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The first part of the study refers to the occurrence of the Indian summer events in Romania, over the 1961-2019 period. The second part analyses the Indian summer event recorded in Romania in October 2019. The datasets used for the first part were daily maximum and minimum temperatures recorded in the past 59 years at 23 climatological weather stations, divided into 6 regions. Regarding the methodology, first step was to determine the annual and seasonal occurrence of the first frost for each weather station, and then the presence of the warm spells (WSs), based on the percentile threshold method. So, we could determine WSs with different types of intensity (using the 90th, 95th, 98th percentile), and durations. For the Indian summer event recorded between 12 and 28 October 2019, daily maximum temperatures from 157 weather stations were compared to absolute maximum temperatures over the period 1961-2018. Synoptic conditions were determined using weather charts at sea level pressure, geopotential height and temperature of 925, 850, 700 and 500 hPa. The main finding is: Indian summer events are frequent in the Carpathians and in the Northern, Central and the Western regions of Romania, especially in November, followed by October; no matter the intensity, short duration events have high number of cases, and severe and extremely severe events were registered in the past 20 years; the Indian summer event from October 2019 was influenced by synoptic and local conditions, as well. Overall the Indian summer is not present in Romania every year, but it is more frequent and intense in the last 20 years.

The fluctuating climatic conditions of the Saharo-Arabian deserts are increasingly linked to human evolutionary events and societal developments. On orbital timescales, the African and Indian Summer Monsoons were displaced northward and increased precipitation to the Arabian Peninsula which led to favorable periods for human occupation in the now arid interior. At least four periods of climatic optima occurred within the last 130,000 years, related to Marine Isotope Stages (MIS) 5e (128–121 ka BP), 5c (104–97 ka BP), 5a (81–74 ka BP) and 1 (10.5–6.2 ka BP), and potentially early MIS 3 (60–50 ka BP). Stalagmites from Southern Arabia have been key to understanding climatic fluctuations and human-environmental interactions; their precise and high-resolution chronologies can be linked to evidence for changes in human distribution and climate/environment induced societal developments. Here, we review the most recent advances in the Southern Arabian Late Pleistocene and Early Holocene stalagmite records. We compare and contrast MIS 5e and Early Holocene climates to understand how these differed, benchmark the extremes of climatic variability and summarize the impacts on human societal development. We suggest that, while the extreme of MIS 5e was important for H. sapeins dispersal, subsequent, less intense, wet phases mitigate against a simplistic narrative. We highlight that while climate can be a limiting and important factor, there is also the potential of human adaptability and resilience. Further studies will be needed to understand spatio-temporal difference in human-environment interactions in a climatically variable region.

We conducted literature searches of records from Illinois, Indiana, Iowa, Minnesota, Missouri, North Dakota, Ohio, and Wisconsin to create a source bibliography of wildland fire descriptions occurring between 1673 and 1905. A total of 795 landscape fire records were identified within or near the eastern tallgrass prairie–forest transition region, including 32 attributed to Native Americans, 194 to Europeans from spontaneous records in the nineteenth century, and 569 to Europeans from a systematic dataset collected during the late nineteenth and early twentieth centuries in Minnesota. From these historical accounts, we find overwhelming evidence that a two- to three-week period during October and November, known then as “Indian summer,” was the primary wildland fire season. Our records indicate that Native Americans used fire primarily for hunting, whereas Euro-American fires were set to reduce fire hazards near their habitations, to eliminate crop residues, and to facilitate plowing, or they were escapes due to mere carelessness. Only five lightning-caused fires were identified. Individual fires frequently burned thousands of hectares, creating dense smoke, damaging trees, personal property, and occasionally burning inhabitants fatally. South and southwest were the most frequent wind directions during wildfires. Drought years, including 1796, 1819, 1856, and 1871, were characterized by extensive fires, which ultimately resulted in legislation to protect property owners and public welfare. Fire events for the study period are certainly underestimated by this dataset because only large, spectacular, threatening fires were recorded, especially during European settlement. In addition, our estimate of Native American fire frequency and prevalence is less than their historical/expected frequency, due to their widespread population collapse and changed hunting methods following contact and dispossession by Europeans.

The sedimentology, geochemistry, and plant microfossils of volcanic lake sediments from Cambodia were analysed to reconstruct a 4700 year record of change in moisture availability. This site sits at the heart of the intersection zone of the East Asian and Indian summer monsoons – a climatic system that is socio-ecologically important but poorly understood. Proxies for lake deepening and shallowing indicate a stepwise weakening of the summer monsoon from c. 4700 to 1700 cal. years BP, after which it appears to gradually strengthen. This trend is punctuated by seven dry events between 4300 and 1540 cal. years BP. The results present one of the longest, continuous records of palaeo-hydrological change in the Asian monsoon intersection zone. In doing so, they suggest that the climate of the region was broadly comparable to the East Asian summer monsoon (EASM) province to approximately 2240 cal. years BP, and the Indian summer monsoon (ISM) province between 2240 and 1700 cal. years BP. The subsequent, late Holocene hydroclimate appears to reflect a combination of both subsystems. These findings highlight dynamism in EASM and ISM dominance over mainland southeast Asia over the past five thousand years, but overall demonstrate regional vs. local scale influence on the hydroclimate of the region. The multi-decadal periods of strong drying that punctuate longer-term monsoon patterns demonstrate the natural variability of the mid- to late- Holocene climate of the intersection zone. This is of consequence given that apparently less severe drought events of the last millennium have had dramatic socio-economic consequences. Resultantly, planning for the resilience of socio-ecological systems within the region needs to account for the real potential of similar scale events occurring in the future, particularly given the increased extremes predicted for Asian summer monsoon region over the 21st century.

