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  Subjects -> METEOROLOGY (Total: 112 journals)
Showing 1 - 36 of 36 Journals sorted by number of followers
Journal of Atmospheric and Solar-Terrestrial Physics     Hybrid Journal   (Followers: 199)
Nature Climate Change     Full-text available via subscription   (Followers: 134)
Journal of the Atmospheric Sciences     Hybrid Journal   (Followers: 81)
Atmospheric Environment     Hybrid Journal   (Followers: 73)
Atmospheric Research     Hybrid Journal   (Followers: 69)
Climatic Change     Open Access   (Followers: 66)
Journal of Climate     Hybrid Journal   (Followers: 54)
Bulletin of the American Meteorological Society     Open Access   (Followers: 51)
Atmospheric Chemistry and Physics (ACP)     Open Access   (Followers: 48)
Climate Policy     Hybrid Journal   (Followers: 45)
Climate Dynamics     Hybrid Journal   (Followers: 44)
Advances in Atmospheric Sciences     Hybrid Journal   (Followers: 43)
Nature Reports Climate Change     Full-text available via subscription   (Followers: 37)
Atmospheric Science Letters     Open Access   (Followers: 36)
Journal of Applied Meteorology and Climatology     Hybrid Journal   (Followers: 35)
Journal of Atmospheric and Oceanic Technology     Hybrid Journal   (Followers: 34)
Monthly Weather Review     Hybrid Journal   (Followers: 34)
International Journal of Climatology     Hybrid Journal   (Followers: 31)
American Journal of Climate Change     Open Access   (Followers: 31)
Advances in Climate Change Research     Open Access   (Followers: 31)
Boundary-Layer Meteorology     Hybrid Journal   (Followers: 31)
Journal of Hydrology and Meteorology     Open Access   (Followers: 29)
Developments in Atmospheric Science     Full-text available via subscription   (Followers: 28)
Weather and Forecasting     Hybrid Journal   (Followers: 28)
The Quarterly Journal of the Royal Meteorological Society     Hybrid Journal   (Followers: 27)
Journal of Space Weather and Space Climate     Open Access   (Followers: 27)
Climate Change Economics     Hybrid Journal   (Followers: 26)
Atmosphere     Open Access   (Followers: 26)
Meteorology and Atmospheric Physics     Hybrid Journal   (Followers: 26)
Space Weather     Full-text available via subscription   (Followers: 25)
Advances in Meteorology     Open Access   (Followers: 24)
Energy & Environment     Hybrid Journal   (Followers: 24)
International Journal of Atmospheric Sciences     Open Access   (Followers: 22)
Tellus A     Open Access   (Followers: 22)
International Journal of Climate Change Strategies and Management     Hybrid Journal   (Followers: 22)
Journal of Atmospheric Chemistry     Hybrid Journal   (Followers: 21)
Tellus B     Open Access   (Followers: 21)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 19)
Weather     Hybrid Journal   (Followers: 19)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 18)
Global Meteorology     Open Access   (Followers: 17)
Weather and Climate Extremes     Open Access   (Followers: 16)
Climate Resilience and Sustainability     Open Access   (Followers: 15)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 15)
Atmospheric Chemistry and Physics Discussions (ACPD)     Open Access   (Followers: 15)
Journal of Meteorology and Climate Science     Full-text available via subscription   (Followers: 14)
Theoretical and Applied Climatology     Hybrid Journal   (Followers: 13)
Monthly Notices of the Royal Astronomical Society     Hybrid Journal   (Followers: 13)
Climate Change Responses     Open Access   (Followers: 12)
Atmospheric and Oceanic Science Letters     Open Access   (Followers: 11)
Journal of Hydrometeorology     Hybrid Journal   (Followers: 11)
Environmental Dynamics and Global Climate Change     Open Access   (Followers: 8)
Current Climate Change Reports     Hybrid Journal   (Followers: 8)
Climate Change Research Letters     Open Access   (Followers: 7)
Advances in Statistical Climatology, Meteorology and Oceanography     Open Access   (Followers: 7)
Climate     Open Access   (Followers: 6)
Open Journal of Modern Hydrology     Open Access   (Followers: 6)
Climate Risk Management     Open Access   (Followers: 6)
Mathematics of Climate and Weather Forecasting     Open Access   (Followers: 6)
Aeolian Research     Hybrid Journal   (Followers: 6)
Climate Research     Hybrid Journal   (Followers: 6)
Journal of the Meteorological Society of Japan     Partially Free   (Followers: 6)
Change and Adaptation in Socio-Ecological Systems     Open Access   (Followers: 5)
The Cryosphere (TC)     Open Access   (Followers: 5)
Dynamics and Statistics of the Climate System     Open Access   (Followers: 5)
International Journal of Environment and Climate Change     Open Access   (Followers: 5)
Climate of the Past (CP)     Open Access   (Followers: 5)
Urban Climate     Hybrid Journal   (Followers: 4)
Environmental and Climate Technologies     Open Access   (Followers: 4)
