The Surface Energy Budget Computed at the Grid-Scale of a Climate Model Challenged by Station Data in West Africa

Abstract. This paper describes the implementation of an improved soil thermodynamics in the hydrological module of Earth system model (ESM) developed at the Institut Pierre Simon Laplace (IPSL) and its effects on land surface meteorology in the IPSL climate model. A common vertical discretization scheme for the soil moisture and for the soil temperature is adopted. In addition to the heat conduction process, the heat transported by liquid water into the soil is modeled. The thermal conductivity and the heat capacity are parameterized as a function of the soil moisture and the texture. Preliminary tests are performed in an idealized 1-D (one-dimensional) framework and the full model is then evaluated in the coupled land–atmospheric module of the IPSL ESM. A nudging approach is used in order to avoid the time-consuming long-term simulations required to account for the natural variability of the climate. Thanks to this nudging approach, the effects of the modified parameterizations can be modeled. The dependence of the soil thermal properties on moisture and texture lead to the most significant changes in the surface energy budget and in the surface temperature, with the strongest effects on the surface energy budget taking place over dry areas and during the night. This has important consequences on the mean surface temperature over dry areas and during the night and on its short-term variability. The parameterization of the soil thermal properties could therefore explain some of the temperature biases and part of the dispersion over dry areas in simulations of extreme events such as heat waves in state-of-the-art climate models.

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Breakup of nocturnal low-level stratiform clouds during the southern West African monsoon season

10.5194/egusphere-egu21-6538 ◽

2021 ◽

Author(s):

Maurin Zouzoua ◽

Fabienne Lohou ◽

Marie Lothon ◽

Paul Assamoi ◽

Véronique Yoboue ◽

...

Keyword(s):

Boundary Layer ◽

Surface Energy ◽

West Africa ◽

Energy Budget ◽

Monsoon Season ◽

Surface Energy Budget ◽

Cloud Base ◽

Shallow Cumulus ◽

Cloud Characteristics ◽

Breakup Time

During monsoon season in southern West Africa (SWA), nocturnal stratiform low-level clouds (LLSC) frequently form over a region extending from Guinean coast to several hundred kilometers inland. The cloud deck persists at least until sunrise next day, affecting surface-energy budget and related processes. However, LLSC lifetime is underestimated by numerical weather prediction and climate models.The DACCIWA (Dynamics-Aerosol-Chemistry-Cloud-Interactions-over-West-Africa) field campaign, in June-July 2016, paved the way for studying LLSC over SWA based on high-quality-observational dataset. The first analyzes of this data highlighted that the LLSC diurnal cycle consists of four main stages: the stable, jet, stratus and convective phases. Unlike the first three, the convective phase, which starts after sunrise and ends when LLSC breaks up, has not been well documented yet.This study analyzes the LLSC evolution during stratus and convective phases, specifically addressing the LLSC transition toward other low-cloud types during sunlight hours. It is based on comprehensive dataset acquired during twenty-two precipitation-free LLSC occurrences at Sav&#232; (Benin) during the DACCIWA fiel campaign. The cloud-characteristics are deduced from ceilometer and cloud-radar measurements. The associated atmospheric conditions are provided by surface meteorological and energy balance stations, radiosoundings and an Ultra-High-Frequency wind profiler.The LLSC forms (beginning of the stratus phase) decoupled from surface. In thirteen cases, the LLSC remains decoupled until the convective phase (case D). Conversely, in the other nine cases, the cloud gets coupled with surface before sunrise, within the four hours after cloud formation (case C). The coupling is accompanied by cloud base lowering and near-neutral thermal stability in subcloud-layer. Almost all cases C are observed during a period with well-established monsoon-flow over SWA. But, the weak differences of thermodynamical conditions between cases C and D suggest that, contributions of both mesoscale and local processes are crucial for coupling LLSC to the surface before sunrise. In early morning, the macrophysical and thermodynamical characteristics of the LLSC in case C are slightly different from the case D, suggesting that, even during night, the coupling with surface impacts the cloud characteristics.The LLSC evolution during convective phase depends upon the coupling at initial stage. In cases C, the evolution pattern is quite similar, the cloud base rises up under solar heating and shallow cumulus form when the cloud deck breaks up, around 11:30 UTC or later. For some of cases D, the LLSC couples with surface as the convective atmospheric boundary-layer grows and reaches the cloud base. The subsequent evolution and breakup time are then similar to case C. For most of cases D, LLSC remains decoupled from surface, and shallow cumulus form at the convective mixed layer top, under the LLSC deck. In this scenario, the LLSC breakup-time mostly occurs before 11:30 UTC. Thus, the coupling between LLSC and surface is a key factor for its evolution and maintenance after sunrise. Correct simulation of this feature may improve models performance over SWA. The impacts of LLSC on surface-energy budget and verical development of boundary-layer are also quantified.

