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/

Enhancement events of solar radiation

Can be the solar radiation at surface recorded under cloudy conditions higher than its equivalent cloud-free value?. The answer is affirmative and the reason is a curious effect called enhancement which is related to broken clouds conditions. Even the extreme cases can origin values of solar radiation at surface higher than the corresponding values at the top of the atmosphere.

My colleague Ana A. Piedehierro has just published a really interesting paper in Atmospheric Research journal about this subject. This article shows a detailed analysis of the enhancement episodes recorded in Granada (Spain) during five years.  For all detected episodes (about 6% of all experimental data), the relative increases over the expected cloud-free values reached values up to 50%. The duration of the analyzed enhancement events exceeded one hour in some occasions which highlight the great interest of these episodes.

Please find the article at:

Piedehierro_Atmos_Res_2013

Workshop on Duststorms and Environmental Impact Assessments

The 7th International Workshop on Sand/Duststorms and Associated Dustfall will be held in Frascati, near Rome, from 2 to 4 December 2013.

The main scientific objectives of the conference are to obtain an update of current knowledge and research programs on dust and its impacts, to disseminate recent  results, to facilitate information exchange, especially with young scientists as  well as to identify current research priorities with a special focus on satellite  remote sensing.

The conference has no registration fee and the deadline for abstract submission is  15 September.

More information can be found at

http://dustworkshop2013.enea.it/

Ph.D. thesis about desert dust aerosols

My colleague Antonio Valenzuela from University of Granada has just presented his Ph.D. thesis entitle “African desert dust event impact over Southeastern Spain (2005-2010): aerosol radiative properties and forcing”.

This thesis focuses on the analysis of the optical and microphysical properties of the atmospheric aerosol during African dust outbreaks recorded at Granada. These properties were classified according to potential source sector and also applying a cluster analysis. Additionally, the influence of the studied desert dust event on shortwave radiative forcing at the surface and the top of the atmosphere were also evaluated using a radiative transfer code fed with experimental sun-photometer data.

Major advances presented in this work are related to the implementation and application of a new methodology for deriving atmospheric columnar optical and microphysical properties using sky radiance in principal plane configuration, and considering that the particles are not spherical

This Ph.D. dissertation can be downloaded at:

PhD_Antonio_Valenzuela.pdf 

Congratulations Dr. Valenzuela !!!.

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

Summer schools on aerosol science in 2013

Two interesting events related to the atmospheric aerosol science will carry out in 2013. In May, the “9th SummerSchool on Atmospheric Aerosol Physics, Measurement, and Sampling” will be held in Hyytiälä (Finland). This summer school is an advanced course to deepen the training aspects for diverse atmospheric aerosol measurements. The course is organized within the frame of the EU-project ACTRIS. Then, University of Vienna will organize the summer school "BasicAerosol Science" in July which offers a broad education in atmospheric aerosol science with lectures, assignments, discussions, and demonstration experiments. Both summer schools are mainly intended for Ph.D students and young scientists.

Some new questions about the ozone layer

A recent paper published in Green and Sustainable Chemistry by Dr. González-Velasco explains the depletion-recovery cycle of the ozone layer on the basis of the paramagnetic or diamagnetic of oxygen, ozone, nitrogen oxides and chlorine combinations. Thus, the effects of the Earth’s magnetic field on gaseous fluxes polar and equatorial-wards could give a novel explanation of the seasonal, latitude and altitude variations in the ozone concentration. Furthermore, changes in the magnetic field strength could also have an influence on the equilibriums of chemical or photochemical reactions participating in those mechanisms related to ozone layer.

The author states that in order to verify that such a magnetic effect is actually playing a role it could be interesting to try to correlate eventual changes in the magnetic field strength produced during the year at different latitudes with variations in the rates of the depletion-recovery cycle of the ozone.

Sky radiance from hemispherical sky images

A paper, recently published in AMT by Román et al., explains a novel method of deriving the sky radiance field from a CCD camera which has the capability to give sky conditions with both angular and time high resolution.

