Observed Evolution of the Tropical Atmospheric Water Cycle with Sea Surface Temperature

AbstractBetter understanding of how moisture, clouds, and precipitation covary under climate warming lacks a comprehensive observational view. This paper analyzes the tropical atmospheric water cycle’s evolution with sea surface temperature (SST), using for the first time, the synergistic dataset of instantaneous observations of the relative humidity profile from the Megha-Tropiques satellite, clouds from the CALIPSO satellite, and near-surface precipitation from the CloudSat satellite, and quantifies their rates of change with SST warming. The dataset is partitioned into three vertical velocity regimes, with cloudy grid boxes categorized by phase (ice or liquid), opacity (opaque or thin), and the presence of near-surface precipitation. Opaque cloud cover is always larger in the presence of near-surface precipitation (high ice clouds especially). Low liquid water clouds in the descending regime dominate for SSTs < 299.25 K, where the free troposphere is dry (~20%), and opaque liquid water cloud cover decreases with SST warming (−8% K−1) and thin liquid water cloud cover stays constant (~20%). High ice clouds dominate the ascending regime in which, for 299.25 < SST < 301.75 K, humidity increases with SST in the lower free troposphere and peaks around 302 K. Over the warm SST range (>301.75 K), in the ascending regime, opaque high ice cloud cover decreases with SST (−13% K−1), while thin ice cloud cover increases (+6% K−1). Over the warm SST range, total cloudiness decreases with warming in all regimes. This paper characterizes fundamental relationships between aspects of the tropical atmospheric water cycle and SST.

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Experimental Investigation of the Atmosphere-Regolith Water Cycle on Present-Day Mars

Sensors ◽

10.3390/s21217421 ◽

2021 ◽

Vol 21 (21) ◽

pp. 7421

Author(s):

Abhilash Vakkada Ramachandran ◽

María-Paz Zorzano ◽

Javier Martín-Torres

Keyword(s):

Water Content ◽

Triple Point ◽

Liquid Water ◽

Water Cycle ◽

Pure Liquid ◽

Martian Surface ◽

Atmospheric Water ◽

Near Surface ◽

Martian Regolith

The water content of the upper layers of the surface of Mars is not yet quantified. Laboratory simulations are the only feasible way to investigate this in a controlled way on Earth, and then compare it with remote and in situ observations of spacecrafts on Mars. Describing the processes that may induce changes in the water content of the surface is critical to determine the present-day habitability of the Martian surface, to understand the atmospheric water cycle, and to estimate the efficiency of future water extraction procedures from the regolith for In Situ Resource Utilization (ISRU). This paper illustrates the application of the SpaceQ facility to simulate the near-surface water cycle under Martian conditions. Rover Environmental Monitoring Station (REMS) observations at Gale crater show a non-equilibrium situation in the atmospheric H2O volume mixing ratio (VMR) at night-time, and there is a decrease in the atmospheric water content by up to 15 g/m2 within a few hours. This reduction suggests that the ground may act at night as a cold sink scavenging atmospheric water. Here, we use an experimental approach to investigate the thermodynamic and kinetics of water exchange between the atmosphere, a non-porous surface (LN2-chilled metal), various salts, Martian regolith simulant, and mixtures of salts and simulant within an environment which is close to saturation. We have conducted three experiments: the stability of pure liquid water around the vicinity of the triple point is studied in experiment 1, as well as observing the interchange of water between the atmosphere and the salts when the surface is saturated; in experiment 2, the salts were mixed with Mojave Martian Simulant (MMS) to observe changes in the texture of the regolith caused by the interaction with hydrates and liquid brines, and to quantify the potential of the Martian regolith to absorb and retain water; and experiment 3 investigates the evaporation of pure liquid water away from the triple point temperature when both the air and ground are at the same temperature and the relative humidity is near saturation. We show experimentally that frost can form spontaneously on a surface when saturation is reached and that, when the temperature is above 273.15 K (0 °C), this frost can transform into liquid water, which can persist for up to 3.5 to 4.5 h at Martian surface conditions. For comparison, we study the behavior of certain deliquescent salts that exist on the Martian surface, which can increase their mass between 32% and 85% by absorption of atmospheric water within a few hours. A mixture of these salts in a 10% concentration with simulant produces an aggregated granular structure with a water gain of approximately 18- to 50-wt%. Up to 53% of the atmospheric water was captured by the simulated ground, as pure liquid water, hydrate, or brine.

