Changes in the simulation of atmospheric instability over the Iberian Peninsula due to the use of 3DVAR data assimilation

Abstract. The ability of two downscaling experiments to correctly simulate thermodynamic conditions over the Iberian Peninsula (IP) is compared in this paper. To do so, three parameters used to evaluate the unstable conditions in the atmosphere are evaluated: the total totals index (TT), convective available potential energy (CAPE), and convective inhibition (CIN). The Weather and Research Forecasting (WRF) model is used for the simulations. The N experiment is driven by ERA-Interim's initial and boundary conditions. The D experiment has the same configuration as N, but the 3DVAR data assimilation step is additionally run at 00:00, 06:00, 12:00, and 18:00 UTC. Eight radiosondes are available over the IP, and the vertical temperature and moisture profiles from the radiosondes provided by the University of Wyoming and the Integrated Global Radiosonde Archive (IGRA) were used to calculate three parameters commonly used to represent atmospheric instability by our own methodology using the R package aiRthermo. According to the validation, the correlation, standard deviation (SD), and root mean squared error (RMSE) obtained by the D experiment for all the variables at most of the stations are better than those for N. The different methods produce small discrepancies between the values for TT, but these are larger for CAPE and CIN due to the dependency of these quantities on the initial conditions assumed for the calculation of a lifted air parcel. Similar results arise from the seasonal analysis concerning both WRF experiments: N tends to overestimate or underestimate (depending on the parameter) the variability of the reference values of the parameters, but D is able to capture it in most of the seasons. In general, D is able to produce more reliable results due to the more realistic values of dew point temperature and virtual temperature profiles over the IP. The heterogeneity of the studied variables is highlighted in the mean maps over the IP. According to those for D, the unstable air masses are found along the entire Atlantic coast during winter, but in summer they are located particularly over the Mediterranean coast. The convective inhibition is more extended towards inland at 00:00 UTC in those areas. However, high values are also observed near the southeastern corner of the IP (near Murcia) at 12:00 UTC. Finally, no linear relationship between TT, CAPE, or CIN was found, and consequently, CAPE and CIN should be preferred for the study of the instability of the atmosphere as more atmospheric layers are employed during their calculation than for the TT index.

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Changes in the simulation of instability indices over the Iberian Peninsula due to the use of 3DVAR data assimilation

10.5194/hess-2020-53 ◽

2020 ◽

Author(s):

Santos J. González-Rojí ◽

Sheila Carreno-Madinabeitia ◽

Jon Sáenz ◽

Gabriel Ibarra-Berastegi

Keyword(s):

Data Assimilation ◽

Iberian Peninsula ◽

Initial Conditions ◽

Atlantic Coast ◽

Wrf Model ◽

R Package ◽

Mediterranean Coast ◽

Convective Precipitation ◽

Seasonal Analysis ◽

Instability Indices

Abstract. The ability of two downscaling experiments to correctly simulate the instability conditions that can trigger thunderstorms over the Iberian Peninsula is compared in this paper. To do so, three instability indices are evaluated: TT index, CAPE and CIN. The WRF model is used for the simulations. The N experiment is driven by ERA-Interim’s initial and boundary conditions; The D experiment has the same configuration as N, but the 3DVAR data assimilation step is additionally run at 00, 06, 12 and 18 UTC. Eight radiosondes are available over the IP, and the values for these indices calculated from the University of Wyoming were chosen as reference in the validation of both simulations. Additionally, measured variables at different pressure levels from the radiosondes provided byWyoming were used to calculate the three instability indices by our own methodology using the R package aiRthermo. According to the validation, the correlation, SD and RMSE obtained by the experiment D for all the indices in most of the stations are better than those for N. The different methodologies produce small discrepancies between the values for TT, but these are larger for CAPE and CIN due to the dependency of these indices on the initial conditions assumed for the calculation of an air parcel’s vertical evolution. Similar results arise from the seasonal analysis concerning both WRF experiments: N tends to overestimate or underestimate (depending on the index) the variability of the reference values, but D is able to capture it in most of the seasons. The heterogeneity of the indices is highlighted in the mean maps over the Iberian Peninsula. According to those from D, the ingredients for the development of convective precipitation during winter are found along the entire Atlantic coast, but in summer they are located particularly in the Mediterranean coast. The chances of developing thunderstorms in those areas at 12 UTC is much higher than at 00 UTC; The convective inhibition is more extended towards inland at 00 UTC in those areas, which prevents storms from developing. However, high values are observed near Murcia also at 12 UTC.

