scholarly journals Evidence for interhemispheric stratosphere-mesosphere coupling derived from noctilucent cloud properties

2007 ◽  
Vol 34 (16) ◽  
Author(s):  
B. Karlsson ◽  
H. Körnich ◽  
J. Gumbel
Keyword(s):  
Noctilucent Cloud ◽  
Cloud Properties

scholarly journals Comparison of retrieved Noctilucent cloud particle properties from Odin tomography scans and model simulations

2016 ◽  
Author(s):  
Linda Megner ◽  
Ole M. Christensen ◽  
Bodil Karlsson ◽  
Susanne Benze ◽  
Victor I. Fomichev
Keyword(s):  
Imaging System ◽  
Mass Density ◽  
Scattered Light ◽  
Measurement Techniques ◽  
Retrieval Algorithm ◽  
Atmospheric Conditions ◽  
Noctilucent Cloud ◽  
Remote Imaging ◽  
Satellite Retrieval ◽  
Cloud Properties

Abstract. Mesospheric ice particles, known as Noctilucent clouds or Polar Mesospheric Clouds, have long been observed by rocket instruments and satellites, while models have been used to simulate ice particle growth and cloud properties. However, the fact that different measurement techniques are sensitive to different parts of the ice particle distribution makes it difficult to compare retrieved parameters such as ice particle radius or particle number density from different experiments. In this work we investigate the accuracy of satellite retrieval based on scattered light and how this affects derived cloud properties. We run the retrieval algorithm on modelled cloud distributions and compare the results to the properties of the original distributions. We find that ice mass density is accurately retrieved whereas mean radius often is overestimated and high number densities generally are underestimated. The reason is that the retrieval algorithm assumes a Gaussian size distribution, whereas the modelled size distributions often are multimodal. Once we know the limits of the satellite retrieval we proceed to compare the properties retrieved from the modelled cloud distributions to those observed by the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) instrument on the Odin satellite. We find that a model with a stationary atmosphere, as given by average atmospheric conditions, does not yield cloud properties that are in agreement with the observations, whereas a model with realistic temperature and vertical wind variations does. This indicates that average atmospheric conditions are insufficient to understand the process of Noctilucent cloud growth and that a realistic atmospheric variability is crucial for cloud formation and growth. Further, the agreement between results from the model – when set up with a realistically variable atmosphere – and the observations suggests that our understanding of the growth process itself is reasonable.

scholarly journals Comparison of retrieved noctilucent cloud particle properties from Odin tomography scans and model simulations

2016 ◽  
Vol 16 (23) ◽  
pp. 15135-15146 ◽  
Author(s):  
Linda Megner ◽  
Ole M. Christensen ◽  
Bodil Karlsson ◽  
Susanne Benze ◽  
Victor I. Fomichev
Keyword(s):  
Imaging System ◽  
Mass Density ◽  
Scattered Light ◽  
Measurement Techniques ◽  
Retrieval Algorithm ◽  
Atmospheric Conditions ◽  
Noctilucent Cloud ◽  
Remote Imaging ◽  
Satellite Retrieval ◽  
Cloud Properties

Abstract. Mesospheric ice particles, known as noctilucent clouds or polar mesospheric clouds, have long been observed by rocket instruments, satellites and ground-based remote sensing, while models have been used to simulate ice particle growth and cloud properties. However, the fact that different measurement techniques are sensitive to different parts of the ice particle distribution makes it difficult to compare retrieved parameters such as ice particle radius or ice concentration from different experiments. In this work we investigate the accuracy of satellite retrieval based on scattered light and how this affects derived cloud properties. We apply the retrieval algorithm on spectral signals calculated from modelled cloud distributions and compare the results to the properties of the original distributions. We find that ice mass density is accurately retrieved whereas mean radius is often overestimated and high ice concentrations are generally underestimated. The reason is partly that measurements based on scattered light are insensitive to the smaller particles and partly that the retrieval algorithm assumes a Gaussian size distribution. Once we know the limits of the satellite retrieval we proceed to compare the properties retrieved from the modelled cloud distributions to those observed by the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) instrument on the Odin satellite. We find that a model with a stationary atmosphere, as given by average atmospheric conditions, does not yield cloud properties that are in agreement with the observations, whereas a model with realistic temperature and vertical wind variations does. This indicates that average atmospheric conditions are insufficient to understand the process of noctilucent cloud growth and that a realistic atmospheric variability is crucial for cloud formation and growth. Further, the agreement between results from the model, when set up with a realistically variable atmosphere, and the observations suggests that our understanding of the growth process itself is reasonable.