Climate and Energy     Full-text available via subscription   (Followers: 4)
The Cryosphere Discussions (TCD)     Open Access   (Followers: 4)
Carbon Balance and Management     Open Access   (Followers: 4)
Weatherwise     Hybrid Journal   (Followers: 4)
Meteorological Applications     Hybrid Journal   (Followers: 4)
Journal of Integrative Environmental Sciences     Hybrid Journal   (Followers: 4)
Russian Meteorology and Hydrology     Hybrid Journal   (Followers: 3)
Meteorologische Zeitschrift     Full-text available via subscription   (Followers: 3)
npj Climate and Atmospheric Science     Open Access   (Followers: 3)
Atmospheric Environment : X     Open Access   (Followers: 3)
Journal of Climate Change     Full-text available via subscription   (Followers: 3)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3)
Economics of Disasters and Climate Change     Hybrid Journal   (Followers: 3)
Frontiers in Climate     Open Access   (Followers: 3)
Ciencia, Ambiente y Clima     Open Access   (Followers: 3)
Journal of Climatology     Open Access   (Followers: 3)
Atmósfera     Open Access   (Followers: 3)
Climate Services     Open Access   (Followers: 3)
Open Atmospheric Science Journal     Open Access   (Followers: 2)
GeoHazards     Open Access   (Followers: 2)
Journal of Weather Modification     Full-text available via subscription   (Followers: 2)
Meteorological Monographs     Hybrid Journal   (Followers: 2)
International Journal of Image and Data Fusion     Hybrid Journal   (Followers: 2)
Meteorologica     Open Access   (Followers: 2)
Climate Summary of South Africa     Full-text available via subscription   (Followers: 2)
气候与环境研究     Full-text available via subscription   (Followers: 1)
Journal of Meteorological Research     Full-text available via subscription   (Followers: 1)
Bulletin of Atmospheric Science and Technology     Hybrid Journal   (Followers: 1)
Michigan Journal of Sustainability     Open Access   (Followers: 1)
Tropical Cyclone Research and Review     Open Access   (Followers: 1)
International Journal of Biometeorology     Hybrid Journal   (Followers: 1)
Modeling Earth Systems and Environment     Hybrid Journal   (Followers: 1)
Mediterranean Marine Science     Open Access   (Followers: 1)
Large Marine Ecosystems     Full-text available via subscription   (Followers: 1)
Weather and Climate Dynamics     Open Access  
Journal of Agricultural Meteorology     Open Access  
Nīvār     Open Access  
Revista Iberoamericana de Bioeconomía y Cambio Climático     Open Access  
Mètode Science Studies Journal : Annual Review     Open Access  
Earth Perspectives - Transdisciplinarity Enabled     Open Access  
Climate of the Past Discussions (CPD)     Open Access  
Revista Brasileira de Meteorologia     Open Access  
Studia Geophysica et Geodaetica     Hybrid Journal  

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Similar Journals
Journal Cover
Climate Dynamics
Journal Prestige (SJR): 2.445
Citation Impact (citeScore): 4
Number of Followers: 44  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1432-0894 - ISSN (Online) 0930-7575
Published by Springer-Verlag Homepage  [2657 journals]
  • Testing the performance of dendroclimatic process-based models at global
           scale with the PAGES2k tree-ring width database
    • Abstract: Tree-rings are one of the most commonly used proxies for reconstructing past climates at annual resolution. The climate information is generally deduced from tree-rings using statistical relationships, but the assumed linearity and stationarity may be inadequate. Process-based models allow for non-stationarity and non-linearity; however, many challenges are associated with their application for global scale reconstructions. In this study, we aim to test the feasibility of using the mechanistic model MAIDEN at the global scale for paleoclimate reconstructions based on data assimilation by applying it to the PAGES2k tree-ring width database. We also compare its performance with the simpler model VS-Lite, often used in global applications. Both models are skillful in terms of calibration and verification correlations for a similar number of sites (63 and 64 for VS-Lite and MAIDEN, respectively). VS-Lite tends to perform better for sites where the climate signal in tree-rings is strong and clear. By contrast, MAIDEN’s performance is likely mostly limited by the lack of data (for example, daily Gross Primary Production data or phenological timings) needed to accurately calibrate the model. However, when the calibration is robust, both models reproduce well the observed link between climate and tree-growth. In general, VS-Lite tends to overestimate the climate signal in tree-rings compared to MAIDEN, which better reproduces the magnitude of the climate signal on average. Our results show that both models are complementary and can be applied at the global scale to reconstruct past climates using an adequate protocol designed to exploit existing tree-ring data.
