Comparative assessment of radio occultation-based refractivity measurements from the COSMIC mission and in-situ atmospheric measurements in equatorial Africa

2021 ◽  
Author(s):  
J. N. Nzeagwu ◽  
J. O. Urama ◽  
A. E. Chukwude ◽  
D. I. Okoh
Keyword(s):  
Radio Occultation ◽  
Comparative Assessment ◽  
Atmospheric Measurements ◽  
Equatorial Africa

Satellite-based phenology products and in-situ pollen dynamics: A comparative assessment

2022 ◽  
Vol 204 ◽  
pp. 111937
Author(s):  
Linze Li ◽  
Dalai Hao ◽  
Xuecao Li ◽  
Min Chen ◽  
Yuyu Zhou ◽  
...  
Keyword(s):  
Comparative Assessment ◽  
Pollen Dynamics

scholarly journals High-precision quasi-continuous atmospheric greenhouse gas measurements at Trainou tower (Orléans forest, France)

2014 ◽  
Vol 7 (7) ◽  
pp. 2283-2296 ◽  
Author(s):  
M. Schmidt ◽  
M. Lopez ◽  
C. Yver Kwok ◽  
C. Messager ◽  
M. Ramonet ◽  
...  
Keyword(s):  
In Situ Measurements ◽  
Atmospheric Measurements ◽  
Flame Ionization ◽  
Gas Detector ◽  
Sampling Height ◽  
The Mean ◽  
Drying System ◽  
Gas Measurements ◽  
Television Tower

Abstract. Results from the Trainou tall tower measurement station installed in 2006 are presented for atmospheric measurements of CO2, CH4, N2O, SF6, CO, H2 mole fractions and radon-222 activity. Air is sampled from four sampling heights (180, 100, 50 and 5 m) of the Trainou 200 m television tower in the Orléans forest in France (47°57'53" N, 2°06'45" E, 131 m a.s.l.). The station is equipped with a custom-built CO2 analyser (CARIBOU), which is based on a commercial non-dispersive, infrared (NDIR) analyser (Licor 6252), and a coupled gas chromatography (GC) system equipped with an electron capture detector (ECD) and a flame ionization detector (FID) (HP6890N, Agilent) and a reduction gas detector (PP1, Peak Performer). Air intakes, pumping and air drying system are shared between the CARIBOU and the GC systems. The ultimately achieved short-term repeatability (1 sigma, over several days) for the GC system is 0.05 ppm for CO2, 1.4 ppb for CH4, 0.25 ppb for N2O, 0.08 ppb for SF6, 0.88 ppb for CO and 3.8 for H2. The repeatability of the CARIBOU CO2 analyser is 0.06 ppm. In addition to the in situ measurements, weekly flask sampling is performed, and flask air samples are analysed at the Laboratoire des Sciences du Climat et de l'Environnement (LSCE) central laboratory for the same species as well for stable isotopes of CO2. The comparison between in situ measurements and the flask sampling showed averaged differences of 0.08 ± 1.40 ppm for CO2, 0.7 ± 7.3 ppb for CH4, 0.6 ± 0.6 ppb for N2O, 0.01 ± 0.10 ppt for SF6, 1.5± 5.3 ppb for CO and 4.8± 6.9 ppb for H2 for the years 2008–2012. At Trainou station, the mean annual increase rates from 2007 to 2011 at the 180 m sampling height were 2.2 ppm yr−1 for CO2, 4 ppb yr−1 for CH4, 0.78 ppb yr−1 for N2O and 0.29 ppt yr−1 for SF6. For all species, the 180 m sampling level showed the smallest diurnal variation. Mean diurnal gradients between the 50 m and the 180 m sampling level reached up to 30 ppm CO2, 15 ppm CH4 or 0.5 ppb N2O during nighttime whereas the mean gradients are smaller than 0.5 ppm for CO2 and 1.5 ppb for CH4 during afternoon.

scholarly journals Overview of and first observations from the TILDAE High-Altitude Balloon Mission

