Royal Dutch Meteorological Institute; Ministery Of Infrastructure And The Environment

Climate Observations
News archive

2014-03-31: Ozone ProfilE Retrieval Algorithm (OPERA) for nadir-looking satellite instruments in the UV-VIS

For the retrieval of the vertical distribution of ozone in the atmosphere the Ozone ProfilE Retrieval Algorithm (OPERA) has been further developed. The new version (1.26) of OPERA is capable of retrieving ozone profiles from UV–VIS observations of most nadir-looking satellite instruments like GOME, SCIAMACHY, OMI and GOME-2.

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2014-02-25: Retrieving Hurricane Wind Speeds using Cross Polarization C-band measurements

Hurricane-force wind speeds can have a large societal impact and in the following paper microwave C-band cross-polarized (VH) signals are investigated to assess if they can be used to derive extreme wind speed conditions.

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2013-12-13: Regional nitrogen oxides emission trends in East Asia observed from space

Due to changing economic activity, emissions of air pollutants in East Asia are changing rapidly in space and time. Monthly emission estimates of nitrogen oxides (NOx) derived from satellite observations provide valuable insight into the evolution of human activity on a regional scale.

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2013-11-04: OMI - News: Antarctic Ozone Hole in 2013

According NASA's Ozone Hole Watch team and based upon a combination of ozone column data from OMI and from the Ozone Monitoring and Profiler Suite (OMPS) on the NASA-NOAA Suomi NPP satellite, the ozone hole over Antarctica was slightly smaller in 2013 than the average for recent decades. The combined set of satellite data showed an the average size of the hole in September-October 2013 of 21.0 million square kilometers. The average size since the mid 1990s is 22.5 million square kilometers.

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2013-10-29: Retrieval of aerosols using the oxygen A band in the presence of vegetation fluorescence

Within ESA's Sentinel-5 Precursor / TROPOMI project researchers at KNMI are currently developing a new operational aerosol product that is specifically dedicated to retrieval of the height of tropospheric aerosols. Aerosol height information will contribute to ash-forecasting systems for aviation safety and it will improve our understanding of aerosol interactions in climate research. The aerosol layer height product is based on the oxygen A band in the near-infrared wavelength range. In the same wavelength region vegetation exhibits fluorescence emissions as a byproduct of photosynthesis. Studies shows that aerosol retrieval may be inaccurate if fluorescene emissions are not taken into account. In a recently published article we have investigated how vegetation fluorescence should be treated in an O2 A band aerosol retrieval algorithm.

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2013-09-30: Inter-calibration of polar imager solar channels using SEVIRI

Accurate calibration of satellite imagers is a prerequisite for using their measurements in climate applications. We have developed a method for the inter-calibration of geostationary and polar-orbiting imager solar channels based on regressions of collocated near-nadir reflectances.

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2013-08-26: Satellites improve air quality monitoring in South Africa

Economic development often means an increase of harmful gases into the atmosphere. ESA’s GlobEmission project uses satellite data to monitor atmospheric pollution from emissions. ESA reported on the GlobEmission project, led by KNMI.

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2013-07-15: Tandem mode for two GOME-2's

Since 15 July 2013, the GOME-2 instruments on EUMETSAT's Metop-A and Metop-B satellites have a new measurement mode, called the tandem mode. In the tandem mode, the youngest instrument, GOME-2 on Metop-B, measures with a wide swath of 1920 km and pixels of 40×80 km2, while the oldest instrument, GOME-2 on Metop-A, measures with a reduced swath of 960 km and pixels of 40×40 km2.


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2013-06-28: Smoke from Colorado wildfires reaches Europe

On 25 June 2013, smoke from the large wildfires in Colorado (USA) reached Europe. This was seen in the GOME-2 and OMI aerosol images, processed at KNMI.


