scholarly journals Validation of INSAT-3D sounder data with in situ measurements and other similar satellite observations over India

2016 ◽  
Vol 9 (12) ◽  
pp. 5735-5745 ◽  
Author(s):  
Madineni Venkat Ratnam ◽  
Alladi Hemanth Kumar ◽  
Achuthan Jayaraman
Keyword(s):  
Water Vapour ◽  
Lower Troposphere ◽  
India Meteorological Department ◽  
Satellite System ◽  
Reanalysis Data ◽  
In Situ Measurements ◽  
Data Sets ◽  
Positive Bias ◽  
3D Data

Abstract. To date, several satellites measurements are available which can provide profiles of temperature and water vapour with reasonable accuracies. However, the temporal resolution has remained poor, particularly over the tropics, as most of them are polar orbiting. At this juncture, the launch of INSAT-3D (Indian National Satellite System) by the Indian Space Research Organization (ISRO) on 26 July 2013 carrying a multi-spectral imager covering visible to long-wave infrared made it possible to obtain profiles of temperature and water vapour over India with higher temporal and vertical resolutions and altitude coverage, besides other parameters. The initial validation of INSAT-3D data is made with the high temporal (3 h) resolution radiosonde observations launched over Gadanki (13.5° N, 79.2° E) during a special campaign and routine evening soundings obtained at 12:00 UTC (17:30 LT). We also compared INSAT-3D data with the radiosonde observations obtained from 34 India Meteorological Department stations. Comparisons were also made over India with data from other satellites like AIRS, MLS and SAPHIR and from ERA-Interim and NCEP reanalysis data sets. INSAT-3D is able to show better coverage over India with high spatial and temporal resolutions as expected. Good correlation in temperature between INSAT-3D and in situ measurements is noticed except in the upper tropospheric and lower stratospheric regions (positive bias of 2–3 K). There is a mean dry bias of 20–30 % in the water vapour mixing ratio. Similar biases are noticed when compared to other satellites and reanalysis data sets. INSAT-3D shows a large positive bias in temperature above 25° N in the lower troposphere. Thus, caution is advised when using these data for tropospheric studies. Finally it is concluded that temperature data from INSAT-3D are of high quality and can be directly assimilated for better forecasts over India.

scholarly journals Validation of INSAT-3D sounder data with in-situ measurements and other similar satellite observations over Indian region

2016 ◽  
Author(s):  
M. Venkat Ratnam ◽  
A. Hemanth Kumar ◽  
A. Jayaraman
Keyword(s):  
Water Vapor ◽  
Lower Troposphere ◽  
India Meteorological Department ◽  
Analysis Data ◽  
Infrared Region ◽  
In Situ Measurements ◽  
Indian Region ◽  
Positive Bias ◽  
3D Data

Abstract. To date, several satellites measurements are available which can provide profiles of temperature and water vapor with reasonable accuracies. However, temporal resolution remained poor, particularly over topics, as most of them are polar orbiting. At this juncture, launch of INSAT-3D (Indian National Satellite) by the Indian Space Research Organization (ISRO) on 26 July 2013 carrying multi-spectral imager covering visible to long wave infrared region made it possible to obtain profiles of temperature and water vapor over Indian region with higher temporal and vertical resolutions and altitude coverage besides the other parameters. The initial validation of INSAT-3D data is made with the high temporal (3 h) resolution radiosonde observations launched over Gadanki (13.5° N, 79.2° E) during a special campaign and routine evening soundings obtained at 12 UTC. We also compared INSAT-3D data with the radiosonde observations obtained from 34 India Meteorological Department stations. Comparisons were also made over Indian region with data from other satellites like AIRS, MLS and SAPHIR and ERA-Interim and NCEP re-analysis datasets. INSAT-3D is able to show a better coverage over Indian region with high spatial and temporal resolutions as expected. Good correlation in temperature between INSAT-3D and in-situ measurements is noticed except in the upper troposphere and lower stratospheric region (positive bias of 2–3 K). There exists mean dry bias of 10–25 % in relative humidity. Similar biases are also noticed when compared to other satellites and re-analysis data sets. INSAT-3D shows large positive bias in temperature above 25° N in the lower troposphere. Thus, caution is advised in using this data at those places for tropospheric studies. Finally it is concluded that temperature data from INSAT-3D is of high quality that can be directly assimilated for better forecast over Indian region.

