Assessing the Surface Radiation Balance and Associated Components in an Intertidal Wetland

The surface radiation budget is an essential component of the total energy exchange between the atmosphere and the Earth&#8217;s surface. Measurements of radiative fluxes near/on ice surfaces are sparse in the polar regions, including on the Greenland Ice Sheet (GrIS), and the effects of cloud on radiative fluxes are still poorly studied. In this work, we assess the impacts of cloud on radiative fluxes using two metrics: the longwave-equivalent cloudiness, derived from long-wave radiation measurements, and the cloud transmittance factor, obtained from short-wave radiation. The metrics are applied to radiation data from two automatic weather stations located over the bare ground near the ice front of Helheim (HG) and Jakobshavn Isbr&#230; (JI) on the GrIS. Comparisons of meteorological parameters, surface radiation fluxes, and cloud metrics show significant differences between the two sites. The cloud transmittance factor is higher at HG than at JI, and the incoming short-wave radiation in the summer at HG is 50.0 W m&#8722;2 larger than at JI. Cloud metrics derived at the two sites reveal&#160; &#160;a high dependency on the wind direction. The total cloud radiative effect (CREnet) generally increases during melt season at the two stations due to long-wave CRE enhancement by cloud fraction.&#160;&#160;CREnet decreases from May to June and increases afterward, due to the strengthened short-wave CRE. The annually averaged CREnet were 3.0 &#177; 7.4 W m-2 and 1.9 &#177; 15.1 W m&#8722;2 at JI and HG.&#160; CREnet estimated from AWS indicates that clouds cool the JI and HG during melt season at different rates.

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Solar irradiance, air pollution and temperature changes in the Arctic

Philosophical Transactions of the Royal Society of London Series A Physical and Engineering Sciences ◽

10.1098/rsta.1995.0068 ◽

1995 ◽

Vol 352 (1699) ◽

pp. 247-258 ◽

Cited By ~ 22

Keyword(s):

Air Pollution ◽

Spatial Distribution ◽

Solar Irradiance ◽

Early Spring ◽

Surface Radiation ◽

The Arctic ◽

Radiation Balance ◽

Temperature Changes ◽

Global Irradiance ◽

Arctic Haze

A highly significant decrease in the annual sums of global irradiance reaching the surface of the Arctic, averaging 0.36 W m -2 per year, was derived from an analysis of 389 complete years of measurement, beginning in 1950, at 22 pyranometer stations within the Arctic Circle. The smaller data base of radiation balance measurements available showed a much smaller and statistically non-significant change. Reductions in global irradiance were most frequent in the early spring months and in the western sectors of the Arctic, coinciding with the seasonal and spatial distribution of the incursions of polluted air which give rise to the Arctic Haze. Irradiance measured in Antarctica during the same period showed a similar and more widespread decline despite the lower concentrations of pollutants. A marked increase in the surface radiation balance was recorded. Possible reasons for these interpolar anomalies and their consequences for temperature change are discussed.

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Simulation of Historic Glacier Variations with a Simple Climate-Glacier Model

Journal of Glaciology ◽

10.3189/s0022143000007103 ◽

1988 ◽

Vol 34 (118) ◽

pp. 333-341 ◽

Cited By ~ 1

Author(s):

Johannes Oerlemans

Keyword(s):