Analysis of Gravity Waves Structures Visible in Noctilucent Cloud Images

2010 ◽  
Author(s):  
P.-D. Pautet ◽  
J. Stegmman ◽  
C. M. Wrasse ◽  
K. Nielsen ◽  
H. Takahashi ◽  
...  
Keyword(s):  
Gravity Waves ◽  
Noctilucent Cloud

scholarly journals Comparison of ISS–CATS and CALIPSO–CALIOP Characterization of High Clouds in the Tropics

2020 ◽  
Vol 12 (23) ◽  
pp. 3946
Author(s):  
Pasquale Sellitto ◽  
Silvia Bucci ◽  
Bernard Legras
Keyword(s):  
Optical Properties ◽  
Space Station ◽  
Satellite Observation ◽  
Observation Data ◽  
Upper Troposphere ◽  
Cloud Properties ◽  
Synchronous Orbit ◽  
The Tropics ◽  
High Clouds

Clouds in the tropics have an important role in the energy budget, atmospheric circulation, humidity, and composition of the tropical-to-global upper-troposphere–lower-stratosphere. Due to its non-sun-synchronous orbit, the Cloud–Aerosol Transport System (CATS) onboard the International Space Station (ISS) provided novel information on clouds from space in terms of overpass time in the period of 2015–2017. In this paper, we provide a seasonally resolved comparison of CATS characterization of high clouds (between 13 and 18 km altitude) in the tropics with well-established CALIPSO (Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observation) data, both in terms of clouds’ occurrence and cloud optical properties (optical depth). Despite the fact that cloud statistics for CATS and CALIOP are generated using intrinsically different local overpass times, the characterization of high clouds occurrence and optical properties in the tropics with the two instruments is very similar. Observations from CATS underestimate clouds occurrence (up to 80%, at 18 km) and overestimate the occurrence of very thick clouds (up to 100% for optically very thick clouds, at 18 km) at higher altitudes. Thus, the description of stratospheric overshoots with CATS and CALIOP might be different. While this study hints at the consistency of CATS and CALIOP clouds characterizaton, the small differences highlighted in this work should be taken into account when using CATS for estimating cloud properties and their variability in the tropics.

scholarly journals A comparison of ship and satellite measurements of cloud properties with global climate model simulations in the southeast Pacific stratus deck

2010 ◽  
Vol 10 (14) ◽  
pp. 6527-6536 ◽  
Author(s):  
M. A. Brunke ◽  
S. P. de Szoeke ◽  
P. Zuidema ◽  
X. Zeng
Keyword(s):  
Diurnal Cycle ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Cloud Fraction ◽  
Cloud Base ◽  
Liquid Water Path ◽  
Cloud Properties ◽  
Southeast Pacific ◽  
Cloud Thickness

Abstract. Here, liquid water path (LWP), cloud fraction, cloud top height, and cloud base height retrieved by a suite of A-train satellite instruments (the CPR aboard CloudSat, CALIOP aboard CALIPSO, and MODIS aboard Aqua) are compared to ship observations from research cruises made in 2001 and 2003–2007 into the stratus/stratocumulus deck over the southeast Pacific Ocean. It is found that CloudSat radar-only LWP is generally too high over this region and the CloudSat/CALIPSO cloud bases are too low. This results in a relationship (LWP~h9) between CloudSat LWP and CALIPSO cloud thickness (h) that is very different from the adiabatic relationship (LWP~h2) from in situ observations. Such biases can be reduced if LWPs suspected to be contaminated by precipitation are eliminated, as determined by the maximum radar reflectivity Zmax>−15 dBZ in the apparent lower half of the cloud, and if cloud bases are determined based upon the adiabatically-determined cloud thickness (h~LWP1/2). Furthermore, comparing results from a global model (CAM3.1) to ship observations reveals that, while the simulated LWP is quite reasonable, the model cloud is too thick and too low, allowing the model to have LWPs that are almost independent of h. This model can also obtain a reasonable diurnal cycle in LWP and cloud fraction at a location roughly in the centre of this region (20° S, 85° W) but has an opposite diurnal cycle to those observed aboard ship at a location closer to the coast (20° S, 75° W). The diurnal cycle at the latter location is slightly improved in the newest version of the model (CAM4). However, the simulated clouds remain too thick and too low, as cloud bases are usually at or near the surface.