scholarly journals Comparison of IAGOS in-situ water vapour measurements and ECMWF ERA-Interim Reanalysis data

2019 ◽  
Author(s):  
Philipp Reutter ◽  
Patrick Neis ◽  
Susanne Rohs ◽  
Bastien Sauvage
Keyword(s):  
Water Vapour ◽  
Spatial Resolution ◽  
Three Dimensional ◽  
Reanalysis Data ◽  
Cirrus Clouds ◽  
Data Sets ◽  
The North ◽  
Tropopause Region ◽  
Good Agreement

Abstract. Cirrus clouds and their potential formation regions, so-called ice-supersaturated regions (ISSRs) occur frequently in the tropopause region. It is assumed that ISSRs and cirrus clouds can change the tropopause structure by diabatic processes, driven by latent heating due to phase transition and interaction with radiation. For many research questions a three-dimensional picture including a sufficient temporal resolution of the water vapour fields in the tropopause region is required. This requirement is fulfilled nowadays by reanalysis products such as the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim reanalysis. However, for a meaningful investigation of water vapour in the tropopause region a comparison of the reanalysis data with measurement is advisable, since it is difficult to measure water vapour and to assimilate meaningful measurements into reanalysis products. Here, we present an intercomparison of high-resolution in-situ measurements aboard passenger aircraft within the European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System; http://www.iagos.org) with ERA-Interim. Temperature and humidity data over the North Atlantic from 2000 to 2010 are compared relative to the dynamical tropopause. The comparison of the temperature shows a good agreement between measurement and ERA-Interim. While ERA-Interim can reproduce the main features of the water vapour measurements of IAGOS, the variability of the data is underestimated by the reanalysis data. The combination of temperature and water vapour leads to the relative humidity with respect to ice (RHi). Here ERA-Interim deviates from the measurements concerning values of larger than RHi=100 %, both in number and strength of supersaturation. The comparison of ISSR pathlengths shows distinct differences, which can be traced back to the spatial resolution of both data sets. IAGOS shows significantly more smaller ISSRs compared to ERA-Interim. A good agreement begins only at pathlengths in the order of the ERA-Interim spatial resolution and larger.

scholarly journals Empirical validation and proof of added value of MUSICA's tropospheric δD remote sensing products

2015 ◽  
Vol 8 (1) ◽  
pp. 483-503 ◽  
Author(s):  
M. Schneider ◽  
Y. González ◽  
C. Dyroff ◽  
E. Christner ◽  
A. Wiegele ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Water Vapour ◽  
Moisture Transport ◽  
Lower Troposphere ◽  
Remote Sensing Data ◽  
Added Value ◽  
Data Sets ◽  
Empirical Validation ◽  
Sensing Data

Abstract. The project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) integrates tropospheric water vapour isotopologue remote sensing and in situ observations. This paper presents a first empirical validation of MUSICA's H2O and δD remote sensing products, generated from ground-based FTIR (Fourier transform infrared), spectrometer and space-based IASI (infrared atmospheric sounding interferometer) observation. The study is made in the area of the Canary Islands in the subtropical northern Atlantic. As reference we use well calibrated in situ measurements made aboard an aircraft (between 200 and 6800 m a.s.l.) by the dedicated ISOWAT instrument and on the island of Tenerife at two different altitudes (at Izaña, 2370 m a.s.l., and at Teide, 3550 m a.s.l.) by two commercial Picarro L2120-i water isotopologue analysers. The comparison to the ISOWAT profile measurements shows that the remote sensors can well capture the variations in the water vapour isotopologues, and the scatter with respect to the in situ references suggests a δD random uncertainty for the FTIR product of much better than 45‰ in the lower troposphere and of about 15‰ for the middle troposphere. For the middle tropospheric IASI δD product the study suggests a respective uncertainty of about 15‰. In both remote sensing data sets we find a positive δD bias of 30–70‰. Complementing H2O observations with δD data allows moisture transport studies that are not possible with H2O observations alone. We are able to qualitatively demonstrate the added value of the MUSICA δD remote sensing data. We document that the δD–H2O curves obtained from the different in situ and remote sensing data sets (ISOWAT, Picarro at Izaña and Teide, FTIR, and IASI) consistently identify two different moisture transport pathways to the subtropical north eastern Atlantic free troposphere.

