Reconstruction of historical aerosol optical depth time series over Romania during summertime

Dumitrescu, Alexandru; Gueymard, C.; Badescu, Viorel

doi:10.1002/joc.5118

Cited by 8 publications

(3 citation statements)

References 39 publications

(66 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A recent study on the reconstruction of AOD values over Romania in the period 1961-2015 [38] confirms the results of the present work. Particularly, these researchers state, "These reconstructed AOD time series reveal an upward trend in AOD until mid-1980s, followed by a downward trend until the present".…”

Section: /Decade)supporting

confidence: 92%

Annual and Seasonal Trends of Solar Radiation in Athens, Greece

Kambezidis¹

2018

J. Solar Eneg. Res. Updat.

View full text Add to dashboard Cite

This study deals with the solar radiation levels recorded at the Actinometric Station of the National Observatory of Athens, focusing on the trends of the global and diffuse horizontal irradiances in the period of 1992-2017 (26 years). The analysis shows that the annual global radiation time series over Athens in the above period presents a positive trend (+0.40%/decade and +2.38%/decade for all and clear skies, respectively), while its diffuse counterpart shows negative trend (-5.19%/decade and -6.77%/decade for the same sky conditions, respectively) during the same period. Also, the seasonal trends of both solar radiation components are examined. The global horizontal radiation shows positive trends in summer (+1.85%/decade and +2.10%/decade under all and clear skies, respectively), while a negative trend is calculated in the winter season (-2.46%/decade and -1.99%/decade for the same sky conditions, respectively). In the case of the diffuse solar radiation there are found negative trends in both seasons and both sky conditions. These findings confirm a recovery in the solar radiation levels over Athens in the recent 26 years.

show abstract

Section: /Decade)supporting

confidence: 92%

Annual and Seasonal Trends of Solar Radiation in Athens, Greece

Kambezidis¹

2018

J. Solar Eneg. Res. Updat.

View full text Add to dashboard Cite

show abstract

“…However, this type of measurement started to become available mainly only after the 1950s, with the establishment of numerous radiation sites during the International Geophysical Year (IGY) 1957(IGY) -1958 To overcome this scarcity of information on the evolution of AOD, especially before 1950, some researchers have used proxy approaches. Thus, some of them have used sunshine duration (SD) measurements to infer AOD under cloud-free conditions (Sanchez-Romero et al, 2016;Li et al, 2016;Dumitrescu et al, 2017), because SD measurements offer remarkably long time series going beyond 1950 and with a noticeable worldwide spatial coverage. SD for a given period, mostly a day, is defined as the sum of the subperiods for which broadband direct normal irradiance (DNI) exceeds the threshold value of 120 W m −2 (World Meteorological Organization, 2008).…”

Section: Introductionmentioning

confidence: 99%

A hybrid method for reconstructing the historical evolution of aerosol optical depth from sunshine duration measurements

et al. 2020

View full text Add to dashboard Cite

Abstract. A novel method has been developed to estimate aerosol optical depth (AOD) from sunshine duration (SD) measurements under cloud-free conditions. It is a physically based method serving for the reconstruction of the historical evolution of AOD during the last century. In addition to sunshine duration data, it requires daily water vapor and ozone products as inputs taken from the ECMWF 20th century reanalysis ERA-20C, available at the global scale over the period 1900–2010. Surface synoptic cloud observations are used to identify cloud-free days. For 16 sites over Europe, the accuracy of the estimated daily AOD, and its seasonal variability, is similar to or better than those from two earlier methods when compared to AErosol RObotic NETwork measurements. In addition, it also improves the detection of the signal from massive aerosol events such as important volcanic eruptions (e.g., Arenal and Fernandina Island in 1968, El Chichón in 1982 and Pinatubo in 1992). Finally, the reconstructed AOD time series are in good agreement with the dimming/brightening phenomenon and also provide preliminary evidence of the early-brightening phenomenon.