2017 ◽  
Vol 10 (4) ◽  
pp. 1595-1607 ◽  
Author(s):  
Bennett A. Maruca ◽  
Raffaele Marino ◽  
David Sundkvist ◽  
Niharika H. Godbole ◽  
Stephane Constantin ◽  
...  
Keyword(s):  
Sonic Anemometer ◽  
Ambient Air ◽  
Small Scale ◽  
New Paradigm ◽  
Intermittent Turbulence ◽  
Atmospheric Measurements ◽  
Long Duration ◽  
In Situ Observations ◽  
Robust Separation

Abstract. Though the presence of intermittent turbulence in the stratosphere has been well established, much remains unknown about it. In situ observations of this phenomenon, which have provided the greatest details of it, have mostly been achieved via sounding balloons (i.e., small balloons which burst at peak altitude) carrying constant-temperature hot-wire anemometers (CTAs). The Turbulence and Intermittency Long-Duration Atmospheric Experiment (TILDAE) was developed to test a new paradigm for stratospheric observations. Rather than flying on a sounding balloon, TILDAE was incorporated as an add-on experiment to the payload of a NASA long-duration balloon mission that launched in January 2016 from McMurdo Station, Antarctica. Furthermore, TILDAE's key instrument was a sonic anemometer, which (relative to a CTA) provides better-calibrated measurements of wind velocity and a more robust separation of velocity components. During the balloon's ascent, TILDAE's sonic anemometer provided atmospheric measurements up to an altitude of about 18 km, beyond which the ambient air pressure was too low for the instrument to function properly. Efforts are currently underway to scientifically analyze these observations of small-scale fluctuations in the troposphere, tropopause, and stratosphere and to develop strategies for increasing the maximum operating altitude of the sonic anemometer.

scholarly journals Quantitative infrared absorption cross sections of isoprene for atmospheric measurements

2014 ◽  
Vol 7 (11) ◽  
pp. 3839-3847 ◽  
Author(s):  
C. S. Brauer ◽  
T. A. Blake ◽  
A. B. Guenther ◽  
S. W. Sharpe ◽  
R. L. Sams ◽  
...  
Keyword(s):  
Cross Sections ◽  
Anthropogenic Sources ◽  
Infrared Detection ◽  
Absorption Cross ◽  
Atmospheric Measurements ◽  
Composite Spectra ◽  
Volatile Organic ◽  
Infrared Studies ◽  
Ftir Spectrometer

Abstract. Isoprene (C5H8, 2-methyl-1,3-butadiene) is a volatile organic compound (VOC) and is one of the primary contributors to annual global VOC emissions. Isoprene is produced primarily by vegetation as well as anthropogenic sources, and its OH- and O3-initiated oxidations are a major source of atmospheric oxygenated organics. Few quantitative infrared studies have been reported for isoprene, limiting the ability to quantify isoprene emissions via remote or in situ infrared detection. We thus report absorption cross sections and integrated band intensities for isoprene in the 600–6500 cm−1 region. The pressure-broadened (1 atmosphere N2) spectra were recorded at 278, 298, and 323 K in a 19.94 cm path-length cell at 0.112 cm−1 resolution, using a Bruker IFS 66v/S Fourier transform infrared (FTIR) spectrometer. Composite spectra are derived from a minimum of seven isoprene sample pressures, each at one of three temperatures, and the number densities are normalized to 296 K and 1 atm.

scholarly journals An automatic precipitation-phase distinction algorithm for optical disdrometer data over the global ocean

2016 ◽  
Vol 9 (4) ◽  
pp. 1637-1652 ◽  
Author(s):  
Jörg Burdanowitz ◽  
Christian Klepp ◽  
Stephan Bakan
Keyword(s):  
Mixed Phase ◽  
Global Ocean ◽  
Human Observer ◽  
Precipitation Data ◽  
Post Processing ◽  
Atmospheric Measurements ◽  
Data Set ◽  
Surface Precipitation ◽  
Precipitation Phase