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2013-06-20: Eruptions from Popocatépetl observed from space

Located about 70 km southeast of Mexico City, Popocatépetl (pronounced poh-poh-kah-TEH-peh-til) is one of Mexico’s most active volcanoes. It reaches an altitude of 5,426 meters above sea level and is permanently covered with ice and snow. Historical records, including Aztec codices, record frequent eruptions from Popocatépetl. The volcano has become quite active during the last 20 years, with frequent venting from fumaroles punctuated by minor steam, gas, and ash emissions, and more or less permanent smoke plume hanging around the volcano.

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2013-05-27: TES tropospheric O3 validated with sonde data: spatial patterns and temporal stability in the bias

Satellite measurements provide a relatively new perspective on global tropospheric ozone (O3) distributions and their changes in time. The Tropospheric Emission Spectrometer, TES, is operational since mid 2004 and is a suitable sensor to investigate multi-annual changes in tropospheric O3 from space.

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2012-12-11: A new pole hole

In winter 2011, an ozone hole appeared over the Arctic for the first time.

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2012-10-05: Monitoring volcanic ash aerosol height from GOME-2 Oxygen A band measurements

Large volcanic ash plumes can have a serious impact on aviation. The height of the ash layer is an relevant parameter in the derivation of aerosol mass concentration which can be harmful for aircraft engines in case of high concentration. Recently Wang et al. (2012) demonstrate that it is possible to derive aerosol height from Oxygen A band measurement for absorbing aerosols such as volcanic ash plumes, biomass burning aerosols and desert dust aerosols.

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2012-09-05: Using daily satellite observations to estimate emissions of short-lived air pollutants

Emission inventories of air pollutants are crucial information for policy makers and form important input data for air quality models. Using satellite observations for emission estimates has important advantages over bottom-up emission inventories: they are spatially consistent, have high temporal resolution, and enable updates shortly after the satellite data become available. We present a new algorithm specifically designed to use daily satellite observations of column concentrations for fast updates of emission estimates of short-lived atmospheric constituents on a mesoscopic scale (about 25 x 25 km2) .

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2012-05-04: Retrieval of the aerosol direct radiative effect over clouds from space-borne spectrometry.

Aerosols play an important role in the Earth's radiation balance, by scattering and absorbing solar radiation. More importantly, aerosols can change cloud dynamics as cloud condensation nuclei and by absorbing solar radiation, thereby heating the atmosphere. This will influence the atmospheric column stability and cloud forming processes. In this paper the absorption of solar radiation by aerosols is quantified using satellite spectrometry, for aerosol layers that are present over clouds.

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2012-02-28: The Cabauw Intercomparison campaign for Nitrogen Dioxide Measuring Instruments (CINDI)

From June to July 2009 more than thirty different in-situ and remote sensing instruments from all over the world participated in the Cabauw Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI). The campaign took place at KNMI's Cabauw Experimental Site for Atmospheric Research (CESAR) in the Netherlands. Its main objectives were to determine the accuracy of state-of-the-art ground-based measurement techniques for the detection of atmospheric nitrogen dioxide (both in-situ and remote sensing), and to investigate their usability in satellite data validation.

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2012-02-20: Smoke cloud reveals process of nuclear winter

Soot in clouds of smoke can absorb much sunlight due to their ‘darkness’ and generate so much heat that smoke clouds can rise up to 20 km within a few days. Scientists from the Royal Netherlands Meteorological Institute have revealed the existence of this process by analyzing measurements of the large smoke cloud that emerged after the severe bush fires in Australia on 7 February 2009. This self-lifting effect of smoke clouds is comparable to the process in dust and smoke clouds that emerge after nuclear attacks and on which nuclear winter scenario’s are based.


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2012-02-01: In-flight degradation correction of SCIAMACHY UV reflectances and Absorbing Aerosol Index

L.G. Tilstra, M. de Graaf, I. Aben, and P. Stammes

In this paper we study the close relationship between the radiometric calibration of a satellite instrument and the Absorbing Aerosol Index (AAI) derived from the observed Earth reflectance.

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2011-12-15: Phd defense of Tim Vlemmix

On Thursday, December 15, Tim Vlemmix succesfully defended his PhD-thesis 'Tropospheric Nitrogen Dioxide Inversions based on Spectral Measurements of Scattered Sunlight' at the technical university of Eindhoven.