scholarly journals Ice supersaturated regions: properties and validation of ERA-Interim reanalysis with IAGOS in situ water vapour measurements

2020 ◽  
Vol 20 (2) ◽  
pp. 787-804 ◽  
Author(s):  
Philipp Reutter ◽  
Patrick Neis ◽  
Susanne Rohs ◽  
Bastien Sauvage
Keyword(s):  
Relative Humidity ◽  
Water Vapour ◽  
Spatial Resolution ◽  
Reanalysis Data ◽  
Cirrus Clouds ◽  
Data Sets ◽  
Data Set ◽  
Tropopause Region ◽  
Good Agreement

Abstract. Cirrus clouds and their potential formation regions, so-called ice supersaturated regions (ISSRs), with values of relative humidity with respect to ice exceeding 100 %, occur frequently in the tropopause region. It is assumed that ISSRs and cirrus clouds can change the tropopause structure by diabatic processes, driven by latent heating due to phase transition and interaction with radiation. For many research questions, a three-dimensional picture including a sufficient temporal resolution of the water vapour fields in the tropopause region is required. This requirement is fulfilled nowadays by reanalysis products such as the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim reanalysis. However, for a meaningful investigation of water vapour in the tropopause region, a comparison of the reanalysis data with measurement is advisable, since it is difficult to measure water vapour and to assimilate meaningful measurements into reanalysis products. Here, we present an intercomparison of high-resolution in situ measurements aboard passenger aircraft within the European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System; http://www.iagos.org, last access: 15 January 2020) with ERA-Interim. Temperature and humidity data over the North Atlantic from 2000 to 2009 are compared relative to the dynamical tropopause. The comparison of the temperature shows good agreement between the measurement and ERA-Interim. While ERA-Interim also shows the main features of the water vapour measurements of IAGOS, the variability of the data is clearly smaller in the reanalysis data set. The combination of temperature and water vapour leads to the relative humidity with respect to ice (RHi). Here, ERA-Interim deviates from the measurements concerning values larger than RHi=100 %, both in number and strength of supersaturation. Also, pathlengths of ISSRs along flight tracks are investigated, representing macrophysical properties as linked to atmospheric flows. The comparison of ISSR pathlengths shows distinct differences, which can be traced back to the spatial resolution of both data sets. Also, the seasonal cycle and height dependence of pathlengths changes for the different data sets due to their spatial resolution. IAGOS shows a significantly greater amount of smaller ISSRs compared to ERA-Interim. Good agreement begins only at pathlengths on the order of the ERA-Interim spatial resolution and larger.

Particulate matter variability in Kathmandu based on in-situ measurements, remote sensing, and reanalysis data

2021 ◽  
pp. 105623
Author(s):  
Stefan Becker ◽  
Ramesh Prasad Sapkota ◽  
Binod Pokharel ◽  
Loknath Adhikari ◽  
Rudra Prasad Pokhrel ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Particulate Matter ◽  
Reanalysis Data ◽  
In Situ Measurements

scholarly journals The chemical connection between 67P/C-G and IRAS 16293-2422

2017 ◽  
Vol 13 (S332) ◽  
pp. 196-201
Author(s):  
Maria Nikolayevna Drozdovskaya ◽  
Ewine F. van Dishoeck ◽  
Martin Rubin ◽  
Jes Kristian Jørgensen ◽  
Kathrin Altwegg
Keyword(s):  
Chemical Composition ◽  
Solar System ◽  
Chemical Evolution ◽  
Protoplanetary Disks ◽  
In Situ Measurements ◽  
Isotopic Ratios ◽  
Data Sets ◽  
Low Mass ◽  
Comet 67P

