scholarly journals A Weather-Type Approach to Analyzing Winter Precipitation in France: Twentieth-Century Trends and the Role of Anthropogenic Forcing

2008 ◽  
Vol 21 (13) ◽  
pp. 3118-3133 ◽  
Author(s):  
J. Boé ◽  
L. Terray
Keyword(s):  
Twentieth Century ◽  
Large Scale ◽  
Precipitation Amount ◽  
Winter Precipitation ◽  
Weather Type ◽  
Weather Types ◽  
Anthropogenic Forcing ◽  
Temperature Changes ◽  
The North ◽  
Precipitation Changes

Abstract The relationship between large-scale atmospheric circulation and November–March precipitation over France during the twentieth century is investigated. A long daily MSLP dataset is used to derive daily weather types that are discriminant for precipitation. A linear regression model is then used to relate the November–March-accumulated precipitation amount and the occurrence frequency of the weather types. This simple model shows that an important part of the interannual variability of precipitation is directly linked to large-scale circulation changes. Trends in observed precipitation and precipitation series reconstructed by regression are computed and compared. Spatially coherent trends in November–March precipitation during the second half of the twentieth century are observed, with an increase in the north and a decrease in the south. The spatial pattern of the trends in reconstructed precipitation is very similar to that observed, even if an underestimation of the positive trends in the north is seen, indicating that other mechanisms play a role. A detection study then leads to a better understanding of the respective roles of anthropogenic forcing (greenhouse gases and sulfate aerosol) and sea surface temperature in the evolution of the weather-type occurrence. Finally, it is shown that intratype dynamical variability has also played a role in precipitation changes in northern France, whereas no impact of temperature changes is seen.

scholarly journals Temporal and spatial distributions of precipitation on the Huang-Huai-Hai Plain during 1960–2019, China

2021 ◽  
Author(s):  
Minhua Ling ◽  
Hongbao Han ◽  
Xingling Wei ◽  
Cuimei Lv
Keyword(s):  
Spatial Distribution ◽  
Large Scale ◽  
Kendall Test ◽  
Winter Precipitation ◽  
Annual Precipitation ◽  
Temporal And Spatial Distribution ◽  
Global Pattern ◽  
The North ◽  
Variance Contribution ◽  
Temporal And Spatial

Abstract The Huang-Huai-Hai Plain is an important commercial grain production base in China. Understanding the temporal and spatial variations in precipitation can help prevent drought and flood disasters and ensure food security. Based on the precipitation data for the Huang-Huai-Hai Plain from 1960 to 2019, this study analysed the spatiotemporal distribution of total precipitation at different time scales using the Mann–Kendall test, the wavelet analysis, the empirical orthogonal function (EOF), and the centre-of-gravity model. The results were as follows: (1) The winter precipitation showed a significant upward trend on the Huang-Huai-Hai Plain, while other seasonal trends were not significant. (2) The precipitation on the Huang-Huai-Hai Plain shows a zonal decreasing distribution from southeast to northwest. (3) The application of the EOF method revealed the temporal and spatial distribution characteristics of the precipitation field. The cumulative variance contribution rate of the first two eigenvectors reached 51.5%, revealing two typical distribution fields, namely a ‘global pattern’ and a ‘north-south pattern’. The ‘global pattern’ is the decisive mode, indicating that precipitation on the Huang-Huai-Hai Plain is affected by large-scale weather systems. (4) The annual precipitation barycentres on the Huang-Huai-Hai Plain were located in Jining city and Taian city, Shandong Province, and the spatial distribution pattern was north-south. The annual precipitation barycentres tended to move southwest, but the trend was not obvious. The annual precipitation barycentre is expected to continue to shift to the north in 2020.

Causes of Late Twentieth-Century Trends in New Zealand Precipitation

2009 ◽  
Vol 22 (1) ◽  
pp. 3-19 ◽  
Author(s):  
Caroline C. Ummenhofer ◽  
Alexander Sen Gupta ◽  
Matthew H. England
Keyword(s):  
Twentieth Century ◽  
New Zealand ◽  
Southern Hemisphere ◽  
Large Scale ◽  
Austral Summer ◽  
Climate Modes ◽  
The North ◽  
Late Twentieth ◽  
Late Twentieth Century ◽  
Large Scale Atmospheric Circulation

