphere, upper troposphere and lower stratosphere (UTLS) region plays a significant role in confining the trace gases and aerosols for a long duration, thus affecting regional and global climate. Though several studies have been carried out, our understanding of the trace gases and aerosols variability in the ASMA is limited during different phases of the Indian monsoon. This work quantifies the role of Indian Summer Monsoon (ISM) activity on the tropopause, trace gases (Water Vapor (WV), Ozone (O3), Carbon Monoxide (CO)) and aerosols (Attenuated Scattering Ratio (ASR)) obtained from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC), Microwave Limb Sounder (MLS), Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite observations, respectively, during the period 2006–2016. Enhancement in the tropopause altitude, WV, CO, ASR and low tropopause temperatures, O3 in the ASMA region is clearly noticed during peak monsoon months (July and August) with large inter-annual variability. Further, a significant increase in the WV and CO, and decrease in O3 during the active phase of the ISM, strong monsoon years and strong La Niña years in the ASMA is noticed. An enhancement in the ASR values during the strong monsoon years and strong La Niña years is also observed. In addition, our results showed that the presence of deep convection spreading from India land regions to the Bay of Bengal with strong updrafts can transport the trace gases and aerosols to the upper troposphere during active spells, strong monsoon years and La Niña years when compared to their counterparts. Observations show that the ASMA is very sensitive to active spells, strong monsoon years and La Niña years compared to break spells, weak monsoon years and El Niño years. It is concluded that the dynamics play a significant role in constraining several trace gases and aerosols in the ASMA and suggested considering the activity of the summer monsoon while dealing with them at sub-seasonal scales.