Corroboration of El Nino and Southern Oscillation (ENSO) events on the climatic variability in the Indian subcontinent is mentioned in various studies. In the Indian context, if we observe the rising number of dengue cases, it could be treated as a major cause of health concern for the government of this country. Nowadays, an increasing number of dengue incidences are reported from different Indian states which are leading to unfortunate hospitalization and fatal death of the people. Keeping the context in mind, we have examined the relationship between the ENSO events, inter-annual variability in dengue cases in major states of India and Indian summer monsoonal rainfall (ISMR). In this study, we use Pearson’s product-moment correlation (hereafter PPMC) to find out the interconnections between ‘+ winter ONI’ (OND, NDJ, DJF, and JFM seasons) events, rainfall index for the JJAS season (June, July, August, September) and annual 10 major state-level data of dengue cases index for the past 14 years. It has been observed through the study that the PPMC result between the ‘rainfall index’ and ‘dengue index’ is showing greater variation among different states of the country. Interestingly, we have observed that the correlation result between the ‘+ winter ONI’ and dengue incidence index have (r) value ranging from highly (−) to very high (+) value −0.53 to + 0.83 across the different states.

Indian Summer and Winter monsoon winds are major drivers of the mixed layer processes in the Arabian Sea. Our study shows that the Arabian Sea &lsq...

The plains of northwest South Asia receive rainfall during both the Indian summer (June–September) and winter (December–March) monsoon. Researchers have long attempted to deconstruct the influence of these precipitation regimes in paleoclimate records, in order to better understand regional climatic drivers and their potential impact on human populations. The mid–late Holocene transition between 5.3 and 3.3 ka is of particular interest in this region because it spans the period of the Indus Civilization from its early development, through its urbanization, and onto eventual transformation into a rural society. An oxygen isotope record of the surface-dwelling planktonic foraminifer Globigerinoides ruber from the northeast Arabian Sea provided evidence for an abrupt decrease in rainfall and reduction in Indus River discharge at 4.2 ka, which the authors linked to the decline in the urban phase of the Indus Civilization (Staubwasser et al., 2003). Given the importance of this study, we used the same core (63KA) to measure the oxygen isotope profiles of two other foraminifer species at decadal resolution over the interval from 5.4 to 3.0 ka and to replicate a larger size fraction of G. ruber than measured previously. By selecting both thermocline-dwelling (Neogloboquadrina dutertrei) and shallow-dwelling (Globigerinoides sacculifer) species, we provide enhanced detail of the climatic changes that occurred over this crucial time interval. We found evidence for a period of increased surface water mixing, which we suggest was related to a strengthened winter monsoon with a peak intensity over 200 years from 4.5 to 4.3 ka. The time of greatest change occurred at 4.1 ka when both the summer and winter monsoon weakened, resulting in a reduction in rainfall in the Indus region. The earliest phase of the urban Mature Harappan period coincided with the period of inferred stronger winter monsoon between 4.5 and 4.3 ka, whereas the end of the urbanized phase occurred some time after the decrease in both the summer and winter monsoon strength by 4.1 ka. Our findings provide evidence that the initial growth of large Indus urban centers coincided with increased winter rainfall, whereas the contraction of urbanism and change in subsistence strategies followed a reduction in rainfall of both seasons.

Loess and stalagmite records in China show different responses of Asian monsoon to the astronomical insolation during Marine Isotope Stage (MIS) 5c and 5e, raising the question whether the amplitudes of the whole Asian monsoon are linearly controlled by the astronomical summer insolation changes and whether the regional differences exist. In this study, a set of numerical experiments are conducted for these stages to examine the sensitivity of Asian summer monsoon to changes in the astronomical parameters. The results highlight a complicated response changing with regions and signals. The East Asian monsoon is remarkably stronger during MIS-5e, which is characterized by southerly winds, primarily due to the anomalous anticyclone over northwestern Pacific. The intensified East Asian monsoon leads to less precipitation in the eastern China and Japan but more in the further north and northwest. However, the Indian monsoon circulation does not vary significantly while the precipitation over Arabian Sea is significantly promoted by the upward air motion. Change in water vapor sources of Indian and Pacific Oceans qualitatively explains the observed differences in stalagmite δ18O records, implying that these proxy changes are primarily controlled by the water vapor delivery from oceans, at least on the astronomical timescale.

The Indian and East Asian summer monsoons are two active components of the global monsoon system and are closely related. However, their relationship is weakened after the late 1970s. This study revisited the possible mechanism for the weakening relationship between Indian and central East Asian summer rainfall, focusing on the influence from the middle-to-high-latitude climate system. The results show that variability in the summer North Atlantic Oscillation since the late 1970s induces a zonal atmospheric teleconnection pattern, resulting in anomalous upper level atmospheric circulation south of the Baikal Lake, which is further closely related to central East Asian summer rainfall over the period after the late 1970s. When the signal of the atmospheric circulation variability south of the Baikal Lake is removed, the relationship between the Indian and central East summer rainfall becomes significant again over the period after the late 1970s. The summer North Atlantic Oscillation thus opposes the influence of the Indian summer rainfall on central East Asian summer rainfall, consequently contributing to the breakdown of the Indian–central East Asian summer rainfall relationship after the late 1970s.

