Wind trends analysis in southern South America from weather station and reanalysis data

Merino, Rodrigo Andres; Gassmann, María Isabel

doi:10.1002/joc.7355

Cited by 3 publications

(6 citation statements)

References 67 publications

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“…On the other hand, the reanalysis presents a very poor representation of the monthly wind speed, especially near the Andes mountain range. This behaviour is consistent with other studies which found issues in ERA5's (and thus ERA5-Land's) ability to accurately represent regional wind speeds (Merino and Gassmann, 2021;Nouri and Homaee, 2022), and may be the origin of most of the overestimations within the aerodynamic term. In the case of surface net radiation, the model reasonably represents the monthly variability, although a negative bias is present for all stations.…”

Section: Discussionsupporting

confidence: 92%

“…The divergence with the results presented here in the analyses carried out for the same region is probably related to the fact that the H model does not consider changes in air humidity, which is an important forcing of atmospheric demand. Furthermore, the H model does not consider also the observed trends in wind speed (Merino and Gassmann, 2021). Aguilera (2018) pointed out that this is an important source of error in the H model and indicated that regional corrections should be included into it to overcome this problem.…”

Section: Discussionmentioning

confidence: 99%

“…(2012) findings for mid‐latitude regions, where aerodynamic conditions are responsible for up to 80% of the evaporative process with a clear latitudinal distribution. Increases of surface wind speeds observed during the warmer seasons in Argentina (Merino and Gassmann, 2021) also play a role in enhancing aerodynamic evapotranspiration.…”

Section: Discussionmentioning

confidence: 99%

“…They conclude that there are no significant trends for all analysed variables. However, detailed analysis on daily wind speed for that region showed heterogeneities in the time series caused by sensor replacement not considered in the decadal average (Merino and Gassmann, 2021). Similar issues in wind speed time‐series were reported by Cechet and Sanabria (2010, 2012) on the Australian weather station time‐series.…”

Section: Introductionmentioning

confidence: 99%

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Trends of reference evapotranspiration and its physical drivers in southern South America

Merino

Gassmann

2022

Intl Journal of Climatology

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Reference evapotranspiration (ETo) is a variable used to characterize the evaporative demand of the atmosphere and its impact on the water balance. During the last decades, significant ETo variabilities have been observed, especially at mid‐latitudes. These variabilities respond mainly to local variations in their physical drivers, such as solar radiation, vapour pressure deficit or wind speed. In this study, the annual and seasonal ETo estimates are generated using the Penman–Monteith method (FAO). Surface weather stations for the Argentine territory and reanalysis data for southern South America of the last four decades (1981–2020) are used. Contributions of both aerodynamic (ETaero) and radiative (ETrad) effects are evaluated to analyse their driving role. Significant positive ETo trends are observed from reanalysis data throughout Argentina, especially on the central east side of the Andes Mountain range with values up to 10 mm·year−1. Most of these ETo changes respond to positive trends in air temperature in the study area, while those in the central Andes also respond to negative trends in dew point temperatures. On the other hand, the increase in energy availability through positive trends in net surface radiation produced a slightly higher ETo in the northern regions of the country. Regional ETo values have shown to be more sensitive to variations in air temperature in the northeastern areas, although changes in humidity and solar radiation could also play a role. In a context of climate change, given that temperature and rainfall are expected to increase in the central and northeastern region of the country and decrease along the eastern side of the Andes Mountains in the coming decades, the characteristics observed over the 1981–2020 period are expected to intensify in the near future.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Trends of reference evapotranspiration and its physical drivers in southern South America

Merino

Gassmann

2022

Intl Journal of Climatology

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“…Climate reanalysis has been widely used to overcome the absence of high-quality and long-term observational records for wind energy users. e new ERA5 dataset has been proven superior to the traditional MERRA2 product in predicting the regional distributions of wind resources in the South China Sea [24], Europe [25], America [26], and other areas worldwide [9]. Here, we analyzed the applicability of these two reanalyses in estimating tall tower wind characteristics using different statistical downscaling methods in South China.…”

