On the Validation of the Simulation of Early Season Precipitation on the Island of Puerto Rico Using a Mesoscale Atmospheric Model

2008 ◽  
Vol 9 (3) ◽  
pp. 507-520 ◽  
Author(s):  
Daniel E. Comarazamy ◽  
Jorge E. González
Keyword(s):  
Puerto Rico ◽  
Spatial Distribution ◽  
Large Scale ◽  
Atmospheric Model ◽  
Atmospheric Modeling ◽  
Precipitation Event ◽  
Precipitation Pattern ◽  
Test Case ◽  
General Tendency ◽  
Mesoscale Atmospheric Model

Abstract The ability of a mesoscale atmospheric model to reproduce the spatial distribution of the precipitation of the Caribbean island of Puerto Rico during an early rainfall season month (April) is evaluated in this paper, taking the month of April 1998 as the primary test case, and analyzed in detail with subsequent simulations for April 1993. The monthly accumulated rainfall was simulated using the Regional Atmospheric Modeling System (RAMS), and the results were validated with precipitation data from 15 cooperative stations located throughout the island. The monthlong numerical simulation for April 1998 replicated the observed precipitation pattern, including the general spatial distribution, and daily and monthly totals, to varying degrees of accuracy. At specific locations, errors ranged from 2% in the rainy mountains to 82% in the San Juan metropolitan area, with a general tendency of the model to produce lower precipitation values throughout the simulation domain. An error analysis proved that the accuracy of the simulation is independent of elevation. The station data showed two dominant precipitation events during the month of April 1998: one on 2 April and the other on 16 April. The model was able to replicate the precipitation observed during the first precipitation event with less precision than for the second event. This might be attributed to the model’s inability to capture the large-scale forcing that produced the recorded amounts of rainfall observed during the second precipitation event. The results for total accumulated precipitation for April 1993 were very similar to the results for the April 1998 simulation, for both the spatial distribution and total values of rainfall.

scholarly journals The Application of an Evolutionary Algorithm to the Optimization of a Mesoscale Meteorological Model

2009 ◽  
Vol 48 (2) ◽  
pp. 317-329 ◽  
Author(s):  
Lance O’Steen ◽  
David Werth
Keyword(s):  
Cost Function ◽  
Evolutionary Algorithm ◽  
Synthetic Data ◽  
Atmospheric Model ◽  
Atmospheric Modeling ◽  
Model Parameters ◽  
Meteorological Model ◽  
Rms Error ◽  
Mesoscale Atmospheric Model ◽  
The Cost

Abstract It is shown that a simple evolutionary algorithm can optimize a set of mesoscale atmospheric model parameters with respect to agreement between the mesoscale simulation and a limited set of synthetic observations. This is illustrated using the Regional Atmospheric Modeling System (RAMS). A set of 23 RAMS parameters is optimized by minimizing a cost function based on the root-mean-square (rms) error between the RAMS simulation and synthetic data (observations derived from a separate RAMS simulation). It is found that the optimization can be done with relatively modest computer resources; therefore, operational implementation is possible. The overall number of simulations needed to obtain a specific reduction of the cost function is found to depend strongly on the procedure used to perturb the “child” parameters relative to their “parents” within the evolutionary algorithm. In addition, the choice of meteorological variables that are included in the rms error and their relative weighting are also found to be important factors in the optimization.

scholarly journals Evaluation of the Wind Power in the State of Paraíba Using the Mesoscale Atmospheric Model Brazilian Developments on the Regional Atmospheric Modelling System

2012 ◽  
Vol 2012 ◽  
pp. 1-16 ◽  
Author(s):  
Francisco José Lopes de Lima ◽  
Enilson Palmeira Cavalcanti ◽  
Enio Pereira de Souza ◽  
Emerson Mariano da Silva
Keyword(s):  
Wind Speed ◽  
Wind Power ◽  
Atmospheric Model ◽  
Atmospheric Modeling ◽  
The State ◽  
Regional Atmospheric Modeling System ◽  
Wind Regime ◽  
Regional Atmospheric Modelling System ◽  
Mesoscale Atmospheric Model ◽  
Regional Atmospheric Modeling

This work aims to describe the wind power density in five sites in the State of Paraiba, as well as to access the ability of the mesoscale atmospheric model Brazilian developments on the regional atmospheric modeling system (BRAMS) in describing the intensity of wind in São Gonçalo Monteiro, Patos, Campina Grande, and João Pessoa. Observational data are wind speed and direction at 10 m high, provided by the National Institute of Meteorology (INMET). We used the numerical model BRAMS in simulations for two different months. We ran the model for rainy months: March and April. It was concluded that the BRAMS model is able to satisfactorily reproduce the monthly cycle of the wind regime considered, as well as the main direction. However the model tends to underestimate the wind speed.