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2011-12-02: OMI instrument used in pollution reduction study

Scientists using the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite observed major reductions in sulfur dioxide (SO2) between 2005 and 2010 in Alabama, Georgia, Indiana, Kentucky, North Carolina, Ohio, Pennsylvania, and West Virginia. Led by Vitali Fioletov of Environment Canada, the research team found that sulfur dioxide levels near the region’s coal-fired power plants fell by nearly half since 2005.

Original Article on NASA's Earth Observatory

2011-09-20: Validation of Operational Ozone Profiles from the Ozone Monitoring Instrument

It is with pleasure that I announce the publication on September 20th, 2011 of our paper “Validation of operational ozone profiles from the Ozone Monitoring Instrument” in the Journal of Geophysical Research - Atmospheres. This paper describes the operational OMI ozone profile retrieval algorithm in ample detail, and presents the results of validation against a multitude of reference data sources, including cross-platform validation with EOS Aura instruments.

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2011-09-12: Climate science: Explaining Antarctic ozone hole anomalies

The strongly reduced Antarctic stratospheric ozone hole destruction in 2010 and several other recent years, results from the occurrence of dramatic meteorological events in the polar winter known as sudden stratospheric warmings (SSWs).
These findings are reported in a paper published in Scientific Reports, a new online and open access publication of the Nature Publishing Group.

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2011-08-31: Evaluation of model predicted top-of-atmosphere radiation and cloud parameters over Africa

In a paper recently published in the Journal of Climate, Wouter Greuell, Erik van Meijgaard, Jan Fokke Meirink present an evaluation of KNMI's regional climate model RACMO for Africa and the surrounding oceans. They compared model output for July 2006 with satellite data by simultaneously looking at cloud properties retrieved from SEVIRI data and at top-of-atmosphere fluxes measured by GERB.

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2011-08-17: Mapping pollutants from space

CNN made an item together with Paul Monks of the University of Leicester (UK) on mapping atmophseric pollutants and carbon from space. In this item OMI NO2 data are used as an example of what can be measured from space.

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2011-07-04: Last ozone data of GOME-1

After more than 16 years of service, the ERS-2 satellite was decommissioned (switched off) by ESA on 4 July 2011. This day marked the end of the very succesfull GOME instrument.

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2011-05-16: Surface solar irradiance from SCIAMACHY measurements

Wang, Stammes and Mueller have, for the first time, derived broadband surface solar irradiances (SSI) from SCIAMACHY satellite measurements. The SCIAMACHY SSI product is validated against globally distributed BSRN measurements and compared with ISCCP surface shortwave downwelling fluxes.

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2011-04-16: Radiative closure achieved for cloudy skies over Cabauw

A long standing problem in atmospheric research is the radiative closure of clouds. Radiative closure means that radiative transfer modelling of clouds agrees with the observations within the measurement uncertainty. This has now been achieved for shortwave radiation at Cabauw by Wang, Knap and Stammes.

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2011-04-11: EGU presentations

For a complete list of the Climate Observation departments presentations and posters at this years EGU conference, click on the link below.


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2011-03-01: The development of a nitrogen dioxide sonde

KNMI has developed a working NO2 sonde. The NO2 sonde can be applied in an operational network and also be used for satellite and AQ-model validation. The sonde is attached to a small meteorological balloon and measures a tropospheric NO2 profile. The NO2 sonde has a vertical resolution of 5m and a measurement range between 1 and 100 ppbv.

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2011-02-18: Satellite measurements provide information on the chemical composition of aerosols

A KNMI study uses satellite data from the Dutch Finnish OMI and the U.S. MODIS instruments to provide global information on the composition of anthropogenic (“man-made”) aerosols. Aerosols are important for climate forcing, but the magnitude of these effects is poorly quantified.

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2011-02-03: Evaluation of rainfall retrievals from SEVIRI reflectances over West Africa using TRMM-PR and CMORPH

Precipitation is a crucial factor in the hydrological cycle and needs to be measured at a high temporal and spatial resolution. Over several regions, such as the tropical areas and over the oceans, the amount of observations from rain gauges and rain radar is insufficient. Geostationary satellite instruments, like SEVIRI onboard the Meteosat Second Generation (MSG) satellites, are suitable to observe precipitation characteristics at various spatio-temporal scales.