      PubDate: 2021-05-13
  • The role of Arctic gateways on sea ice and circulation in the Arctic and
           North Atlantic Oceans: a sensitivity study with an ocean-sea-ice model
    • Abstract: The impact of changes in volume, heat and freshwater fluxes through Arctic gateways on sea ice, circulation and fresh water and heat contents of the Arctic and North Atlantic Oceans is not fully understood. To explore the role played by each gateway, we use a regional sea-ice ocean general circulation model with a fixed atmospheric forcing. We run sensitivity simulations with combinations of Bering Strait (BS) and Canadian Arctic Archipelago (CAA) open and closed inspired by paleogeography of the Arctic. We show that fluxes through BS influence the Arctic, Atlantic and Nordic Seas while the impact of the CAA is more dominant in the Nordic Seas. In the experiments with BS closed, there is a change in the surface circulation of the Arctic with a weakening of the Beaufort Gyre by about thirty percent. As a consequence, the Siberian river discharge is spread offshore to the west, rather than being directly advected away by the Transpolar Drift. This results in a decrease of salinity in the upper 50 m across much of the central Arctic and East Siberian and Chukchi Seas. We also find an increase in stratification between the surface and subsurface layers after closure of BS. Moreover, closure of the BS results in an upward shift of the relatively warm waters lying between 50 and 120 m, as well as a reorganization of heat storage and transport. Consequently, more heat is kept in the upper layers of the Arctic Ocean, thus increasing the heat content in the upper 50 m and leading to a thinner sea ice cover. The CAA closing has a large impact on sea ice, temperature and salinity in the subarctic North Atlantic with opposite responses in the Greenland-Iceland-Norwegian Seas and Baffin Bay. It is also found that CAA being open or closed strongly controls the sea ice export through the Fram Strait. In all our experiments, the changes in temperature and salinity of the Barents and Kara Seas, and in fluxes through Barents Sea Opening are relatively small, suggesting that they are likely controlled by the atmospheric processes. Our results demonstrate the need to take into consideration the fluxes through the Arctic gateways when addressing the ocean and climate changes during deglaciations as well as for predictions of future climate.
      PubDate: 2021-05-12
  • The role of interannual ENSO events in decadal timescale transitions of
           the Interdecadal Pacific Oscillation
    • Abstract: The build-up of decadal timescale upper ocean heat content in the off-equatorial western tropical Pacific can provide necessary conditions for interannual El Niño/Southern Oscillation (ENSO) events to contribute to decadal timescale transitions of tropical Pacific SSTs to the opposite phase of the Interdecadal Pacific Oscillation (IPO). This can be viewed as a corollary to subseasonal westerly wind burst events contributing to El Niño interannual timescale transitions. A long pre-industrial control run with CESM1 is analyzed to show that there is a greater chance of ENSO activity to contribute to an IPO transition when off-equatorial western Pacific Ocean heat content reaches either a maximum (for El Niño to contribute to a transition to positive IPO) or minimum (for La Niña to contribute to a transition to negative IPO) as seen in observations. If above a necessary ocean heat content threshold, the convergence associated with westerly anomaly near-equatorial surface winds associated with El Niño activity can draw that heat content equatorward to sustain anomalously warm western and central Pacific SSTs. These are associated with positive precipitation and convective heating anomalies, a Gill-type response and wind stress curl anomalies that continue to feed warm water into the near-equatorial western Pacific. These conditions then sustain the decadal-timescale transition to positive IPO (with the opposite sign for transition to negative IPO). Associated central equatorial Pacific convective heating anomalies produce SLP and wind stress anomalies in the North and South Pacific that can excite westward-propagating off-equatorial oceanic Rossby waves to contribute to the western Pacific thermocline depth and consequent heat content anomalies.
      PubDate: 2021-05-12
  • Impacts of orography on large-scale atmospheric circulation: application
           of a regional climate model
    • Abstract: Orography has considerable impacts on the large-scale atmospheric circulation, emphasizing the necessity of adequate representation of the impacts of orography in numerical models. The regional climate model version 4 (RegCM4) is used to investigate the impacts of orography on the large-scale atmospheric circulation. Three numerical experiments in four different years for winter and summer have been conducted over a large geographical area, covering Eurasia, Africa and Oceania. These experiments include control simulations using the real orography, simulations with the removed orography of the whole domain and simulations with the removed orography of the whole domain except the Tibetan Plateau. In winter, the Tibetan Plateau prevents the development of the sea-level high pressure in South Asia and contributes to the intensification of the Siberian high through blocking cold air advection from Siberia toward India. The Tibetan Plateau is also responsible for the southward displacement of low-level easterly flows in the North Indian Ocean, such that elimination of this Plateau is associated with more zonal orientation and intensification of easterly winds, as well as an increase of moisture flux over India and the Arabian Sea. Descending motions associated with lee waves of the Western Ghat Mountains contribute to a decrease of precipitation over the Arabian Sea. In summer, the Tibetan Plateau reinforces the South Asian low-pressure system and pushes the South Asian monsoon to South Asia. Both the tropical easterly jet stream over the southern Tibetan Plateau and the subtropical westerly jet stream over the Tibetan Plateau are weakened when the whole orography is removed. Removal of the whole orography is associated with a considerable equatorward displacement of the intertropical convergence zone over South Asia. In austral winter, low-level subtropical anticyclones in Southern Africa and Australia are intensified when the whole orography is removed.