scholarly journals A statistical framework for conditional extreme event attribution

2017 ◽  
Vol 3 (1) ◽  
pp. 17-31 ◽  
Author(s):  
Pascal Yiou ◽  
Aglaé Jézéquel ◽  
Philippe Naveau ◽  
Frederike E. L. Otto ◽  
Robert Vautard ◽  
...  
Keyword(s):  
Atmospheric Circulation ◽  
Large Scale ◽  
Extreme Event ◽  
Climate Extremes ◽  
Atmospheric Model ◽  
Precipitation Event ◽  
Atmospheric Variability ◽  
Extreme Climate ◽  
Statistical Framework ◽  
Event Attribution

Abstract. The goal of the attribution of individual events is to estimate whether and to what extent the probability of an extreme climate event evolves when external conditions (e.g., due to anthropogenic forcings) change. Many types of climate extremes are linked to the variability of the large-scale atmospheric circulation. It is hence essential to decipher the roles of atmospheric variability and increasing mean temperature in the change of probabilities of extremes. It is also crucial to define a background state (or counterfactual) to which recent observations are compared. In this paper we present a statistical framework to determine the dynamical (linked to the atmospheric circulation) and thermodynamical (linked to slow forcings) contributions to the probability of extreme climate events. We illustrate this methodology on a record precipitation event that hit southern United Kingdom in January 2014. We compare possibilities for the creation of two states (or worlds) in which probability change is determined. These two worlds are defined in a large ensemble of atmospheric model simulations (Weather@Home factual and counterfactual simulations) and separate periods (new: 1951–2014, and old: 1900–1950) in reanalyses and observations. We discuss how the atmospheric circulation conditioning can affect the interpretation of extreme event attribution. We eventually show the qualitative coherence of results between the choice of worlds (factual/counterfactual vs. new/old).

scholarly journals A moist aquaplanet variant of the Held–Suarez test for atmospheric model dynamical cores

2015 ◽  
Vol 8 (9) ◽  
pp. 8263-8340 ◽  
Author(s):  
D. R. Thatcher ◽  
C. Jablonowski
Keyword(s):  
Large Scale ◽  
Atmospheric Model ◽  
Test Case ◽  
Physical Forcing ◽  
Scientific Investigations ◽  
Rayleigh Damping ◽  
Community Atmosphere Model ◽  
New Variant ◽  
Temperature Relaxation ◽  
Moist Processes

Abstract. A moist idealized test case (MITC) for atmospheric model dynamical cores is presented. The MITC is based on the Held–Suarez (HS) test that was developed for dry simulations on a flat Earth and replaces the full physical parameterization package with a Newtonian temperature relaxation and Rayleigh damping of the low-level winds. This new variant of the HS test includes moisture and thereby sheds light on the non-linear dynamics-physics moisture feedbacks without the complexity of full physics parameterization packages. In particular, it adds simplified moist processes to the HS forcing to model large-scale condensation, boundary layer mixing, and the exchange of latent and sensible heat between the atmospheric surface and an ocean-covered planet. Using a variety of dynamical cores of NCAR's Community Atmosphere Model (CAM), this paper demonstrates that the inclusion of the moist idealized physics package leads to climatic states that closely resemble aquaplanet simulations with complex physical parameterizations. This establishes that the MITC approach generates reasonable atmospheric circulations and can be used for a broad range of scientific investigations. This paper provides examples of two application areas. First, the test case reveals the characteristics of the physics-dynamics coupling technique and reproduces coupling issues seen in full-physics simulations. In particular, it is shown that sudden adjustments of the prognostic fields due to moist physics tendencies can trigger undesirable large-scale gravity waves, which can be remedied by a more gradual application of the physical forcing. Second, the moist idealized test case can be used to intercompare dynamical cores. These examples demonstrate the versatility of the MITC approach and suggestions are made for further application areas. The new moist variant of the HS test can be considered a test case of intermediate complexity.

scholarly journals Mesoscale numerical analysis of the historical November 1982 heavy precipitation event over Andorra (Eastern Pyrenees)

2013 ◽  
Vol 1 (3) ◽  
pp. 2495-2545 ◽  
Author(s):  
L. Trapero ◽  
J. Bech ◽  
F. Duffourg ◽  
P. Esteban ◽  
J. Lorente
Keyword(s):  
Large Scale ◽  
Flash Flood ◽  
Heavy Precipitation ◽  
Atmospheric Model ◽  
Mediterranean Coast ◽  
Precipitation Event ◽  
Heavy Precipitation Event ◽  
Water Vapour Content ◽  
Initial Water ◽  
Eastern Pyrenees

