scholarly journals Large-Scale Patterns and Long-Term Trends of Circulation Variability Associated with Sahel Rainfall Anomalies

1992 ◽  
Vol 70 (6) ◽  
pp. 1045-1056 ◽  
Author(s):  
Stefan Hastenrath ◽  
Klaus Wolter ◽  
Klaus Wolter
Keyword(s):  
Large Scale ◽  
Long Term Trends ◽  
Sahel Rainfall ◽  
Rainfall Anomalies

Large-scale, long-term trends in British river macroinvertebrates

2012 ◽  
Vol 18 (7) ◽  
pp. 2184-2194 ◽  
Author(s):  
Ian P. Vaughan ◽  
Steve J. Ormerod
Keyword(s):  
Large Scale ◽  
Long Term Trends

scholarly journals Reply to “Comment on ‘Bias Correction, Quantile Mapping, and Downscaling: Revisiting the Inflation Issue’”

2014 ◽  
Vol 27 (4) ◽  
pp. 1821-1825 ◽  
Author(s):  
Douglas Maraun
Keyword(s):  
Large Scale ◽  
Weather Forecasting ◽  
Small Scale ◽  
Quantile Mapping ◽  
Spatiotemporal Structure ◽  
Weather Forecasts ◽  
Long Term Trends ◽  
Climate Signals ◽  
Local Variability

Abstract In his comment, G. Bürger criticizes the conclusion that inflation of trends by quantile mapping is an adverse effect. He assumes that the argument would be “based on the belief that long-term trends and along with them future climate signals are to be large scale.” His line of argument reverts to the so-called inflated regression. Here it is shown, by referring to previous critiques of inflation and standard literature in statistical modeling as well as weather forecasting, that inflation is built upon a wrong understanding of explained versus unexplained variability and prediction versus simulation. It is argued that a sound regression-based downscaling can in principle introduce systematic local variability in long-term trends, but inflation systematically deteriorates the representation of trends. Furthermore, it is demonstrated that inflation by construction deteriorates weather forecasts and is not able to correctly simulate small-scale spatiotemporal structure.

scholarly journals Central-Eastern China Persistent Heat Waves: Evaluation of the AMIP Models

2018 ◽  
Vol 31 (9) ◽  
pp. 3609-3624 ◽  
Author(s):  
N. Freychet ◽  
S. F. B. Tett ◽  
G. C. Hegerl ◽  
J. Wang
Keyword(s):  
Heat Wave ◽  
Large Scale ◽  
Heat Waves ◽  
Eastern China ◽  
Ground Station ◽  
Significant Difference ◽  
Long Term Trends ◽  
Central Eastern ◽  
Seasonal Signal

Abstract Large-scale and persistent heat waves affecting central-eastern China are investigated in 40 different simulations of sea surface temperature driven global atmospheric models. The different models are compared with results from reanalysis and ground station datasets. It is found that the dynamics of heat-wave events is well reproduced by the models. However, they tend to produce too-persistent heat-wave events (lasting more than 20 days), and several hypotheses were tested to explain this bias. The daily variability of the temperatures or the seasonal signal did not explain the persistence. However, interannual variability of the temperatures in the models, and especially the sharp transition in the mid-1990s, has a large impact on the duration of heat waves. A filtering method was applied to select the models closest to the observations in terms of events persistence. The selected models do not show a significant difference from the other models for the long-term trends. Thus, the bias on the duration of the events does not impact the reliability of the model positive trends, which is mainly controlled by the changes in mean temperatures.

scholarly journals Landfalling Tropical Cyclones along the Eastern Pacific Coast between the Sixteenth and Twentieth Centuries

2013 ◽  
Vol 26 (12) ◽  
pp. 4219-4230 ◽  
Author(s):  
Marni Pazos ◽  
Blanca Mendoza
Keyword(s):  
Tropical Cyclones ◽  
Large Scale ◽  
Pacific Coast ◽  
Eastern Pacific ◽  
Historical Time ◽  
Eastern Pacific Ocean ◽  
Mexican Pacific ◽  
Long Term Trends ◽  
Landfalling Tropical Cyclones

Abstract Numerous studies have been conducted to document long-term trends in tropical cyclone (TC) activity. However, the eastern Pacific has not received as much attention as other basins. Here the authors attempt the identification of TC formation in the Mexican eastern Pacific Ocean before 1950. Using bibliographical and historical file consultation, they constructed a catalog of events related to intense storms and possible TCs that made landfall on the Mexican Pacific coasts. Between 1536 and 1948 they found a total of 119 events related to TCs. Then, using the Saffir–Simpson scale and the climatology of the region as the criteria to evaluate each event, they found 85 TCs. Furthermore, they constructed a historical time series of TCs between 1701 and 2010. The spectral analysis showed periodicities of ~2.6, 4, 5, 12, 16, 39, and 105 years that coincide with some large-scale climatic phenomena and also with solar activity. In particular, the ~12-yr cycle is the most persistent periodicity in this study.