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Lacunarity, predictability and predictive instability of the daily pluviometric regime in the Iberian Peninsula

Nonlinear Processes in Geophysics ◽

10.5194/npg-14-109-2007 ◽

2007 ◽

Vol 14 (2) ◽

pp. 109-121 ◽

Cited By ~ 8

Author(s):

M. D. Martínez ◽

X. Lana ◽

A. Burgueño ◽

C. Serra

Keyword(s):

Spatial Distribution ◽

Iberian Peninsula ◽

Lyapunov Exponents ◽

Atlantic Coast ◽

Power Laws ◽

Rain Gauge ◽

Mediterranean Coast ◽

Western Atlantic ◽

Dry Spells ◽

Dry Spell

Abstract. The complexity of the daily pluviometric regime of the Iberian Peninsula is analysed from the point of view of its lacunarity, predictability and predictive instability. The database consists of daily pluviometric records obtained from 43 rain gauges in Spain and Portugal for the period 1950–1990. Five different series are generated for every rain gauge. The first series is constituted by the consecutive daily amounts. The other four consist of dry spell lengths with respect to daily amount thresholds of 0.1, 1.0, 5.0 and 10.0 mm/day. A dry spell length is defined as the number of consecutive days with rainfall amounts below one of these thresholds. The empirical lacunarity for every rain gauge is well reproduced by two power laws, the exponents varying notably from one gauge to another. The spatial distribution of the lacunarity is characterised by a north to south or southeast gradient, thus suggesting that this parameter can be a useful tool to distinguish between different pluviometric regimes. The predictability of the five series is quantified by means of the rescaled analysis and the interpretation of the Hurst exponent. Its patterns reveal that most part of the Iberian Peninsula shows signs of persistence for the daily rainfall and the dry spell series, although persistence is only clearly manifested in some small domains. The instability of possible predictive algorithms is analysed through the Lyapunov exponents. They are only computed for the series of daily amounts and for dry lengths respect to the threshold level of 0.1 mm/day due to the short number of dry spells for larger threshold levels. The series of daily amounts depict the highest instability along the Mediterranean coast. The series of dry spells show an increasing instability from NE to SW Spain, with a relevant nucleus of high Lyapunov values in the south-western Atlantic coast. As a summary, lacunarity and Hurst and Lyapunov exponents depict a relevant spatial variation, which is in agreement with well known patterns of the pluviometric regime, such as annual amount spatial distribution and return periods of dry spells.

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Peaks-over-Threshold Study of Trends in Extreme Rainfall over the Iberian Peninsula

Journal of Climate ◽

10.1175/2010jcli3627.1 ◽

2011 ◽

Vol 24 (4) ◽

pp. 1089-1105 ◽

Cited By ~ 55

Author(s):

Francisco Javier Acero ◽

José Agustín García ◽

María Cruz Gallego

Keyword(s):

Iberian Peninsula ◽

Extreme Events ◽

Atlantic Coast ◽

Generalized Pareto Distribution ◽

Extreme Rainfall ◽

Mediterranean Coast ◽

Return Level ◽

Positive Trend ◽

Peaks Over Threshold ◽

Daily Scale

Abstract A peaks-over-threshold (POT) approach is used to study trends in extreme rainfall over the Iberian Peninsula (IP) at a daily scale. Records from 52 observatories regularly distributed over Iberia with no missing data were available for the common period from 1958 to 2004. The POT approach was used because it is particularly effective at extracting information concerning true extreme events. A generalized Pareto distribution fit was made to the data involving time-dependent parameters to account for possible temporal changes in the frequency distribution. These parameters were analyzed for trends in the return-level period, of importance for engineering purposes. A time-varying threshold was defined and an automatic declustering scheme was used to select independent extreme events exceeding the threshold. The results indicate a high variability of extreme events over the coastline of the IP, greater over the Mediterranean coast than over the Atlantic coast. The calculation of the trends for the 2-yr return level yielded a large proportion of negative trends for all three seasons considered: 58% for winter, 63% for spring, and 69% for autumn. The parametric approach also revealed an increase in the area with a positive trend of the 20-yr return level relative to the 2-yr return period, especially in autumn in the east of the IP.

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The spreading of the non-native caprellid (Crustacea: Amphipoda) Caprella scaura Templeton, 1836 into southern Europe and northern Africa: a complicated taxonomic history.

