A solar radiation database for Chile Molina, Alejandra; Falvey, Mark; Rondanelli, Roberto
Scientific reports,
11/2017, Letnik:
7, Številka:
1
Journal Article
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Chile hosts some of the sunniest places on earth, which has led to a growing solar energy industry in recent years. However, the lack of high resolution measurements of solar irradiance becomes a ...critical obstacle for both financing and design of solar installations. Besides the Atacama Desert, Chile displays a large array of "solar climates" due to large latitude and altitude variations, and so provides a useful testbed for the development of solar irradiance maps. Here a new public database for surface solar irradiance over Chile is presented. This database includes hourly irradiance from 2004 to 2016 at 90 m horizontal resolution over continental Chile. Our results are based on global reanalysis data to force a radiative transfer model for clear sky solar irradiance and an empirical model based on geostationary satellite data for cloudy conditions. The results have been validated using 140 surface solar irradiance stations throughout the country. Model mean percentage error in hourly time series of global horizontal irradiance is only 0.73%, considering both clear and cloudy days. The simplicity and accuracy of the model over a wide range of solar conditions provides confidence that the model can be easily generalized to other regions of the world.
In this study, we explored the connection between anomalies in springtime Antarctic ozone and all-year precipitation in the Southern Hemisphere by using observations from 1960–2018 and coupled ...simulations for 1960–2050. The observations showed that this correlation was enhanced during the last several decades, when a simultaneously increased coupling between ozone and Southern Annular Mode (SAM) anomalies became broader, covering most of the following summer and part of the previous winter. For eastern Australia, the ozone–precipitation connection shows a greater persistence toward the following summer than for other regions. On the other hand, for South America, the ozone–precipitation correlation seems more robust, especially in the early summer. There, the correlation also covers part of the previous winter, suggesting that winter planetary waves could affect both parameters. Further, we estimated the sensitivity of precipitation to changes in Antarctic ozone. In both observations and simulations, we found comparable sensitivity values during the spring–summer period. Overall, our results indicate that ozone anomalies can be understood as a tracer of stratospheric circulation. However, simulations indicate that stratospheric ozone chemistry still contributes to strengthening the interannual relationship between ozone and surface climate. Because simulations reproduced most of the observed connections, we suggest that including ozone variability in seasonal forecasting systems can potentially improve predictions.
Ozone (O
3
) soundings have been performed on Easter Island or Rapa Nui (27 °S, 109 °W, 51 m a.s.l.) since 1994 as part of the Global Atmospheric Watch Programme of the World Meteorological ...Organization. In this work, we analyse 260 soundings compiled over the period 1994-2014, and make the data available for the international community. We characterise O
3
profiles over this remote area of the Pacific by means of statistical analyses that consider, on the one hand, a traditional climatology that describes the data in terms of seasonal cycles based on monthly averages and, on the other hand, a process-oriented analysis based on self-organising maps. Our analyses show the influence of both tropical and subtropical/mid-latitude air masses at Rapa Nui. The former occurs in summer and fall when convective conditions prevail, and the latter in late winter and spring when subsiding conditions are recurrent. The occurrence of stratospheric intrusions in late winter and spring in connection with deep troughs and the presence of the subtropical jet stream is also apparent in the data set. The tropospheric ozone column is in good agreement with the corresponding data derived from satellites but with a systematic overestimate of summer and fall values. There is evidence of an upward trend in ozone near the surface, which suggests the impact of local pollution. We look forward to an enhancement of the Rapa Nui observing site, given its location that offers a privileged position to observe climate change over the sparsely sampled and vast South Pacific Ocean.
Abstract
Interannual variability of precipitation in Central Chile has long been associated with changes in the dry atmospheric dynamics of the Southern Pacific. This is due to the interaction ...between the extratropical storm track and the polar anticyclonic circulations established by the Pacific South American (PSA) teleconnection mode, which results from changes in tropical convection. Here, we show that an enhanced subtropical moisture transport during the warm ENSO phase leads to an increase in the frequency of atmospheric rivers, larger values of precipitable water, and heightened zonal integrated water vapor transport. This occurs in a region of the Southern Pacific situated between the tropical high and the subtropical low of the PSA mode. These increases in zonal water vapor transport result in greater precipitation and moister, long‐lived atmospheric rivers making landfall in Central Chile.
Plain Language Summary
Changes in the amount of rain Central Chile gets from year to year is often related to how the atmosphere behaves over the Southern Pacific Ocean. Specifically, it is connected to the interaction between storm tracks and certain wind patterns that respond to changes in the amount of rainfall in tropical areas. Our research shows that during the warm part of a natural climate cycle known as ENSO, there is more moisture transported from subtropical areas. This leads to more occurrences of what are known as atmospheric rivers, which are essentially large streams of water vapor in the sky. It also leads to a greater amount of water vapor in the air and more of this vapor being moved across the Pacific. These changes mean that there is more rain and atmospheric rivers, which carry a lot of moisture and stick around for a long time, affecting Central Chile. So our work is helping to reveal how changes in the rainfall in tropical areas can influence the amount of rain that falls in distant places like Central Chile.
