Coupling between land surface fluxes and lifting condensation level: mechanisms and sensitivity to model physics parameterizations

The ECMWF operational land surface model, based on the Carbon-Hydrology Tiled ECMWF Scheme for Surface Exchanges over Land (CHTESSEL) is the baseline for global weather, climate and environmental applications at ECMWF. In order to expedite its progress and benefit from international collaboration, an ECLand platform has been designed to host advanced and modular schemes. ECLand is paving the way toward a land model that could support a wider range of modelling applications, facilitating global kilometer scales testing as envisaged in the Copernicus and Destination Earth programmes. This presentation&#160;introduces the CHTESSEL and its recent new developments that aims at hosting new research applications.These new improvements touch upon different components of the model: (i) vegetation, (ii) snow, (iii) soil hydrology, (iv) open water/lakes (v) rivers and (vi) urban areas. The developments are evaluated separately with either offline simulations or coupled experiments, depending on their level of operational readiness, illustrating the benchmarking criteria for assessing process fidelity with regards to land surface fluxes and reservoirs involved in water-energy-carbon exchange, and within the Earth system prediction framework, as foreseen to enter upcoming ECMWF operational cycles.Reference: Souhail Boussetta, Gianpaolo Balsamo*, Anna Agust&#236;-Panareda, Gabriele Arduini, Anton Beljaars, Emanuel Dutra, Glenn Carver, Margarita Choulga, Ioan Hadade, Cinzia Mazzetti, Joaqu&#236;n Mun&#245;z-Sabater, Joe McNorton, Christel Prudhomme, Patricia De Rosnay, Irina Sandu, Nils Wedi, Dai Yamazaki, Ervin Zsoter, 2021: ECLand: an ECMWF land surface modelling platform, MDPI Atmosphere, (in prep).

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Peering into the internal structure of cold pools and their interactions with a dense observational network

10.5194/dach2022-51 ◽

2021 ◽

Author(s):

Cathy Hohenegger ◽

Jaemyeong Seo ◽

Hannes Nevermann ◽

Bastian Kirsch ◽

Nima Shokri ◽

...

Keyword(s):

Internal Structure ◽

Land Surface ◽

Surface Fluxes ◽

Cold Pool ◽

Convective Clouds ◽

Cold Pools ◽

Soil Sensors ◽

Modelling Studies ◽

Surface Network ◽

Shed Light

Melting and evaporation of hydrometeors in and below convective clouds generates cold, dense air that falls through the atmospheric column and spreads at the surface like a density current, the cold pool. In modelling studies, the importance of cold pools in controlling the lifecycle of convection has often been emphasized, being through their organization of the cloud field or through their sheer deepening of the convection. Larger, longer-lived cold pools benefit convection, but little is actually known on the size and internal structure of cold pools from observations as the majority of cold pools are too small to be captured by the operational surface network. &#160;One aim of the field campaign FESSTVaL was to peer into the internal structure of cold pools and their interactions with the underlying land surface by deploying a dense network of surface observations. This network consisted of 80 self-designed cold pool loggers, 19 weather stations and 83 soil sensors deployed in an area of 15 km around Lindenberg. FESSTVaL took place from 17 May to 27 August 2021. In principle, cold pool characteristics are affected both by the atmospheric state, which fuels cold pools through melting and evaporation of hydrometeors, and the land surface, which acts to destroy cold pools through friction and warming by surface fluxes. In this talk, the measurements collected during FESSTVaL will be used to shed light on these interactions. &#160;We are particularly interested to assess how homogeneous the internal structure of cold pools is and whether heterogeneities of the land surface imprint themselves on this internal structure. The results will be compared to available model simulations.

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Vegetation dynamics and soil water balance in a water-limited Mediterranean ecosystem on Sardinia, Italy

Hydrology and Earth System Sciences ◽

10.5194/hess-12-1257-2008 ◽

2008 ◽

Vol 12 (6) ◽

pp. 1257-1271 ◽

Cited By ~ 25

Author(s):

N. Montaldo ◽

J. D. Albertson ◽

M. Mancini

Keyword(s):