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2011-02-02: OMI mentioned in NASA's Earth Observatory newsletter

This time there are two subjects in NASA's Earth Observatory newsletter in which OMI is involved:

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2010-12-03: Thirty year ozone record: the Multi Sensor Reanalysis (MSR)

A single coherent total ozone dataset, called the Multi Sensor Reanalysis (MSR), has been created from all available ozone column data measured by polar orbiting satellites in the near-ultraviolet Huggins band in the last thirty years.

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2010-12-02: Optimized fractional cloudiness determination from five ground-based remote sensing techniques

A 1 year record of fractional cloudiness at 10 min intervals was generated for the Cabauw Experimental Site for Atmospheric Research (CESAR) (51°58'N, 4°55'E) using an integrated assessment of five different observational methods. The five methods are based on active as well as passive systems and use either a hemispheric or column remote sensing technique.

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2010-12-01: Lifting potential of solar-heated aerosol layers

Absorption of shortwave solar radiation can potentially heat aerosol layers and create buoyancy that can result in the ascent of the aerosol layer over several kilometres altitude within 24–48 hours. Such heating is seasonally dependent with the summer pole region producing the largest lifting in solstice because aerosol layers are exposed to sunshine for close to 24 hours a day.

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2010-08-13: Ozone hole shift exposed South America to increased ultraviolet light

The ozone layer, which protects humans, plants, and animals from potentially damaging ultraviolet (UV) light from the Sun, develops a hole above Antarctica in September that typically lasts until early December. However, in November 2009, that hole shifted its position, leaving the southern tip of South America exposed to UV light at levels much greater than normal.

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2010-05-29: The impact of broken and inhomogeneous clouds on the retrieval of effective radius and cloud phase

In the retrieval of cloud properties from space, a generally applied assumption is that each pixel labeled as cloud-filled contains overcast clouds that are horizontally homogeneous. However, in nature a considerable amount of the clouds are broken and inhomogeneous. Wolters et al. (2010) investigated the effect of broken clouds and inhomogeneous overcast clouds on the cloud particle effective radius (re) and cloud-phase retrieval.

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2010-01-14: An aerosol boomerang observed from space.

In December 2006 southeastern Australia suffered from severe forest fires. Using the OMI instrument we observed how a smoke plume released by these fires on 14 December rapidly crossed the Pacific and reached southern America only five days later. After passing south America the plume continued its journey over the Atlantic and the Indian Ocean to return to home base on 25 December, making it the first-time observation of rapid around-the-world transport in the extra-tropical southern hemisphere.

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2009-07-06: Reductions of air pollution detected from space during the 2008 Beijing Olympic Games.

During the 2008 Olympic and Paralympic Games in Beijing (from 8 August to 17 September), local authorities enforced strong measures to reduce air pollution during the events. Inside and outside Beijing traffic was restricted, polluting industry was shut down temporarily and construction activities were put on hold.

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2009-05-14: Ozone hole tomography with GOME-2

The evolution and three dimensional structure of the Antarctic ozone hole can now be studied on a day-to-day basis using the latest data from the GOME-2 satellite instrument, as shown in a new study that just has been accepted for publication in Geophysical Research Letters.

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2009-04-20: Towards a standard procedure for validation of satellite-derived cloud properties.

Validation of satellite-derived cloud properties with ground-based data is necessary to ensure meaningful use of satellite cloud observations. Validation is difficult because differences between satellite and ground values are not only due to errors in the data, but also due to validation issues.

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2009-03-23: Collection 3: improved level-1b data for OMI retrievals.

OMI retrievals of trace gases, clouds and aerosols depend critically on the quality of the observed radiance and irradiance data. The Ozone Monitoring Instrument is equipped with a CCD-camera that allows simultaneous Earth-viewing under 60 individual angles. In the first years of operation, this novel technique appeared susceptible to calibration offsets that changed with viewing angle. In a recent paper, Dobber et al. [2008] have significantly improved the calibration of the OMI level-1b data.