      PubDate: 2021-05-10
  • Regional differences in surface air temperature changing patterns from
           1960 to 2016 of China
    • Abstract: A thorough understanding of regional differences in change patterns of surface air temperature (SAT) at various spatial scales can help people cope well with global warming. In this study, a SAT change pattern recognition method was firstly established based on k-mean++ algorithm. By creating a clustering effect evaluation index (DBWk) to select the optimal cluster number k, the pattern of SAT change in 1960–2016 of China was recognized at national and regional scales. Results showed that China’s SAT change patterns were grouped into 3 clusters, namely, Clusters I, II and III, at the national scale. These clusters were further divided into 3, 7, and 4 subclusters at the regional scale, respectively. The SAT change in Cluster I was intense, with a relatively cold period (1960–1987) and a relatively warm period (1988–2016). The SAT of Cluster II decreased slightly in the first phase (1960–1983), minimally increased in the third phase (1999–2016), but rose strongly in the second phase (1984–1998). The linear trend (LT) of SAT increase of Cluster III was high and statistically significant, especially in 1983–2016. The analysis of the SAT change pattern of subclusters showed that the SAT fluctuations of the Altai Mountains and Junggar Basin were the strongest. The Northern Qinghai–Tibet Plateau had the highest warming rate, and the LT of warming was statistically the most significant in China.
      PubDate: 2021-05-10
  • Associations of atmospheric teleconnections with wintertime extratropical
           cyclones over East Asia and Northwest Pacific
    • Abstract: Extratropical cyclones (ETCs) over East Asia and Northwest Pacific are identified and tracked by applying an objective algorithm to the 850-hPa relative vorticity fields from the ERA-Interim reanalysis. A total of 2866 ETCs originating at the western side of the date line have been identified in the extended November–March winters from 1979 to 2018. The ETC tracks are counted and visualized using a hexagonal tessellation rather than the regular longitude–latitude grids. Two generalized linear models (GLMs), Poisson regression model and Gamma regression model, are firstly applied to investigate the associations of wintertime ETCs with three atmospheric teleconnection patterns. The West Pacific (WP) pattern and the Pacific/North American (PNA) pattern are more responsible for the meridional variability of ETC activities in the North Pacific, while the influence of the Polar/Eurasia pattern on ETC activities is negligible. Results of composite analysis are qualitatively consistent with that of regression analysis. Composite maps of differences of jet stream, thermal gradient and mid-tropospheric baroclinicity in the positive and negative phases of teleconnection patterns also support the close associations of ETC activities with WP and PNA teleconnection patterns.
      PubDate: 2021-05-10
  • Studies of the seasonal prediction of heavy late spring rainfall over
           southeastern China
    • Abstract: The late spring rainfall may account for 15% of the annual total rainfall, which is crucial to early planting in southeastern China. A better understanding of the precipitation variations in the late spring and its predictability not only greatly increase our knowledge of related mechanisms, but it also benefits society and the economy. Four models participating in the North American Multi-Model Ensemble (NMME) were selected to study their abilities to forecast the late spring rainfall over southeastern China and the major sources of heavy rainfall from the perspective of the sea surface temperature (SST) field. We found that the models have better abilities to forecast the heavy rainfall over the middle and lower reaches of the Yangtze River region (MLYZR) with only a 1-month lead time, but they failed for a 3-month lead time since the occurrence of the heavy rainfall was inconsistent with the observations. The observations indicate that the warm SST anomalies in the tropical eastern Indian Ocean are vital to the simultaneously heavy rainfall in the MLYZR in May, but an El Niño event is not a necessary condition for determining the heavy rainfall over the MLYZR. The heavy rainfall over the MLYZR in May is always accompanied by warming of the northeastern Indian Ocean and of the northeastern South China Sea (NSCS) from April to May in the models and observations, respectively. In the models, El Niño events may promote the warming processes over the northeastern Indian Ocean, which leads to heavy rainfall in the MLYZR. However, in the real world, El Niño events are not the main reason for the warming of the NSCS, and further research on the causes of this warming is still needed.