show abstract

“…На теренах Західної України виявлено, що мінливість інтенсивності приземної сонячної радіації залежить від повторюваності та інтенсивності баричних систем регіональної атмосферної циркуляції (циклонів та антициклонів) (Kholiavchuk 2022).Тривалість сонячного сяйва, яку визначають як час, протягом якого пряма сонячна радіація перевищує певний поріг (зазвичай на рівні 120 Вт м 2 ) обернено пов'язана з хмарністю. Вона також може бути цінною для виявлення довгострокових коливань вмісту аерозолів у приземній атмосфері(Dumitrescu et al 2017). Довгі ряди спостережень і більша об'єктивність, ніж хмарність чи видимість, визначають придатність використання тривалості сонячного сяйва для пояснення змін клімату, спричинених як природними (радіаційним і циркуляційним), так і антропогенними чинниками (забруднення повітря).…”

unclassified

Variability of Sunshine Duration in Western Ukraine

Kholiavchuk,

Marko

2023

Chern. Univ. Geo.

View full text Add to dashboard Cite

The duration of sunshine is a crucial radiation characteristic of climate, serving as an indicator for both regional atmospheric circulation and surface atmospheric pollution variability. Ground observations using a heliograph, spanning a long duration, enable the detection of changes in the impact of climate-forming factors on modern warming. Since the 1980s, more precise, high-resolution CMSAF satellite data has allowed for the determination of spatial variability in sunshine duration over recent decades. From 1371 to 1934 hours of sunshine per year were observed in Western Ukraine during 1961–1990, with the southwestern regions of the Transcarpathian lowland being the sunniest. Some years exceeded 2000 hours, indicative of a Mediterranean climate. Typical latitudinal changes were not found, but instead, a noticeable development of continentality, expressed in an increase in annual sunshine duration from west to east was found. Over the year in 1961–1990, significant differences in sunshine duration exist. Generally, the highest values occur in July, exceeding 250 hours in the southeast, southwest, and even in the northwest. The northwest and other western weather stations show high sunlight variability in June and July, linked to North Atlantic cyclones and increased cloudiness. The lowest seasonally determined total duration of sunshine during 1961–1990 occurred in December (<50 hours), with low values and a high number of days without sunshine (up to 20 days) typical for low-mountain valleys of the Carpathians and the northwest (27–38 hours). The most complex distribution is in autumn and spring, with a well-expressed latitudinal distribution from north to south: an increase in autumn and a decrease in spring due to transformation of seasonal circulation processes. In the last thirty years, changes in sunshine duration in Western Ukraine correspond to pan-European trends associated with global brightening. These changes are generally insignificant throughout the year, except for January and the western part of the region. In July, a slight statistically significant increase in the duration of sunshine was detected only in the west and in the foothills during 1961–2020. We associate these features with the higher frequency of anticyclonic types of weather and therefore with fewer cloudy days. These changes are noticeable in the Prut-Dniester highland and the eastern Podilska highland. The spatial distribution of sunlight duration indicates variability near the Carpathian Mountain system and above the highlands. The manifestation of the barrier function of mountains is manifested in an increase in values in winter due to altitudinal differentiation and a decrease in summer. Disctinctive changes east from the influence of the Carpathians are observed in the summer period. Similar peculiarities on a smaller scale were found over the Khotyn and Podilska highlands. The seasonal distribution of sunshine duration in Chernivtsi from 1991–2020 shows significant variability in spring and autumn. In the first decade of this period, low values corresponded to the low solar activity of the 22nd solar cycle. The last two decades, with significant fluctuations, especially in May, August, and September, and extremely high values in separate years, did not coincide with the least active recent solar cycles. Instead, they indicate the variability of circulation systems, especially in the west of the region. Identifying the impact of this factor, along with the growing atmospheric pollution in recent years, constitutes the perspective of our research. Keywords: sunshine duration, climate variability, regional atmospheric circulation, atmospheric pollution, satellite data.

show abstract

Reconstruction of historical aerosol optical depth time series over Romania during summertime

Cited by 8 publications

References 39 publications

Annual and Seasonal Trends of Solar Radiation in Athens, Greece

Annual and Seasonal Trends of Solar Radiation in Athens, Greece

A hybrid method for reconstructing the historical evolution of aerosol optical depth from sunshine duration measurements

Variability of Sunshine Duration in Western Ukraine

Contact Info

Product

Resources

About