Abstract. The lack of high-quality in situ surface precipitation data over the global ocean so far limits the capability to validate satellite precipitation retrievals. The first systematic ship-based surface precipitation data set OceanRAIN (Ocean Rainfall And Ice-phase precipitation measurement Network) aims at providing a comprehensive statistical basis of in situ precipitation reference data from optical disdrometers at 1 min resolution deployed on various research vessels (RVs). Deriving the precipitation rate for rain and snow requires a priori knowledge of the precipitation phase (PP). Therefore, we present an automatic PP distinction algorithm using available data based on more than 4 years of atmospheric measurements onboard RV Polarstern that covers all climatic regions of the Atlantic Ocean. A time-consuming manual PP distinction within the OceanRAIN post-processing serves as reference, mainly based on 3-hourly present weather information from a human observer. For automation, we find that the combination of air temperature, relative humidity, and 99th percentile of the particle diameter predicts best the PP with respect to the manually determined PP. Excluding mixed phase, this variable combination reaches an accuracy of 91 % when compared to the manually determined PP for 149 635 min of precipitation from RV Polarstern. Including mixed phase (165 632 min), an accuracy of 81.2 % is reached for two independent PP distributions with a slight snow overprediction bias of 0.93. Using two independent PP distributions represents a new method that outperforms the conventional method of using only one PP distribution to statistically derive the PP. The new statistical automatic PP distinction method considerably speeds up the data post-processing within OceanRAIN while introducing an objective PP probability for each PP at 1 min resolution.

scholarly journals Six years of high-precision quasi-continuous atmospheric greenhouse gas measurements at Trainou Tower (Orléans Forest, France)

2014 ◽  
Vol 7 (1) ◽  
pp. 569-604 ◽  
Author(s):  
M. Schmidt ◽  
M. Lopez ◽  
C. Yver Kwok ◽  
C. Messager ◽  
M. Ramonet ◽  
...  
Keyword(s):  
In Situ Measurements ◽  
Atmospheric Measurements ◽  
Short Term ◽  
Gas Detector ◽  
Sampling Height ◽  
The Mean ◽  
Drying System ◽  
Gas Measurements ◽  
Television Tower

Abstract. Results from the Trainou tall tower measurement station installed in 2006, are presented for atmospheric measurements of CO2, CH4, N2O, SF6, CO, H2 mole fractions and Radon-222 activity. Air is sampled from four sampling heights (180 m, 100 m, 50 m and 5 m) of the Trainou 200 m television tower in the Orléans forest in France (47°57'53'' N, 2°06'45'' E, 131 m a.s.l.). The station is equipped with a custom-build CO2 analyzer (CARIBOU), which is based on a commercial NDIR analyser (Licor 6252), and a coupled gas chromatographic GC system equipped with ECD and FID (HP6890N, Agilent) and a reduction gas detector (PP1, Peak Performer). Air intakes, pumping and air drying system are shared between the CARIBOU and the GC systems. After some initial problems, we achieved short-term repeatability (1 sigma, over several days) for the GC system of of 0.05 ppm for CO2, 1.4 ppb for CH4, 0.25 ppb for N2O, 0.08 ppb for SF6, 0.88 ppb for CO and 3.8 for H2. The repeatability of the CARIBOU CO2 analyser is 0.06 ppm. In addition to the in-situ measurements, weekly flask sampling is performed, and flask air samples are analysed at the LSCE central laboratory for the same species as well for stable isotopes of CO2. The comparison between in-situ measurements and the flask sampling showed averaged differences of 0.08 ± 1.4 ppm CO2, 0.69 ± 7.3 ppb CH4, 0.64 ± 0.62 ppb N2O, 0.01 ± 0.1 ppt SF6 and 1.5 ± 5.3 ppb CO for the years 2008–2012. At Trainou station, the mean annual increase rates from 2007 to 2011 at the 180 m sampling height were 2.2 ppm yr−1 for CO2, 4 ppb yr−1 for CH4, 0.78 ppb yr−1 for N2O and 0.29 ppt yr−1 for SF6 respectively. For all species the 180 m sampling level showed the smallest diurnal variation. Mean diurnal gradients between the 50 m and the 180 m sampling level reached up to 30 ppm CO2, 15 ppm CH4 or 0.5 ppb N2O during night whereas the mean gradients are smaller than 0.5 ppm for CO2 and 1.5 ppb for CH4 during afternoon.