Section: Discussionmentioning

confidence: 99%

Comparison of the Applicability of Two Reanalysis Products in Estimating Tall Tower Wind Based on Multiple Linear Regression and Artificial Neural Network in South China

Li¹,

Qin²,

Yang³

et al. 2022

Advances in Meteorology

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Climate reanalysis products have been widely used to overcome the absence of high-quality and long-term observational records for wind energy users. In this study, the applicability of two popular reanalysis datasets (ERA5 and MERRA2) in estimating wind characteristics for four tall tower observatories (TTOs) in South China was assessed. For each TTO, linear and nonlinear downscaling techniques, namely, multiple linear regression (MLR) and an artificial neural network (ANN), respectively, were adopted for the downscaling of the scalar wind speed and the corresponding U/V components. The downscaled wind speed and U/V components were subsequently compared with the TTO observations by correlation coefficient (Pearson’s r), the root mean square error (RMSE), the uncertainty analysis (U95), and the reliability analysis (RE). According to the results, ERA5 had a better applicability (higher Pearson’s r and RE, but lower RMSE and U95) in estimating TTO wind speed than MERRA2 when using both the MLR and ANN downscaling method. The average Pearson’s r, RE, RMSE, and U95 of the downscaled wind from ERA5 by the MLR (ANN) method were 0.66 (0.69), 40.8% (41.8%), 2.20 m/s (2.11 m/s), 0.181 m/s (0.179 m/s), respectively, and 0.60 (0.63), 38.0% (39.7%), 2.32 m/s (2.25 m/s), 0.189 m/s (0.187 m/s), respectively, for MERRA2. The wind components analysis showed that the better performance of ERA5 was attributed to its smaller error in estimating V component than MERRA2. For the wind direction, the two reanalysis datasets did not display distinct differences. Additionally, the misalignment of the wind direction between the reanalysis products and the TTOs was higher for the secondary predominant wind direction (SPWD) than for the predominant wind direction (PWD). Furthermore, we found that the reanalysis U wind had a higher RMSE but a lower RE and Pearson’s r than the V wind, which indicates that the misalignment in the wind direction was mainly associated with the deviation in the U component.

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Summer upper-level jets modulate the response of South American climate to ENSO

Collazo,

García-Herrera,

Barriopedro

2023

Clim Dyn

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The upper-level jet stream is a critical element of atmospheric circulation, driving synoptic systems and extreme weather events. This study analyzes the impact of upper-level jets on South American (SA) summer temperature and precipitation under different El Niño-Southern Oscillation (ENSO) phases. Using the ERA5 reanalysis dataset from 1979 to 2022, we perform a daily multiparametric characterization of the jet stream, considering its spatial and temporal discontinuities. Besides latitude and intensity, we find that the departure and number of branches of the subtropical jet (STJ) and the longitudinal extent of the Pacific branch of the polar front jet (PFJ) are needed for their description. An additional parameter is required to characterize the STJ due to its absence on around 40% of summer days over SA. Moreover, we observe distinct long-term changes in PFJ parameters across different ocean basins. Three synoptic weather types (WTs) of the upper-level zonal wind are identified: normal conditions, a prominent STJ pattern, and a PFJ-only pattern. The latter pattern is associated with anticyclonic anomalies at 500 hPa in the South Atlantic Ocean and an active SA Convergence Zone, which favors clear skies and warm (wet and cold) conditions in southern SA (Brazil). Consistently, the probability of experiencing warm spells in central Argentina is increased more than twofold. Finally, we detect that the temperature anomalies associated with the WTs are independent of the ENSO phase. However, ENSO modulates the frequency of the WTs: during La Niña (El Niño), the PFJ-only (prominent STJ) pattern is more common.

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Wind trends analysis in southern South America from weather station and reanalysis data

Cited by 3 publications

References 67 publications

Trends of reference evapotranspiration and its physical drivers in southern South America

Trends of reference evapotranspiration and its physical drivers in southern South America

Comparison of the Applicability of Two Reanalysis Products in Estimating Tall Tower Wind Based on Multiple Linear Regression and Artificial Neural Network in South China

Summer upper-level jets modulate the response of South American climate to ENSO

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