Abstract Late twentieth-century trends in New Zealand precipitation are examined using observations and reanalysis data for the period 1979–2006. One of the aims of this study is to investigate the link between these trends and recent changes in the large-scale atmospheric circulation in the Southern Hemisphere. The contributions from changes in Southern Hemisphere climate modes, particularly the El Niño–Southern Oscillation (ENSO) and the southern annular mode (SAM), are quantified for the austral summer season, December–February (DJF). Increasingly drier conditions over much of New Zealand can be partially explained by the SAM and ENSO. Especially over wide parts of the North Island and western regions of the South Island, the SAM potentially contributes up to 80% and 20%–50% to the overall decline in DJF precipitation, respectively. Over the North Island, the contribution of the SAM and ENSO to precipitation trends is of the same sign. In contrast, over the southwest of the South Island the two climate modes act in the opposite sense, though the effect of the SAM seems to dominate there during austral summer. The leading modes of variability in summertime precipitation over New Zealand are linked to the large-scale atmospheric circulation. The two dominant modes, explaining 64% and 9% of the overall DJF precipitation variability respectively, can be understood as local manifestations of the large-scale climate variability associated with the SAM and ENSO.

Increasing Frequency of Flood Events across the Central United States: A Weather-Type Perspective

2020 ◽  
Author(s):  
Gabriele Villarini ◽  
Wei Zhang
Keyword(s):  
United States ◽  
Large Scale ◽  
Weather Type ◽  
Jet Stream ◽  
Flood Events ◽  
Weather Types ◽  
Study Region ◽  
Central United States ◽  
Upper Level ◽  
Increasing Trends

<p>The frequency of flood events has been increasing across large areas of the central United States since the second half of the 20<sup>th</sup> century; these increasing trends have been largely related to changes in precipitation. The aim of this presentation is to provide insights into the possible reasons responsible for these changes, providing basic information that may enhance our capability of predicting and projecting these changes.</p><p>This study highlights the role of weather types in explaining the observed changes in precipitation and, consequently, in the frequency of flood events. More specifically, we identify five weather types from daily 500-hPa geopotential height using the k-means cluster analysis. Consistent with their distinct large-scale atmospheric patterns, these weather types exert different effects on precipitation in the central United States. Because of the strong moisture transport, strengthened low-level jet stream and wavy upper-level polar jet stream located in the western United States, among the five weather types weather-type 1 exerts the strongest impacts on precipitation, accounting for up to 40% of the total precipitation over the study region. Moreover, we detect a significant upward trend in the number and persistency of these two weather types for 1948–2019, suggesting a rising risk of heavy and long-lasting precipitation across the central United States.</p>

scholarly journals Winter Orographic Precipitation Ratios in the Sierra Nevada—Large-Scale Atmospheric Circulations and Hydrologic Consequences

2004 ◽  
Vol 5 (6) ◽  
pp. 1102-1116 ◽  
Author(s):  
Michael Dettinger ◽  
Kelly Redmond ◽  
Daniel Cayan
Keyword(s):  
Sierra Nevada ◽  
Large Scale ◽  
Precipitation Amount ◽  
Heavy Precipitation ◽  
Winter Precipitation ◽  
Orographic Precipitation ◽  
Simple Experiment ◽  
Westerly Direction ◽  
Winter Flood ◽  
Precipitation Events

Abstract The extent to which winter precipitation is orographically enhanced within the Sierra Nevada of California varies from storm to storm, and season to season, from occasions when precipitation rates at low and high altitudes are almost the same to instances when precipitation rates at middle elevations (considered here) can be as much as 30 times more than at the base of the range. Analyses of large-scale conditions associated with orographic precipitation variations during storms and seasons from 1954 to 1999 show that strongly orographic storms most commonly have winds that transport water vapor across the range from a more nearly westerly direction than during less orographic storms and than during the largest overall storms, and generally the strongly orographic storms are less convectively stable. Strongly orographic conditions often follow heavy precipitation events because both of these wind conditions are present in midlatitude cyclones that form the cores of many Sierra Nevada storms. Storms during La Niña winters tend to yield larger orographic ratios (ORs) than do those during El Niños. A simple experiment with a model of streamflows from a river basin draining the central Sierra Nevada indicates that, for a fixed overall basin-precipitation amount, a decrease in OR contributes to larger winter flood peaks and smaller springtime flows, and thus to an overall hastening of the runoff season.