AbstractThe chemical evolution of a star- and planet-forming system begins in the prestellar phase and proceeds across the subsequent evolutionary phases. The chemical trail from cores to protoplanetary disks to planetary embryos can be studied by comparing distant young protostars and comets in our Solar System. One particularly chemically rich system that is thought to be analogous to our own is the low-mass IRAS 16293-2422. ALMA-PILS observations have made the study of chemistry on the disk scales (<100 AU) of this system possible. Under the assumption that comets are pristine tracers of the outer parts of the innate protosolar disk, it is possible to compare the composition of our infant Solar System to that of IRAS 16293-2422. The Rosetta mission has yielded a wealth of unique in situ measurements on comet 67P/C-G, making it the best probe to date. Herein, the initial comparisons in terms of the chemical composition and isotopic ratios are summarized. Much work is still to be carried out in the future as the analysis of both of these data sets is still ongoing.

scholarly journals Comparison of GNSS and INSAT-3D sounder retrieved precipitable water vapour and validation with the GPS Sonde data over Indian Subcontinent

MAUSAM ◽  
2021 ◽  
Vol 71 (1) ◽  
pp. 1-10
Author(s):  
YADAV RAMASHRAY ◽  
PUVIARASAN N ◽  
GIRI R K ◽  
TOMAR C S ◽  
SINGH VIRENDRA
Keyword(s):  
Water Vapour ◽  
Indian Subcontinent ◽  
India Meteorological Department ◽  
Precipitable Water ◽  
Satellite System ◽  
Atmospheric Water ◽  
Precipitable Water Vapour ◽  
Vertical Column ◽  
Atmospheric Water Vapour ◽  
Channel Sounder

Precipitable water vapour (PWV) plays a key role in the atmospheric processes from climate change to micrometeorology. Its distribution and quantity are critical for the description of state and evaluation of the atmosphere in NWP model. Lack of precise and continuous water vapour data is one of the major error sources in short term forecast of precipitation. The task of accurately measuring atmospheric water vapour is challenging. Conventional in situ measurements of atmospheric water vapour is provided by GPS Sonde humidity sensors profile twice a day at 0000 and 1200 UTC mainly from limited land regions. In recent years India Meteorological Department (IMD) is computing PWV from 19 channel sounder of INSAT-3D in three layers 1000-900 hPa, 900-700 hPa and 700-300 hPa and total PWV in the vertical column of atmosphere stretching from surface to about 100 hPa under cloud free condition. These data most commonly were validated using spatially and temporally collocated GPS Sonde measurements. In this paper, INSAT-3D satellite retrieved PWV data are validated with column integrated PWV estimates from a network of ground based Global Navigation Satellite System (GNSS) over Indian subcontinent. The PWV retrieved by INSAT-3D sounder platform is very promising, being in a good agreement with the GNSS data recorded over India for the period June, 2017 to May, 2018. The root-mean-square (rms) differences of 5.4 to 7.1 mm, bias of -4.7 to +2.1 mm and correlations coefficient of 0.79 to 0.92 was observed between INSAT-3D and GNSS PWV. The correlations coefficient between GPS Sonde and GNSS derived PWV ranges from 0.85 to 0.98.

scholarly journals Deep learning for Chinese NOx emission inversion and the integration of in situ observations: a case study on the COVID-19 pandemic

2021 ◽  
Author(s):  
Tai-Long He ◽  
Dylan Jones ◽  
Kazuyuki Miyazaki ◽  
Kevin Bowman ◽  
Zhe Jiang ◽  
...  
Keyword(s):  
Deep Learning ◽  
Reanalysis Data ◽  
Data Sets ◽  
Computationally Efficient ◽  
Transport Models ◽  
The Neural Network ◽  
In Situ Observations ◽  
Typical Variation