Volcanic Activity ◽

Climate Model ◽

Ring Width ◽

Volcanic Eruptions ◽

Solar Variability ◽

Surface Radiation ◽

Greenhouse Warming ◽

Radiation Balance ◽

Equilibrium Line Altitude ◽

Modelling Studies

AbstractGlacier variations during the last few centuries have shown a marked coherence over the globe. Characteristic features are the maximum stand somewhere in the middle of the nineteenth century, and the steady retreat afterwards (with some minor interruptions depending on the particular region). In many papers, qualitative statements have been made about the causes of these fluctuations. Lower temperatures associated with solar variability and/or volcanic activity are the most popular explanations. In particular, the statistical relation between glacier activity and major volcanic eruptions appears to be strong.In this paper, an attempt is made to simulate recent glacier fluctations with a physics-based model. A simple climate model, calculating perturbations of surface-radiation balance and air temperature (not necessarily in phase!), is coupled to a schematic time-dependent glacier model. The climate model is forced by volcanic activity (Greenland acidity and/or Lamb’s dust-veil index) and greenhouse warming. Solar variability was not considered, because its effect on climate has still not been demonstrated in a convincing way. The output is translated into variations in equilibrium-line altitude, driving the glacier model.The simulated variations in glacier length show good agreement with the observed record, but the amplitude is too small. This is improved when mass-balance gradients are assumed to be larger in warmer climates. Compared to recently published modelling studies of particular glaciers, in which series of local parameters (e.g. tree-ring width and temperature) were used as forcing, the present simulation is better. This suggests that the radiation balance is a decisive factor with regard to glacier variations on longer time-scales. The model experiments lend support to the results of Porter (1986), who concluded from a more qualitative study that a strong relation exists between periods of increased volcanic activity and glacier advances.A comparison of some selected runs shows that, according to the present model, the greenhouse warming would be responsible for about 50% of the glacier retreat observed over the last 100 years.

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Sea ice representation in sea ice model of CICE and Icepack

10.5194/egusphere-egu2020-21935 ◽

2020 ◽

Author(s):

Caixin Wang ◽

Mats A. Granskog ◽

Jens Boldingh Debernard ◽

Keguang Wang

Keyword(s):

Sea Ice ◽

Mass Balance ◽

National Laboratory ◽

Arctic Sea Ice ◽

Surface Radiation ◽

Radiation Balance ◽

Momentum Exchange ◽

Spectral Radiation ◽

Ice Mass Balance ◽

Ice Model

Sea ice is a critical component of the Earth system, playing an important role in high-latitude surface radiation balance and heat, moisture and momentum exchange between atmosphere and ocean. In recent years, rapid changes have been occurring in Arctic sea ice, including decline in ice extent/area, decreasing in ice thickness and volume, and shifting towards a first- year ice (FYI) dominated, rather than multi-year ice (MYI) dominated ice pack. These are one of the most well-known and striking examples of climate change. However, representing these changes in the model is still in question since most of our knowledge is based on MYI. CICE is a sea ice model developed at Los Alamos National Laboratory since 1994. It is widely used to simulate the growth, melt and movement of sea ice, and to resolve the biogeochemical processes. Its column version, Icepack, has been separated from CICE after CICE V5.1.2, which provides additional opportunity for simulating the evolution of drifting sea ice floes. How about the representation of sea ice in a column model (Icepack) and a 3d model (CICE)? In 2012, an ice mass balance buoy (IMB) and a Spectral Radiation Buoy (SRB) were deployed on FYI near the North Pole, and later drifted towards Fram Strait. These buoys collected a complete summer melt season of in-band (350-800 nm) spectral solar radiation and sea ice mass balance data. In this study, we apply the Icepack (version 1.1.1) and CICE (version 5.1.2) to investigate the seasonal evolution of sea ice in 2012 in these two models, and assess how well the physical processes are represented in CICE and Icepack, with the focus on the surface changes.