The absolute calibration of this instrument is based on the comparison against clear sky outputs of a radiative transfer model (libRadtran), which in turn is compared to measurements taken with a CIMEL sun-photometer (mean absolute differences between 2% and 15%). The calibration method proposed in this paper is simpler and cheaper than the methodologies found in literature which need laboratory calibration. Additionally, the authors analyze the sky radiances for three particular cases corresponding to cloud-free, overcast and partially cloudy skies.

A very interesting application of this calibration method could be the use of radiances for the retrieval of cloud properties at any angular direction such as, for example, the cloud optical depth which is one of the most poorly measured climate variables due to the difficulty for its remotely observing.

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

Striking case of the UV-A rays effects

UV-A solar radiation is scarcely attenuated by stratospheric ozone. Thus, the contribution of this spectral range to total UV radiation reaching at Earth’s surface is very high (about 90%). Although UV-A rays are less energetic, and so less dangerous than UV-B rays, the former can also induce detrimental effects on human health. For instance, a shocking case of “Unilateral dermatoheliosis” has been published in The New England Journal of Medicine. A 69-year-old man shows this syndrome which is associated with photo-damaged skin. He drove a delivery truck for 28 years and the left side of his face was particularly vulnerable to UV-A rays transmitted through window glass.

You can read the research note and see the striking photo at:

http://www.nejm.org/doi/full/10.1056/NEJMicm1104059

Initial Training for Atmospheric Remote Sensing

Initial Training for Atmospheric Remote Sensing (ITARS) is a research project in the framework of the interdisciplinary Marie-Curie Initial Training Networks. ITARS aims at improving our understanding of aerosols, clouds, and aerosol-cloud interaction processes and their role in both climate and weather.

ITRAS invites applications for 11 Early Stage Researcher (ESR, 3 year PhD) positions in 7 European countries. For this purpose, the PhD projects will focus on high-end ground-based remote-sensing instrumentation, synergistic observations and/or mathematical methods. For more information please click here.

Lectures on Atmospheric Mineral Dust

A training course focused on the mineral dust observation and modelling will take place the next November in Barcelona, Spain. The event will be held at the UPC Campus Nord with a total duration of 25 hours and will be coordinated by the WMO SDS-WAS Regional Center for Northern Africa, Middle East and Europe. Participants (operational meteorologists, PhD students and postdoctoral researchers) will attend a series of lectures and practical exercises. Registration will open April 16, 2012.

More information at:

http://sds-was.aemet.es/events/ii-lectures-on-atmospheric-mineral-dust

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.

Atmospheric Composition Portal

The Atmospheric Composition Portal (ACP) aims to provide a community-oriented framework that applies best practices in information science and technology to atmospheric composition science. This portal is being developed by the Atmospheric Composition Constellation (ACC) and the Workgroup for Information Systems and Services (WGISS) within the Committee on Earth Observation Satellites (CEOS).

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.

ACTRIS Project

ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network) is a European Project aiming at integrating European ground-based stations equipped with advanced atmospheric probing instrumentation for aerosols, clouds, and short-lived gas-phase species. This European ground-based network will contribute to:

- providing long-term observational data relevant to climate and air quality research produced with standardized or comparable procedures;

- supporting transnational access to large infrastructures strengthening collaboration in and outside the EU and access to high quality information and services to the user communities;

- developing new integration tools to fully exploit the use of atmospheric techniques at ground-based stations, in particular for the calibration/validation/integration of satellite sensors and for the improvement of global and regional-scale climate and air quality models.

New version of TOGOMI/TOSOMI retrieval algorithms

The two European satellite-borne atmospheric sensors Global Ozone Monitoring Experiment (GOME) and the SCanning Imaging Absorption spectrometer for Atmospheric CHartographY (SCIAMACHY) are currently operational and offer the potential for an assessment of the global total ozone distribution covering an expected time span of over 18 years.