Previous studies have found a link between north China and Indian rainfall during summer, with significantly increased rainfall in north China related to a stronger Indian summer monsoon. This link is weakened after the late 1970s, generally attributed to the reduced magnitude of interannual variability in the Indian summer rainfall. This study reveals a similar change in this rainfall link in early summer after the late 1970s. Related to a heavier Indian early summer rainfall, rainfall in north China enhances significantly before the late 1970s but not thereafter. The change in rainfall teleconnection is caused by the weakened impact on north China rainfall of a midlatitude wave train along the Asian jet in the upper troposphere. After the late 1970s, the portion of the wave train over East Asia displaces eastward, leading to an eastward shift in the associated ascending motion and, subsequently, enhanced rainfall from north China to the Yellow Sea. Moreover, the change in the midlatitude wave train is attributed to the change in the basic state over East Asia (i.e., a northward shift of the East Asian upper-tropospheric westerly jet after the late 1970s). The latter reduces stationary Rossby wavenumber and increases wavelength of the midlatitude wave train, leading to an eastward shift of the wave train over East Asia. Therefore, in this study a mechanism is proposed for the change in early summer, different from the previous mechanism for the entire summer period.

The article is dedicated to the investigation of the two-component nominative unit “Indian Summer” meaning a period of warm weather in autumn. The analysis of the dictionary entries was done, possible theories of its origin were given and the ways of its motivation were found. We used the method of cognitive onomasiological analysis that consists of two stages: the interpretation of the onomasiological structure of the nominative unit and the simulation of the corresponding structure of knowledge about the unit nominated. 5 theories of the origin of the lexical unit “Indian Summer” were found. Each of them has different type of motivation of nomination. The unit investigated has both direct and indirect meanings that can be explained by the significance of the notion in the minds of people. “Indian Summer” is the realia of North America but its lexical equivalents are used all over the world to denote the climatic phenomenon of unusually warm weather in autumn.

Hydroclimatic variations during the summer monsoon season (June–September) across the Himalaya are examined over the past several hundred years using tree-ring oxygen isotope records. Owing to their strong associations with hydroclimatic variables including precipitation, relative humidity, and the Palmer Drought Severity Index, tree-ring δ18O chronologies from the Himalaya can be used to reconstruct summer monsoon intensity precisely. A regional chronology derived from five local chronologies across the Himalaya shows a significant correlation with Indian summer rainfall data. One of the most noteworthy features of the regional chronology is a drying trend over the past 180 years, indicating that summer monsoon intensity in the Himalayan region has weakened. A declining land–ocean thermal gradient over South Asia seems to be responsible for the weakened summer monsoon. By analyzing spatio-temporal correlations between zonally distributed tree-ring data over the Himalaya, we also explore possible changes in the relative contributions of source water originating in the Arabian Sea and the Bay of Bengal.

The Indian subcontinent receives most of its annual precipitation due to Indian summer (June, July, August and September) monsoon. Southeastern coastal region of the India receives significant amount of precipitation due to the northeast monsoon (October and November). Over northern Indian region almost one-third of annual precipitation is received during winter (December, January and February) by eastward moving extratropical cyclone called ‘western disturbances (WDs)’ in Indian meteorological parlance. Various studies are conducted to understand the Indian summer and northeast monsoons. However, the dynamics and characterization of winter precipitation is not well understood except with reference to the western disturbances (WDs). In this study, wintertime dynamics associated with large-scale flows and WDs influencing winter precipitation is proposed and termed ‘Indian winter monsoon’. In addition, winter precipitation – the Indian winter monsoon – is proposed as eastward traveling WDs embedded in the large-scale subtropical westerlies over the Indian sub-continent. During winter (December, January and February) upper level subtropical westerly jet moves southwards and passes over the Indian sub-continent and provides associated precipitation over the northern Indian region. With concurrent research and changing global context, increased understanding of the Indian winter monsoon is imperative. Equally important is the behavior of WDs showing different patterns in the Peninsular India and the Himalaya particularly during the Holocene. During the Little Ice Age (LIA), it appears that high frequency of El Nino events was responsible for drier conditions in the core monsoon zone but generated more monsoon “breaks” over the Himalaya and thus the climatic conditions in the core Indian summer monsoon area were generally opposite to those in the foothills of the Himalaya during the Holocene period. During this period, a higher frequency of El Nino events might have restricted transport of warm water to the North Atlantic Ocean and brought about a cooling of adjacent continents including Central Asia and this may have amplified the extent of snow over Asia during the winter, and may even have been accounted for early snow in the region at the expanse of reduction in the Indian summer monsoon strength. Thus, this study delineates the Indian winter monsoon at intraseasonal-sub seasonal-interannual-paleoclimate scale and provides comprehensive details on defining the Indian winter monsoon and makes an attempt to understand the WDs particularly from mid-Holocene onwards as well.

