scholarly journals Icing Cloud Microstructure from in Situ Measurements

1983 ◽  
Vol 4 ◽  
pp. 66-72 ◽  
Author(s):  
J. F. Gayet ◽  
M. Bain
Keyword(s):  
Ivory Coast ◽  
In Situ Measurements ◽  
Physical Parameters ◽  
Research Aircraft ◽  
Radar Signatures ◽  
The Republic

In several experiments carried out in France, the Republic of the Ivory Coast, and Spain, icing clouds were penetrated at different heights by instrumented research aircraft. This paper describes the range and the frequencies of occurrence of the relevant icing parameters computed on the cloud scale and for different cloud types. Comparisons between micro-physical parameters and meteorolagical radar signatures show the limitations of these radars when used as a means of locating icing clouds.

scholarly journals Icing Cloud Microstructure from in Situ Measurements

1983 ◽  
Vol 4 ◽  
pp. 66-72
Author(s):  
J. F. Gayet ◽  
M. Bain
Keyword(s):  
Ivory Coast ◽  
In Situ Measurements ◽  
Physical Parameters ◽  
Research Aircraft ◽  
Radar Signatures ◽  
The Republic

In several experiments carried out in France, the Republic of the Ivory Coast, and Spain, icing clouds were penetrated at different heights by instrumented research aircraft. This paper describes the range and the frequencies of occurrence of the relevant icing parameters computed on the cloud scale and for different cloud types. Comparisons between micro-physical parameters and meteorolagical radar signatures show the limitations of these radars when used as a means of locating icing clouds.

Definition of soil water content and rainfall thresholds for landslide occurrence

2020 ◽  
Author(s):  
Luca Piciullo ◽  
Graham Gilbert
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Climate Adaptation ◽  
Early Warning Systems ◽  
In Situ Measurements ◽  
Physical Parameters ◽  
Rainfall Thresholds ◽  
Reanalysis Dataset

<p>In the last decades, rainfall thresholds for landslide occurrences were thoroughly investigated, producing several different test cases and relevant technical and scientific advances. However, a recent literature review on rainfall thresholds articles (Segoni et al., 2018), published in journals indexed in SCOPUS or ISI Web of knowledge databases in the period 2008-2016, highlighted significant advances and critical issues about this topic. Only in the 11% of the analysed papers (a total of 115) there were installed instruments for measuring physical parameters other than rainfall. The implication was that, in most cases, the occurrence of landslides was forecasted considering exclusively a rainfall correlation, completely neglecting soil characteristics.</p><p>A reanalysis dataset (ERA5-Land) providing a consistent view of the evolution of land variables over several decades at an enhanced resolution has been used to evaluate the soil water content. Reanalysis combines numerical model data with observations from across the world into a globally complete and consistent dataset using the laws of physics. A comparison between in situ measurements with the results of the model has been carried out for two sites in Norway (Eidsvoll, Morsa catchmen) with 3 different vegetation types: grass, bush, tree. The results showed a good agreement between the modelled soil water content layer 2 and 3 (respectively representing 2 - 28 cm and 28 -100 cm depths) and, respectively, in-situ measurements at 30 and 50 cm depths.</p><p>Then, 15 Norwegian basins with moraine and peat covers and, previous landslide occurrences in the period 2009-2018, have been selected for correlations. Combinations of rainfall and soil water contents that triggered and not-triggered landslides have been analysed. Rainfall-soil water content thresholds have been defined for the selected basins highlighting the important role played by soil water content, together with rainfall, in triggering landslides. The use of the soil water content contributed to increase the performance of the thresholds and to reduce the uncertainties of landslide forecast.</p><p>This paper has been conceived in the context of the project "Klima 2050-Risk reduction through climate adaptation of buildings and infrastructure" http://www.klima2050.no/, and it is included into Work Package 3.3-Early warning systems.</p><p> </p>

Remote and in situ measurements of aerosol concentration in the Arctic troposphere from the Yak-42D “Roshydromet” research aircraft

2016 ◽  
Vol 41 (5) ◽  
pp. 365-372
Author(s):  
A. S. Kuz’michev ◽  
T. I. Babukhina ◽  
A. V. Gan’shin ◽  
A. N. Luk’yanov ◽  
R. M. Markov ◽  
...  
Keyword(s):  
In Situ Measurements ◽  
Aerosol Concentration ◽  
The Arctic ◽  
Research Aircraft

Project aguila: In situ measurements of Mexico City air pollution by a research aircraft

1992 ◽  
Vol 26 (4) ◽  
pp. 445-451 ◽  
Author(s):  
Everett C. Nickerson ◽  
Gustavo Sosa ◽  
Heidy Hochstein ◽  
Paula Mccaslin ◽  
Winston Luke ◽  
...  
Keyword(s):  
Air Pollution ◽  
Mexico City ◽  
In Situ Measurements ◽  
Research Aircraft

scholarly journals CCN concentration and INP-relevant aerosol profiles in the Saharan Air Layer over Barbados from polarization lidar and airborne in situ measurements