Abstract. From 6 to 8 November 1982 was recorded one of the most catastrophic flash-flood events in the Eastern Pyrenees affecting Andorra and also France and Spain with rainfall accumulations exceeding 400 mm in 24 h, 44 fatal victims and widespread damage. This paper aims to document exhaustively this heavy precipitation event and examines mesoscale simulations performed by the French Meso-NH non-hydrostatic atmospheric model. Large scale simulations show the slow-evolving synoptic environment favourable for the development of a deep Atlantic cyclone which induced a strong southerly flow over the Eastern Pyrenees. From the evolution of the synoptic pattern four distinct phases have been identified during the event. The mesoscale analysis presents the second and the third phase as the most intense in terms of rainfall accumulations and highlights the interaction of the moist and conditionally unstable flows with the mountains. The presence of a SW low level jet (30 m s−1) around 1500 m also had a crucial role on focusing the precipitation over the exposed south slopes of the Eastern Pyrenees. Backward trajectories based on Eulerian on-line passive tracers indicate that the orographic uplift was the main forcing mechanism which triggered and maintained the precipitating systems more than 30 h over the Pyrenees. The moisture of the feeding flow mainly came from the Atlantic Ocean (7–9 g kg−1) and the role of the Mediterranean as a local moisture source was very limited (2–3 g kg−1) due to the high initial water vapour content of the parcels and the rapid passage over the basin along the Spanish Mediterranean coast (less than 12 h).

scholarly journals Mesoscale numerical analysis of the historical November 1982 heavy precipitation event over Andorra (Eastern Pyrenees)

2013 ◽  
Vol 13 (11) ◽  
pp. 2969-2990 ◽  
Author(s):  
L. Trapero ◽  
J. Bech ◽  
F. Duffourg ◽  
P. Esteban ◽  
J. Lorente
Keyword(s):  
Large Scale ◽  
Flash Flood ◽  
Heavy Precipitation ◽  
Atmospheric Model ◽  
Mediterranean Coast ◽  
Precipitation Event ◽  
Heavy Precipitation Event ◽  
Water Vapour Content ◽  
Initial Water ◽  
Eastern Pyrenees

Abstract. From 6 to 8 November 1982 one of the most catastrophic flash-flood events was recorded in the Eastern Pyrenees affecting Andorra and also France and Spain with rainfall accumulations exceeding 400 mm in 24 h, 44 fatalities and widespread damage. This paper aims to exhaustively document this heavy precipitation event and examines mesoscale simulations performed by the French Meso-NH non-hydrostatic atmospheric model. Large-scale simulations show the slow-evolving synoptic environment favourable for the development of a deep Atlantic cyclone which induced a strong southerly flow over the Eastern Pyrenees. From the evolution of the synoptic pattern four distinct phases have been identified during the event. The mesoscale analysis presents the second and the third phase as the most intense in terms of rainfall accumulations and highlights the interaction of the moist and conditionally unstable flows with the mountains. The presence of a SW low level jet (30 m s−1) around 1500 m also had a crucial role on focusing the precipitation over the exposed south slopes of the Eastern Pyrenees. Backward trajectories based on Eulerian on-line passive tracers indicate that the orographic uplift was the main forcing mechanism which triggered and maintained the precipitating systems more than 30 h over the Pyrenees. The moisture of the feeding flow mainly came from the Atlantic Ocean (7–9 g kg−1) and the role of the Mediterranean as a local moisture source was very limited (2–3 g kg−1) due to the high initial water vapour content of the parcels and the rapid passage over the basin along the Spanish Mediterranean coast (less than 12 h).

scholarly journals A moist aquaplanet variant of the Held–Suarez test for atmospheric model dynamical cores

2016 ◽  
Vol 9 (4) ◽  
pp. 1263-1292 ◽  
Author(s):  
Diana R. Thatcher ◽  
Christiane Jablonowski
Keyword(s):  
Large Scale ◽  
Atmospheric Model ◽  
Test Case ◽  
Physical Forcing ◽  
Scientific Investigations ◽  
Rayleigh Damping ◽  
Community Atmosphere Model ◽  
New Variant ◽  
Temperature Relaxation ◽  
Moist Processes

