scholarly journals First retrieval of global water vapour column amounts from SCIAMACHY measurements

2003 ◽  
Vol 3 (6) ◽  
pp. 5659-5688
Author(s):  
S. Noël ◽  
M. Buchwitz ◽  
J. P. Burrows
Keyword(s):  
Water Vapour ◽  
Absorption Spectroscopy ◽  
Near Infrared ◽  
Weighting Function ◽  
Global Scale ◽  
Visible Spectral Region ◽  
Mean Deviation ◽  
Differential Absorption ◽  
Scanning Imaging ◽  
Global Water

Abstract. Global water vapour column amounts have been derived for the first time from measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) on the European environmental satellite ENVISAT. For this purpose, two different existing retrieval algorithms have been adapted, namely the Air Mass Corrected Differential Absorption Spectroscopy (AMC-DOAS) which was originally designed for GOME and the Weighting Function Modified Differential Absorption Spectroscopy (WFM-DOAS) which was mainly designed for the retrieval of CH4, CO2 and CO from SCIAMACHY near-infrared spectra. Here, both methods have been applied to SCIAMACHY's nadir measurements in the near-visible spectral region around 700 nm. The results of these two methods agree within a scatter of ±0.5 g/cm2 with corresponding SSM/I and ECMWF water vapour data. This deviation includes contributions from the temporal and spatial variability of water vapour. In fact, the mean deviation between the SCIAMACHY and the correlative data sets is much smaller: the SCIAMACHY total water vapour columns are typically about 0.2 g/cm2 lower than the SSM/I values and less than 0.1 g/cm2 lower than corresponding ECMWF data. The SCIAMACHY water vapour results agree well with correlative data not only over ocean but also over land, thus showing the capability of SCIAMACHY to derive water vapour concentrations on the global scale.

scholarly journals First retrieval of global water vapour column amounts from SCIAMACHY measurements

2004 ◽  
Vol 4 (1) ◽  
pp. 111-125 ◽  
Author(s):  
S. Noël ◽  
M. Buchwitz ◽  
J. P. Burrows
Keyword(s):  
Water Vapour ◽  
Absorption Spectroscopy ◽  
Near Infrared ◽  
Weighting Function ◽  
Global Scale ◽  
Visible Spectral Region ◽  
Mean Deviation ◽  
Differential Absorption ◽  
Scanning Imaging ◽  
Global Water

Abstract. Global water vapour column amounts have been derived for the first time from measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) on the European environmental satellite ENVISAT. For this purpose, two different existing retrieval algorithms have been adapted, namely the Air Mass Corrected Differential Absorption Spectroscopy (AMC-DOAS) which was originally designed for GOME and the Weighting Function Modified Differential Absorption Spectroscopy (WFM-DOAS) which was mainly designed for the retrieval of CH4, CO2 and CO from SCIAMACHY near-infrared spectra. Here, both methods have been applied to SCIAMACHY's nadir measurements in the near-visible spectral region around 700 nm. Taking into account a systematic offset of 10%, the results of these two methods agree within a scatter of about ±0.5 g/cm2 with corresponding SSM/I and ECMWF water vapour data. This deviation includes contributions from the temporal and spatial variability of water vapour. In fact, the mean deviation between the SCIAMACHY and the correlative data sets is much smaller: the SCIAMACHY total water vapour columns are typically about 0.15 g/cm2 lower than the SSM/I values and less than 0.1 g/cm2 lower than corresponding ECMWF data. The SCIAMACHY water vapour results agree well with correlative data not only over ocean but also over land, thus showing the capability of SCIAMACHY to derive water vapour concentrations on the global scale.

scholarly journals A First Step towards Determining the Ionic Content in Water with an Integrated Optofluidic Chip Based on Near-Infrared Absorption Spectroscopy

Optics ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 175-190
Author(s):  
Gerwin W. Steen ◽  
Adam D. Wexler ◽  
Elmar C. Fuchs ◽  
Herman L. Offerhaus
Keyword(s):  
Absorption Spectroscopy ◽  
Near Infrared ◽  
Early Stage ◽  
Ion Concentration ◽  
Differential Absorption ◽  
Ionic Content ◽  
Stretch Vibration ◽  
Dissolved Ions ◽  
Optofluidic Chip