Mediterranean Marine Science ◽

10.12681/mms.469 ◽

2013 ◽

Vol 15 (1) ◽

pp. 145 ◽

Cited By ~ 1

Author(s):

M. ROS CLEMENTE

Keyword(s):

Iberian Peninsula ◽

North Atlantic ◽

Atlantic Coast ◽

Mediterranean Coast ◽

Strait Of Gibraltar ◽

Fouling Communities ◽

Morphological Form ◽

The North ◽

Survey Report ◽

First Time

Caprella scaura, originally described by Templeton (1836) from Mauritius and later reported as several subspecies from numerous areas of the world, was found for the first time in the Mediterranean in 1994. Since this report, the species was found in several Mediterranean locations. To explore the current distribution of C. scaura in the Iberian Peninsula and adjacent areas, we surveyed marine fouling communities from 88 marinas along the whole Iberian Peninsula and North Africa, 3 from Italy, 1 from France, 1 from Malta and 1 from Greece between June 2011 and June 2012. The results of this survey report the first confirmed record of C. scaura in Corsica (France), Creta (Greece) and Morocco, and confirm an extensive distribution of C. scaura along the Spanish Mediterranean coast and the Strait of Gibraltar. The species was absent in the north Atlantic coast of Spain and the upper distribution limit in the eastern Atlantic coast is the locality of Cascais, in the south coast of Portugal. All populations studied belong to the same morphological form, with match with the subspecies C. scaura typica from Brazil and C. scaura scaura from Mauritius, suggesting that these two subspecies could correspond to the same “variety”.

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Coupling between the JULES land-surface scheme and the CCATT-BRAMS atmospheric chemistry model (JULES-CCATT-BRAMS1.0): applications to numerical weather forecasting and the CO<sub>2</sub> budget in South America

Geoscientific Model Development Discussions ◽

10.5194/gmdd-6-453-2013 ◽

2013 ◽

Vol 6 (1) ◽

pp. 453-494 ◽

Cited By ~ 4

Author(s):

D. S. Moreira ◽

S. R. Freitas ◽

J. P. Bonatti ◽

L. M. Mercado ◽

N. M. É. Rosário ◽

...

Keyword(s):

South America ◽

Atmospheric Chemistry ◽

Land Surface ◽

Amazon Basin ◽

Mean Squared Error ◽

Weather Forecasting ◽

Dew Point ◽

Surface Model ◽

Co2 Concentrations ◽

Wide Range

Abstract. This article presents the development of a new numerical system denominated JULES-CCATT-BRAMS, which resulted from the coupling of the JULES surface model to the CCATT-BRAMS atmospheric chemistry model. The performance of this system in relation to several meteorological variables (wind speed at 10 m, air temperature at 2 m, dew point temperature at 2 m, pressure reduced to mean sea level and 6 h accumulated precipitation) and the CO2 concentration above an extensive area of South America is also presented, focusing on the Amazon basin. The evaluations were conducted for two periods, the wet (March) and dry (September) seasons of 2010. The statistics used to perform the evaluation included bias (BIAS) and root mean squared error (RMSE). The errors were calculated in relation to observations at conventional stations in airports and automatic stations. In addition, CO2 concentrations in the first model level were compared with meteorological tower measurements and vertical CO2 profiles were compared with aircraft data. The results of this study show that the JULES model coupled to CCATT-BRAMS provided a significant gain in performance in the evaluated atmospheric fields relative to those simulated by the LEAF (version 3) surface model originally utilized by CCATT-BRAMS. Simulations of CO2 concentrations in Amazonia and a comparison with observations are also discussed and show that the system presents a gain in performance relative to previous studies. Finally, we discuss a wide range of numerical studies integrating coupled atmospheric, land surface and chemistry processes that could be produced with the system described here. Therefore, this work presents to the scientific community a free tool, with good performance in relation to the observed data and re-analyses, able to produce atmospheric simulations/forecasts at different resolutions, for any period of time and in any region of the globe.