scholarly journals Uncertainty in El Niño-like warming and California precipitation changes linked by the Interdecadal Pacific Oscillation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lu Dong ◽  
L. Ruby Leung ◽  
Fengfei Song ◽  
Jian Lu
Keyword(s):  
El Niño ◽  
El Nino ◽  
Internal Variability ◽  
Winter Precipitation ◽  
Adaptation Planning ◽  
Interdecadal Pacific Oscillation ◽  
The North ◽  
Westerly Jet ◽  
Precipitation Changes

AbstractMarked uncertainty in California (CA) precipitation projections challenges their use in adaptation planning in the region already experiencing severe water stress. Under global warming, a westerly jet extension in the North Pacific analogous to the El Niño-like teleconnection has been suggested as a key mechanism for CA winter precipitation changes. However, this teleconnection has not been reconciled with the well-known El Niño-like warming response or the controversial role of internal variability in the precipitation uncertainty. Here we find that internal variability contributes > 70% and > 50% of uncertainty in the CA precipitation changes and the El Niño-like warming, respectively, based on analysis of 318 climate simulations from several multi-model and large ensembles. The Interdecadal Pacific Oscillation plays a key role in each contribution and in connecting the two via the westerly jet extension. This unifying understanding of the role of internal variability in CA precipitation provides critical guidance for reducing and communicating uncertainty to inform adaptation planning.

scholarly journals Seasonal Forecasts of Canadian Winter Precipitation by Postprocessing GCM Integrations

2008 ◽  
Vol 136 (3) ◽  
pp. 769-783 ◽  
Author(s):  
Hai Lin ◽  
Gilbert Brunet ◽  
Jacques Derome
Keyword(s):  
General Circulation ◽  
Large Scale ◽  
General Circulation Models ◽  
Winter Precipitation ◽  
Second Phase ◽  
Seasonal Forecasts ◽  
Large Area ◽  
Ensemble Forecasts ◽  
The North ◽  
Ensemble Mean

Abstract In the second phase of the Canadian Historical Forecasting Project (HFP2), four global atmospheric general circulation models (GCMs) were used to perform seasonal forecasts over the period of 1969–2003. Little predictive skill was found from the uncalibrated GCM ensemble seasonal predictions for the Canadian winter precipitation. This study is an effort to improve the precipitation forecasts through a postprocessing approach. Canadian winter precipitation is significantly influenced by two of the most important atmospheric large-scale patterns: the Pacific–North American pattern (PNA) and the North Atlantic Oscillation (NAO). The time variations of these two patterns were found to be significantly correlated with those of the leading singular value decomposition (SVD) modes that relate the ensemble mean forecast 500-mb geopotential height over the Northern Hemisphere and the tropical Pacific SST in the previous month (November). A statistical approach to correct the ensemble forecasts was formulated based on the regression of the model’s leading forced SVD patterns and the observed seasonal mean precipitation. The performance of the corrected forecasts was assessed by comparing its cross-validated skill with that of the original GCM ensemble mean forecasts. The results show that the corrected forecasts predict the Canadian winter precipitation with statistically significant skill over the southern prairies and a large area of Québec–Ontario.

An n-alkane-based Holocene climate reconstruction in the Altai Mountains, northern Xinjiang, China

2020 ◽  
Author(s):  
Min Ran
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Time Lag ◽  
Geographic Location ◽  
Early Holocene ◽  
Altai Mountains ◽  
Temperature Changes ◽  
The Holocene ◽  
The North ◽  
Highly Sensitive

<p>The climate in the Altai Mountains is highly sensitive to large-scale forcing factors because of its special geographic location. Based on n-alkane data of 150 samples and with a chronologic support of 15 accelerator mass spectrometry (AMS) dates from a 600-cm core at GHZ Peat, the Holocene climatic changes in the Altai Mountains were reconstructed. The reconstruction revealed a warming and drying early Holocene (~10,750-~8500 cal. yr BP), a cooling and persistent dry middle Holocene (~8500-~4500 cal. yr BP), and a cooling and wetting late Holocene (~4500-~700 cal. yr BP). The Holocene temperature changes were primarily controlled by the summer solar radiation with a certain time lag in the early Holocene and also modulated by solar activity, and the time lag in the early Holocene was probably resulted from ice and permafrost melting. The Holocene moisture in the southern Altai Mountains was likely modulated by the North Atlantic Oscillations (NAO) or by the Atlantic Multi-centennial Oscillations (i.e., AMO-like) or by temperature, and or by any combination of the three (NAO, AMO-like, and temperature).</p>

scholarly journals Mapping Weather-Type Influence on Senegal Precipitation Based on a Spatial–Temporal Statistical Model*