In this work, we present a feasibility study of integrated optofluidic chips to measure the ionic content in water using differential absorption spectroscopy. The second overtone of the OH-stretch vibration of water is used as indicator for both the type and concentration of the dissolved ions. The optofluidic chips are based on silicon nitride (TripleX) containing Mach–Zehnder interferometers (MZI) with two 5 cm sensing paths for the sample and reference arms, respectively. Simulations show that, theoretically, the determination of both the type and concentration of a mixture of four electrolytes is possible with the techniques presented. However, the performance of the chips deviated from the expected results due to the insufficient reproducibility and precision in the fabrication process. Therefore, at this early stage, the chips presented here could only determine the ion concentration, but not differentiate between the different ion types. Still, this work represents the first steps towards the realization of an online and real-time sensor of ionic content in water.

scholarly journals Validation of SCIAMACHY AMC-DOAS water vapour columns

2005 ◽  
Vol 5 (7) ◽  
pp. 1835-1841 ◽  
Author(s):  
S. Noël ◽  
M. Buchwitz ◽  
H. Bovensmann ◽  
J. P. Burrows
Keyword(s):  
Water Vapour ◽  
Visible Spectral Region ◽  
Optical Absorption Spectroscopy ◽  
Data Sets ◽  
Monthly Means ◽  
Data Set ◽  
Weather Forecasts ◽  
Microwave Imager ◽  
Scanning Imaging

Abstract. A first validation of water vapour total column amounts derived from measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) in the visible spectral region has been performed. For this purpose, SCIAMACHY water vapour data have been determined for the year 2003 using an extended version of the Differential Optical Absorption Spectroscopy (DOAS) method, called Air Mass Corrected (AMC-DOAS). The SCIAMACHY results are compared with corresponding water vapour measurements by the Special Sensor Microwave Imager (SSM/I) and with model data from the European Centre for Medium-Range Weather Forecasts (ECMWF). In confirmation of previous results it could be shown that SCIAMACHY derived water vapour columns are typically slightly lower than both SSM/I and ECMWF data, especially over ocean areas. However, these deviations are much smaller than the observed scatter of the data which is caused by the different temporal and spatial sampling and resolution of the data sets. For example, the overall difference with ECMWF data is only -0.05 g/cm2 whereas the typical scatter is in the order of 0.5 g/cm2. Both values show almost no variation over the year. In addition, first monthly means of SCIAMACHY water vapour data have been computed. The quality of these monthly means is currently limited by the availability of calibrated SCIAMACHY spectra. Nevertheless, first comparisons with ECMWF data show that SCIAMACHY (and similar instruments) are able to provide a new independent global water vapour data set.

scholarly journals Analysis of global water vapour trends from satellite measurements in the visible spectral range

2007 ◽  
Vol 7 (4) ◽  
pp. 11761-11796 ◽  
Author(s):  
S. Mieruch ◽  
S. Noël ◽  
H. Bovensmann ◽  
J. P. Burrows
Keyword(s):  
Time Series ◽  
Water Vapour ◽  
Statistical Significance ◽  
Visible Spectral Range ◽  
Optical Absorption Spectroscopy ◽  
Data Set ◽  
Factors Affecting ◽  
Scanning Imaging ◽  
Global Water

Abstract. Global water vapour total column amounts have been retrieved from spectral data provided by the Global Ozone Monitoring Experiment (GOME) flying on ERS-2, which was launched in April 1995, and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) onboard ENVISAT launched in March 2002. For this purpose the Air Mass Corrected Differential Optical Absorption Spectroscopy (AMC-DOAS) approach has been used. The combination of the data from both instruments provides us with a long-term global data set spanning more than 11 years with the potential of extension up to 2020 by GOME-2 data, on Metop. Using linear and non-linear methods from time series analysis and standard statistics the trends of H2O contents and their errors have been calculated. In this study, factors affecting the trend such as the length of the time series, the magnitude of the variability of the noise, and the autocorrelation of the noise are investigated. Special emphasis has been placed on the calculation of the statistical significance of the observed trends, which reveal significant local changes of water vapour columns distributed over the whole globe.