Soil Water ◽

Land Surface ◽

Vegetation Dynamics ◽

Mediterranean Ecosystems ◽

Surface Fluxes ◽

Annual Rainfall ◽

Woody Vegetation ◽

Wide Range ◽

Hydrometeorological Conditions

Abstract. Mediterranean ecosystems are commonly heterogeneous savanna-like ecosystems, with contrasting plant functional types (PFTs, e.g. grass and woody vegetation) competing for water. Mediterranean ecosystems are also commonly characterized by strong inter-annual rainfall variability, which influences the distributions of PFTs that vary spatially and temporally. An extensive field campaign in a Mediterranean setting was performed with the objective to investigate interactions between vegetation dynamics, soil water budget and land-surface fluxes in a water-limited ecosystem. Also a vegetation dynamic model (VDM) is coupled to a 3-component (bare soil, grass and woody vegetation) Land surface model (LSM). The case study is in Orroli, situated in the mid-west of Sardegna within the Flumendosa river basin. The landscape is a mixture of Mediterranean patchy vegetation types: trees, including wild olives and cork oaks, different shrubs and herbaceous species. Land surface fluxes, soil moisture and vegetation growth were monitored during the May 2003–June 2006 period. Interestingly, hydrometeorological conditions of the monitored years strongly differ, with dry and wet years in turn, such that a wide range of hydrometeorological conditions can be analyzed. The coupled VDM-LSM model is successfully tested for the case study, demonstrating high model performance for the wide range of eco-hydrologic conditions. Results demonstrate also that vegetation dynamics are strongly influenced by the inter-annual variability of atmospheric forcing, with grass leaf area index changing significantly each spring season according to seasonal rainfall amount.

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The Jena Diversity-Dynamic Global Vegetation Model (JeDi-DGVM): a diverse approach to representing terrestrial biogeography and biogeochemistry based on plant functional trade-offs

Biogeosciences ◽

10.5194/bg-10-4137-2013 ◽

2013 ◽

Vol 10 (6) ◽

pp. 4137-4177 ◽

Cited By ~ 121

Author(s):

R. Pavlick ◽

D. T. Drewry ◽

K. Bohn ◽

B. Reu ◽

A. Kleidon

Keyword(s):

Functional Diversity ◽

Land Surface ◽

Grid Cell ◽

Surface Fluxes ◽

Growth Strategies ◽

Vegetation Model ◽

Terrestrial Biosphere ◽

Dynamic Global Vegetation Model ◽

Trade Offs ◽

Global Vegetation

Abstract. Terrestrial biosphere models typically abstract the immense diversity of vegetation forms and functioning into a relatively small set of predefined semi-empirical plant functional types (PFTs). There is growing evidence, however, from the field ecology community as well as from modelling studies that current PFT schemes may not adequately represent the observed variations in plant functional traits and their effect on ecosystem functioning. In this paper, we introduce the Jena Diversity-Dynamic Global Vegetation Model (JeDi-DGVM) as a new approach to terrestrial biosphere modelling with a richer representation of functional diversity than traditional modelling approaches based on a small number of fixed PFTs. JeDi-DGVM simulates the performance of a large number of randomly generated plant growth strategies, each defined by a set of 15 trait parameters which characterize various aspects of plant functioning including carbon allocation, ecophysiology and phenology. Each trait parameter is involved in one or more functional trade-offs. These trade-offs ultimately determine whether a strategy is able to survive under the climatic conditions in a given model grid cell and its performance relative to the other strategies. The biogeochemical fluxes and land surface properties of the individual strategies are aggregated to the grid-cell scale using a mass-based weighting scheme. We evaluate the simulated global biogeochemical patterns against a variety of field and satellite-based observations following a protocol established by the Carbon-Land Model Intercomparison Project. The land surface fluxes and vegetation structural properties are reasonably well simulated by JeDi-DGVM, and compare favourably with other state-of-the-art global vegetation models. We also evaluate the simulated patterns of functional diversity and the sensitivity of the JeDi-DGVM modelling approach to the number of sampled strategies. Altogether, the results demonstrate the parsimonious and flexible nature of a functional trade-off approach to global vegetation modelling, i.e. it can provide more types of testable outputs than standard PFT-based approaches and with fewer inputs. The approach implemented here in JeDi-DGVM sets the foundation for future applications that will explore the impacts of explicitly resolving diverse plant communities, allowing for a more flexible temporal and spatial representation of the structure and function of the terrestrial biosphere.