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The improvement of soil thermodynamics and its effects on land surface meteorology in the IPSL climate model

Geoscientific Model Development Discussions ◽

10.5194/gmdd-8-8411-2015 ◽

2015 ◽

Vol 8 (10) ◽

pp. 8411-8450

Author(s):

F. Wang ◽

F. Cheruy ◽

J.-L. Dufresne

Keyword(s):

Soil Moisture ◽

Thermal Properties ◽

Surface Energy ◽

Surface Temperature ◽

Energy Budget ◽

Land Surface ◽

Climate Model ◽

Surface Energy Budget ◽

Dry Areas ◽

Soil Thermal Properties

Abstract. This paper describes the implementation of an improved soil thermodynamics in the hydrological module of Earth System Model (ESM) developed at the Institut Pierre Simon Laplace (IPSL) and its effects on land surface meteorology in the IPSL climate model. A common vertical discretization scheme for the soil moisture and for the soil temperature is adopted. In addition to the heat conduction process, the heat transported by liquid water into the soil is modeled. The thermal conductivity and the heat capacity are parameterized as a function of the soil moisture and the texture. Preliminary tests are performed in an idealized 1-D framework and the full model is then evaluated in the coupled land/atmospheric module of the IPSL ESM. A nudging approach is used in order to avoid the time-consuming long-term simulations required to account for the natural variability of the climate. Thanks to this nudging approach, the effects of the modified parameterizations can be modeled. The dependence of the soil thermal properties on moisture and texture lead to the most significant changes in the surface energy budget and in the surface temperature, with the strongest effects on the surface energy budget taking place over dry areas and during the night. This has important consequences on the mean surface temperature over dry areas and during the night and on its short-term variability. The parameterization of the soil thermal properties could therefore explain some of the temperature biases and part of the dispersion over dry areas in simulations of extreme events such as heat waves in state-of-the-art climate models.

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Dust radiative forcing and its impact on surface energy budget over West Africa

Scientific Reports ◽

10.1038/s41598-020-69223-4 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 3

Author(s):

Abdoul Aziz Saidou Chaibou ◽

Xiaoyan Ma ◽

Tong Sha

Keyword(s):

Surface Energy ◽

West Africa ◽

Energy Budget ◽

Radiative Forcing ◽

Surface Energy Budget

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Influence of Subfacet Heterogeneity and Material Properties on the Urban Surface Energy Budget

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-13-0286.1 ◽

2014 ◽

Vol 53 (9) ◽

pp. 2114-2129 ◽

Cited By ~ 23

Author(s):

Prathap Ramamurthy ◽

Elie Bou-Zeid ◽

James A. Smith ◽

Zhihua Wang ◽

Mary L. Baeck ◽

...