scholarly journals Validation of SCIAMACHY AMC-DOAS water vapour columns

2005 ◽  
Vol 5 (2) ◽  
pp. 1925-1942 ◽  
Author(s):  
S. Noël ◽  
M. Buchwitz ◽  
H. Bovensmann ◽  
J. P. Burrows
Keyword(s):  
Water Vapour ◽  
Visible Spectral Region ◽  
Optical Absorption Spectroscopy ◽  
Data Sets ◽  
Monthly Means ◽  
Data Set ◽  
Weather Forecasts ◽  
Microwave Imager ◽  
Scanning Imaging

Abstract. A first validation of water vapour total column amounts derived from measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) in the visible spectral region has been performed. For this purpose, SCIAMACHY water vapour data have been determined for the year 2003 using an extended version of the Differential Optical Absorption Spectroscopy (DOAS) method, called Air Mass Corrected (AMC-DOAS). The SCIAMACHY results are compared with corresponding water vapour measurements by the Special Sensor Microwave Imager (SSM/I) and with model data from the European Centre for Medium-Range Weather Forecasts (ECMWF). In confirmation of previous results it could be shown that SCIAMACHY derived water vapour columns are typically slightly lower than both SSM/I and ECMWF data, especially over ocean areas. However, these deviations are much smaller than the observed scatter of the data which is caused by the different temporal and spatial sampling and resolution of the data sets. For example, the overall difference with ECMWF data is only −0.05 g/cm2 whereas the typical scatter is in the order of 0.5 g/cm2. Both values show almost no variation over the year. In addition, first monthly means of SCIAMACHY water vapour data have been computed. The quality of these monthly means is currently limited by the availability of calibrated SCIAMACHY spectra. Nevertheless, first comparisons with ECMWF data show that SCIAMACHY (and similar instruments) are able to provide a new independent global water vapour data set.

scholarly journals Analysis of global water vapour trends from satellite measurements in the visible spectral range

2008 ◽  
Vol 8 (3) ◽  
pp. 491-504 ◽  
Author(s):  
S. Mieruch ◽  
S. Noël ◽  
H. Bovensmann ◽  
J. P. Burrows
Keyword(s):  
Time Series ◽  
Water Vapour ◽  
Statistical Significance ◽  
Central Africa ◽  
Visible Spectral Range ◽  
Optical Absorption Spectroscopy ◽  
Data Set ◽  
Factors Affecting ◽  
Scanning Imaging ◽  
Global Water

Abstract. Global water vapour total column amounts have been retrieved from spectral data provided by the Global Ozone Monitoring Experiment (GOME) flying on ERS-2, which was launched in April 1995, and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) onboard ENVISAT launched in March 2002. For this purpose the Air Mass Corrected Differential Optical Absorption Spectroscopy (AMC-DOAS) approach has been used. The combination of the data from both instruments provides us with a long-term global data set spanning more than 11 years with the potential of extension up to 2020 by GOME-2 data on MetOp. Using linear and non-linear methods from time series analysis and standard statistics the trends of H2O columns and their errors have been calculated. In this study, factors affecting the trend such as the length of the time series, the magnitude of the variability of the noise, and the autocorrelation of the noise are investigated. Special emphasis has been placed on the calculation of the statistical significance of the observed trends, which reveal significant local changes from −5% per year to +5% per year. These significant trends are distributed over the whole globe. Increasing trends have been calculated for Greenland, East Europe, Siberia and Oceania, whereas decreasing trends have been observed for the northwest USA, Central America, Amazonia, Central Africa and the Arabian Peninsular.

scholarly journals UTLS water vapour from SCIAMACHY limb measurements V3.01 (2002–2012)

2015 ◽  
Vol 8 (7) ◽  
pp. 7953-8021 ◽  
Author(s):  
K. Weigel ◽  
A. Rozanov ◽  
F. Azam ◽  
K. Bramstedt ◽  
R. Damadeo ◽  
...  
Keyword(s):  
Water Vapour ◽  
Radiative Forcing ◽  
Near Infrared ◽  
Temporal Stability ◽  
Data Sets ◽  
Infrared Spectral ◽  
Volcanic Aerosols ◽  
Scanning Imaging ◽  
Mean Differences