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Tropical Cyclone Count Forecasting Using a Dynamical Seasonal Prediction System: Sensitivity to Improved Ocean Initialization

Journal of Climate ◽

10.1175/2010jcli3585.1 ◽

2011 ◽

Vol 24 (12) ◽

pp. 2963-2982 ◽

Cited By ~ 16

Author(s):

Andrea Alessandri ◽

Andrea Borrelli ◽

Silvio Gualdi ◽

Enrico Scoccimarro ◽

Simona Masina

Keyword(s):

Tropical Cyclone ◽

Indian Ocean ◽

Wind Shear ◽

Large Scale ◽

Initial Conditions ◽

North Pacific Ocean ◽

Convective Available Potential Energy ◽

Seasonal Prediction ◽

Boreal Summer ◽

Prediction System

Abstract This study investigates the predictability of tropical cyclone (TC) seasonal count anomalies using the Centro Euro-Mediterraneo per i Cambiamenti Climatici–Istituto Nazionale di Geofisica e Vulcanologia (CMCC-INGV) Seasonal Prediction System (SPS). To this aim, nine-member ensemble forecasts for the period 1992–2001 for two starting dates per year were performed. The skill in reproducing the observed TC counts has been evaluated after the application of a TC location and tracking detection method to the retrospective forecasts. The SPS displays good skill in predicting the observed TC count anomalies, particularly over the tropical Pacific and Atlantic Oceans. The simulated TC activity exhibits realistic geographical distribution and interannual variability, thus indicating that the model is able to reproduce the major basic mechanisms that link the TCs’ occurrence with the large-scale circulation. TC count anomalies prediction has been found to be sensitive to the subsurface assimilation in the ocean for initialization. Comparing the results with control simulations performed without assimilated initial conditions, the results indicate that the assimilation significantly improves the prediction of the TC count anomalies over the eastern North Pacific Ocean (ENP) and northern Indian Ocean (NI) during boreal summer. During the austral counterpart, significant progresses over the area surrounding Australia (AUS) and in terms of the probabilistic quality of the predictions also over the southern Indian Ocean (SI) were evidenced. The analysis shows that the improvement in the prediction of anomalous TC counts follows the enhancement in forecasting daily anomalies in sea surface temperature due to subsurface ocean initialization. Furthermore, the skill changes appear to be in part related to forecast differences in convective available potential energy (CAPE) over the ENP and the North Atlantic Ocean (ATL), in wind shear over the NI, and in both CAPE and wind shear over the SI.

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Implementation of a 3-D-Var system for atmospheric profiling data assimilation into the RAMS model: initial results

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-6-3581-2013 ◽

2013 ◽

Vol 6 (2) ◽

pp. 3581-3610

Author(s):

S. Federico

Keyword(s):

Relative Humidity ◽

Data Assimilation ◽

Initial Conditions ◽

Weather Prediction ◽

Wind Profiler ◽

Short Term ◽

Recursive Filters ◽

Data Assimilation System ◽

Rams Model ◽

Assimilation System

Abstract. This paper presents the current status of development of a three-dimensional variational data assimilation system. The system can be used with different numerical weather prediction models, but it is mainly designed to be coupled with the Regional Atmospheric Modelling System (RAMS). Analyses are given for the following parameters: zonal and meridional wind components, temperature, relative humidity, and geopotential height. Important features of the data assimilation system are the use of incremental formulation of the cost-function, and the use of an analysis space represented by recursive filters and eigenmodes of the vertical background error matrix. This matrix and the length-scale of the recursive filters are estimated by the National Meteorological Center (NMC) method. The data assimilation and forecasting system is applied to the real context of atmospheric profiling data assimilation, and in particular to the short-term wind prediction. The analyses are produced at 20 km horizontal resolution over central Europe and extend over the whole troposphere. Assimilated data are vertical soundings of wind, temperature, and relative humidity from radiosondes, and wind measurements of the European wind profiler network. Results show the validity of the analysis solutions because they are closer to the observations (lower RMSE) compared to the background (higher RMSE), and the differences of the RMSEs are consistent with the data assimilation settings. To quantify the impact of improved initial conditions on the short-term forecast, the analyses are used as initial conditions of a three-hours forecast of the RAMS model. In particular two sets of forecasts are produced: (a) the first uses the ECMWF analysis/forecast cycle as initial and boundary conditions; (b) the second uses the analyses produced by the 3-D-Var scheme as initial conditions, then is driven by the ECMWF forecast. The improvement is quantified by considering the horizontal components of the wind, which are measured at a-synoptic times by the European wind profiler network. The results show that the RMSE is effectively reduced at the short range (1–2 h). The results are in agreement with the set-up of the numerical experiment.