      PubDate: 2021-05-10
  • Correction to: A low order dynamical model for runoff predictability
    • Abstract: A correction to this paper has been published: https://doi.org/10.1007/s00382-021-05775-z
      PubDate: 2021-05-06
  • A perturbed parameter ensemble of HadGEM3-GC3.05 coupled model
           projections: part 1: selecting the parameter combinations
    • Abstract: This is the first of two papers that describe the generation of a 25-member perturbed parameter ensemble (PPE) of high-resolution, global coupled simulations for the period 1900–2100, using CMIP5 historical and RCP8.5 emissions. Fifteen of these 25 coupled simulations now form a subset of the global projections provided for the UK Climate Projections 2018 (UKCP18). This first paper describes the selection of 25 variants (combinations of 47 parameters) using a set of cheap, coarser-resolution atmosphere-only simulations from a large sample of nearly 3000 variants. Retrospective 5-day weather forecasts run at climate resolution, and simulations of 2004–2009 with prescribed SST and sea ice are evaluated to filter out poor performance. We opted for a single design choice and sensitivity tests were done after the PPE was generated to demonstrate the effect of design choices on the filtering. Given our choice, only 38 of the parameter combinations were found to have acceptable performance at this stage. Idealised atmosphere-only simulations were then used to select the subset of 25 members that were as diverse as possible in terms of their CO2 and aerosol forcing, and their response to warmer SSTs. Using our parallel set of atmosphere-only and coupled PPEs (the latter from paper 2), we show that local biases in the atmosphere-only experiments are generally informative about the biases in the coupled PPE. Biases in radiative fluxes and cloud amounts are strongly informative for most regions, whereas this is only true for a smaller fraction of the globe for precipitation and dynamical variables. Therefore, the cheap experiments are an affordable way to search for promising parameter combinations but have limitations.
      PubDate: 2021-05-06
  • A perturbed parameter ensemble of HadGEM3-GC3.05 coupled model
           projections: part 2: global performance and future changes
    • Abstract: This paper provides a quantitative assessment of large-scale features in a perturbed parameter ensemble (PPE) of Met Office Unified Model HadGEM-GC3.05 in coupled global historical and future simulations. The main motivation for the simulations is to provide a major component of the UK Climate Projections 2018 (UKCP18), but they will also be used to make worldwide projections and inform future model development. Initially, a 25-member PPE, with 25 different parameter combinations, was simulated. Five members were subsequently dropped because either their simulated climate was unrealistically cool by 1970 or they suffered from numerical instabilities. The remaining 20 members were evaluated after completing the historical phase (1900–2005) against 13 separately selected Climate Model Intercomparison Project Phase 5 (CMIP5) models, and five more members were dropped. The final product is a combined projection system of 15 PPE members and 13 CMIP5 models, which has a number of benefits. In particular, the range of outcomes available from the combined set of 28 is often larger than from either of the two constituent ensembles, thus providing users with a more complete picture of plausible impacts. Here we mainly describe the evaluation process of the 20 PPE members. We evaluate biases in a number of important properties of the global coupled system, including assessment of climatological averages, coupled modes of internal variability and historical and future changes. The parameter combinations yielded plausible yet diverse atmosphere and ocean model behaviours. The range of global temperature changes is narrow, largely driven by use of different CO2 pathways. The range of global warming is seemingly not linked to range of feedbacks estimated from atmosphere-only runs, though we caution that the range of the latter is narrow relative to CMIP5, and therefore this result is not unexpected. This is the second of two papers describing the generation of the PPE for UKCP18 projections. Part 1 (Sexton et al. 2021) describes the selection of 25 parameter combinations of 47 atmosphere and land surface parameters, using a set of cheap atmosphere-only runs at a coarser resolution from nearly 3000 samples of parameter space.