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Thermodynamic Phase and Ice Cloud Properties in Northern Hemisphere Winter Extratropical Cyclones Observed by Aqua AIRS

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-15-0045.1 ◽

2015 ◽

Vol 54 (11) ◽

pp. 2283-2303 ◽

Cited By ~ 8

Author(s):

Catherine M. Naud ◽

Brian H. Kahn

Keyword(s):

Northern Hemisphere ◽

Cloud Cover ◽

Frontal Region ◽

Extratropical Cyclones ◽

Ice Clouds ◽

Ice Cloud ◽

Cloud Properties ◽

Hemisphere Winter ◽

Thermodynamic Phase ◽

Northern Hemisphere Winter

AbstractIce cloud properties in Northern Hemisphere winter extratropical cyclones are examined using the Atmospheric Infrared Sounder (AIRS), version 6, cloud products. The cloud thermodynamic phase product indicates that warm frontal clouds are dominated by ice, liquid-phase clouds occur outside of the warm frontal region, and supercooled or mixed-phase clouds are found in the southwestern quadrant of the cyclones. Stratiform ice clouds populate the warm frontal region and portions of the cold sector while convective ice clouds populate southeastern portions of the warm front and the southeastern quadrant. Total cloud cover is smaller in land cyclones than in ocean cyclones, especially in the southwestern quadrant and the warm frontal region. Ice cloud cover is less over land in the warm frontal region, because land cyclones are generally weaker and drier than ocean cyclones. The impact of cyclone average precipitable water (PW) and the magnitude of 850-hPa vertical ascent ω850 on the thermodynamic phase, occurrence of stratiform or convective ice cloud, ice particle effective diameter, optical thickness, and cloud-top temperature are discussed. When comparing land and ocean cyclones with similar PW and ω850, ice cloud coverage is found to be greater over land. Convective ice cloud occurs more often and is deeper over land. Supercooled cloud appears to persist to colder temperatures over ocean than over land, especially in the warm frontal region. These results suggest that, over land, ice cloud formation in warm fronts is possibly more efficient because of a greater aerosol amount from local or regional sources.

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A spectral method for discriminating thermodynamic phase and retrieving cloud optical thickness and effective radius using transmitted solar radiance spectra

Atmospheric Measurement Techniques ◽

10.5194/amt-8-1361-2015 ◽

2015 ◽

Vol 8 (3) ◽

pp. 1361-1383 ◽

Cited By ~ 14

Author(s):

S. E. LeBlanc ◽

P. Pilewskie ◽

K. S. Schmidt ◽

O. Coddington

Keyword(s):

Root Mean Square ◽

Optical Thickness ◽

Liquid Water ◽

Effective Radius ◽

Least Square ◽

Mean Square ◽

Ice Cloud ◽

Cloud Optical Thickness ◽

Water Cloud ◽

Thermodynamic Phase

Abstract. A new retrieval scheme for cloud optical thickness, effective radius, and thermodynamic phase was developed for ground-based measurements of cloud shortwave solar spectral transmittance. Fifteen parameters were derived to quantify spectral variations in shortwave transmittance due to absorption and scattering of liquid water and ice clouds, manifested by shifts in spectral slopes, curvatures, maxima, and minima. To retrieve cloud optical thickness and effective particle radius, a weighted least square fit that matched the modeled parameters was applied. The measurements for this analysis were made with the ground-based Solar Spectral Flux Radiometer in Boulder, Colorado, between May 2012 and January 2013. We compared the cloud optical thickness and effective radius from the new retrieval to two other retrieval methods. By using multiple spectral features, we find a closer fit (with a root mean square difference over the entire spectra of 3.1% for a liquid water cloud and 5.9% for an ice cloud) between measured and modeled spectra compared to two other retrieval methods which diverge by a root mean square of up to 6.4% for a liquid water cloud and 22.5% for an ice cloud. The new retrieval introduced here has an average uncertainty in effective radius (± 1.2 μm) smaller by factor of at least 2.5 than two other methods when applied to an ice cloud.