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Using adjoint sensitivity as a local structure function in variational data assimilation

Nonlinear Processes in Geophysics ◽

10.5194/npg-8-347-2001 ◽

2001 ◽

Vol 8 (6) ◽

pp. 347-355 ◽

Cited By ~ 10

Author(s):

G. Hello ◽

F. Bouttier

Keyword(s):

Data Assimilation ◽

Structure Function ◽

Local Structure ◽

Initial Conditions ◽

Storm Track ◽

Variational Data Assimilation ◽

Sensitive Area ◽

Adjoint Sensitivity ◽

Weather Events ◽

Gradient Fields

Abstract. One approach recently proposed in order to improve the forecast of weather events, such as cyclogenesis, is to increase the number of observations in areas depending on the flow configuration. These areas are obtained using, for example, the sensitivity to initial conditions of a selected predicted cyclone. An alternative or complementary way is proposed here. The idea is to employ such an adjoint sensitivity field as a local structure function within variational data assimilation, 3D-Var in this instance. Away from the sensitive area, observation increments project on the initial fields with the usual climatological (or weakly flow-dependent, in the case of 4D-Var) structure functions. Within the sensitive area, the gradient fields are projected using all the available data in the zone, conventional or extra, if any. The formulation of the technique is given and the approach is further explained by using a simple 1D scheme. The technique is implemented in the ARPEGE/IFS code and applied to 11 FASTEX (Fronts and Atlantic Storm-Track Experiment) cyclone cases, together with the targeted observations performed at the time of the campaign. The new approach is shown to allow for the desired stronger impact of the available observations and to systematically improve the forecasts of the FASTEX cyclones, unlike the standard 3D-Var.

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Analysis of Severe Elevated Thunderstorms over Frontal Surfaces Using DCIN and DCAPE

Atmosphere ◽

10.3390/atmos10080449 ◽

2019 ◽

Vol 10 (8) ◽

pp. 449

Author(s):

Patrick Market ◽

Kevin Grempler ◽

Paula Sumrall ◽

Chasity Henson

Keyword(s):

Weather Prediction ◽

Convective Available Potential Energy ◽

Numerical Weather Prediction Model ◽

Surface Boundary ◽

Storm Events ◽

Cold Side ◽

Severe Thunderstorms ◽

Stable Surface Layer ◽

Different Populations ◽

Convective Inhibition

A 10-year study of elevated severe thunderstorms was performed using The National Centers for Environmental Information Storm Events Database. A total of 80 elevated thunderstorm cases were identified, verified, and divided into “Prolific” and “Marginal” classes. These severe cases occurred at least 80 km away from, and on the cold side of, a surface boundary. The downdraft convective available potential energy (DCAPE), downdraft convective inhibition (DCIN), and their ratio are tools to help estimate the potential for a downdraft to penetrate through the depth of a stable surface layer. The hypothesis is that as the DCIN/DCAPE ratio decreases, there exists enhanced possibility of severe surface winds. Using the initial fields from the Rapid Refresh numerical weather prediction model, datasets of DCIN, DCAPE, and their ratio were created. Mann-Whitney U tests on the Prolific versus Marginal case sets were undertaken to determine if the DCAPE and DCIN values come from different populations for the two different case sets. Results show that the Prolific cases have values of DCIN closer to zero, suggesting the downdraft is able to penetrate to the surface causing severe winds. Thus, comparing DCIN and DCAPE is a viable tool in determining if downdrafts will reach the surface from elevated thunderstorms.

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Data assimilation method in flood forecasting for Red river system using high performent computer

Vietnam Journal of Mechanics ◽

10.15625/0866-7136/37/1/5213 ◽

2015 ◽

Vol 37 (1) ◽

pp. 29-42

Author(s):

Nguyen Thanh Don ◽

Nguyen Van Que ◽

Tran Quang Hung ◽

Nguyen Hong Phong

Keyword(s):

Data Assimilation ◽

Flow Rate ◽

New Technologies ◽

Weather Forecasting ◽

Initial Conditions ◽

River System ◽

Red River ◽

Time Dependent ◽

Complex Case ◽

Flood Model

Around the world, the data assimilation framework has been reported to be of great interest for weather forecasting, oceanography modeling and for shallow water flows particularly for flood model. For flood model this method is a power full tool to identify time-independent parameters (e.g. Manning coefficients and initial conditions) and time-dependent parameters (e.g. inflow). This paper demonstrates the efficiency of the method to identify time-dependent parameter: inflow discharge with a real complex case Red River. Firstly, we briefly discuss about current methods for determining flow rate which encompasses the new technologies, then present the ability to recover flow rate of this method. For the case of very long time series, a temporal strategy with time overlapping is suggested to decrease the amount of memory required. In addition, some different aspects of data assimilation are covered from this case.

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