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Developing Best Practices for Observing Global Surface Shortwave and Longwave Radiation across the Land and Ocean

10.5194/egusphere-egu2020-6018 ◽

2020 ◽

Author(s):

Robert Weller ◽

Christian Lanconelli ◽

Martin Wild ◽

Joerg Trenmann

Keyword(s):

Climate Models ◽

Global Climate ◽

Surface Radiation ◽

Global Ocean ◽

Radiation Balance ◽

Radiative Fluxes ◽

Temporal Sampling ◽

The Earth ◽

Calibration Methods

In-situ shortwave or solar radiation and longwave or thermal radiation are observed at the earth&#8217;s surface on both the land and the ocean.&#160; In addition, satellites are used to develop fields of surface radiation balance.&#160; Planning for the Global Ocean Observing System (GOOS) and the Global Climate Observing System (GCOS) has identified surface heat flux, including the radiative fluxes, as an Essential Ocean Variable (EOV) and Essential Climate Variable (ECV), respectively.&#160; The GOOS and GCOS requirements for surface radiative fluxes (spatial and temporal sampling, accuracies) are summarized here.&#160; Surface radiation sites will continue to be sparse in the future, especially in the ocean; and satellite-derived products developed in concert with in-situ observing system will be important.&#160; To make better progress towards meeting those requirements, we propose the goal of establishing dialog across the different methods of in-situ observing surface radiation and with the remote sensing community.&#160; Objectives of the effort would include sharing knowledge and experience of how to make the observations, documentation of calibration methods, and assessment of the uncertainties to be associated with the different observing methods.&#160; The resulting metadata and quantitative understanding of the different approaches would support improved combination of surface radiation observations across land and sea into homogeneous products at global scale.&#160; At the same time, improved in-situ sampling would help assess and validate climate models and contribute to our understanding of the earth&#8217;s energy balance.&#160; We review here the different observing methods now in use on land and at sea and discuss the challenges faced in making the observations.&#160; We also propose future field inter-comparison and standardization of calibration methods to better establish the accuracy and comparability of surface radiation observations on land and at sea.

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Contributions of Clouds, Surface Albedos, and Mixed-Phase Ice Nucleation Schemes to Arctic Radiation Biases in CAM5

Journal of Climate ◽

10.1175/jcli-d-13-00608.1 ◽

2014 ◽

Vol 27 (13) ◽

pp. 5174-5197 ◽

Cited By ~ 34

Author(s):

Jason M. English ◽

Jennifer E. Kay ◽

Andrew Gettelman ◽

Xiaohong Liu ◽

Yong Wang ◽

...

Keyword(s):

Radiant Energy ◽

Cloud Amount ◽

Ice Nucleation ◽

Radiative Flux ◽

Mixed Phase ◽

Surface Radiation ◽

Nucleation Theory ◽

The Arctic ◽

Radiation Balance ◽

Ice Nuclei

The Arctic radiation balance is strongly affected by clouds and surface albedo. Prior work has identified Arctic cloud liquid water path (LWP) and surface radiative flux biases in the Community Atmosphere Model, version 5 (CAM5), and reductions to these biases with improved mixed-phase ice nucleation schemes. Here, CAM5 net top-of-atmosphere (TOA) Arctic radiative flux biases are quantified along with the contributions of clouds, surface albedos, and new mixed-phase ice nucleation schemes to these biases. CAM5 net TOA all-sky shortwave (SW) and outgoing longwave radiation (OLR) fluxes are generally within 10 W m−2 of Clouds and the Earth’s Radiant Energy System Energy Balanced and Filled (CERES-EBAF) observations. However, CAM5 has compensating SW errors: Surface albedos over snow are too high while cloud amount and LWP are too low. Use of a new CAM5 Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) lidar simulator that corrects an error in the treatment of snow crystal size confirms insufficient cloud amount in CAM5 year-round. CAM5 OLR is too low because of low surface temperature in winter, excessive atmospheric water vapor in summer, and excessive cloud heights year-round. Simulations with two new mixed-phase ice nucleation schemes—one based on an empirical fit to ice nuclei observations and one based on classical nucleation theory with prognostic ice nuclei—improve surface climate in winter by increasing cloud amount and LWP. However, net TOA and surface radiation biases remain because of increases in midlevel clouds and a persistent deficit in cloud LWP. These findings highlight challenges with evaluating and modeling Arctic cloud, radiation, and climate processes.

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