      PubDate: 2021-05-06
  • Effects of cumulus parameterization and land-surface hydrology schemes on
           Tibetan Plateau climate simulation during the wet season: insights from
           the RegCM4 model
    • Abstract: Dynamical downscaling generally performs poorly on the Tibetan Plateau (TP), due to the region’s complex topography and several aspects of model physics, especially convection and land surface processes. This study investigated the effects of the cumulus parameterization scheme (CPS) and land-surface hydrology scheme (LSHS) on TP climate simulation during the wet season using the RegCM4 regional climate model. To address these issues and seek an optimal simulation, we conducted four experiments at a 20 km resolution using various combinations of two CPSs (Grell and MIT-Emanuel), two LSHSs (the default TOPMODEL [TOP], and Variable Infiltration Capacity [VIC]). The simulations in terms of 2-m air temperature, precipitation (including large-scale precipitation [LSP] and convective precipitation [CP]), surface energy-water balance, as well as atmospheric moisture flux transport and vertical motion were compared with surface and satellite-based observations as well as the ERA5 reanalysis dataset for the period 2006–2016. The results revealed that the model using the Grell and TOP schemes better reproduced air temperature but with a warm bias, part of which could be significantly decreased by the MIT scheme. All schemes simulated a reasonable spatial distribution of precipitation, with the best performance in the experiment using the MIT and VIC schemes. Excessive precipitation was produced by the Grell scheme, mainly due to overestimated LSP, while the MIT scheme largely reduced the overestimation, and the simulated contribution of CP to total precipitation was in close agreement with the ERA5 data. The RegCM4 model satisfactorily captured diurnal cycles of precipitation amount and frequency, although there remained some differences in phase and magnitude, which were mainly caused by the CPSs. Relative to the Grell scheme, the MIT scheme yielded a weaker surface heating by reducing net radiation fluxes and the Bowen ratio. Consequently, anomalous moisture flux transport was substantially reduced over the southeastern TP, leading to a decrease in precipitation. The VIC scheme could also help decrease the wet bias by reducing surface heating. Further analysis indicated that the high CP in the MIT simulations could be attributed to destabilization in the low and mid-troposphere, while the VIC scheme tended to inhibit shallow convection, thereby decreasing CP. This study’s results also suggest that CPS interacts with LSHS to affect the simulated climate over the TP.
      PubDate: 2021-05-05
  • Recent weakening in the winter ENSO teleconnection over the North
           Atlantic-European region
    • Abstract: New observational evidence for variability of the atmospheric response to wintertime El Niño-Southern Oscillation (ENSO) is found. Using different approaches and datasets, a weakening in the recent ENSO teleconnection over the North Atlantic-European (NAE) region is demonstrated. Changes in both pattern and strength of the teleconnection indicate a turning point in the 1970s with a shift from a response resembling the North Atlantic Oscillation (NAO) to an anomaly pattern orthogonal to NAO with very weak or statistically non-significant values; and to nearly non-existent teleconnection in the most recent decades. Results shows the importance of the background sea surface temperature (SST) state and sea-ice climatology having opposite effects in modulating the ENSO-NAE teleconnection. As indicated with targeted simulations, the recent change in the SST climatology in the Atlantic and Arctic has contributed to the weakening of the ENSO effect. The findings of this study can have implications on our understanding of modulations of ENSO teleconnections and ENSO as a source of predictability in the NAE sector.
      PubDate: 2021-05-04
  • El Niño teleconnection to the Euro-Mediterranean late-winter: the role of
           extratropical Pacific modulation
    • Abstract: El Niño Southern Oscillation (ENSO) represents the major driver of interannual climate variability at global scale. Observational and model-based studies have fostered a long-standing debate on the shape and intensity of the ENSO influence over the Euro-Mediterranean sector. Indeed, the detection of this signal is strongly affected by the large internal variability that characterizes the atmospheric circulation in the North Atlantic–European (NAE) region. This study explores if and how the low-frequency variability of North Pacific sea surface temperature (SST) may impact the El Niño-NAE teleconnection in late winter, which consists of a dipolar pattern between middle and high latitudes. A set of idealized atmosphere-only experiments, prescribing different phases of the anomalous SST linked to the Pacific Decadal Oscillation (PDO) superimposed onto an El Niño-like forcing in the tropical Pacific, has been performed in a multi-model framework, in order to assess the potential modulation of the positive ENSO signal. The modelling results suggest, in agreement with observational estimates, that the PDO negative phase (PDO−) may enhance the amplitude of the El Niño-NAE teleconnection, while the dynamics involved appear to be unaltered. On the other hand, the modulating role of the PDO positive phase (PDO+) is not reliable across models. This finding is consistent with the atmospheric response to the PDO itself, which is robust and statistically significant only for PDO−. Its modulation seems to rely on the enhanced meridional SST gradient and the related turbulent heat-flux released along the Kuroshio–Oyashio extension. PDO− weakens the North Pacific jet, whereby favoring more poleward propagation of wave activity, strengthening the El Niño-forced Rossby wave-train. These results imply that there might be conditional predictability for the interannual Euro-Mediterranean climate variability depending on the background state.
