UV Index and UV-B solar measurements at Valladolid University, Spain

Different meteorological and solar variables are being monitored and recorded in outdoor conditions by the Atmosphere and Energy Laboratory, through the research Project “Ultraviolet solar radiation, measurements, models and series reconstruction”, (CGL2011-25363), funded by the Spanish Ministry of Economy and Competitivity. The measurement station is located at the Science Faculty of Valladolid University, Spain, whose geographical coordinates are, (41º39’48” N; 4º42’20” W; and 705 m asl). The UV Index is evaluated every 5 -min from the erythemal UV-B irradiance and total ozone column measurements.

Values of air temperature, solar broadband global and ultraviolet -B horizontal irradiances, and UV-index are shown graphically online, in real time, at the following web page:

 http://www5.uva.es/laten

The European Brewer Network

The COST Action ES1207 coordinates Brewer spectrophotometer measurements of total ozone column, spectral UV irradiance and aerosol optical depth (AOD) in the UV range within Europe. The main objective of this initiative is to unite the ozone, UV and AOD European communities through a formally network (EUBREWNET) capable of delivering a consistent, spatially homogeneous European data resource.

A Brewer ozone spectrophotometer open congress will take place in Tenerife 24-28 of March 2014. This event is a joint collaboration of EUBREWNET and WMO-GAW Brewer Users Group and will focus on operational, scientific and technical issues of the Brewer instrument.

More information at:

http://www.eubrewnet.org/cost1207/

The UVNews 2013

UVNews #9 has appeared in January 2013. This new Issue contains progress reports of the European Metrology Research Program (EMRP) Project ENV03 “Traceability for surface spectral solar ultraviolet radiation.” In addition, other articles on interesting topics in UV measurements are also included. UVNews #10 will appear in July 2014.

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UVNews #9 can be downloaded in:

http://metrology.tkk.fi/uvnet/reports.htm

Correction models for diffuse solar irradiance from shadow rings

JGR-Atmospheres has highlighted a recent paper published in this journal about shadow-ring correction models for diffuse solar irradiance. The leader of this relevant paper is Guadalupe Sanchez from AIRE Research Team at University of Extremadura. Diffuse data measured by a shadow ring must be corrected for the portion of irradiance blocked by the ring. The authors found that the shadow ring itself blocks about 11% of the diffuse radiation reaching a sensor. They state the need to adjust empirical models to local conditions since local factors, such as aerosols and cloud cover, significantly affect estimates of diffuse radiation. Thus, the results of this study show that locally fitted empirical models perform better than globally valid theoretical models.

More information at:

Editors' Highlight

Increasing ultraviolet radiation levels

I have found a very interesting video surfing the net. It deals with the main factors that affect the UV radiation reaching the Earth’s surface. In five minutes, it explains clearly the role of atmospheric and astronomical factors on the variability of UV radiation levels at surface. This video could be very useful for academic purposes.

You can see the video “Increasing ultraviolet radiation levels” at:

http://www.clinuvel.com/en/news/webcasts/item/1307-increasing-ultraviolet-levels

Traceability for surface spectral solar ultraviolet radiation

"Traceability for surface spectral solar ultraviolet radiation" is a European Union funded project that will last until 2014.

The project aims to significantly enhance the reliability of spectral solar UV radiation measured at the Earth surface. New methods of observation (techniques and instruments) are developed to provide traceable for solar UV irradiance measurements with an uncertainty of less than 2%.

The project will include three workshops, and a large field intercomparison campaign near the end of the project which will be opened for external collaborators.

More information on the project activities can be found in the project web pages.

Atmospheric Science Events in 2012

During the next year 2012, there will take place several interesting conferences related to the Atmospheric Sciences:

- International Radiation Symposium, 6-10 August, Berlin, Germany

- Quadrennial Ozone Symposium, 27-31 August, Toronto, Canada

- European Aerosol Conference, 2-7 September, Granada, Spain

- Atmospheric Science Conference, 18-22 June, Bruges, Belgium

- EUMETSAT Meteorological Satellite Conference, 3-7 September, Sopot, Poland

- EGU General Assembly, 22-27 April, Vienna, Austria

- SPIE Remote Sensing, 24-27 September, Edinburgh, United Kingdom.

- IEEE Geoscience and Remote Sensing Symposium, 22-27 July, Munich, Germany

- International Conference on Clouds and Precipitation, July 30 - August 03, Leipzyg, Germany

- European Meeting on Atmospheric Studies by Optical Methods, 20-24 August, Sopot, Poland

- International Conference on Meteorology, Climatology and Atmospheric Physics, May 30 - 1 June, Athens, Grecee

Long‐term solar erythemal UV irradiance data reconstruction

A very interesting paper has been just published in JGR (doi:10.1029/2011JD015836). My colleagues from the University of Valladolid (Julia Bilbao, Roberto Román, Argimiro de Miguel and David Mateos) have proposed a semiempirical method to obtain a long-term reconstructed series of ultraviolet erythemal irradiance (UVER) in Spain. For that, total shortwave radiation and total ozone columns measurements from satellite have been used.