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2008-12-18: FRESCO+: an improved O2-A band cloud retrieval algorithm for trace gas retrievals

More than 85% of the ground pixels of GOME(-2) and SCIAMACHY are influenced by clouds. Therefore, detection of clouds is essential in obtaining precise tropospheric pollution information from these satellite sensors.

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2008-11-14: Earth surface reflectance climatology from 3 years of OMI data

The reflectance of the Earth surface is a critical parameter for satellite retrievals of the atmospheric trace gases, clouds and aerosols. Also, it is often a critial parameter to describe the radiation balance in climate models. Kleipool et al. [2008] used three years of data from the Ozone Monitoring Instrument (OMI) to derive the surface reflectance of the globe on a 0.5 by 0.5 degree grid for every month of the year. The reflectance is given for 23 wavelengths between 328 and 500 nm. The data compares well with existing albedo climatologies derived from other satellite instruments (TOMS, GOME, MODIS), and significantly improves on these data sets by better spectral and/or spatial resolution.

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2008-10-01: Evaluation of satellite cloud phase retrieval methods from SEVIRI data

The thermodynamic phase of clouds plays an important role in the Earth's energy balance, as water clouds reflect incoming shortwave radiation back to space and ice clouds absorb and emit terrestrial radiation back to the surface. Geostationary satellite instruments, such as SEVIRI onboard METEOSAT-8 and -9, are capable of providing cloud phase information at both high temporal and spatial resolution. Wolters et al. [2008] evaluated three methods for cloud phase determination from SEVIRI data against collocated and synchronized cloud phase observations from lidar and cloud radar at Cabauw, The Netherlands.

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2008-09-03: DANDELIONS 2005 and 2006 Campaigns at Cabauw: Intercomparisons of NO2 measurements

The 2005 and 2006 DANDELIONS campaigns were unique because they brought together an unprecedented variety of measurement techniques to measure NO2, aerosols and ozone at Cabauw, The Netherlands. Also unique was that in 2006, the vertical dimension was used by placing instrumentation at ground level as well as in the 220 m. tower.

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2008-07-27: Daily Air Quality Forecast for China

The AMFIC project addresses atmospheric environmental monitoring over China. The aim is to develop an integrated information system for monitoring and forecasting tropospheric pollutants over China. The web site of the forecast service has been launched recently. Every day it publishes a 3-day forecast calculated by the chemical transport model Chimere, which has been implemented for a domain covering the densely populated eastern part of China.

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2008-07-01: Assuring quality for long-term ozone trend studies

The record of total ozone derived from the TOMS instrument series since November 1978 and continued by the Ozone Monitoring Instrument (OMI) since July 2004, is the longest to date and essential to study the recovery of the ozone layer. To verify the quality of the OMI-TOMS ozone data and its potential for trend analysis, Kroon et al. [2008] compare two ozone retrieval methods applied for the OMI instrument.

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2008-06-02: The eye of the beholder

The Ozone Monitoring Instrument (OMI) uses reflected sunlight to retrieve concentrations of trace gases in the atmosphere, like O3 and NO2. These retrieved trace gas amounts must be corrected for the presence of clouds in the atmosphere. Cloud heights are derived from OMI observations of scattered light in the UV-visible range. However, satellite imagers like MODIS use thermal infra-red radiation, emitted by the clouds themselves. The two observation methods give a different view of clouds: OMI sees the middle of the cloud, whereas MODIS sees the top of the cloud.

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2008-05-01: A ten year trend in NOx emissions measured from space

For the period 1996-2006 tropospheric nitrogen dioxide (NO2) measurements from GOME and SCIAMACHY have been analyzed to derive trends and seasonal variability for this period on a global scale. We see significant reductions (up to 7% per year) in NO2 in Europe and parts of the eastern United States, and a strong increase in Asia, most particularly in China (up to 29% per year) but also in Iran and Russia.

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Last updated by Jacob van Peet