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Distinguishing cirrus cloud presence in autonomous lidar measurements

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-7-7207-2014 ◽

2014 ◽

Vol 7 (7) ◽

pp. 7207-7243

Author(s):

J. R. Campbell ◽

M. A. Vaughan ◽

M. Oo ◽

R. E. Holz ◽

J. R. Lewis ◽

...

Keyword(s):

Orthogonal Polarization ◽

Cirrus Cloud ◽

Ice Clouds ◽

Ice Cloud ◽

Lidar Measurements ◽

Abstract Level ◽

Water Cloud ◽

Cloud Top Temperature ◽

Level 2 ◽

Global Mean

Abstract. Level 2 Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite-based cloud datasets from 2012 are investigated for metrics that help distinguish the cirrus cloud presence of in autonomous lidar measurements, using temperatures, heights, optical depth and phase. A thermal threshold, proposed by Sassen and Campbell (2001; SC2001) for cloud top temperature Ttop ≤ −37 °C, is evaluated vs. CALIOP algorithms that identify ice-phase cloud layers alone using depolarized backscatter. Global mean cloud top heights (11.15 vs. 10.07 km a.m.s.l.), base heights (8.76 vs. 7.95 km a.m.s.l.), temperatures (−58.48 °C vs. −52.18 °C and −42.40 °C vs. −38.13 °C, respectively for tops and bases) and optical depths (1.18 vs. 1.23) reflect the sensitivity to these competing constraints. Over 99% of all Ttop ≤ −37 °C clouds are classified as ice by CALIOP Level 2 algorithms. Over 81% of all ice clouds correspond with Ttop ≤ −37 °C. For instruments lacking polarized measurements, and thus practical phase estimates, Ttop ≤ −37 °C proves stable for distinguishing cirrus, as opposed to the risks of glaciated liquid water cloud contamination occurring in a given sample from clouds identified at warmer temperatures. Uncertainties in temperature profiles use to collocate with lidar data (i.e., model reanalyses/sondes) may justifiably relax the Ttop ≤ −37 °C threshold to include warmer cases. The ambiguity of "warm" (Ttop > −37 °C) ice cloud genus cannot be reconciled completely with available measurements, however, conspicuously including phase. Cloud top heights and optical depths are evaluated as potential constraints, as functions of CALIOP-retrieved phase. However, these data provide, at best, additional constraint in regional samples, compared with temperature alone, and may exacerbate classification uncertainties overall globally.

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On the Fidelity of Large-Eddy Simulation of Shallow Precipitating Cumulus Convection

Monthly Weather Review ◽

10.1175/2011mwr3599.1 ◽

2011 ◽

Vol 139 (9) ◽

pp. 2918-2939 ◽

Cited By ~ 62

Author(s):

Georgios Matheou ◽

Daniel Chung ◽

Louise Nuijens ◽

Bjorn Stevens ◽

Joao Teixeira

Keyword(s):

Large Eddy Simulation ◽

Liquid Water ◽

Cloud Cover ◽

Scale Model ◽

Trade Wind ◽

Numerical Dissipation ◽

Surface Precipitation ◽

Eddy Simulation ◽

Large Eddy ◽

The Impact

The present study considers the impact of various choices pertaining to the numerical solution of the governing equations on large-eddy simulation (LES) prediction and the association of these choices with flow physics. These include the effect of dissipative versus nondissipative advection discretizations, different implementations of the constant-coefficient Smagorinsky subgrid-scale model, and grid resolution. Simulations corresponding to the trade wind precipitating shallow cumulus composite case of the Rain in Cumulus over the Ocean (RICO) field experiment were carried out. Global boundary layer quantities such as cloud cover, liquid water path, surface precipitation rate, power spectra, and the overall convection structure were used to compare the effects of different discretization implementations. The different discretization implementations were found to exert a significant impact on the LES prediction even for the cases where the process of precipitation was not included. Increasing numerical dissipation decreases cloud cover and surface precipitation rates. For nonprecipitating cases, grid convergence is achieved for grid spacings of 20 m. Cloud cover was found to be particularly sensitive, exhibiting variations between different resolution runs even when the mean liquid water profile had converged.