Hydroclimatic process in the Yarlung Tsangpo River (YTR) basin, a sensitive area to climate change, is obviously changing during recent years, but there has limited understanding about it. In this study, we investigated the spatiotemporal variation of precipitation over last four decades in the basin and the impact thereon of the changing Indian summer monsoon at interannual and decadal time scales. All the precipitation series have similar scaling behavior, reflecting similar climatic regime throughout the basin. However, the effect of the Indian monsoon strengthens from the downstream to upstream, causing spatial variability in the seasonal distribution of precipitation, and on this basis, the YTR basin is roughly divided into three regions: east, middle, and west. Both the occurrence times and magnitude of precipitation extremes, ranging 25-50mm/d, are exhibiting downward trends over the last four decades, which bodes well for water disaster controls in the basin. The Indian summer monsoon index, as an intensity indicator for the Indian summer monsoon, shows a positive relationship with the summer precipitation in the YTR basin. Periodic variability of the Indian monsoon determines the interannual nonstationary fluctuations of precipitation. Especially, the weakening effect of the Indian summer monsoon has caused an obvious decrease in precipitation over the rainy season after 1998. If the Indian summer monsoon keeps weakening, the precipitation would decrease and potentially water shortage would become more severe in the basin. Effective adaptation strategy should therefore be developed proactively to handle the unfavorable water situation, which is likely to occur in the future.

The El Nino–Southern Oscillation (ENSO) is a main driving force of the northern hemisphere summer monsoon rainfall, including the Indian Summer Rainfall (ISR). The impacts of typical ENSO and atypical ENSO events on the ISR remain unclear during their developing summers. This study examines the different linkages between a typical ENSO and the ISR and between an a typical ENSO and the ISR. During the developing summer of a typical El Nino, negative rainfall anomalies are seen over the northeastern Indian subcontinent, while the anomalous rainfall pattern is almost the opposite for a typical La Nina; as for an atypical ENSO, the approximate “linear opposite” phenomenon vanishes. Furthermore, an anomalous global zonal wave train is found at mid-latitudes, with a local tripole circulation pattern over central–eastern Eurasia during the developing summer of a typical ENSO, which might explain the corresponding rainfall response over the Indian Peninsula. By contrast, such features are not obvious duri...

Monthly correlation of Indian monsoon rainfall (IMR) index with various monsoon indices changes predominantly and peaks within summer season (Ailikun and Yasunari, 2001). There is transition in this lead and lagged correlation during spring (March, April and May). This spring transition could not be captured in many general circulation models (GCMs) and is termed as “predictability barrier” (Latif and Graham, 1991). It has been less investigated and hence reasons for dampening/reversal of associated large scale fields during spring are intriguing. Present study illustrates dynamics of spring predictability barrier with Indian summer (June, July, August and September) monsoon (ISM). In this study, based on data from 1979 to 2008, an internal dynamics between various monsoon indices and corresponding IMR anomaly is diagnosed. It is found that secular behaviour of El Nino– Southern Oscillation (ENSO) during preceding spring of monsoon months (June, July, August and September) gets reversed in succeeding spring. Though correlation between various monsoon indices and ISM index remains similar during preceding and succeeding springs with peaks during monsoon (June, July, August and September), corresponding large scale fields show that strong significant convection dominates over the southern equatorial eastern Pacific Ocean, northern equatorial western Pacific Ocean, Indonesian throughflow and weaker significant convection dominates over the Head Bay of Arabian Sea and western to central Indian sub-continent during preceding spring. Such patterns reverse during succeeding spring.

The onset/progression phase of theIndian summer monsoon (ISM) is very crucial for the agricultural sector of the country as it has strong bearing on the sowing of kharif crops, which in turn affects overall food grain production and hence food security. The recent ISMs of 2013 and 2014 exhibited quite distinct progression phases. While 2013 had one of the fastest advancement in the last 70 years, 2014 witnessed a comparatively lethargic progression phase. The major difference was felt in the early monsoon month of June, with 2013 (2014) monthly rainfall being +34% (−43%) of its long period average. Observational investigations reveal that, during June 2013, the monsoon trough was very active in its normal position favouring low-level positive vorticity generation and moisture convergence, whereas the absence of monsoon trough during June 2014 facilitated the prevalence of a strong low-level anticyclonic circulation over central India hampering the northward progression of the ISM. It is found that June 2013 (2014) was associated with (i) stronger (weaker) north-south tropospheric temperature (TT) gradient with positive (negative) TT anomalies over Eurasia and north of 60°N; (ii) negative (positive) SST anomalies over the equatorial Indian Ocean, northwestern Arabian Sea and equatorial eastern Pacific; (iii) stronger (weaker) monsoonal Hadley circulation; and (iv) stronger (weaker) Walker circulation in response to the negative (positive) SST anomalies over the equatorial Pacific. The study also examines the skill of an Ensemble Prediction System (EPS) in predicting the observed contrasting behaviour during June 2013/2014 on extended range (∼15–20 days in advance) in real time. The EPS not only forecasted the observed discrepancy, but also predicted the influential role of the large-scale meteorological conditions prevalent during June 2013 (2014), thus demonstrating the remarkable skill of the EPS in predicting June extremes.