The Royal Netherlands Meteorological Institute (KNMI) has developed two retrieval algorithms to derive the total ozone data from these two European satellite instruments. These two retrieval algorithms are the Total Ozone retrieval scheme for the GOME instrument based on the OMI DOAS algorithm (TOGOMI), and the corresponding application to the SCIAMACHY instrument (TOSOMI).

A new version (2.0) of these two retrieval algorithms has been prepared by KNMI staff, and the new total ozone data are distributed via internet from the Tropospheric Emission Monitoring Internet Service (TEMIS)

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.

Ozone_cci project

The Ozone_cci project is part of the ESA Climate Change Initiative (CCI) Programme. Ozone_cci will develop, produce and validate long-term series of high quality global observations of atmospheric ozone derived from multiple satellite instruments that are essential to assess the fate of atmospheric ozone.
The task of the ESA Ozone-cci project is to improve on the scientific and operational exploitation of current European and Third Party Mission ozone monitoring sensors, by creating merged multi-sensors Essential Climate Variable (ECV) ozone time series that match the requirements formulated by GCOS, and allow reducing current uncertainties on the determination of ozone trends.
The Ozone_cci project team consists of 13 European partner institutions which are experts in the area of satellite retrieval algorithms, geophysical validation, system engineering and chemistry-climate modelling.

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.

The empirically corrected TOMS data

In July 1996, the Total Ozone Mapping Spectrometer (TOMS) instrument was launched on the Earth Probe (EP) satellite. The total ozone column (TOC) observations derived from this satellite instrument began to display significant deviations from the ground truth by the middle of the year 2000. Haffner et al. (2004) indicated that the detected error in the instrument performance appears to depend on latitude, season, lifetime, and wavelength Thus, NASA GSFC warned users that EP-TOMS TOC data after the year 2000 are not recommended for the calculation of long-term ozone trends. To correct the influence of this instrument degradation, an empirical calibration technique was applied to the TOC data according to the personal comunication of McPeters et al. (2007). This empirically corrected TOMS data (EP-TOMS V8-corrected) has been made available since September 2007. The recent paper of Antón et al. (2010) presented the global comparisons between the TOC satellite observations derived from the V8-original and V8-corrected EP-TOMS data using reliable ground-based measurements as reference.This work showed that EP-TOMS V8-corrected total ozone data present a remarkable improvement concerning the significant negative bias of around ∼3% detected in the EP-TOMS V8-originnal observations after the year 2000.

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.

The First WMO Antarctic Ozone Bulletin of 2010

The WMO Antarctic Ozone Bulletin contains information on the state of the ozone layer in the Antarctic at roughly two week intervals from August to November. The bulletins are based on ground-based ozone data provided by WMO Members and satellites to observe ozone globally. The first bulletin in 2010 (7.2 MB) indicates "that the area where total ozone is less than 220 DU (“ozone hole area”) is low compared to recent years", adding that its evolution will depend on the meteorological conditions between now and early October, when depletion usually ends. Thus, "it is still too early to give a definitive statement about the development of this year's ozone hole and the degree of ozone loss that will occur", the bulletin stated.

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

Final Report COST 726

The final report of the the COST Action 726 “Long term changes and climatology of UV radiation over Europe” is available in its web page . The main objective of this action was to advance the understanding of UV radiation distribution under various meteorological conditions in order to determine a UV radiation climatology and assess UV changes over Europe.

The report has been written by leader authors, but it is a result of the collective efforts of the members of the four Working Groups, coming from 23 countries. CONGRATULATIONS!!!!!

The 25 anniversary of the discovery of the Antarctic ozone hole

To mark the 25 anniversary of the discovery of the Antarctic ozone hole, the prestigious journal Nature presents the original research paper reporting the high ozone decline over Antarctica in spring. In addition, a new Opinion piece from one of the paper's authors, plus a collection of related articles that have advanced our understanding of the stratosphere and the ozone layer.

Access selected content from the web focus free online:
the 25 anniversary of the discovery of the Antarctic ozone hole

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/