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On the regional climatic impact of contrails: microphysical and radiative properties of contrails and natural cirrus clouds

Annales Geophysicae ◽

10.1007/s00585-997-1457-4 ◽

1997 ◽

Vol 15 (11) ◽

pp. 1457-1467 ◽

Cited By ~ 31

Author(s):

B. Strauss ◽

R. Meerkoetter ◽

B. Wissinger ◽

P. Wendling ◽

M. Hess

Keyword(s):

Surface Temperature ◽

Temperature Increase ◽

Cloud Cover ◽

Cirrus Clouds ◽

Radiative Properties ◽

Atmospheric Conditions ◽

Ice Clouds ◽

Ice Cloud ◽

The Impact ◽

Radiative Characteristics

Abstract. The impact of contrail-induced cirrus clouds on regional climate is estimated for mean atmospheric conditions of southern Germany in the months of July and October. This is done by use of a regionalized one-dimensional radiative convective model (RCM). The influence of an increased ice cloud cover is studied by comparing RCM results representing climatological values with a modified case. In order to study the sensitivity of this effect on the radiative characteristics of the ice cloud, two types of additional ice clouds were modelled: cirrus and contrails, the latter cloud type containing a higher number of smaller and less of the larger cloud particles. Ice cloud parameters are calculated on the basis of a particle size distribution which covers the range from 2 to 2000 µm, taking into consideration recent measurements which show a remarkable amount of particles smaller than 20 µm. It turns out that a 10% increase in ice cloud cover leads to a surface temperature increase in the order of 1K, ranging from 1.1 to 1.2K in July and from 0.8 to 0.9K in October depending on the radiative characteristics of the air-traffic-induced ice clouds. Modelling the current contrail cloud cover which is near 0.5% over Europe yields a surface temperature increase in the order of 0.05K.

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Antarctic clouds, supercooled liquid water and mixed-phase investigated with DARDAR: geographical and seasonal variations

10.5194/acp-2018-1222 ◽

2018 ◽

Author(s):

Constantino Listowski ◽

Julien Delanoë ◽

Amélie Kirchgaessner ◽

Tom Lachlan-Cope ◽

John King

Keyword(s):

Sea Ice ◽

Liquid Water ◽

Supercooled Liquid ◽

Mixed Phase ◽

Ice Clouds ◽

Ice Cloud ◽

The One ◽

Autumn And Winter ◽

Mixed Phase Clouds ◽

Ice Fraction

Abstract. Antarctic tropospheric clouds are investigated using the radar-lidar DARDAR (raDAR/liDAR)-MASK products. The cloud fraction is divided into the supercooled liquid water (SLW)-containing clouds and the all-ice clouds. The low-level SLW fraction varies according to temperature and sea ice fraction. It is the largest over water. In East Antarctica, the SLW fraction decreases sharply polewards. It is twice to three times higher in West Antarctica. The all-ice cloud geographical distribution is shaped by the interaction of the main low-pressure systems surrounding the continent and the orography, with little links with sea ice fraction. We demonstrate the largest impact of sea ice on SLW (mostly mixed-phase clouds, MPC) in autumn and winter, while it is almost null in summer and intermediate in spring. Monthly variability of MPC shows a maximum fraction at the end of summer and minimum in winter. Conversely, the unglaciated (pure) SLW (USLW) fraction has a maximum at the beginning of summer. Monthly evolutions of MPC and USLW fractions do not differ on the continent. This demonstrates a seasonality in the glaciation process in marine liquid-bearing clouds. From the literature, we identify the pattern of the monthly evolution of the MPC fraction as being similar to the one of the aerosols, which is related to marine biological activity. Marine bioaerosols are known to be efficient Ice Nucleating Particles (INPs). The emission of these INPs into the atmosphere from open waters would come on top of the temperature and sea ice fraction seasonalities as factors explaining the mixed-phase clouds monthly evolution.