The plains of northwest South Asia receive rainfall during both the Indian Summer (June–September) and Winter (December–March) Monsoon. Researchers have long attempted to deconstruct the influence of both precipitation regimes in paleoclimate records, in order to better understand regional climatic drivers and their potential impact on human populations. The Mid–Late Holocene transition between 5.3–3.3 ka BP is of particular interest in this region because it spans the period of the Indus Civilization from its early development to eventual transformation. The oxygen isotope record of the surface-dwelling planktonic foraminifer Globigerinoides ruber from the northeast Arabian Sea provided evidence for an abrupt decrease in rainfall and reduction in Indus River discharge at 4.2 ka BP, which the authors linked to the decline of the urban phase of the Indus Civilization (Staubwasser et al., 2003). Given the importance of this study, we used the same core (63KA) to replicate the oxygen isotope profiles of a larger size fraction of G. ruber than measured previously and, in addition, we measured two other foraminifer species at decadal resolution over the interval from 5.4 to 3.0 ka BP. By selecting both thermocline-dwelling (Neogloboquadrina dutertrei) and shallow-dwelling (Globigerinoides sacculifer) species, we provide enhanced detail of the climatic changes that occurred over this crucial time interval. We found evidence for a period of increased surface water mixing, which we suggest was related to a strengthened winter monsoon with a peak intensity over 200 years from 4.5 to 4.3 ka BP. The time of greatest change occurred at 4.1 ka BP when both the summer and winter monsoon weakened, resulting in a reduction in rainfall in the Indus region. The earliest phase of the Mature Harappan period coincided with the period of inferred stronger winter monsoon between 4.5–4.3 ka BP, whereas the end of the urbanized phase followed the decrease in both the summer and winter monsoon strength by 4.1 ka BP. Our findings provide evidence that the initial growth of large Indus urban centers was coincident with increased winter rainfall, whereas the contraction of urbanism and change in subsistence strategies followed a reduction in rainfall of both seasons.

Atmospheric CH4 observations from two ground-based stations within Indian subcontinent, namely, Sinhagad (SNG) and Cape Rama station (CRI) showed a strong seasonality with a minima (∼1800 ± 20 ppb) during southwest monsoon (SWM; i.e. June–September, JJAS) and a maxima (2000 ± 30 ppb) during northeast monsoon (NEM i.e. December–February, DJF) with a peak-to-peak seasonality close to 200 ppb. The Indian summer (winter) monsoon is characterized with strong southwesterly (northeasterly) winds of oceanic (land) origin at the surface level and strong easterly (westerly) jet streams aloft. The monsoon dynamics has pronounced impact on CH4 variability over India and is analyzed with winds, Lagrangian trajectories, and 3-dimentional distributions of CH4 simulated by a general circulation model. The model simulations suggest a consistent annual vertical structure (mean and sub-seasonal uncertainty) of CH4 over India with a stark contrast in concentration from summer to winter at surface levels (below 750 mb) in confirmation with what is identified by the ground-based observations. During SWM (NEM) the air with comparatively lower (higher) CH4 concentrations from southern (northern) hemisphere reduces the CH4 over India by 1814 ± 26 ppb (enhances by 1950 ± 51 ppb). The contribution of local fluxes to this seasonality appears to be albeit weak as the synthesized CH4 fluxes (from EDGAR dataset) of the Indian peninsula itself show a peak in summer and a dip in winter. Similar property of CH4 is also common to nearby oceanic region (i.e. over Arabian Sea, 1765 ± 10 ppb during summer) suggesting the role of monsoon dynamics as the controlling factor. Further the mixing and convection carries the CH4 to the upper atmosphere and advect inward or outward aloft according the seasonal monsoon dynamics.

The thermal forcing of the Tibetan Plateau (TP) is analyzed to investigate the formation and variability of Tibetan Plateau Summer Monsoon (TPSM), which affects the climates of the surrounding regions, in particular the Indian summer monsoon precipitation. Dynamic composites and statistical analyses indicate that the Indian summer monsoon precipitation is less/greater than normal during the strong/weak TPSM. Strong (weak) TPSM is associated with an anomalous near surface cyclone (anticyclone) over the western part of the Tibetan Plateau, enhancing (reducing) the westerly flow along its southern flank, suppressing (favoring) the meridional flow of warm and moist air from the Indian ocean and thus cutting (providing) moisture supply for the northern part of India and its monsoonal rainfall. These results are complemented by a dynamic and thermodynamic analysis: (i) A linear thermal vorticity forcing primarily describes the influence of the asymmetric heating of TP generating an anomalous stationary wave flux. Composite analysis of anomalous stationary wave flux activity (after Plumb in J Atmos Sci 42:217–229, 1985) strongly indicate that non-orographic effects (diabatic heating and/or interaction with transient eddies) of the Tibetan Plateau contribute to the generation of an anomalous cyclone (anti-cyclone) over the western TP. (ii) Anomalous TPSM generation shows that strong TPSM years are related to the positive surface sensible heating anomalies over the eastern TP favoring the strong diabatic heating in summer. While negative TPSM years are associated with the atmospheric circulation anomalies during the preceding spring, enhancing northerly dry-cold air intrusions into TP, which may weaken the condensational heat release in the middle and upper troposphere, leading to a weaker than normal summer monsoon over the TP in summer.