scholarly journals On the performance of satellite-based observations of <i>CO</i><sub>2</sub> in capturing the NOAA Carbon Tracker model and ground-based flask observations over Africa land mass

2019 ◽  
Author(s):  
Anteneh Getachew Mengistu ◽  
Gizaw Mengistu Tsidu
Keyword(s):  
Model Simulation ◽  
Satellite Observation ◽  
Satellite Observations ◽  
Lower Altitude ◽  
Equatorial Africa ◽  
In Situ Observations ◽  
The Mean ◽  
Data Gap ◽  
Good Agreement

Abstract. Africa is one of the most data-scarce regions as satellite observation at the equator is limited by cloud cover and there are a very limited number of ground-based measurements. As a result, the use of simulations from models are mandatory to fill this data gap. A comparison of satellite observation with model and available in-situ observations will be useful to estimate the performance of satellites in the region. In this study, GOSAT XCO2 is compared with the NOAA CT2016 and six flask observations over Africa using five years of data covering the period from May 2009 to April 2014. Ditto for OCO-2 XCO2 against NOAA CT16NRT17 and eight flask observations over Africa using two years of data covering the period from January 2015 to December 2016. The analysis shows that the XCO2 from GOSAT is higher than XCO2 simulated by CT2016 by 0.28 ppm whereas OCO-2 XCO2 is lower than CT16NRT17 by 0.34 ppm on African landmass on average. The mean correlations of 0.83 and 0.60 and average RMSD of 2.30 and 2.57 ppm are found between the model and the respective datasets from GOSAT and OCO-2 implying the existence of a reasonably good agreement between CT and the two satellites over Africa's land region. However, significant variations were observed in some regions. For example, OCO-2 XCO2 are lower than that of CT16NRT17 by up to 3 ppm over some regions in North Africa (e.g., Egypt, Libya, and Mali) whereas it exceeds CT16NRT17 XCO2 by 2 ppm over Equatorial Africa (10° S–10° N). This regional difference is also noted in the comparison of model simulations and satellite observations with flask observations over the continent. For example, CT shows a better sensitivity in capturing flask observations over sites located in Northern Africa. In contrast, satellite observations have better sensitivity in capturing flask observations in lower altitude island sites. CT2016 shows a high spatial mean of seasonal mean RMSD of 1.91 ppm during DJF with respect to GOSAT while CT16NRT17 shows 1.75 ppm during MAM with respect to OCO-2. On the other hand, low RMSD of 1.00 and 1.07 ppm during SON in the model XCO2 with respect to GOSAT and OCO-2 are determined respectively indicating better agreement during autumn. The model simulation and satellite observations exhibit similar seasonal cycles of XCO2 with a small discrepancy over Southern Africa and during wet seasons over all regions.

scholarly journals On the performance of satellite-based observations of <i>X</i>CO<sub>2</sub> in capturing the NOAA Carbon Tracker model and ground-based flask observations over Africa's land mass

2020 ◽  
Vol 13 (7) ◽  
pp. 4009-4033
Author(s):  
Anteneh Getachew Mengistu ◽  
Gizaw Mengistu Tsidu
Keyword(s):  
North Africa ◽  
Model Simulation ◽  
Satellite Observation ◽  
Satellite Observations ◽  
Lower Altitude ◽  
Equatorial Africa ◽  
Land Mass ◽  
Data Gap ◽  
Good Agreement