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Assessing the Impact of Changes in Land Surface Conditions on WRF Predictions in Arid Regions

Journal of Hydrometeorology ◽

10.1175/jhm-d-20-0083.1 ◽

2020 ◽

Vol 21 (12) ◽

pp. 2829-2853 ◽

Cited By ~ 1

Author(s):

Marouane Temimi ◽

Ricardo Fonseca ◽

Narendra Nelli ◽

Michael Weston ◽

Mohan Thota ◽

...

Keyword(s):

Eddy Covariance ◽

Soil Texture ◽

Land Surface ◽

Surface Wind ◽

Surface Fluxes ◽

Abu Dhabi ◽

Horizontal Wind ◽

Cold Bias ◽

Near Surface ◽

The Impact

AbstractA thorough evaluation of the Weather Research and Forecasting (WRF) Model is conducted over the United Arab Emirates, for the period September 2017–August 2018. Two simulations are performed: one with the default model settings (control run), and another one (experiment) with an improved representation of soil texture and land use land cover (LULC). The model predictions are evaluated against observations at 35 weather stations, radiosonde profiles at the coastal Abu Dhabi International Airport, and surface fluxes from eddy-covariance measurements at the inland city of Al Ain. It is found that WRF’s cold temperature bias, also present in the forcing data and seen almost exclusively at night, is reduced when the surface and soil properties are updated, by as much as 3.5 K. This arises from the expansion of the urban areas, and the replacement of loamy regions with sand, which has a higher thermal inertia. However, the model continues to overestimate the strength of the near-surface wind at all stations and seasons, typically by 0.5–1.5 m s−1. It is concluded that the albedo of barren/sparsely vegetated regions in WRF (0.380) is higher than that inferred from eddy-covariance observations (0.340), which can also explain the referred cold bias. At the Abu Dhabi site, even though soil texture and LULC are not changed, there is a small but positive effect on the predicted vertical profiles of temperature, humidity, and horizontal wind speed, mostly between 950 and 750 hPa, possibly because of differences in vertical mixing.

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Sensitivity of land surface and Cumulus schemes for Thunderstorm prediction

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xli-b8-271-2016 ◽

2016 ◽

Vol XLI-B8 ◽

pp. 271-275

Author(s):

Dinesh Kumar ◽

U. C. Mohanty ◽

Krishan Kumar

Keyword(s):

Land Surface ◽

Process Model ◽

Atmospheric Condition ◽

Surface Fluxes ◽

Lower Atmosphere ◽

Freezing Process ◽

Precipitation Process ◽

Convective System ◽

Cumulus Schemes ◽

Physical Parameterizations

The cloud processes play an important role in all forms of precipitation. Its proper representation is one of the challenging tasks in mesoscale numerical simulation. Studies have revealed that mesoscale feature require proper initialization which may likely to improve the convective system rainfall forecasts. Understanding the precipitation process, model initial condition accuracy and resolved/sub grid-scale precipitation processes representation, are the important areas which needed to improve in order to represent the mesoscale features properly. Various attempts have been done in order to improve the model performance through grid resolution, physical parameterizations, etc. But it is the physical parameterizations which provide a convective atmosphere for the development and intensification of convective events. Further, physical parameterizations consist of cumulus convection, surface fluxes of heat, moisture, momentum, and vertical mixing in the planetary boundary layer (PBL). How PBL and Cumulus schemes capture the evolution of thunderstorm have been analysed by taking thunderstorm cases occurred over Kolkata, India in the year 2011. PBL and cumulus schemes were customized for WSM-6 microphysics because WSM series has been widely used in operational forecast. Results have shown that KF (PBL scheme) and WSM-6 (Cumulus Scheme) have reproduced the evolution of surface variable such as CAPE, temperature and rainfall very much like observation. Further, KF and WSM-6 scheme also provided the increased moisture availability in the lower atmosphere which was taken to higher level by strong vertical velocities providing a platform to initiate a thunderstorm much better. Overestimation of rain in WSM-6 occurs primarily because of occurrence of melting and freezing process within a deeper layer in WSM-6 scheme. These Schemes have reproduced the spatial pattern and peak rainfall coverage closer to TRMM observation. It is the the combination of WSM-6, and KF schemes which have preformed reasonably well to reproduce the right atmospheric condition for a thunderstorm leading to improved spatial and temporal rainfall over the study domain. Thus the parameterization schemes of WMS-6 and KF have shown significant improvement by capturing the location, intensity and surface meteorological parameters closer to observed details.

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