Spring snow cover variations over Eurasia consist of a same-sign component and a west-east dipole component. The same-sign component is dominant during late 1970s through 1980s, and the two components are equally important during 1990s and 2000s. Present study contrasted Eurasian spring and summer climate anomalies associated with western and eastern Eurasian spring snow cover variations and between 1975–1989 and 1993–2007 and found notable differences and obvious interdecadal changes in Eurasian climate anomalies. After 1990, spring surface temperature anomalies display an obvious west-east contrast pattern, consistent with a prominent atmospheric wave pattern over Eurasia. The temperature anomalies are larger corresponding to western than eastern Eurasian snow cover change. Snow-albedo effect plays a main role in temperature change during 1975–1989, whereas atmospheric processes also contribute largely to temperature change during 1993–2007. Large soil moisture anomalies occur corresponding to western Eurasian snow cover and during 1975–1989. The snow-hydrological effect on summer precipitation is mainly detected over the West Siberian Plain where soil moisture anomalies persist over 3 months. Over most of other Eurasian regions, atmospheric circulation pattern plays a dominant role in summer surface temperature and precipitation variations. The relationship of Indian summer rainfall to western Eurasian spring snow cover was weakened since the mid-1990s, and the correlation of Northeast China summer rainfall with local spring snow cover changed from positive to negative around 1990.

Using observational and reanalyses data, we investigated the impact of dust aerosols over the Middle East and the Arabian Sea (AS) on the Indian summer monsoon (ISM) rainfall. Satellite and aerosol reanalysis data show extremely heavy aerosol loading, mainly mineral dust, over the Middle East and AS during the ISM season. Multivariate empirical orthogonal function analyses suggest an aerosol-monsoon connection. This connection may be attributed to dust-induced atmospheric heating centered over the Iranian Plateau (IP), which enhances the meridional thermal contrast and strengthens the ISM circulation and rainfall. The enhanced circulation further transports more dust to the AS and IP, heating the atmosphere (positive feedback). The aerosols over the AS and the Arabian Peninsula have a significant correlation with rainfall over central and eastern India about 2 weeks later. This finding highlights the nonlocal radiative effect of dust on the ISM circulation and rainfall and may improve ISM rainfall forecasts.

It has been demonstrated in climate models that both the Indian and East Asian summer monsoons (ISM and EASM) are strengthened by the uplift of the entire Asian orography or Tibetan Plateau (TP) (i.e. bulk mountain uplift). Such an effect is widely perceived as the major mechanism contributing to the evolution of Asian summer monsoons in the Neogene. However, geological evidence suggests more diachronous growth of the Asian orography (i.e. regional mountain uplift) than bulk mountain uplift. This demands a re-evaluation of the relation between mountain uplift and the Asian monsoon in the geological periods. In this study, sensitivity experiments considering the diachronous growth of different parts of the Asian orography are performed using the regional climate model COSMO-CLM to investigate their effects on the Asian summer monsoons. The results show that, different from the bulk mountain uplift, the regional mountain uplift can lead to an asynchronous development of the ISM and EASM. While the ISM is primarily intensified by the thermal insulation (mechanical blocking) effect of the southern TP (Zagros Mountains), the EASM is mainly enhanced by the surface sensible heating of the central, northern and eastern TP. Such elevated surface heating can induce a low-level cyclonic anomaly around the TP that reduces the ISM by suppressing the lower tropospheric monsoon vorticity, but promotes the EASM by strengthening the warm advection from the south of the TP that sustains the monsoon convection. Our findings provide new insights to the evolution of the Asian summer monsoons and their interaction with the tectonic changes in the Neogene.

Western China, defined here as the land falling within the geographical boundaries of the People's Republic of China in the west, south and north, and the approximate eastern extent of the Tibetan and Alaxa Plateaux to the east, occupies an important climatic region, influenced by the Asian and Indian summer monsoons, the mid-latitude westerlies and the dry, cold central Asian winter monsoon. The Tibetan Plateau itself is a prominent topographic feature that exerts major control on regional atmospheric circulation. Previous compilations of meteorological data and documentary sources suggest that western China, and the Tibetan Plateau in particular, is highly sensitive to anthropogenically induced climate change. Temperature increases appear to be greatest at higher altitudes: moreover, precipitation variations seem to have been marked, although spatially complex. The region contains a wealth of information about past climate derived from instrumental, documentary and proxy sources although meteorological time series are generally too short to capture the full range of recent climatic variability. Documentary and proxy sources are therefore important. We review studies of climate change in western China for the past two millennia. Documentary records are complemented by proxy data from ice cores, tree rings, lake sediments, groundwater profiles and glacial geomorphology. Although general patterns of change can be identified, proxy records of past climate are often semi-quantitative at best, open to alternative interpretations and sometimes poorly dated. Despite evidence for marked variations in climate over the past 2000 years, changes during the 20th century, especially in temperature, may have been unprecedented. The density of data points over western China is currently too low for spatial patterns to be identified, especially in precipitation variation. However, there does seem to have been an increase in warming with altitude over the most recent past.