The reconstructed hourly UVER irradiance values are in good agreement with the measurements in the seven locations, showing low RMSE values in summer (from 5% to 9%). A reconstructed 10 min UVER data set from 1991 to 2010 has been derived from the proposed method. Statistically significant UVER trends appear in summer and autumn when UVER levels increased 3.5% and 4.1% per decade, respectively.

Effects of an asteroid strike into ocean on the ozone layer

A very interesting paper “Ozone perturbation from medium-size asteroid impacts in the ocean” by Pierazzo et al. has been published in Earth and Planetary Science Letters. These authors have shown by simulations that if an asteroid 500 m to 1 km in diameter were to hit the Pacific Ocean it would eject enough water vapor and sea salt into the atmosphere to affect the ozone layer.

The simulations showed that mid-latitude oceanic impacts of 1 km asteroids could produce a significant, global perturbation of upper atmospheric chemistry, including multi-year global ozone depletion comparable to ozone hole records registered in the mid-1990s. In addition, this ozone depletion would produce ultraviolet index (UVI) levels higher than 20 at the Earth’s surface during about two years in both the northern and southern hemispheres.

Ozone depletion and climate change: impacts on UV radiation

A really interesting paper has been recently published by McKenzie et al. in Photochem. Photobiol. Sci.. This article presents a well documented review of the relationship between ozone depletion and climate change and its influence on the UV radiation at Earth’s surface. The paper indicates that because of the success of the Montreal Protocol, increases in UV-B radiation during the last two decades have been small outside regions affected by the Antarctic ozone hole. In addition, other atmospheric factors (mainly clouds and aerosols) also play an outstanding role on the variability of UV radiation at surface. Thus, the influence of the ozone depletion (and its recovery) on the UV radiation has been difficult to detect at mid-latitudes. The authors state that “without the Montreal Protocol, peak values of sunburning UV radiation could have been tripled by 2065 at mid-northern latitudes.”.

Regarding the interactions between ozone and climate change, the paper analyses both the effects of the implementation of the Montreal Protocol on climate change, and the influence of the increasing greenhouse gases on ozone recovery.

Sixth Regional Brewer Calibration Center for Europe intercomparison

The 6th Regional Brewer Calibration Center for Europe (RBCC-E) intercomparison will be held at El Arenosillo Atmospheric Sounding Station of the "Instituto de Técnica Aeroespacial" (INTA) during the period July 5 to 15 2011. This will be a join execercise of the Dobson and Brewer calibration centers for Europe. The QASUME unit of the Physikalisch-Meteorologisches Observatorium Davos / World Radiation Center (PMOD /WRC) will participate and provide a global UV reference spectrum for the ultraviolet measurements.
The campaign is scheduled in three main phases:
* Initial calibration to assess the current calibration of the instruments.
* Servicing, adjustments and maintenance works characterization test of the instruments.
* Final calibration. In this phase the ‘UV’ calibrations against the QASUME
Specific measurements for Brewer/Dobson comparison

Detailed information is available at the RBCC-E web page.

Scientific Assessment of Ozone Depletion 2010

The WMO/UNEP “Scientific Assessment of Ozone Depletion: 2010” will be ready in early 2011, but the executive summary of this report is already available. It provides new information about the relationship between the ozone layer and climate change, and highlights the successful implementation of the Montreal Protocol and its amendments.
The summary states that over the past decade, global ozone is no longer decreasing but is not yet increasing. Using numerical models of the Earth’s atmosphere, the report predicts that the stratospheric ozone layer will fully recover within the next 50 years.
Regarding the influence of ozone changes on ultraviolet radiation, the executive summary says that large UV levels in Antarctica continue to be seen when the springtime ozone hole is large. For instance, the Antarctic spring erythemal irradiance is approximately twice that measured in the Arctic for the same season. In addition, it is reaffirmed that at mid-latitudes, surface UV radiation has been about constant over the last decade, consistent with total ozone column observations over this period.

Solar minimum 2008-2009

The descending phase of solar cycle 23 was long and gradual, and during 2008–2009, solar activity became extremely low. In late 2009, solar activity finally started to increase, but the period between mid-2007 and mid-2009 was one of the longest of recent solar minima. Recently, several interesting papers have been published about this subject. The work of Fröhlich (2010) has shown that the value of total solar irradiance during the solar minimum of 2008-2009 was more than 0.2 Wm−2 smaller than during the last minimum in 1996. Solomon et al. (2010) have indicated that that solar extreme ultraviolet irradiance levels during the solar minimum of 2008-2009 were also lower than they were during the previous solar minimum. Haigh et al. (2010) have shown that these spectral changes appear to have led to a significant decline from 2004 to 2007 in stratospheric ozone below an altitude of 45 km. Garcia (2010) states that these implications for Earth’s atmosphere must be viewed as provisional.