Abstract. Africa is one of the most data-scarce regions as satellite observation at the Equator is limited by cloud cover and there is a very limited number of ground-based measurements. As a result, the use of simulations from models is mandatory to fill this data gap. A comparison of satellite observation with model and available in situ observations will be useful to estimate the performance of satellites in the region. In this study, GOSAT column-averaged carbon dioxide dry-air mole fraction (XCO2) is compared with the NOAA CT2016 and six flask observations over Africa using 5 years of data covering the period from May 2009 to April 2014. Ditto for OCO-2 XCO2 against NOAA CT16NRT17 and eight flask observations over Africa using 2 years of data covering the period from January 2015 to December 2016. The analysis shows that the XCO2 from GOSAT is higher than XCO2 simulated by CT2016 by 0.28±1.05 ppm, whereas OCO-2 XCO2 is lower than CT16NRT17 by 0.34±0.9 ppm on the African land mass on average. The mean correlations of 0.83±1.12 and 0.60±1.41 and average root mean square deviation (RMSD) of 2.30±1.45 and 2.57±0.89 ppm are found between the model and the respective datasets from GOSAT and OCO-2, implying the existence of a reasonably good agreement between CT and the two satellites over Africa's land region. However, significant variations were observed in some regions. For example, OCO-2 XCO2 are lower than that of CT16NRT17 by up to 3 ppm over some regions in North Africa (e.g. Egypt, Libya, and Mali), whereas it exceeds CT16NRT17 XCO2 by 2 ppm over Equatorial Africa (10∘ S–10∘ N). This regional difference is also noted in the comparison of model simulations and satellite observations with flask observations over the continent. For example, CT shows a better sensitivity in capturing flask observations over sites located in North Africa. In contrast, satellite observations have better sensitivity in capturing flask observations in lower-altitude island sites. CT2016 shows a high spatial mean of seasonal mean RMSD of 1.91 ppm during DJF with respect to GOSAT, while CT16NRT17 shows 1.75 ppm during MAM with respect to OCO-2. On the other hand, low RMSDs of 1.00 and 1.07 ppm during SON in the model XCO2 with respect to GOSAT and OCO-2 are respectively determined, indicating better agreement during autumn. The model simulation and satellite observations exhibit similar seasonal cycles of XCO2 with a small discrepancy over Southern Africa (35–10∘ S) and during wet seasons over all regions.

scholarly journals The comparison of topmost radio occultation electron densities with in-situ ion densities from FORMOSAT-7/COSMIC-2

2021 ◽  
Vol 32 (6.1) ◽  
Author(s):  
Chia-Hung Chen ◽  
Ho-Fang Tsai ◽  
Li-Yuan Wang ◽  
Chien-Hung Charles Lin ◽  
Jann-Yenq Liu ◽  
...  
Keyword(s):  
Radio Occultation ◽  
Electron Densities

Airborne Atmospheric Measurements with the Max Planck CloudKites

2021 ◽  
Author(s):  
Marcel Schröder ◽  
Freja Nordsiek ◽  
Oliver Schlenczek ◽  
Antonio Ibañez Landeta ◽  
Johannes Güttler ◽  
...  
Keyword(s):  
Particle Image Velocimetry Data ◽  
Cloud Microphysics ◽  
Max Planck ◽  
Atmospheric Measurements ◽  
Field Campaign ◽  
Flight Data ◽  
Microphysical Properties ◽  
Image Velocimetry ◽  
The Caribbean

&lt;p&gt;To investigate cloud microphysics and turbulence in clouds and in the atmospheric boundary layer, we specially developed airborne platforms, one Max-Planck-CloudKite + (MPCK+) and two mini-Max-Planck-CloudKites (mini-MPCK). They are deployed aboard balloon-kite hybrids conducting &lt;em&gt;in situ&lt;/em&gt; measurements of meteorological and cloud microphysical properties with high spatial and temporal resolution. During the EUREC4A-ATOMIC field campaign in the Caribbean January-February 2020, the MPCK+ and one mini-MPCK sampled clouds aboard a 250 m&lt;sup&gt;3&lt;/sup&gt; aerostat launched from the R.V. Maria S. Merian where both instruments were operated between MSL and 1500m MSL. In addition, one mini-MPCK profiled the atmosphere between MSL and 1000 m MSL aboard a 74 m&lt;sup&gt;3&lt;/sup&gt; aerostat launched from the R.V. Meteor. In total, we acquired 145 h of flight-data on RV Maria S. Merian and 52 h of flight-data on RV Meteor. For the MPCK+, this included 5 hr of Particle Image Velocimetry data and 3 hr of inline holography data inside clouds and near the cloud edges. We present &lt;em&gt;in situ&lt;/em&gt; data measured by the MPCKs during the EUREC4A-ATOMIC field campaign and report on preliminary assessment of turbulence features.&lt;/p&gt;

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