      PubDate: 2021-05-03
  • Megadroughts and pluvials in southwest Australia: 1350–2017 CE
    • Abstract: Declining winter rainfall coupled with recent prolonged drought poses significant risks to water resources and agriculture across southern Australia. While rainfall declines over recent decades are largely consistent with modelled climate change scenarios, particularly for southwest Australia, the significance of these declines is yet to be assessed within the context of long-term hydroclimatic variability. Here, we present a new 668-year (1350–2017 CE) tree-ring reconstruction of autumn–winter rainfall over inland southwest Australia. This record reveals that a recent decline in rainfall over inland southwest Australia (since 2000 CE) is not unusual in terms of either magnitude or duration relative to rainfall variability over the last seven centuries. Drought periods of greater magnitude and duration than those in the instrumental record occurred prior to 1900 CE, including two ‘megadroughts’ of > 30 years duration in the eighteenth and nineteenth centuries. By contrast, the wettest > decadal periods of the last seven centuries occurred after 1900 CE, making the twentieth century the wettest of the last seven centuries. We conclude that the instrumental rainfall record (since ~ 1900 CE) does not capture the full scale of natural hydroclimatic variability for inland southwest Australia and that the risk of prolonged droughts in the region is likely much higher than currently estimated.
      PubDate: 2021-05-02
  • Correction to: The role of transient eddies and diabatic heating in the
           maintenance of European heat waves: a nonlinear quasi-stationary wave
    • Abstract: A correction to this paper has been published: https://doi.org/10.1007/s00382-021-05704-0
      PubDate: 2021-05-01
  • Markov Chain Monte Carlo simulation and regression approach guided by El
           Niño–Southern Oscillation to model the tropical cyclone occurrence over
           the Bay of Bengal
    • Abstract: Tropical cyclone (TC) is one of the most devastating weather systems that causes enormous loss of life and property in the coastal regions of Bay of Bengal (BoB). Statistical forecasting of TC occurrence can help decision-makers and inhabitants in shoreline zones to take necessary planning and actions in advance. In this study, we have investigated the impact of El Niño–Southern Oscillation (ENSO) on the frequency of TC over the BoB by using 100 years TC and Southern Oscillation Index data. The frequency of TC is approximated through observation and Markov Chain Monte Carlo (MCMC) simulation. Two-sample Student’s t test has been applied for examining the statistical significance where the results are significant at 5% level for all cyclonic disturbances. The monthly and seasonal distribution show this feature more distinctly. The total annual frequency of depressions and cyclonic storms in El Niño and La Niña conditions does not differ much, but the monthly/seasonal distribution shows high differences for certain months and seasons. The simulated frequency of TC landfall using MCMC matches well with the observation. The proposed methodology is illustrated through a case study in BoB rim countries-Bangladesh, India, Sri Lanka and Myanmar. Poisson and Bayesian regression have also been used to predict the probabilities of TC frequency over the BoB. Both the regression approaches show 10 and 32% improvement than climatology for the forecast and cross-validation skill respectively. We have also analyzed TC impact over Bangladesh as a case study. Possible links of the variation of TC activities with the largescale geographical distribution of sea surface temperature, vertical wind shear, vorticity, moisture and relative humidity are also explored.
      PubDate: 2021-05-01
  • Impact of tibetan plateau snow cover on tropical cyclogenesis via the
           Madden–Julian oscillation during the following boreal summer
    • Abstract: This study investigates the role of the interannual variation of boreal winter (December–February) snow cover over the Tibetan Plateau (TPSC) in modulating the relationship between the Madden Julian Oscillation (MJO) and tropical cyclogenesis over the western North Pacific (WNP) during the following boreal summer (June–October). During the boreal summer following a high snow cover anomaly (SCA), MJO-associated convection tends to be confined to the west of 140 °E, coinciding with more frequent tropical cyclone (TC) activity in this region. By contrast, there tends to be stronger MJO-associated convection extending farther east during years following low SCA. The MJO-associated convection extends to ~ 160 °E over the WNP basin with a peak around 140 °E. Thus, more TCs form farther east in the WNP in these years. We use composite analyses of large-scale environmental factors to demonstrate that low-level relative vorticity is one of the most important factors in controlling TCs in response to the change of MJO-associated convection between years with high SCA and low SCA. Meanwhile, eddy kinetic energy variations associated with the MJO are consistent with changes in tropical cyclogenesis over the WNP basin between years with high and low SCA. The Asian summer monsoon plays an important role in linking prior winter TPSC to MJO activity in the following summer. During high-SCA years, increased snow cover results in positive soil moisture anomalies and cooling over the Tibetan Plateau, thus weakening the following summer Asian monsoon and weakening associated water vapor advection, while the opposite chain of events occurs in low-SCA years. These changes in high-SCA years are favorable for MJO propagation and are unfavorable for MJO propagation in low-SCA years. Meanwhile, the interannual variation of SCA exerts a significant impact on the upper-tropospheric circulation and thus changes in vertical wind shear. During high-SCA years, there are anomalous upper-level easterlies in the Indian Ocean and upper-level westerlies in the Pacific Ocean, which result in anomalous easterly wind shear in the Indian Ocean and anomalous westerly shear in the Pacific Ocean. The opposite shear pattern arises in low-SCA years. In addition to changes in wind shear, the background vertical motion associated with changes in TPSC may also be partly responsible for changes in MJO activity.
