Graupel Precipitating from Thin Arctic Clouds with Liquid Water Paths less than 50 g m ‐2

2021 ◽  
Author(s):  
Kyle E. Fitch ◽  
Timothy J. Garrett
Keyword(s):  
Liquid Water ◽  
Arctic Clouds

scholarly journals The Influence of Cloud and Surface Properties on the Arctic Ocean Shortwave Radiation Budget in Coupled Models*

2008 ◽  
Vol 21 (5) ◽  
pp. 866-882 ◽  
Author(s):  
Irina V. Gorodetskaya ◽  
L-Bruno Tremblay ◽  
Beate Liepert ◽  
Mark A. Cane ◽  
Richard I. Cullather
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Liquid Water ◽  
Surface Albedo ◽  
Liquid Water Content ◽  
Radiation Budget ◽  
The Arctic ◽  
Coupled Models ◽  
Arctic Clouds ◽  
The Arctic Ocean

Abstract The impact of Arctic sea ice concentrations, surface albedo, cloud fraction, and cloud ice and liquid water paths on the surface shortwave (SW) radiation budget is analyzed in the twentieth-century simulations of three coupled models participating in the Intergovernmental Panel on Climate Change Fourth Assessment Report. The models are the Goddard Institute for Space Studies Model E-R (GISS-ER), the Met Office Third Hadley Centre Coupled Ocean–Atmosphere GCM (UKMO HadCM3), and the National Center for Atmosphere Research Community Climate System Model, version 3 (NCAR CCSM3). In agreement with observations, the models all have high Arctic mean cloud fractions in summer; however, large differences are found in the cloud ice and liquid water contents. The simulated Arctic clouds of CCSM3 have the highest liquid water content, greatly exceeding the values observed during the Surface Heat Budget of the Arctic Ocean (SHEBA) campaign. Both GISS-ER and HadCM3 lack liquid water and have excessive ice amounts in Arctic clouds compared to SHEBA observations. In CCSM3, the high surface albedo and strong cloud SW radiative forcing both significantly decrease the amount of SW radiation absorbed by the Arctic Ocean surface during the summer. In the GISS-ER and HadCM3 models, the surface and cloud effects compensate one another: GISS-ER has both a higher summer surface albedo and a larger surface incoming SW flux when compared to HadCM3. Because of the differences in the models’ cloud and surface properties, the Arctic Ocean surface gains about 20% and 40% more solar energy during the melt period in the GISS-ER and HadCM3 models, respectively, compared to CCSM3. In twenty-first-century climate runs, discrepancies in the surface net SW flux partly explain the range in the models’ sea ice area changes. Substantial decrease in sea ice area simulated during the twenty-first century in CCSM3 is associated with a large drop in surface albedo that is only partly compensated by increased cloud SW forcing. In this model, an initially high cloud liquid water content reduces the effect of the increase in cloud fraction and cloud liquid water on the cloud optical thickness, limiting the ability of clouds to compensate for the large surface albedo decrease. In HadCM3 and GISS-ER, the compensation of the surface albedo and cloud SW forcing results in negligible changes in the net SW flux and is one of the factors explaining moderate future sea ice area trends. Thus, model representations of cloud properties for today’s climate determine the ability of clouds to compensate for the effect of surface albedo decrease on the future shortwave radiative budget of the Arctic Ocean and, as a consequence, the sea ice mass balance.

scholarly journals Effects of long-range aerosol transport on the microphysical properties of low-level liquid clouds in the Arctic

2016 ◽  
Vol 16 (7) ◽  
pp. 4661-4674 ◽  
Author(s):  
Quentin Coopman ◽  
Timothy J. Garrett ◽  
Jérôme Riedi ◽  
Sabine Eckhardt ◽  
Andreas Stohl
Keyword(s):  
Long Range ◽  
Liquid Water ◽  
Specific Humidity ◽  
The Arctic ◽  
Liquid Water Path ◽  
Arctic Clouds ◽  
Low Level ◽  
Microphysical Properties ◽  
Lower Tropospheric Stability ◽  
Pollution Concentrations