scholarly journals Evaluation of Fengyun-4A Lightning Mapping Imager (LMI) Performance during Multiple Convective Episodes over Beijing

2021 ◽  
Vol 13 (9) ◽  
pp. 1746
Author(s):  
Zhixiong Chen ◽  
Xiushu Qie ◽  
Juanzhen Sun ◽  
Xian Xiao ◽  
Yuxin Zhang ◽  
...  
Keyword(s):  
Doppler Radar ◽  
Detection Efficiency ◽  
Ground Truth ◽  
Radar Data ◽  
Detection Capability ◽  
Cloud Properties ◽  
Order Of Magnitude ◽  
Total Lightning ◽  
Matching Criteria ◽  
Event Based

This study investigates the characteristics of space-borne Lightning Mapping Imager (LMI) lightning products and their relationships with cloud properties using ground-based total lightning observations from the Beijing Broadband Lightning Network (BLNET) and cloud information from S-band Doppler radar data. LMI showed generally consistent lightning spatial distributions with those of BLNET, and yielded a considerable lightning detection capability over regions with complex terrain. The ratios between the LMI events, groups and flashes were approximately 9:3:1, and the number of LMI-detected flashes was roughly one order of magnitude smaller than the number of BLNET-detected flashes. However, in different convective episodes, the LMI detection capability was likely to be affected by cloud properties, especially in strongly electrified convective episodes associated with frequent lightning discharging and thick cloud depth. As a result, LMI tended to detect lightning flashes located in weaker and shallower cloud portions associated with fewer cloud shielding effects. With reference to the BLNET total lightning data as the ground truth of observation (both intra-cloud lightning and cloud-to-ground lightning flashes), the LMI event-based detection efficiency (DE) was estimated to reach 28% under rational spatiotemporal matching criteria (1.5 s and 65 km) over Beijing. In terms of LMI flash-based DE, it was much reduced compared with event-based DE. The LMI flash-based ranged between 1.5% and 3.5% with 1.5 s and 35–65 km matching scales. For 330 ms and 35 km, the spatiotemporal matching criteria used to evaluate Geostationary Lightning Mapper (GLM), the LMI flash-based DE was smaller (<1%).

Relations between marine biogeochemical indices and cloud properties over the Arabian Sea

2021 ◽  
Vol 130 (3) ◽  
Author(s):  
V D Rao ◽  
M Dileep Kumar ◽  
B Sridevi ◽  
V V S S Sarma
Keyword(s):  
Arabian Sea ◽  
Cloud Properties

A critical review of the paper ‘The earliest datable noctilucent cloud observation (Parma, Italy, AD 1840)’

The Holocene ◽  
2020 ◽  
Vol 30 (8) ◽  
pp. 1220-1221
Author(s):  
Peter Dalin
Keyword(s):  
Critical Review ◽  
Theory And Practice ◽  
Noctilucent Clouds ◽  
Noctilucent Cloud ◽  
The University

In the present critical review, my aim is to address serious calculation mistakes made by the authors. I do not want to review their interpretation of a given observation on 18 June 1840 made by Antonio Colla, who was a professor of Astronomy and Meteorology at the University of Parma. There is no sense interpreting Colla’s observation since the basic astronomical calculations have been made incorrectly by the authors Chiara Bertolin and Fernando Domínguez-Castro. Summarizing, in theory and practice, astronomer Antonio Colla could not have observed noctilucent clouds (NLC) at Parma on 18 June 1840. That is why the conclusions of the present paper are not valid.

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