Abstract. The SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) aboard the Envisat satellite provided measurements from August 2002 until April 2012. SCIAMACHY measured the scattered or direct sunlight using different observation geometries. The limb viewing geometry allows the retrieval of water vapour at about 10 to 25 km height from the near infrared spectral range (1353–1410 nm). These data cover the Upper Troposphere and Lower Stratosphere (UTLS), a region in the atmosphere, which is of special interest for a variety of dynamical and chemical processes as well as for the radiative forcing. Here, the latest data version of water vapour (V3.01) from SCIAMACHY limb measurements is presented and validated by comparisons with data sets from other satellite and in situ measurements. Considering retrieval tests and the results of these comparisons, the V3.01 data is reliable from about 11 to 23 km and the best results are found in the middle of the profiles between about 14 and 20 km. Above 20 km in the extra tropics V3.01 is drier than all other data sets. Additionally, for altitudes above about 19 km the vertical resolution of the retrieved profile is not sufficient to resolve signals with a short vertical structure like the tape recorder. Below 14 km SCIAMACHY water vapour V3.01 is wetter than most collocated data sets, but the high variability of water vapour in the troposphere complicates the comparison. For 14 to 20 km height, the expected errors from the retrieval and simulations and the mean differences to collocated data sets are usually smaller than 10 % when the resolution of the SCIAMACHY data is taken into account. In general, the temporal changes agree well with collocated data sets except for the Northern Hemisphere extratropical stratosphere, where larger differences are observed. This indicates a possible drift in V3.01 most probably caused by the incomplete treatment of volcanic aerosols in the retrieval. In all other regions a good temporal stability is shown. In the tropical stratosphere an increase in water vapour is found between 2002 and 2012, which is in agreement with other satellite data sets for overlapping time periods.

scholarly journals UTLS water vapour from SCIAMACHY limb measurementsV3.01 (2002–2012)

2016 ◽  
Vol 9 (1) ◽  
pp. 133-158 ◽  
Author(s):  
K. Weigel ◽  
A. Rozanov ◽  
F. Azam ◽  
K. Bramstedt ◽  
R. Damadeo ◽  
...  
Keyword(s):  
Water Vapour ◽  
Radiative Forcing ◽  
Near Infrared ◽  
Temporal Stability ◽  
Data Sets ◽  
Infrared Spectral ◽  
Volcanic Aerosols ◽  
Scanning Imaging ◽  
Mean Differences

Abstract. The SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) aboard the Envisat satellite provided measurements from August 2002 until April 2012. SCIAMACHY measured the scattered or direct sunlight using different observation geometries. The limb viewing geometry allows the retrieval of water vapour at about 10–25 km height from the near-infrared spectral range (1353–1410 nm). These data cover the upper troposphere and lower stratosphere (UTLS), a region in the atmosphere which is of special interest for a variety of dynamical and chemical processes as well as for the radiative forcing. Here, the latest data version of water vapour (V3.01) from SCIAMACHY limb measurements is presented and validated by comparisons with data sets from other satellite and in situ measurements. Considering retrieval tests and the results of these comparisons, the V3.01 data are reliable from about 11 to 23 km and the best results are found in the middle of the profiles between about 14 and 20 km. Above 20 km in the extra tropics V3.01 is drier than all other data sets. Additionally, for altitudes above about 19 km, the vertical resolution of the retrieved profile is not sufficient to resolve signals with a short vertical structure like the tape recorder. Below 14 km, SCIAMACHY water vapour V3.01 is wetter than most collocated data sets, but the high variability of water vapour in the troposphere complicates the comparison. For 14–20 km height, the expected errors from the retrieval and simulations and the mean differences to collocated data sets are usually smaller than 10 % when the resolution of the SCIAMACHY data is taken into account. In general, the temporal changes agree well with collocated data sets except for the Northern Hemisphere extratropical stratosphere, where larger differences are observed. This indicates a possible drift in V3.01 most probably caused by the incomplete treatment of volcanic aerosols in the retrieval. In all other regions a good temporal stability is shown. In the tropical stratosphere an increase in water vapour is found between 2002 and 2012, which is in agreement with other satellite data sets for overlapping time periods.

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