Abstract. The properties of low-level liquid clouds in the Arctic can be altered by long-range pollution transport to the region. Satellite, tracer transport model, and meteorological data sets are used here to determine a net aerosol–cloud interaction (ACInet) parameter that expresses the ratio of relative changes in cloud microphysical properties to relative variations in pollution concentrations while accounting for dry or wet scavenging of aerosols en route to the Arctic. For a period between 2008 and 2010, ACInet is calculated as a function of the cloud liquid water path, temperature, altitude, specific humidity, and lower tropospheric stability. For all data, ACInet averages 0.12 ± 0.02 for cloud-droplet effective radius and 0.16 ± 0.02 for cloud optical depth. It increases with specific humidity and lower tropospheric stability and is highest when pollution concentrations are low. Carefully controlling for meteorological conditions we find that the liquid water path of arctic clouds does not respond strongly to aerosols within pollution plumes. Or, not stratifying the data according to meteorological state can lead to artificially exaggerated calculations of the magnitude of the impacts of pollution on arctic clouds.

scholarly journals Effects of 20–100 nanometre particles on liquid clouds in the clean summertime Arctic

2016 ◽  
Author(s):  
W. R. Leaitch ◽  
A. Korolev ◽  
A. A. Aliabadi ◽  
J. Burkart ◽  
M. Willis ◽  
...  
Keyword(s):  
Liquid Water ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Cloud Droplet ◽  
The Arctic ◽  
Arctic Clouds ◽  
Aerosol Cloud ◽  
Clean Environment ◽  
Albedo Effect ◽  
20 Nm

Abstract. Aerosol-cloud research in the Arctic has largely focused on the springtime resulting in relatively little information about the effects of the atmospheric aerosol on Arctic clouds during summer. An airborne study, carried out during July, 2014 from Resolute Bay, Nunavut, Canada, provides a comprehensive in-situ look into some effects of aerosol particles on liquid clouds in the clean environment of the Arctic summer. The median cloud droplet number concentrations (CDNC) are 10 cm−3 and 101 cm−3 for low altitude cloud (LA: clouds topped below 200 m) and higher altitude cloud (HA: clouds based above 200 m), respectively. The mean lower activation size of aerosol particles is ≤ 50 nm diameter in 40 % of the cases, and particles as small as 20 nm activated in the HA clouds consistent with the higher supersaturations inferred for those clouds. Over 60 % of the LA cloud cases fall into the cloud condensation nuclei (CCN)-limited regime of Mauritsen et al. (2011) within which increases in CDNC may increase liquid water and warm the surface. In that CCN-limited regime, the liquid water contents (LWC) and the CDNC are positively correlated, but there is no dependence of changes in either the CDNC or LWC on the aerosol, suggesting no aerosol limitation. Above the Mauritsen limit, where indirect cooling may result, particles with diameters from 20 nm to 100 nm exert a strong influence on the CDNC. Based on CO concentrations, the background CDNC are estimated to range between 16 cm−3 and 160 cm−3, implying a large uncertainty for the baseline of the aerosol cloud albedo effect.

scholarly journals Stability dependent increases in liquid water with droplet number in the Arctic

2021 ◽  
Author(s):  
Rebecca Jonette Murray-Watson ◽  
Edward Gryspeerdt
Keyword(s):  
Liquid Water ◽  
Cloud Droplet ◽  
Surface Energy Budget ◽  
Radiative Properties ◽  
The Arctic ◽  
Polar Regions ◽  
Liquid Water Path ◽  
Arctic Clouds ◽  
Microphysical Properties ◽  
The Relationship