&lt;p&gt;The COVID-19 pandemic led to the lockdown of over one-third of Chinese cities in early 2020. Observations have shown significant reductions of atmospheric abundances of NO&lt;sub&gt;2&lt;/sub&gt; over China during this period. This change in atmospheric NO&lt;sub&gt;2&lt;/sub&gt; implies a dramatic change in emission of NO&lt;sub&gt;x&lt;/sub&gt;, which provides a unique opportunity to study the response of the chemistry of the atmospheric to large reductions in anthropogenic emissions. We use a deep learning (DL) model to quantify the change in surface emissions of NO&lt;sub&gt;x&lt;/sub&gt; in China that are associated with the observed changes in atmospheric NO&lt;sub&gt;2&lt;/sub&gt; during the lockdown period. Compared to conventional data assimilation systems, deep neural networks are free of the potential errors associated with parameterized subgrid-scale processes. Furthermore, they are not susceptible to the chemical errors typically found in atmospheric chemical transport models. The neural-network-based approach also offers a more computationally efficient means of inverse modeling of NO&lt;sub&gt;x&lt;/sub&gt; emissions at high spatial resolutions. Our DL model is trained using meteorological predictors and reanalysis data of surface NO&lt;sub&gt;2&lt;/sub&gt; from 2005 to 2017. The evaluation is conducted using in-situ measurements of NO&lt;sub&gt;2&lt;/sub&gt; in 2019 and 2020. The Baidu 'Qianxi' migration data sets are used to evaluate the model's performance in capturing the typical variation in Chinese NOx emissions during the Chinese New Year holidays. The TROPOMI-derived TCR-2 chemical reanalysis is used to evaluate the DL analysis in 2020. We show that the DL-based approach is able to better reproduce the variation in anthropogenic NO&lt;sub&gt;x&lt;/sub&gt; emissions and capture the reduction in Chinese NO&lt;sub&gt;x&lt;/sub&gt; emissions during the period of the COVID-19 pandemic.&lt;/p&gt;

scholarly journals In-situ comparison of the NO<sub>y</sub> instruments flown in MOZAIC and SPURT

2006 ◽  
Vol 6 (1) ◽  
pp. 649-671
Author(s):  
H.-W. Pätz ◽  
A. Volz-Thomas ◽  
M. I. Hegglin ◽  
D. Brunner ◽  
H. Fischer ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Water Vapour ◽  
Time Lag ◽  
Data Sets ◽  
Upper Limit ◽  
Measurement Principle ◽  
Combined Uncertainty ◽  
Potential Losses ◽  
Odd Nitrogen

Abstract. Two aircraft instruments for the measurement of total odd nitrogen (NOy) were compared side by side aboard a Learjet A35 in April 2003 during a campaign of the AFO2000 project SPURT (Spurengastransport in der Tropopausenregion). The instruments albeit employing the same measurement principle (gold converter and chemiluminescence) had different inlet configurations. The ECO-Physics instrument operated by ETH-Zürich in SPURT had the gold converter mounted outside the aircraft, whereas the instrument operated by FZ-Jülich in the European project MOZAIC III (Measurements of ozone, water vapour, carbon monoxide and nitrogen oxides aboard Airbus A340 in-service aircraft) employed a Rosemount probe with 80 cm of FEP-tubing connecting the inlet to the gold converter. The NOy concentrations during the flight ranged between 0.3 and 3 ppb. The two data sets were compared in a blind fashion and each team followed its normal operating procedures. On average, the measurements agreed within 6%, i.e. within the combined uncertainty of the two instruments. This puts an upper limit on potential losses of HNO3 in the Rosemount inlet of the MOZAIC instrument. Larger transient deviations were observed during periods after calibrations and when the aircraft entered the stratosphere. The time lag of the MOZAIC instrument observed in these instances is in accordance with the time constant of the MOZAIC inlet line determined in the laboratory for HNO3.

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