SUMMARY This paper reviews qualitative results of study of 35 mm. moving pictures taken of PPI scopes of 23 cm. radar installations on the southeast coast of New England during spring and autumn migrations in 1959 and 1960. Gulls, waders and passerines are readily distinguished from each other; small, medium, and large movements are easily separated. New England weather is controlled by eastward flow of large air masses out of the continent of North America or the Gulf of Mexico. These take several days to cross New England, so that short-range weather forecasts are more reliable than in northwestern Europe. Winter is characterized by regular eastward passage of air masses. Wintering buntings increase their fat deposits in low temperatures and move their feeding grounds with storms. Unstable early spring weather marks the end of winter. Early spring migrants respond to 10° rise in temperature and usually move with overcast skies. The dispersal of flocks of wintering Tree Sparrows studied over five years and conspicuous first arrivals of spring migrants, including large flocks of day-migrating icterids, may be as early as 22 February or as late as 10 April and coincide with the first moderate movements on radar. Late spring is marked by orderly flow of maritime air up the east coast of North America, either with the movement of low-pressure systems or with circulation around the Bermuda high. Late spring migrants are more regular in their schedule of arrival and respond to clear skies, rising temperatures, and favourable winds. In mid- and late May, stalling of the warm air in a reentrant centred over coastal New England results in the grounding of large numbers of birds which winter in Central and South America. Week-long rain resulting from such stalled weather produces especially large movements when the skies clear. Passage of a sharp cold front stimulates reversed migration during spring months, more marked in March and April, but still evident in May. In early August, adults start to migrate and continue as a steady flow in small numbers, which increase with the passage of each cold front until early September. As the sun's declination falls, cold continental polar air masses cross New England, accompanied by increasingly evident cold fronts and falls of temperature during September and October. Warblers and thrushes move with each cold front in early September; buntings join them in late September and become predominant among night migrants in October. In September, tropical storms on the Atlantic coast bring southern stragglers with them. Wintering buntings appear and day-migrant icterids again are conspicuous in October and November, with continued cold fronts and stalled high-pressure systems of Indian Summer. The first freezing weather sends icterids, geese, White-throated and Fox Sparrows farther south in reversed order of spring arrivals. Unstable early spring weather marks the end of winter. Unstable stalled air masses and late autumn northeast storms forecast winter's arrival. Early spring migrations, especially of diurnal migrants, are reliably reported by ground observers. Large movements are similarly well reflected, especially by reports of a general exodus. Ground observer reports which indicate small movements every day are usually correct. Laboratory recordings of migratory unrest accurately show the span of the instinctive period and closely approximate the schedule of movements seen in the field; but recordings do not yet clearly show effects of weather stimuli. We suggest the hypothesis that specific changes of weather, for example in autumn, overcast and rain, followed by heavier rain and squalls, followed by clearing and cold weather, combine (including the proper sequence of changes) to make additive stimuli whereby a population reacts to fly in an air mass which will be most suitable for migration. Radar shows three regular offshore movements across eastern and coastal Massachusetts in autumn. Although adaptations exist which allow certain species to avoid the overwater crossing or to re-orient and regain land, most of the birds continue to cross the sea, presumably because they fly non-stop to their goal. The three offshore movements are as follows. Regular southeastward movements on radar are of waders, are not consistently weather-controlled, and are most frequent from mid-July to mid-October. Regular southwestward movements on radar are of passerines, primarily thrushes, wood warblers and buntings, and form the eastern limit of the general southwestward flow of these species. These movements follow cold fronts from early August through mid-November. The unexplained puzzle of heavy concentrations of immature songbirds on the coast is discussed. Regular southward movements on radar are of passerines, and follow cold fronts, occurring most frequently from early September to mid-October. We believe these movements to represent a previously unrecorded migration of wood warblers that winter in the Antilles and South America, whose track cuts directly across the western Atlantic from New England and the Maritime Provinces. Some estimates are made of the rate of energy consumption during these flights, based on the observed departure weights and the recognition that the flights are successful. Calculations based on weights of birds in New England and in Bermuda show that the birds possess abundant energy resources for this flight.

The relative impacts of the ENSO and Indian Ocean dipole (IOD) events on Indian summer (June–September) monsoon rainfall at sub-regional scales have been examined in this study. GISST datasets from 1958 to 1998, along with Willmott and Matsuura gridded rainfall data, all India summer monsoon rainfall data, and homogeneous and sub-regional Indian rainfall datasets were used. The spatial distribution of partial correlations between the IOD and summer rainfall over India indicates a significant impact on rainfall along the monsoon trough regions, parts of the southwest coastal regions of India, and also over Pakistan, Afghanistan, and Iran. ENSO events have a wider impact, although opposite in nature over the monsoon trough region to that of IOD events. The ENSO (IOD) index is negatively (positively) correlated (significant at the 95% confidence level from a two-tailed Student t-test) with summer monsoon rainfall over seven (four) of the eight homogeneous rainfall zones of India. During summer, ENSO events also cause drought over northern Sri Lanka, whereas the IOD events cause surplus rainfall in its south. On monthly scales, the ENSO and IOD events have significant impacts on many parts of India. In general, the magnitude of ENSO-related correlations is greater than those related to the IOD. The monthly-stratified IOD variability during each of the months from July to September has a significant impact on Indian summer monsoon rainfall variability over different parts of India, confirming that strong IOD events indeed affect the Indian summer monsoon.

This paper examines the relationships between Indian rainfall and the sea-surface temperature anomalies (SSTA) in different areas, including the Arabian Sea, the equatorial Indian Ocean, the southern Indian Ocean and the equatorial eastern Pacific. Their relationships have clear temporal and spatial variabilities. Before the 1980s, the correlation between Indian summer rainfall and ENSO was much stronger than the correlation between Indian summer rainfall and other SSTA. Thus, Indian summer rainfall was mainly affected by ENSO during that period. But in recent decades, ENSO has become less decisive and the Indian rain is influenced by combinations of SSTA in all the regions. The influences of the Arabian Sea on the Indian summer rainfall are affected by ENSO and are much weaker than those of the equatorial Indian Ocean and the southern Indian Ocean. SSTA in the equatorial Indian Ocean could affect rainfall over India independently. When the amplitude of SSTA in the southern Indian Ocean is large enough, SSTA in the southern Indian Ocean can play an important role in controlling rainfall, which is evident in the late 1980s. Copyright © 2006 Royal Meteorological Society.