      PubDate: 2021-05-01
  • Formation of the northern East Asian low: role of diabatic heating
    • Abstract: The northern East Asian low (NEAL), characterized by a mid-latitude closed low (or trough) in the lower troposphere, is an important component of the East Asian summer monsoon system. This study investigates formation mechanism of the summer NEAL, with emphasis on the roles of diabatic heating and transient eddy forcing, using a linear baroclinic model (LBM) with prescribed forcing derived from the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR) dataset during the 1979–2010 period. The LBM simulations show that the formation of NEAL is induced by the diabatic heating, and the effect of transient eddy forcing is negligible. Further investigation indicates that the diabatic heating over northern East Asia (NEA) is the key factor for the NEAL’s formation, in which the latent heating and radiative cooling in concert to play a major role and the vertical diffusion sensible heating plays a secondary role. In response to the NEA diabatic heating (latent and sensible heating), a local northerly is induced that advects cold air to partially balance the diabatic heat source and forms a low to the east. On the other hand, the radiative cooling induces a southerly anomaly over NEA, shaping the position and intensity of the low induced by the latent and sensible heating. The total effect of the diabatic heating and radiative cooling causes a closed NEAL. Results are similar for the NEAL’s formation in June, July, and August, respectively. Moreover, we further investigate sub-seasonal change of the NEAL in summer. The weakened intensity of the NEAL in August, relative to that in June and July, is contributed to mainly by the enhanced offset effect of the radiative cooling over NEA and partially by the weakened impact of the latent and diffusion sensible heating.
      PubDate: 2021-05-01
  • Cool season precipitation projections for California and the Western
           United States in NA-CORDEX models
    • Abstract: Understanding future precipitation changes is critical for water supply and flood risk applications in the western United States. The North American COordinated Regional Downscaling EXperiment (NA-CORDEX) matrix of global and regional climate models at multiple resolutions (~ 50-km and 25-km grid spacings) is used to evaluate mean monthly precipitation, extreme daily precipitation, and snow water equivalent (SWE) over the western United States, with a sub-regional focus on California. Results indicate significant model spread in mean monthly precipitation in several key water-sensitive areas in both historical and future projections, but suggest model agreement on increasing daily extreme precipitation magnitudes, decreasing seasonal snowpack, and a shortening of the wet season in California in particular. While the beginning and end of the California cool season are projected to dry according to most models, the core of the cool season (December, January, February) shows an overall wetter projected change pattern. Daily cool-season precipitation extremes generally increase for most models, particularly in California in the mid-winter months. Finally, a marked projected decrease in future seasonal SWE is found across all models, accompanied by earlier dates of maximum seasonal SWE, and thus a shortening of the period of snow cover as well. Results are discussed in the context of how the diverse model membership and variable resolutions offered by the NA-CORDEX ensemble can be best leveraged by stakeholders faced with future water planning challenges.
      PubDate: 2021-05-01
  • The impact of snow loss and soil moisture on convective precipitation over
           the Rocky Mountains under climate warming
    • Abstract: Warm season moist diurnal convection can be particularly sensitive to changes in land surface characteristics such as snow cover and soil moisture. Over regions of mountainous terrain, climate change is expected to reduce snow cover along the low-elevation seasonal snowpack margin. These snow reductions alter surface albedo and soil moisture content, leading to changes in surface fluxes and alterations in mesoscale orographic circulations that act to transport moisture and provide ascent. A set of convection-permitting regional climate simulations centered on the Rocky Mountains of Colorado are conducted from April through July across a period of 12 years (2002–2013). These include a reanalysis forced control run (CTR), a pseudo global warming run (PGW), and an additional altered land surface run (DSURF) used to isolate the effects of the snow albedo and soil moisture changes on orographic convection. Over the mountains, daytime hourly precipitation accumulation (0900–1800 MST) decreased in PGW by an average of 4.2% while precipitation in DSURF increased by 12.5%. On days with weak synoptic forcing, the PGW response more closely follow the DSURF response with daytime hourly increases averaging 29.7% for PGW and 28.7% for DSURF. For PGW, hourly daytime precipitation intensity increases of up to 82% overcome reductions in precipitation frequency to produce higher accumulations. DSURF shows smaller increases in intensity of up to 23% and broad increases in daytime frequency indicating that surface changes act to moderate reductions in the frequency of convective precipitation. Reduced snow cover contributes to this convective response by increasing convective instability and boundary layer moisture and decreasing lifting condensation level over the high terrain. Alterations in orographic thermal circulations contribute to this response by converging moisture over the high terrain and enhancing mesoscale ascent.
      PubDate: 2021-05-01
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762

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