New UV forecasting website

The new UV forecasting website - http://uvawareness.com/ - is a very useful tool. It provides a four day hourly UV forecast from 6 a.m. to 6 p.m. for just about any location world wide.
This UV forecast data is harnessed from NOAA UV Index forecasting which uses the TUV radiative transfer code for deriving the erythemally weighted downwelling UV fluxes. This NOAA UV Index is computed using forecasted ozone data, and cloud amounts. In addition, climatological aerosol loading, variable snow and constant bare earth albedo, and elevation are used in the model.

Influence of ozone mini-holes on UV radiation

The International Journal of Climatology has recently published two papers about the ozone mini-holes effects over the UV radiation. Sola and Lorente study the impact of two mini-holes on erythemal UV irradiance over Barcelona (Spain). They find that this irradiance at noon was 36% higher on 10 January 2004 than the day before. This date corresponds with the minimum total ozone value recorded over the Iberian Peninsula. On the other hand, Martinez-Lozano et al. analyzed the low ozone level episodes over Valencia (Spain) during 2000-2007. The increase of UV radiation related to the decrease in total ozone is quantified at 1.29 times this decrease

UV radiation, Ozone and Aerosols over the Iberian Peninsula

The JGR has recently published three papers about these topics. Bilbao and de Miguel (2010) studied an empirical relationship between the solar ultraviolet-B (UV-B) in the range (280–315 nm) and the total global solar irradiation (G) in Valladolid (Spain). The results showed that G is an appropriate variable to obtain UV-B daily values in places where UV radiation is not measured or to extend the existing data set back in time. Mladenove et al. (2010) analyzed the relationships between spectroscopic (fluorescence and absorbance) properties of the water-soluble organic compounds in aerosol deposition and ground-based remote sensing measurements of aerosols in the atmospheric column in Granada (Spain). They found important differences between Saharan- and marine-dominated organic aerosols. Antón et al (2010) compared the total ozone retrieved with the passive DOAS methodology from zenith-sky observations by the SPATRAM spectrometer located in Evora (Portugal) with highly accurate total ozone data retrieved from direct-sun recordings by a well-calibrated Brewer instrument in El Arenosillo (Spain). The results showed that the differences observed between both systems is not associated with the natural spatial variability of the total ozone.

e-Atlas of erythemally UV Climatology over Europe

The COST ACTION 726 - Long term changes and climatology of Ultraviolet radiation over Europe - has just presented the "Electronic Atlas" of UV Climatology over Europe. This atlas enables you to extract reconstructed erythemally weighted daily dose values for a certain location and a certain period. Data are available from 1.1.1958 to 31.8.2002 for longitudes from 25°E to 35°W and latitudes from 30°N to 80°N. These data are mean values over an area of 1°x 1°. It is possible to extract daily values, monthly sums and to calculate a simple annual statistics.

The atlas is free for non-comercial use, and it can be downloaded in the following web:

http://www.cost726.org/

Interesting events in 2010

During the year 2010, there will take place several interesting events related to the Atmospheric Sciences:

- EGU (European Geosciences Union, General Assembly 2010), 2-7 May, Vienna, Austria.

- 37th Annual European Meeting on Atmospheric Studies by Optical Methods , 23-27 August, Valladolid, Spain.

- IAC (International Aerosol Conference) , 29 August- 3 September, Helsinki, Finland.

- SPIE Remote Sensing, 20-23 September, Toulouse, France.

- EUMETSAT Meteorological Satellite Conference, 20-24 September, Cordoba, Spain.

Report of the “El Arenosillo”/INTA-COST Calibration Campaign of UVER Radiometers

The El Arenosillo/INTA calibration and intercomparison campaign of UVER Broadband radiometers held in the observatory “El Arenosillo” (Spain) from 15 August to 21 September 2007. This event was part of the COST Action 726 Working Group 4 activities. The main procedures and results of this campaign have been published in the following report:

COST Action 726 - Report of the “El Arenosillo”/INTA-COST Calibration and Intercomparison Campaign of UVER Broadband Radiometers
ISBN: 978-84-692-2640-7

View/Download this Publication (pdf, 4 MB)

Interesting events in September 2009

In the next month of September, two important events will take place in Spain:

- The FOURTH INTERCOMPARISON CAMPAIGN OF THE REGIONAL BREWER CALIBRATION CENTER-EUROPE (RBCC-E) in a joint intercomparison campaign with the Regional Dobson Calibration Center-Europe (RDCC-E) will be held at the El Arenosillo Atmospheric Sounding Station - INTA (Huelva) during the period September 7th-17th, 2009

- The ATMOSPHERIC SCIENCE CONFERENCE, organised by the European Space Agency in Barcelona, 7-11 September 2009.