2013 ◽  
Vol 26 (20) ◽  
pp. 8189-8209 ◽  
Author(s):  
Henning W. Rust ◽  
Mathieu Vrac ◽  
Benjamin Sultan ◽  
Matthieu Lengaigne
Keyword(s):  
Atmospheric Circulation ◽  
Large Scale ◽  
Pearson Correlation ◽  
Precipitation Amount ◽  
Correlation Coefficients ◽  
Drought Risk ◽  
Synoptic Scale ◽  
Weather Types ◽  
Easterly Waves ◽  
Precipitation Occurrence

Abstract Senegal is particularly vulnerable to precipitation variability. To investigate the influence of large-scale circulation on local-scale precipitation, a full spatial–statistical description of precipitation occurrence and amount for Senegal is developed. These regression-type models have been built on the basis of daily records at 137 locations and were developed in two stages: (i) a baseline model describing the expected daily occurrence probability and precipitation amount as spatial fields from monsoon onset to offset, and (ii) the inclusion of weather types defined from the NCEP–NCAR reanalysis 850-hPa winds and 925-hPa relative humidity establishing the link to the synoptic-scale atmospheric circulation. During peak phase, the resulting types appear in two main cycles that can be linked to passing African easterly waves. The models allow the investigation of the spatial response of precipitation occurrence and amount to a discrete set of preferred states of the atmospheric circulation. As such, they can be used for drought risk mapping and the downscaling of climate change projections. Necessary choices, such as filtering and scaling of the atmospheric data (as well as the number of weather types to be used), have been made on the basis of the precipitation models' performance instead of relying on external criteria. It could be demonstrated that the inclusion of the synoptic-scale weather types lead to skill on the local and daily scale. On the interannual scale, the models for precipitation occurrence and amount capture 26% and 38% of the interannual spatially averaged variability, corresponding to Pearson correlation coefficients of rO = 0.52 and ri = 0.65, respectively.

scholarly journals Die spätglazialen sowie die frühpostglazialen Klimaverhältnisse im Bereiche der Alpen : Sauerstoffisotopenkurven kalkhaltiger Sedimente

1987 ◽  
Vol 42 (2) ◽  
pp. 99-104 ◽  
Author(s):  
U. Eicher
Keyword(s):  
Central Europe ◽  
Large Scale ◽  
North Atlantic Ocean ◽  
Ice Cores ◽  
Stratigraphic Correlation ◽  
Deep Sea Sediment ◽  
Temperature Changes ◽  
The North ◽  
The Alps ◽  
Isotope Analyses

Abstract. 180/160 isotope analyses on carbonate lake Sediments from Central Europe exhibit abrupt, characteristic variations reflecting temperature changes. Between 13,000 and 11,000 years before present, a more or less continuous warm period (Bölling-Alleröd) existed separated from the Postglacial by the Younger Dryas cold phase. Results from 25 Sites in Central Europe, especially the forelands ot the Alps indicate, with the exception of 3 Sites south of the Alps, a synchronous large-scale climatic development. Indirect dating and stratigraphic correlation of the different records was mostly performed by means of pollen analysis. Our results correlate very well with 180/160 measurements on Greenland ice cores, and they agree well with results from deep sea sediment studies in the North Atlantic Ocean covering the Glacial-Postglacial transition.

scholarly journals The Demographic Sustainability of Empty Spain

2017 ◽  
pp. 1-4
Author(s):  
Joaquín Recaño
Keyword(s):  
Twentieth Century ◽  
European Union ◽  
Iberian Peninsula ◽  
Large Scale ◽  
Basic Problem ◽  
Public Policies ◽  
The European Union ◽  
The North ◽  
Relative Scarcity ◽  
Vast Area

On 1 January 2016, 60 per cent of Spanish municipalities had fewer than 1,001 inhabitants, occupied 40% of the country’s surface and concentrated barely 3.1% of the population. Eurostat data situate 19 Spanish provinces among the least dense of the European Union in 2015. This notable imbalance between population and territory, the basic problem of a vast area in the north and centre of the Iberian peninsula, is characterized by ageing, a relative scarcity of women because of large-scale differential emigration based on gender, and transitory immigration that has been unable to compensate for the demographic outflow which has affected these places since the middle of the twentieth century. The demographic sustainability of this heterogeneous set of municipalities is hanging in the balance. This situation constitutes a major challenge and, moreover, the great diversity of these towns should be borne in mind when it comes to applying public policies.

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