2019 ◽  
Author(s):  
Moritz Haarig ◽  
Adrian Walser ◽  
Albert Ansmann ◽  
Maximilian Dollner ◽  
Dietrich Althausen ◽  
...  
Keyword(s):  
Surface Area ◽  
Cloud Condensation Nuclei ◽  
Number Concentration ◽  
In Situ Measurements ◽  
Saharan Air Layer ◽  
Lidar Measurements ◽  
Research Aircraft ◽  
Lidar Observations ◽  
Aerosol Properties

Abstract. The present study aims to validate lidar retrievals of cloud-relevant aerosol properties by using polarization lidar and coincident airborne in situ measurements in the Saharan Air Layer over the Barbados region. Vertical profiles of the number concentration of cloud condensation nuclei (CCN), large particles (diameter d > 500 nm), surface area, and ice nucleating particles (INP) are estimated from the lidar measurements and compared with CCN concentrations and the INP-relevant aerosol properties in situ measured with aircraft in the framework of the Saharan Aerosol Long-range Transport and Aerosol–Cloudinteraction Experiment (SALTRACE) in summer 2013. The CCN number concentrations derived from lidar observations were up to a factor of two higher than the ones measured in situ on board the research aircraft Falcon. However, a reasonable agreement was obtained when taking the lidar uncertainty into account. The number concentration of particles with dry radius > 250 nm and the surface area concentration obtained from the lidar observations and used as input for the INP parameterizations agreed well (

scholarly journals Nitric Acid Trihydrate (NAT) formation at low NAT supersaturation in Polar Stratospheric Clouds (PSCs)

2005 ◽  
Vol 5 (5) ◽  
pp. 1371-1380 ◽  
Author(s):  
C. Voigt ◽  
H. Schlager ◽  
B. P. Luo ◽  
A. Dörnbrack ◽  
A. Roiger ◽  
...  
Keyword(s):  
Nitric Acid ◽  
High Altitude ◽  
Equilibrium Temperature ◽  
In Situ Measurements ◽  
The Arctic ◽  
Polar Stratospheric Clouds ◽  
Research Aircraft ◽  
Stratospheric Clouds ◽  
Polar Ozone

Abstract. A PSC was detected on 6 February 2003 in the Arctic stratosphere by in-situ measurements onboard the high-altitude research aircraft Geophysica. Low number densities (~10-4cm-3) of small nitric acid (HNO3) containing particles (d<6µm) were observed at altitudes between 18 and 20km. Provided the temperatures remain below the NAT equilibrium temperature TNAT, these NAT particles have the potential to grow further and to remove HNO3 from the stratosphere, thereby enhancing polar ozone loss. Interestingly, the NAT particles formed in less than a day at temperatures just slightly below TNAT (T>TNAT-3.1K). This unique measurement of PSC formation at extremely low NAT saturation ratios (SNAT≤10) constrains current NAT nucleation theories. We suggest, that the NAT particles have formed heterogeneously, but for certain not on ice. Conversely, meteoritic particles may be favorable candidates for triggering NAT nucleation at the observed low number densities.

scholarly journals Validation of GOSAT and OCO-2 against In Situ Aircraft Measurements and Comparison with CarbonTracker and GEOS-Chem over Qinhuangdao, China

2021 ◽  
Vol 13 (5) ◽  
pp. 899
Author(s):  
Farhan Mustafa ◽  
Huijuan Wang ◽  
Lingbing Bu ◽  
Qin Wang ◽  
Muhammad Shahzaman ◽  
...  
Keyword(s):  
Vertical Structure ◽  
Co2 Concentration ◽  
In Situ Measurements ◽  
Vertical Profiles ◽  
Aircraft Measurements ◽  
Research Aircraft ◽  
Carbon Dioxide Co2 ◽  
Air Column ◽  
Good Agreement

Carbon dioxide (CO2) is the most important greenhouse gas and several satellites have been launched to monitor the atmospheric CO2 at regional and global scales. Evaluation of the measurements obtained from these satellites against accurate and precise instruments is crucial. In this work, aircraft measurements of CO2 were carried out over Qinhuangdao, China (39.9354°N, 119.6005°E), on 14, 16, and 19 March 2019 to validate the Greenhous gases Observing SATellite (GOSAT) and the Orbiting Carbon Observatory 2 (OCO-2) CO2 retrievals. The airborne in situ instruments were mounted on a research aircraft and the measurements were carried out between the altitudes of ~0.5 and 8.0 km to obtain the vertical profiles of CO2. The profiles captured a decrease in CO2 concentration from the surface to maximum altitude. Moreover, the vertical profiles from GEOS-Chem and the National Oceanic and Atmospheric Administration (NOAA) CarbonTracker were also compared with in situ and satellite datasets. The satellite and the model datasets captured the vertical structure of CO2 when compared with in situ measurements, which showed good agreement among the datasets. The dry-air column-averaged CO2 mole fractions (XCO2) retrieved from OCO-2 and GOSAT showed biases of 1.33 ppm (0.32%) and −1.70 ppm (−0.41%), respectively, relative to the XCO2 derived from in situ measurements.

