Supplementary material to "Introducing Ice Nucleating Particles functionality into the Unified Model and its impact on the Southern Ocean short-wave radiation biases"

Abstract. Insufficient reflection of short-wave radiation especially over the Southern Ocean region is still a leading issue in many present-day global climate models. One of the potential reasons for this observed bias is an inadequate representation of clouds. In a previous study, we modified the cloud micro-physics scheme in the Unified Model and showed that choosing a more realistic value for the capacitance or shape parameter of atmospheric ice-crystals, in better agreement with theory and observations, benefits the simulation of short-wave radiation over the Southern Ocean by brightening the clouds. However, attempts to modify the cloud phase by directly adjusting the micro-physics process rates like capacitance tend to affect both the hemispheres symmetrically whereas we seek to brighten only the high-latitude Southern Hemisphere clouds. In this study we implement a simple prognostic parametrisation whereby the heterogeneous ice nucleation temperature is made to vary three-dimensionally as a function of the mineral dust distribution in the model. As a result, those regions with less dust number density would have lower nucleation temperature compared to the default global value of −10 °C. By using mineral dust as an indicator for ice nucleating particles in the model, this parametrisation thus captures the impact of ice nucleating particles on the cloud distribution due to its general paucity over the Southern Ocean region. This approach thus improves the physics of the model with minimal complexity.

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Improved simulation of clouds over the Southern Ocean in a General Circulation Model

10.5194/acp-2019-884 ◽

2019 ◽

Author(s):

Vidya Varma ◽

Olaf Morgenstern ◽

Paul Field ◽

Kalli Furtado ◽

Jonny Williams ◽

...

Keyword(s):

Southern Ocean ◽

General Circulation ◽

Climate Models ◽

Circulation Model ◽

Supercooled Liquid ◽

Short Wave ◽

Global Climate Models ◽

Ice Crystals ◽

Wave Radiation ◽

Short Wave Radiation

Abstract. The present generation of global climate models is characterized by insufficient reflection of short-wave radiation over the Southern Ocean due to a misrepresentation of clouds. This is a significant concern as it leads to excessive heating of the ocean surface, sea surface temperature biases, and subsequent problems with atmospheric dynamics. In this study we modify cloud micro-physics in a recent version of the Met Office's Unified Model and show that choosing a more realistic value for the shape parameter of atmospheric ice-crystals, in better agreement with theory and observations, benefits the simulation of short-wave radiation. In the model, for calculating the growth rate of ice crystals through deposition, the default assumption is that all ice particles are spherical in shape. We modify this assumption to effectively allow for oblique shapes or aggregates of ice crystals. Along with modified ice nucleation temperatures, we achieve a reduction in the annual-mean short-wave cloud radiative effect over the Southern Ocean by up to 4 W/m2, and seasonally much larger reductions. By slowing the growth of the ice phase, the model simulates substantially more supercooled liquid cloud. We hypothesize that such abundant supercooled liquid cloud is the result of a paucity of ice nucleating particles in this part of the atmosphere.

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Improving the Southern Ocean cloud albedo biases in a general circulation model

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-7741-2020 ◽

2020 ◽

Vol 20 (13) ◽

pp. 7741-7751

Author(s):

Vidya Varma ◽

Olaf Morgenstern ◽

Paul Field ◽

Kalli Furtado ◽

Jonny Williams ◽

...

Keyword(s):

Southern Ocean ◽

General Circulation ◽

Climate Models ◽

Circulation Model ◽

Short Wave ◽

Cloud Microphysics ◽

Global Climate Models ◽

Ice Crystals ◽

Wave Radiation ◽

Short Wave Radiation

Abstract. The present generation of global climate models is characterised by insufficient reflection of short-wave radiation over the Southern Ocean due to a misrepresentation of clouds. This is a significant concern as it leads to excessive heating of the ocean surface, sea surface temperature biases and subsequent problems with atmospheric dynamics. In this study, we modify cloud microphysics in a recent version of the Met Office's Unified Model and show that choosing a more realistic value for the shape parameter of atmospheric ice crystals, in better agreement with theory and observations, benefits the simulation of short-wave radiation. In the model, for calculating the growth rate of ice crystals through deposition, the default assumption is that all ice particles are spherical in shape. We modify this assumption to effectively allow for oblique shapes or aggregates of ice crystals. Along with modified ice nucleation temperatures, we achieve a reduction in the annual-mean short-wave cloud radiative effect over the Southern Ocean by up to ∼4 W m−2 and seasonally much larger reductions compared to the control model. By slowing the growth of the ice phase, the model simulates substantially more supercooled liquid cloud.

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Excitation of Short-Wave Radiation by Nonrelativistic Oscillators

2007 International Kharkiv Symposium Physics and Engrg. of Millimeter and Sub-Millimeter Waves (MSMW) ◽

10.1109/msmw.2007.4294737 ◽

2007 ◽

Author(s):

A.N. Antonov ◽

V.A. Buts ◽

A.M Egorov ◽

O.F. Kovpik ◽

E.A. Kornilov ◽

...