Keyword(s):

Surface Energy ◽

Energy Budget ◽

Material Properties ◽

Sensible Heat Flux ◽

Role Reversal ◽

Surface Energy Budget ◽

Urban Surface ◽

Urban Site ◽

Peak Time ◽

Sensible Heat

AbstractUrban facets—the walls, roofs, and ground in built-up terrain—are often conceptualized as homogeneous surfaces, despite the obvious variability in the composition and material properties of the urban fabric at the subfacet scale. This study focuses on understanding the influence of this subfacet heterogeneity, and the associated influence of different material properties, on the urban surface energy budget. The Princeton Urban Canopy Model, which was developed with the ability to capture subfacet variability, is evaluated at sites of various building densities and then applied to simulate the energy exchanges of each subfacet with the atmosphere over a densely built site. The analyses show that, although all impervious built surfaces convert most of the incoming energy into sensible heat rather than latent heat, sensible heat fluxes from asphalt pavements and dark rooftops are 2 times as high as those from concrete surfaces and light-colored roofs. Another important characteristic of urban areas—the shift in the peak time of sensible heat flux in comparison with rural areas—is here shown to be mainly linked to concrete’s high heat storage capacity as well as to radiative trapping in the urban canyon. The results also illustrate that the vegetated pervious soil surfaces that dot the urban landscape play a dual role: during wet periods they redistribute much of the available energy into evaporative fluxes but when moisture stressed they behave more like an impervious surface. This role reversal, along with the direct evaporation of water stored over impervious surfaces, significantly reduces the overall Bowen ratio of the urban site after rain events.

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Surface energy budget over the central Arctic Ocean during late summer and early freeze-up

Journal of Geophysical Research Atmospheres ◽

10.1029/2000jd900083 ◽

2001 ◽

Vol 106 (D23) ◽

pp. 32187-32205 ◽

Cited By ~ 18

Author(s):

E. Douglas Nilsson ◽

Üllar Rannik ◽

Måns Håkansson

Keyword(s):

Surface Energy ◽

Arctic Ocean ◽

Energy Budget ◽

Late Summer ◽

Surface Energy Budget ◽

Central Arctic Ocean

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Measuring the impact of a new snow model using surface energy budget process relationships

10.1002/essoar.10502951.1 ◽

2020 ◽

Author(s):

Jonathan Day ◽

Gabriele Arduini ◽

Irina Sandu ◽

Linus Magnusson ◽

Anton Beljaars ◽

...

Keyword(s):

Surface Energy ◽

Energy Budget ◽

Surface Energy Budget ◽

Budget Process ◽

Snow Model ◽

The Impact

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Projected Changes in Soil Temperature and Surface Energy Budget Components over the Alps and Northern Italy

Water ◽

10.3390/w10070954 ◽

2018 ◽

Vol 10 (7) ◽

pp. 954 ◽

Cited By ~ 2

Author(s):

Claudio Cassardo ◽

Seon Park ◽

Sungmin O ◽

Marco Galli

Keyword(s):

Heat Flux ◽

Surface Energy ◽

Soil Temperature ◽

Energy Budget ◽

Regional Climate ◽

Northern Italy ◽

Surface Energy Budget ◽

Future Climate ◽

Radiative Properties ◽

The Alps

This study investigates the potential changes in surface energy budget components under certain future climate conditions over the Alps and Northern Italy. The regional climate scenarios are obtained though the Regional Climate Model version 3 (RegCM3) runs, based on a reference climate (1961–1990) and the future climate (2071–2100) via the A2 and B2 scenarios. The energy budget components are calculated by employing the University of Torino model of land Processes Interaction with Atmosphere (UTOPIA), and using the RegCM3 outputs as input data. Our results depict a significant change in the energy budget components during springtime over high-mountain areas, whereas the most relevant difference over the plain areas is the increase in latent heat flux and hence, evapotranspiration during summertime. The precedence of snow-melting season over the Alps is evidenced by the earlier increase in sensible heat flux. The annual mean number of warm and cold days is evaluated by analyzing the top-layer soil temperature and shows a large increment (slight reduction) of warm (cold) days. These changes at the end of this century could influence the regional radiative properties and energy cycles and thus, exert significant impacts on human life and general infrastructures.

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