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A generalized method for discriminating thermodynamic phase and retrieving cloud optical thickness and effective radius using transmitted shortwave radiance spectra

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-7-5293-2014 ◽

2014 ◽

Vol 7 (6) ◽

pp. 5293-5346 ◽

Cited By ~ 4

Author(s):

S. E. LeBlanc ◽

P. Pilewskie ◽

K. S. Schmidt ◽

O. Coddington

Keyword(s):

Root Mean Square ◽

Optical Thickness ◽

Liquid Water ◽

Effective Radius ◽

Least Square ◽

Mean Square ◽

Ice Cloud ◽

Cloud Optical Thickness ◽

Water Cloud ◽

Thermodynamic Phase

Abstract. A new retrieval scheme for cloud optical thickness, effective radius, and thermodynamic phase was developed for ground-based measurements of cloud shortwave spectral transmittance. 15 parameters were derived to quantify spectral variations in shortwave transmittance due to absorption and scattering of liquid water and ice clouds, manifested by shifts in spectral slopes, curvatures, maxima, and minima. To retrieve cloud optical thickness and effective particle radius a weighted least square fit that matched the modeled parameters was applied. The measurements for this analysis were made with a ground-based Solar Spectral Flux Radiometer (SSFR) in Boulder, Colorado, between May 2012 and January 2013. We compared the cloud optical thickness and effective radius from the new retrieval to two other retrieval methods. By using multiple spectral features, we find a closer fit (with a root mean square difference over the entire spectra of 3.1% for a liquid water cloud and 5.9% for an ice cloud) between measured and modeled spectra compared to two other retrieval methods, which diverge by a root-mean-square of up to 6.4% for a liquid water cloud and 22.5% for an ice cloud. The new retrieval introduced here has an average uncertainty in effective radius (±1.2 μm) smaller by factor of at least 2.5 than two other methods when applied to an ice cloud.

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A model sensitivity study of the impact of clouds on satellite detection and retrieval of volcanic ash

Atmospheric Measurement Techniques ◽

10.5194/amt-8-1935-2015 ◽

2015 ◽

Vol 8 (5) ◽

pp. 1935-1949 ◽

Cited By ~ 10

Author(s):

A. Kylling ◽

N. Kristiansen ◽

A. Stohl ◽

R. Buras-Schnell ◽

C. Emde ◽

...

Keyword(s):

Radiative Transfer ◽

Liquid Water ◽

Volcanic Ash ◽

Spectral Band ◽

Sensitivity Study ◽

Transfer Model ◽

Mass Loading ◽

Ice Clouds ◽

Medium Range Weather Forecast ◽

The Impact

Abstract. Volcanic ash is commonly observed by infrared detectors on board Earth-orbiting satellites. In the presence of ice and/or liquid-water clouds, the detected volcanic ash signature may be altered. In this paper the sensitivity of detection and retrieval of volcanic ash to the presence of ice and liquid-water clouds was quantified by simulating synthetic equivalents to satellite infrared images with a 3-D radiative transfer model. The sensitivity study was made for the two recent eruptions of Eyjafjallajökull (2010) and Grímsvötn (2011) using realistic water and ice clouds and volcanic ash clouds. The water and ice clouds were taken from European Centre for Medium-Range Weather Forecast (ECMWF) analysis data and the volcanic ash cloud fields from simulations by the Lagrangian particle dispersion model FLEXPART. The radiative transfer simulations were made both with and without ice and liquid-water clouds for the geometry and channels of the Spinning Enhanced Visible and Infrared Imager (SEVIRI). The synthetic SEVIRI images were used as input to standard reverse absorption ash detection and retrieval methods. Ice and liquid-water clouds were on average found to reduce the number of detected ash-affected pixels by 6–12%. However, the effect was highly variable and for individual scenes up to 40% of pixels with mass loading >0.2 g m−2 could not be detected due to the presence of water and ice clouds. For coincident pixels, i.e. pixels where ash was both present in the FLEXPART (hereafter referred to as "Flexpart") simulation and detected by the algorithm, the presence of clouds overall increased the retrieved mean mass loading for the Eyjafjallajökull (2010) eruption by about 13%, while for the Grímsvötn (2011) eruption ash-mass loadings the effect was a 4% decrease of the retrieved ash-mass loading. However, larger differences were seen between scenes (standard deviations of ±30 and ±20% for Eyjafjallajökull and Grímsvötn, respectively) and even larger ones within scenes. The impact of ice and liquid-water clouds on the detection and retrieval of volcanic ash, implies that to fully appreciate the location and amount of ash, hyperspectral and spectral band measurements by satellite instruments should be combined with ash dispersion modelling.