Abstract. A moist idealized test case (MITC) for atmospheric model dynamical cores is presented. The MITC is based on the Held–Suarez (HS) test that was developed for dry simulations on “a flat Earth” and replaces the full physical parameterization package with a Newtonian temperature relaxation and Rayleigh damping of the low-level winds. This new variant of the HS test includes moisture and thereby sheds light on the nonlinear dynamics–physics moisture feedbacks without the complexity of full-physics parameterization packages. In particular, it adds simplified moist processes to the HS forcing to model large-scale condensation, boundary-layer mixing, and the exchange of latent and sensible heat between the atmospheric surface and an ocean-covered planet. Using a variety of dynamical cores of the National Center for Atmospheric Research (NCAR)'s Community Atmosphere Model (CAM), this paper demonstrates that the inclusion of the moist idealized physics package leads to climatic states that closely resemble aquaplanet simulations with complex physical parameterizations. This establishes that the MITC approach generates reasonable atmospheric circulations and can be used for a broad range of scientific investigations. This paper provides examples of two application areas. First, the test case reveals the characteristics of the physics–dynamics coupling technique and reproduces coupling issues seen in full-physics simulations. In particular, it is shown that sudden adjustments of the prognostic fields due to moist physics tendencies can trigger undesirable large-scale gravity waves, which can be remedied by a more gradual application of the physical forcing. Second, the moist idealized test case can be used to intercompare dynamical cores. These examples demonstrate the versatility of the MITC approach and suggestions are made for further application areas. The new moist variant of the HS test can be considered a test case of intermediate complexity.

Large-scale mapping of the catenas vegetation in Subarctic tundra

1995 ◽  
pp. 3-21
Author(s):  
S. S. Kholod
Keyword(s):  
Spatial Distribution ◽  
Vegetation Cover ◽  
Large Scale ◽  
Block Diagram ◽  
Abiotic Factors ◽  
Ecological Factors ◽  
Spatial Arrangement ◽  
Geological Time ◽  
Ecological Barriers ◽  
Functional Zones

One of the most difficult tasks in large-scale vegetation mapping is the clarification of mechanisms of the internal integration of vegetation cover territorial units. Traditional way of searching such mechanisms is the study of ecological factors controlling the space heterogeneity of vegetation cover. In essence, this is autecological analysis of vegetation. We propose another way of searching the mechanisms of territorial integration of vegetation. It is connected with intracoenotic interrelation, in particular, with the changing role of edificator synusium in a community along the altitudinal gradient. This way of searching is illustrated in the model-plot in subarctic tundra of Central Chukotka. Our further suggestion concerns the way of depicting these mechanisms on large-scale vegetation map. As a model object we chose the catena, that is the landscape formation including all geomorphjc positions of a slope, joint by the process of moving the material down the slope. The process of peneplanation of a mountain system for a long geological time favours to the levelling the lower (accumulative) parts of slopes. The colonization of these parts of the slope by the vegetation variants, corresponding to the lowest part of catena is the result of peneplanation. Vegetation of this part of catena makes a certain biogeocoenotic work which is the levelling of the small infralandscape limits and of the boundaries in vegetation cover. This process we name as the continualization on catena. In this process the variants of vegetation in the lower part of catena are being broken into separate synusiums. This is the process of decumbation of layers described by V. B. Sochava. Up to the slope the edificator power of the shrub synusiums sharply decreases. Moss and herb synusium have "to seek" the habitats similar to those under the shrub canopy. The competition between the synusium arises resulting in arrangement of a certain spatial assemblage of vegetation cover elements. In such assemblage the position of each element is determined by both biotic (interrelation with other coenotic elements) and abiotic (presence of appropriate habitats) factors. Taking into account the biogeocoenotic character of the process of continualization on catena we name such spatial assemblage an exolutionary-biogeocoenotic series. The space within each evolutionary-biogeocoenotic series is divided by ecological barriers into some functional zones. In each of the such zones the struggle between synusiums has its individual expression and direction. In the start zone of catena (extensive pediment) the interrelations of synusiums and layers control the mutual spatial arrangement of these elements at the largest extent. Here, as a rule, there predominate edificator synusiums of low and dwarfshrubs. In the first order limit zone (the bend of pediment to the above part of the slope) one-species herb and moss synusiums, oftenly substituting each other in similar habitats, get prevalence. In the zone of active colonization of slope (denudation slope) the coenotic factor has the least role in the spatial distribution of the vegetation cover elements. In particular, phytocoenotic interactions take place only within separate microcoenoses of herbs, mosses and lichens. In the zone of the attenuation of continualization process (the upper most parts of slope, crests) phytocoenotic interactions are almost absent and the spatial distribution of vegetation cover elements depends exclusively on the abiotic factors. The principal scheme of the distribution of vegetation cover elements and the disposition of functional zones on catena are shown on block-diagram (fig. 1).

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