Keyword(s):

Short Wave ◽

Wave Radiation ◽

Short Wave Radiation

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Evaluating the Effects of Façade Greening on Human Bioclimate in a Complex Urban Environment

Advances in Meteorology ◽

10.1155/2015/747259 ◽

2015 ◽

Vol 2015 ◽

pp. 1-15 ◽

Cited By ~ 43

Author(s):

Britta Jänicke ◽

Fred Meier ◽

Marie-Therese Hoelscher ◽

Dieter Scherer

Keyword(s):

Heat Stress ◽

Short Wave ◽

Wave Radiation ◽

Short Wave Radiation ◽

Long Wave ◽

Building Facades ◽

Urban Heat ◽

The Mean ◽

Human Bioclimate ◽

Radiant Temperature

The evaluation of the effectiveness of countermeasures for a reduction of urban heat stress, such as façade greening, is challenging due to lacking transferability of results from one location to another. Furthermore, complex variables such as the mean radiant temperature(Tmrt)are necessary to assess outdoor human bioclimate. We observedTmrtin front of a building façade in Berlin, Germany, which is half-greened while the other part is bare.Tmrtwas reduced (mean 2 K) in front of the greened compared to the bare façade. To overcome observational shortcomings, we applied the microscale models ENVI-met, RayMan, and SOLWEIG. We evaluated these models based on observations. Our results show thatTmrt(MD = −1.93 K) and downward short-wave radiation (MD = 14.39 W/m2) were sufficiently simulated in contrast to upward short-wave and long-wave radiation. Finally, we compare the simulated reduction ofTmrtwith the observed one in front of the façade greening, showing that the models were not able to simulate the effects of façade greening with the applied settings. Our results reveal that façade greening contributes only slightly to a reduction of heat stress in front of building façades.

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Albedo of Melting Sea Ice in the Southern Beaufort Sea

Journal of Glaciology ◽

10.3189/s0022143000013022 ◽

1971 ◽

Vol 10 (58) ◽

pp. 101-104 ◽

Cited By ~ 1

Author(s):

M.P. Langleben

Keyword(s):

Sea Ice ◽

Northwest Territories ◽

Beaufort Sea ◽

Ice Cover ◽

Short Wave ◽

Wave Radiation ◽

Short Wave Radiation ◽

Melting Period ◽

Fast Ice ◽

Made In

AbstractTwo Kipp hemispherical radiometers mounted back to back and suspended by an 18 m cable from a helicopter flying at an altitude of about 90 m were used to make measurements of incident and reflected short-wave radiation. The helicopter was brought to a hovering position at the instant of measurement to ensure that the radiometers were in the proper attitude and a photograph of the ice cover was taken at the same time. The observations were made in 1969 during 16 flights out of Tuktoyaktuk, Northwest Territories (lat. 69° 26’N., long. 133° 02’W.) over the fast ice extending 80 km north of Tuktoyaktuk. Values of albedo of the ice cover were found to decrease during the melting period according to the equation A = 0.59 —0.32P where P is the degree of puddling of the surface.

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Short-wave radiation from a tube with a gas screen

Journal of Applied Spectroscopy ◽

10.1007/bf00941427 ◽

1974 ◽

Vol 20 (4) ◽

pp. 434-438

Author(s):

E. M. Golubev ◽

N. N. Ogurtsova ◽

I. V. Podmoshenskii ◽

P. N. Rogovtsev

Keyword(s):

Short Wave ◽

Wave Radiation ◽

Short Wave Radiation ◽

Gas Screen

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Minimizing heterogeneity of VOS observations for improving estimates of short-wave radiation over the oceans

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/606/1/012001 ◽

2020 ◽

Vol 606 ◽

pp. 012001

Author(s):

M Aleksandrova

Keyword(s):

Short Wave ◽

Wave Radiation ◽

Short Wave Radiation

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Evaluation of the heat balance components over the Baltic Sea using four gridded meteorological databases and direct observations

Hydrology Research ◽

10.2166/nh.2005.0029 ◽

2005 ◽

Vol 36 (4-5) ◽

pp. 381-396 ◽

Cited By ~ 1

Author(s):

A. Rutgersson ◽

A. Omstedt ◽

Y. Chen

Keyword(s):

Baltic Sea ◽

Short Wave ◽

Heat Fluxes ◽

Wave Radiation ◽

Turbulent Heat ◽

The Baltic Sea ◽

Short Wave Radiation ◽

Turbulent Heat Fluxes ◽

The Baltic ◽

The Heat Balance

In this paper, which reports on part of the BALTEX project, various components of the heat balance over the Baltic Sea are calculated using a number of gridded meteorological databases. It is the heat exchange between the Baltic Sea surface and the atmosphere that is of interest. The databases have different origins, comprising synoptic data, data re-analysed with a 3D assimilation system, an ocean model forced with gridded synoptic data, ship data and satellite data. We compared the databases and found that the greatest variation between them is in the long- and short-wave radiation values. However, considerable upward long-wave radiation is followed by considerable downward short-wave radiation, so the total radiation component is partly compensated for in the total budget. The variation in the total heat transport in the databases therefore appears smaller (1.5±3 W m−2) as the average and one standard deviation. The turbulent heat fluxes estimated from satellite data have very low values; this can largely be explained by the method of calculating air temperature, which also produces an unrealistic stratification over the Baltic Sea. The ERA40 data was compared with measured values: there, we found a certain land influence even in the centre of the Baltic proper. The indicated turbulent heat fluxes were too large, mainly in the fall and winter, and the sensible heat flux was too large in a downward direction in spring and summer.

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