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A Comparison of Aphelion Cloud Belt Phase Functions Before and After the Mars Year 34 Global Dust Storm

10.5194/epsc2021-372 ◽

2021 ◽

Author(s):

Alex Innanen ◽

Brittney Cooper ◽

Charissa Campbell ◽

Scott Guzewich ◽

Jacob Kloos ◽

...

Keyword(s):

Dust Storm ◽

Phase Function ◽

Dust Storms ◽

Ice Crystal ◽

Ice Clouds ◽

Water Ice ◽

Ice Cloud ◽

Sky Survey ◽

Scattering Phase ◽

Scattering Phase Function

1. INTRODUCTIONThe Mars Science Laboratory (MSL) is located in Gale Crater (4.5&#176;S, 137.4&#176;E), and has been performing cloud observations for the entirety of its mission, since its landing in 2012 [eg. 1,2,3]. One such observation is the Phase Function Sky Survey (PFSS), developed by Cooper et al [3] and instituted in Mars Year (MY) 34 to determine the scattering phase function of Martian water-ice clouds. The clouds of interest form during the Aphelion Cloud Belt (ACB) season (Ls=50&#176;-150&#176;), a period of time during which there is an increase in the formation of water-ice clouds around the Martian equator [4]. The PFSS observation was also performed during the MY 35 ACB season and the current MY 36 ACB season.Following the MY 34 ACB season, Mars experienced a global dust storm which lasted from Ls~188&#176; to Ls~250&#176; of that Mars year [5]. Global dust storms are planet-encircling storms which occur every few Mars years and can significantly impact the atmosphere leading to increased dust aerosol sizes [6], an increase in middle atmosphere water vapour [7], and the formation of unseasonal water-ice clouds [8]. While the decrease in visibility during the global dust storm itself made cloud observation difficult, comparing the scattering phase function prior to and following the global dust storm can help to understand the long-term impacts of global dust storms on water-ice clouds.2. METHODSThe PFSS consists of 9 cloud movies of three frames each, taken using MSL&#8217;s navigation cameras, at a variety of pointings in order to observe a large range of scattering angles. The goal of the PFSS is to characterise the scattering properties of water-ice clouds and to determine ice crystal geometry.&#160; In each movie, clouds are identified using mean frame subtraction, and the phase function is computed using the formula derived by Cooper et al [3]. An average phase function can then be computed for the entirety of the ACB season.<img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.eda718c85da062913791261/sdaolpUECMynit/1202CSPE&app=m&a=0&c=67584351a5c2fde95856e0760f04bbf3&ct=x&pn=gnp.elif&d=1" alt="Figure 1 &#8211; Temporal Distribution of Phase Function Sky Survey Observations for Mars Years 34 and 35" width="800" height="681">Figure 1 shows the temporal distributions of PFSS observations taken during MYs 34 and 35. We aim to capture both morning and afternoon observations in order to study any diurnal variability in water-ice clouds.3. RESULTS AND DISCUSSIONThere were a total of 26 PFSS observations taken in MY 35 between Ls~50&#176;-160&#176;, evenly distributed between AM and PM observations. Typically, times further from local noon (i.e. earlier in the morning or later in the afternoon) show stronger cloud features, and run less risk of being obscured by the presence of the sun. In all movies in which clouds are detected, a phase function can be calculated, and an average phase function determined for the whole ACB season. &#160;Future work will look at the water-ice cloud scattering properties for the MY 36 ACB season, allowing us to get more information about the interannual variability of the ACB and to further constrain the ice crystal habit. The PFSS observations will not only assist in our understanding of the long-term atmospheric impacts of global dust storms but also add to a more complete image of time-varying water-ice cloud properties.

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