Using the NCEP–NCAR reanalysis for 1948–98, this study identifies a dominant pattern for the interannual variation of upper-level winds over mid-latitude Asia in boreal summer. This pattern, called the mid-latitude Asian summer (MAS) pattern, features two anomalous anticyclones: one centred at 37.5° N, 65° E and the other at 42.5° N, 130° E. The MAS pattern significantly influences East Asian summer monsoon variability. In the positive phase of the MAS pattern, contrasting meridional wind anomalies between eastern China and Japan lead to above- and below-normal summer rainfall in north China and south Japan respectively. The year-to-year change of the MAS pattern is related to that of the Indian summer rainfall, especially in central and northern India. Thus, the MAS pattern plays a role in connecting anomalous Indian heating with the East Asian summer monsoon variability. The East Asian anomalous anticyclone displays a southeastward shift after the late 1970s. This results in a similar change of anomalous summer rainfall regions in East Asia. The West Asian anomalous anticyclone moves northeastward after the late 1970s. The relation of the MAS pattern with the Indian summer rainfall experienced an obvious weakening in the late 1970s. As a result, the statistical relation between the Indian and north China summer rainfall becomes weak after the late 1970s. Copyright © 2002 Royal Meteorological Society

This study examines the fidelity of portable unified model's Atmospheric General Circulation Model in ensemble seasonal prediction of Indian Summer Monsoons of 1999-2004, driven by May SST anomaly persistent boundary conditions. Simple Ensemble-mean (EM) is inappropriate due to the presence of large deviation among the ensemble members in simulation of Indian Summer Monsoon Rainfall (ISMR). Thus 'Weighted Ensemble Mean' (WEM) method is used in the present study. In WEM method, weights are determined for all ensemble members at each model grid point using daily precipitation anomaly to distinguish the most reliable members and outliers among the ensemble members. Ensemble-mean then obtained by weighted combinations of all ensemble members is referred as 'Weighted Ensemble Mean'. The WEM prediction of ISMR better matches with observations than EM in majority of the monsoons. Further, WEM estimated using monthly and seasonal mean weights are assessed with respect to WEM from daily mean weights. WEM with monthly/seasonal weighting is found to be similar to EM in most of the monsoons and hence daily weighting is more suited approach than monthly/seasonal weighting.

This chapter talks about the Circassiens who had burned registers. Next, it focuses on Ottoman practices, and this is followed by a discussion on the officials and records before 1517. The chapter focuses on the Indian Summer civil servants between 1517-1521. It concludes with a discussion on Ali Pasha and late Mamluk. Keywords: Circassiens; Indian Summer civil servants; Ali Pasha; Mamluk

In this work, correlation analysis is applied to study the interannual relationships between Indian summer mon-soon rainfall of different homogeneous regions and Eurasian Snow Cover (ESC) during winter and spring seasons for the time period from 1973 to 1992. The monsoon rainfall of the western and central regions of India, as well as the all-India monsoon rainfall, is significantly negatively correlated with the ESC averaged for the months December-March and with, especially, the ESC of February. This study may provide some useful information for the long-range prediction of the regional Indian monsoon rainfall.

The evidence from Wisbech Barton broadly supports the notion that the quarter century after the Black Death witnessed an ‘Indian summer’ for demesne farming, for the rural economy here was surprisingly buoyant. However, it also suggests that the implications of this metaphor can be misleading. Farm officials faced significant economic and environmental difficulties, not least a more grudging workforce and severe flooding. Moreover, reeves worked with great skill to overcome these and other problems, and implemented considerable change in order to ensure economic success. In order to achieve a high net income it was often necessary to reduce the costs of cultivation, whether through operational changes, such as substituting customary for hired labour or grazing livestock on marshland rather than demesne grassland, or by reducing inputs. Falling yields of corn, hay, and livestock were often again the result of a series of deliberate and rational decisions.

This paper will examine ways that the Shoshone-Bannock Tribe has been integrating science with Native American culture. This paper will explain how and why technology mixed with traditional education can take place in the remote wilderness mountains of Idaho. Finally, we will explain how we are doing this and helping two endangered species at the same time: Salmon/Steelhead and Native American youth. These mountains are our living classroom.

In the Indian summer of 1935, about when the issue of Time that concentrated on praise of Sir Samuel Hoare’s diplomatic skill, Moral Rearmament, and the fiction of A. J. Cronin appeared, J. B. Priestley (1894–1984) was in New York on his second visit to America. At the height of his popularity in England—The Good Companions was his first successful novel in 1929 and had been followed by Angel Pavement (1930) and the travel ramble of English Journey (1934); his plays also achieved a wide English public, particularly Dangerous Corner in 1932, Laburnum Grove in 1933, and Eden End in 1934—Priestley had come to New York to supervise the production of Eden End because he thought New York productions of three of his previous plays had been badly done. At first he was exhilarated by the energy of New York, as he had been on his first visit. But he found that, for days, the people he met would talk of nothing except the heavyweight championship fight in which Joe Louis knocked out Max Baer. Walking the streets in his heavy suits and starched shirts in the hot weather, and reading whatever news from Europe he could, Priestley became despondent. As his recent biographer, Vincent Brome, records his impressions, they bear no resemblance to those of the writers of Time magazine