Abstract. The effects of aerosols on cloud microphysical properties are a large source of uncertainty when assessing anthropogenic climate change. The aerosol-cloud relationship is particularly unclear in high-latitude polar regions due to a limited number of observations. Cloud liquid water path (LWP) is an important control on cloud radiative properties, particularly in the Arctic, where clouds play a central role in the surface energy budget. Therefore, understanding how aerosols may alter cloud LWP is important, especially as aerosol sources such as industry and shipping move further north in a warming Arctic. Using satellite data, this work investigates the effects of aerosols on liquid Arctic clouds over open ocean by considering the relationship between cloud droplet number concentration (Nd) and LWP, an important component of the aerosol-LWP relationship. The LWP response to Nd varies significantly across the region, with increases in LWP with Nd observed at very high latitudes in multiple satellite datasets, with this positive signal observed most strongly during the summer months. This result is in contrast to the negative response typically seen in global satellite studies and previous work on Arctic clouds showing little LWP response to aerosols. The lower tropospheric stability (LTS) was found to be the driving force behind the spatial variations in LWP response, strongly influencing the sign and magnitude of the Nd-LWP relationship, with increases in LWP in high stability environments. The influence of humidity varied depending on the stability, with little impact at low LTS but a strong influence at high. The background Nd state does not seem to dominate the LWP response, despite the non-linearities in the relationship. As the LTS is projected to decrease in a future, warmer Arctic, these results show that increases may produce lower cloud water paths, offsetting their shortwave cooling effect.

Reciprocal Polarizable Embedding with a Transferable H2O Potential Function II: Application to (H2O)n Clusters & Liquid Water

2019 ◽  
Author(s):  
Asmus Ougaard Dohn ◽  
Elvar Jónsson ◽  
Hannes Jonsson
Keyword(s):  
Density Functional Theory ◽  
Liquid Water ◽  
Density Functional ◽  
Water Clusters ◽  
Theory Model ◽  
Coupling Scheme ◽  
Functional Theory ◽  
Total Polarization ◽  
Electrostatic Embedding ◽  
Polarizable Embedding

The manuscript analyzes the accuracy of our recently developed reciprocal polarizable embedding scheme, where a density functional theory model of the QM region is coupled to a dipole- and quadrupole polarizable water potential of the MM region. We present calculations of water clusters and liquid water where we analyze the energy, atomic forces and total polarization to demonstrate that artifacts in energy and polarization introduced by the QM/MM coupling are small and well-behaved. Furthermore, our methodology improves the consistency of the structure of optimized water hexamer geometries when compared to results obtained with models that neglect polarization. Additionally, the manuscript provides evidence that our coupling scheme eliminates artifacts in the structure of liquid water obtained with simpler electrostatic embedding models.

Lichens of the Oasis Molodyozhnyi and adjacent areas (Enderby Land, Antarctic)

2013 ◽  
Vol 47 ◽  
pp. 167-178 ◽  
Author(s):  
M. P. Andreev
Keyword(s):  
Liquid Water ◽  
Climate Conditions ◽  
Water Ice ◽  
Buellia Frigida ◽  
Antarctic Continent ◽  
Harsh Climate ◽  
The Antarctic ◽  
First Time ◽  
Lichen Flora

Lichen flora and vegetation in the vicinity of the Russian base «Molodyozhnaya» (Enderby Land, Antarctica) were investigated in 2010–2011 in details for the first time. About 500 specimens were collected in 100 localities in all available ecotopes. The lichen flora is the richest in the region and numbers 39 species (21 genera, 11 families). The studied vegetation is very poor and sparse, but typical for coastal oases of the Antarctic continent. The poorness is caused by the extremely harsh climate conditions, insufficient availability of liquid water, ice-free land, and high insolation levels. The dominant and most common lichens are Rinodina olivaceobrunnea, Amandinea punctata, Candelariella flava, Physcia caesia, Caloplaca tominii, Lecanora expectans, Caloplaca ammiospila, Lecidea cancriformis, Pseudephebe minuscula, Lecidella siplei, Umbilicaria decussata, Buellia frigida, Lecanora fuscobrunnea, Usnea sphacelata, Lepraria and Buellia spp.

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