Opposite trends of sea-breeze speeds and gusts in Eastern Iberian Peninsula, 1961-2019

2021 ◽  
Author(s):  
Shalenys Bedoya-Valestt ◽  
Cesar Azorin-Molina ◽  
José A. Guijarro ◽  
Victor J. Sanchez-Morcillo
Keyword(s):  
Wind Speed ◽  
Iberian Peninsula ◽  
Atmospheric Circulation ◽  
Air Temperature ◽  
Large Scale ◽  
Sea Breeze ◽  
Sea Breezes ◽  
Long Term Trends ◽  
Large Scale Atmospheric Circulation

<p>Long-term trends of local winds such as sea breezes have been less addressed in climate research, despite their impacts on broad environmental and socioeconomic spheres, such as weather and climate, agriculture and hydrology, wind-power industry, air quality or even human health, among many others. In a warming climate, sea breezes could be affected by changes on air temperature, as these onshore winds are thermally-driven by gradients between the sea-land air, but also by ocean-atmosphere oscillations or changes in large-scale atmospheric circulation. In the last few decades, advances in wind trends studies evidenced a recovery in global wind stilling during the last 10 years, and differences in the sign-magnitude of wind speed trends were found at seasonal-scale, suggesting the hypothetic effect of the reinforcement of local wind circulations in the warm seasons.</p><p>In this study, we analyze for the first time the long-term trends, multidecadal variability and possible drivers of the sea-breeze speeds and gusts in Eastern Iberian Peninsula during the last 58 years (1961-2019), using homogenized wind speed and gusts data from 16 meteorological stations. To identify potential sea breeze episodes, we developed a robust automated method based on alternative criteria. Our results suggest a decoupling between the declining sea-breeze speeds and the strengthening of the maximum gusts for much of the 1961-2019 period at annual, seasonal and monthly scales, but differences based on locations were also found. Because sea breeze changes can be driven by multiple complex factors (i.e. land use changes, land-sea air temperature gradient, complex orography, etc.), the attribution of causes is challenging. To better understand the causes behind the opposite trends between sea-breeze speeds and gusts, we investigate the effect of e.g. the changes in large-scale atmospheric circulation or physical-local factors.</p>

Long-term trends in age-specific recruitment of sockeye salmon (Oncorhynchus nerka) in a changing environment

2004 ◽  
Vol 61 (12) ◽  
pp. 2455-2470 ◽  
Author(s):  
Carrie A Holt ◽  
Randall M Peterman
Keyword(s):  
Kalman Filter ◽  
Sockeye Salmon ◽  
Large Scale ◽  
Oncorhynchus Nerka ◽  
Age At Maturity ◽  
Age Class ◽  
Sibling Models ◽  
Long Term Trends ◽  
Forecasting Errors

Sibling – age-class (sibling) models, which relate abundance of one age-class of adult sockeye salmon (Oncorhynchus nerka) to abundance of the previous age-class in the previous year, are commonly used to forecast abundance 1 year ahead. Standard sibling models assume constant parameters over time. However, many sockeye salmon populations have shown temporal changes in age-at-maturity. We therefore developed a new Kalman filter sibling model that allowed for time-varying parameters. We found considerable evidence for long-term trends in parameters of sibling models for 24 sockeye salmon stocks in British Columbia and Alaska; most trends reflected increasing age-at-maturity. In a retrospective analysis, the Kalman filter forecasting models reduced mean-squared forecasting errors compared with standard sibling models in 29%–39% of the stocks depending on the age-class. The Kalman filter models also had mean percent biases closer to zero than the standard models for 54%–94% of the stocks. Parameters of these sibling models are positively correlated among stocks from different regions, suggesting that large-scale factors (e.g., competition among stocks for limited marine prey) may be important drivers of long-term changes in age-at-maturity schedules in sockeye salmon.

scholarly journals Modeling point and non-point nutrient fluxes in river systems of lake Peipsi drainage basi

2019 ◽  
pp. 389-398
Author(s):  
Kristjan Piirimäe
Keyword(s):  
Large Scale ◽  
Sharp Decrease ◽  
Paper Analysis ◽  
Cyanobacterial Blooms ◽  
Nutrient Loads ◽  
Lake Peipsi ◽  
Baltic Sea Region ◽  
Long Term Trends ◽  
The Baltic

N and P compounds work as key elements causing bioproduction and eutrophication inwater bodies of the Baltic Sea region, A large-scale dynamic GIS-embedded PolFlowmodel considers all point and diffuse emission sources in a river basin simulating alsotransport and retention of nutrients in time steps of five years, This modeling approachwas originally developed for simulating past and present nutrient loads for the Rhine andElbe rivers. In addition, a statistical model MESAW was employed for nutrient sourceapportionment and emission estimations. This paper analysis the modeling results in LakePeipsi basin, shared by Estonia, Russia and Latvia, for long-term trends since 1985 till1999. Results of modeling, as well as monitoring data indicate quite stable long-term Pload while agricultural N load has decreased significantly in connection with dramaticchanges in agricultural structures. That, in turn, has lead to sharp decrease ofN/P ratio inriverine runoff while in lakes (L Peipsi, L Vortsjii.rv) and coastal seas, NIP ratio hasdropped below 10. These changes, enhancing cyanobacterial blooms, have significantlyworsened the ecological state of these water bodies, in the conditions of decreasedemissions. The paper concludes that wastewater treatment should focus on better removalofphosphorus.

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