Key Points
Moisture transport in the Southern Pacific is enhanced during the El Niño, between a large‐scale tropical high and a subtropical low
The frequency of atmospheric rivers maximize in a region at around 110°W and 25°S consistent with an increase in transient eddies
The increased moisture transport is connected to longer‐lasting and moister atmospheric rivers landfalling in Central Chile
This study delves into the photochemical atmospheric changes reported globally during the pandemic by analyzing the change in emissions from mobile sources and the contribution of local meteorology ...to ozone (O3) and particle formation in Bogotá (Colombia), Santiago (Chile), and São Paulo (Brazil). The impact of mobility reductions (50%–80%) produced by the early coronavirus-imposed lockdown was assessed through high-resolution vehicular emission inventories, surface measurements, aerosol optical depth and size, and satellite observations of tropospheric nitrogen dioxide (NO2) columns. A generalized additive model (GAM) technique was also used to separate the local meteorology and urban patterns from other drivers relevant for O3 and NO2 formation. Volatile organic compounds, nitrogen oxides (NOx), and fine particulate matter (PM2.5) decreased significantly due to motorized trip reductions. In situ nitrogen oxide median surface mixing ratios declined by 70%, 67%, and 67% in Bogotá, Santiago, and São Paulo, respectively. NO2 column medians from satellite observations decreased by 40%, 35%, and 47%, respectively, which was consistent with the changes in mobility and surface mixing ratio reductions of 34%, 25%, and 34%. However, the ambient NO2 to NOx ratio increased, denoting a shift of the O3 formation regime that led to a 51%, 36%, and 30% increase in the median O3 surface mixing ratios in the 3 respective cities. O3 showed high sensitivity to slight temperature changes during the pandemic lockdown period analyzed. However, the GAM results indicate that O3 increases were mainly caused by emission changes. The lockdown led to an increase in the median of the maximum daily 8-h average O3 of between 56% and 90% in these cities.
This paper focuses on the relation between local sea surface temperature (SST) and convective precipitation fraction and stratiform rainfall area from radar observations of precipitation, using data ...from the Kwajalein atoll ground‐based radar as well as the precipitation radar on board the TRMM satellite. We find that the fraction of convective precipitation increases with SST at a rate of about 6 to 12%/K and the area of stratiform rainfall normalized by total precipitation decreases with SST at rates between −5 and −28%/K. These relations are observed to hold for different regions over the tropical oceans and also for different periods of time. Correlations are robust to outliers and to undersampled precipitation regions. Kwajalein results are relatively insensitive to the parameters in the stratiform‐convective classification algorithm. Quantitative differences between the results obtained using the two different radars could be explained by the smoothing in the reflectivity of convective regions due to the relatively large pixel size of the TRMM precipitation radar compared to the size of the convective clouds. Although a dependence on temperature such as the one documented is consistent with an increase in the efficiency of convective precipitation (and therefore consistent with one of the mechanisms invoked to explain the original Iris effect observations) this is but one step in studying the possibility of a climate feedback. Further work is required to clarify the particular mechanism involved.
Santiago de Chile frequently suffers from atmospheric pollution that contributes to the decrease of solar irradiance on the surface, leading to losses in the energy output of photovoltaic systems. In ...this study, a simple model is used to estimate the effect of aerosols on the solar irradiance over the city throughout the year, using as input AERONET sunphotometer data and other in-situ measurements. The results show reductions of 3.5% and 14.1% for global horizontal and direct normal irradiance respectively and an increase of 35.4% for diffuse horizontal irradiance between the actual condition in Santiago and a hypothetical atmosphere free of aerosols. These effects translate approximately to an annual difference in the energy output of −7.2% and −8.7% for monocrystalline and amorphous silicon PV technologies respectively, and an annual difference of −16.4% for a CPV technology, showing that aerosols can have a significant effect on the photovoltaic energy production.
•Aerosols produce a significant decrease of incoming solar irradiance in Santiago.•This reduction also translate to less power output using different PV technologies.•Observations and a model were used to estimate the irradiance and PV power year long.•Losses due to the atmospheric column of aerosols depends on the PV technology.
Central Chile, home to more than 10 million inhabitants, has experienced an uninterrupted sequence of dry years since 2010 with mean rainfall deficits of 20–40%. The so‐called Mega Drought (MD) is ...the longest event on record and with few analogues in the last millennia. It encompasses a broad area, with detrimental effects on water availability, vegetation and forest fires that have scaled into social and economical impacts. Observations and reanalysis data reveal that the exceptional length of the MD results from the prevalence of a circulation dipole‐hindering the passage of extratropical storms over central Chile—characterized by deep tropospheric anticyclonic anomalies over the subtropical Pacific and cyclonic anomalies over the Amundsen–Bellingshausen Sea. El Niño Southern Oscillation (ENSO) is a major modulator of such dipole, but the MD has occurred mostly under ENSO‐neutral conditions, except for the winters of 2010 (La Niña) and 2015 (strong El Niño). Climate model simulations driven both with historical forcing (natural and anthropogenic) and observed global SST replicate the south Pacific dipole and capture part of the rainfall anomalies. Idealized numerical experiments suggest that most of the atmospheric anomalies emanate from the subtropical southwest Pacific, a region that has experienced a marked surface warming over the last decade. Such warming may excite atmospheric Rossby waves whose propagation intensifies the circulation pattern leading to dry conditions in central Chile. On the other hand, anthropogenic forcing (greenhouse gases concentration increase and stratospheric ozone depletion) and the associated positive trend of the Southern Annular Mode also contribute to the strength of the south Pacific dipole and hence to the intensity and longevity of the MD. Given the concomitance of the seemingly natural (ocean sourced) and anthropogenic forcing, we anticipate only a partial recovery of central Chile precipitation in the decades to come.
Geographic and climate features of Central Chile. (a) Topographic map (dark grey: Terrain elevation <500 m asl; light grey: 500–3,000 m asl; white: > 3,000 m asl). Blue dots are rain gauges stations operated by DMC/DGA. Red circles are the location of the six stations used to define the regional precipitation index. Stations that provide records for Figure 4 are also indicated. (b) Station‐based annual mean rainfall (1980–2010) according to latitude.
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