scholarly journals Nitric acid trihydrate (NAT) formation at low NAT supersaturations

2004 ◽  
Vol 4 (6) ◽  
pp. 8579-8607 ◽  
Author(s):  
C. Voigt ◽  
H. Schlager ◽  
B. P. Luo ◽  
A. Dörnbrack ◽  
A. Roiger ◽  
...  
Keyword(s):  
Nitric Acid ◽  
High Altitude ◽  
Equilibrium Temperature ◽  
In Situ Measurements ◽  
The Arctic ◽  
Ozone Loss ◽  
Polar Stratospheric Cloud ◽  
Research Aircraft ◽  
Polar Ozone

Abstract. A polar stratospheric cloud (PSC) was observed on 6 February 2003 in the Arctic stratosphere by in-situ measurements onboard the high-altitude research aircraft Geophysica. Low number densities (~10−4 cm−3) of nitric acid (HNO3) containing particles – probably NAT – with diameters up to 6 µm were measured at altitudes between 18 and 20 km. These particles have the potential to grow further and to remove HNO3 from the stratosphere, thereby enhancing polar ozone loss. Interestingly, the NAT particles formed in less than a day at temperatures T>TNAT−3.5 K, just slightly below the NAT equilibrium temperature TNAT. This unique measurement of PSC formation at extremely low NAT saturation ratios (SNAT≤11) constrains current NAT nucleation theories. In particular, NAT formation on ice can for certain be excluded. Conversely, we suggest that meteoritic particles may be favorable candidates for triggering nucleation of NAT at the observed low number densities.

scholarly journals The retrieval of cloud microphysical properties using satellite measurements and an in situ database

1996 ◽  
Vol 14 (1) ◽  
pp. 98-106 ◽  
Author(s):  
Christophe Poix ◽  
Guy Febvre ◽  
Anne Fouilloux ◽  
Howard Larsen ◽  
Jean-Francois Gayet
Keyword(s):  
Large Scale ◽  
In Situ Measurements ◽  
Global Circulation ◽  
The North ◽  
Microphysical Properties ◽  
Microphysical Parameters ◽  
Research Aircraft ◽  
The North Sea

Abstract. By combining AVHRR data from the NOAA satellites with information from a database of in situ measurements, large-scale maps can be generated of the microphysical parameters most immediately significant for the modelling of global circulation and climate. From the satellite data, the clouds can be classified into cumuliform, stratiform and cirrus classes and then into further sub-classes by cloud top temperature. At the same time a database of in situ measurements made by research aircraft is classified into the same sub-classes and a statistical analysis is used to derive relationships between the sub-classes and the cloud microphysical properties. These two analyses are then linked to give estimates of the microphysical properties of the satellite observed clouds. Examples are given of the application of this technique to derive maps of the probability of occurrence of precipitating clouds and of precipitating water content derived from a case study within the International Cirrus Experiment (ICE) held in 1989 over the North Sea.

scholarly journals Deep convective injection of boundary layer air into the lowermost stratosphere at midlatitudes

2003 ◽  
Vol 3 (3) ◽  
pp. 739-745 ◽  
Author(s):  
H. Fischer ◽  
M. de Reus ◽  
M. Traub ◽  
J. Williams ◽  
J. Lelieveld ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Trace Gases ◽  
In Situ Measurements ◽  
Background Concentrations ◽  
Upper Troposphere ◽  
German Research ◽  
Research Aircraft ◽  
The Mediterranean

Abstract. On 22 August 2001 a measurement flight was performed with the German research aircraft FALCON from Sardinia to Crete as part of the Mediterranean Oxidant Study (MINOS). Cruising at 8.2 km, the aircraft was forced to climb to 11.2 km over the southern tip of Italy to stay clear of the anvil of a large cumulonimbus tower. During ascent into the lowermost stratosphere in-situ measurements onboard the FALCON indicated several sharp increases in the concentrations of tropospheric trace gases, e.g. CO, acetone, methanol, benzene and acetonitrile, above the anvil. During one particular event deep in the stratosphere, at O3 concentrations exceeding 200 ppv, CO increased from about 60 to 90 ppv, while the concentration of acetone and methanol increased by more than a factor of 2 (0.7 to 1.8 ppv for acetone; 0.4 to 1.4 ppv for methanol). Enhancements for the short lived species benzene are even higher, increasing from 20 pptv in the stratosphere to approx. 130 pptv. The concentrations during the event were higher than background concentrations in the upper troposphere, indicating that polluted boundary layer air was directly mixed into the lowermost stratosphere.

Sign in / Sign up

Export Citation Format

Share Document