Ricardo Navarro García

Surface ozone in Spain

Abstract This article presents an analysis of the surface ozone in five Spanish rural stations with the aim of studying the diurnal and seasonal variations of ozone concentration, the mechanisms that control it and its geographical sources. Results show diurnal cycles in three of the five considered stations, as well as spring maxima in four and summer maxima in three of them. The Conditional Probability Functions (CPFs) are used to identify the geographical sources of O3 . The most important source areas are those with strong NOx emissions and far away the stations. Another objective of the article is to essay a method to identifify the temporal and spatial domain of the mechanisms to produce O3. This method suggests that the photochemical production of O3 from focal NOx seems to be the main mechanism to produce O3 when the length of the trajectory of the air mass is short. When this length increases, NOx emission gains importance as the main mechanism controlling O3 concentration.

Mesoscale Convective Complexes over the Western Mediterranean Area during 1990-1994

SummaryMesoscale Convective Systems (MCSs) data registers from June to December during 1990–94 were obtained from the Spanish National Meteorological Institute (INM). Fifteen Mesoscale Convective Complexes (MCCs) were identified through this database. Most of the MCCs developed during the last week of September. The dominant synoptic patterns related to the mesoscale systems were cold fronts at the surface with warm and moist low-level cores, and cut-off low or deep trough throughout the middle and upper levels. These synoptic patterns were found in all the fifteen cases studied.The hourly centroid location of each MCC was used to trace their tracks, which followed a general direction towards the E or NE in almost all cases. These trajectories are clearly related to the synoptic patterns found. Finally, two MCCs chosen as representative of their evolution are described and the related physical processes are discussed.

Interannual variability of hail-days in the Andes region since 1885

Abstract Using documentary sources, a series of the annual number of hail-days in a region near Mendoza, Argentina was constructed. The analysis of the temporal series by means of singular spectrum analysis (SSA) and the maximum entropy method (MEM) found that the number of hail-days exhibits a similar interannual variability as the global surface temperature [M. Ghil, R. Vautard, Nature 350 (1991) 324-327]. The oscillations exhibit interdecadal periods of 22 years and interannual oscillations of about 4 and 8 years.

Predictability of global surface temperature by means of nonlinear analysis

Abstract The time series of annually averaged global surface temperature anomalies for the years 1856–1998 is studied through nonlinear time series analysis with the aim of estimating the predictability time. Detection of chaotic behaviour in the data indicates that there is some internal structure in the data; the data may be considered to be governed by a deterministic process and some predictability is expected. Several tests are performed on the series, with results indicating possible chaotic behaviour.

Time Modeling of Daily UVB Values in Madrid, Spain

Abstract This paper presents the daily solar ultraviolet-B (UVB) values measured in Madrid, Spain, during the period 1994–97 with a Brewer MKIV spectrophotometer. The range of the measured values was 0.042–6.41 kJ m−2. A description of the values is shown. Periodicities of 7 and 3 days, associated with synoptic patterns, are significant. Ozone (with 5- and 3-day periodicities) and cloudiness also are studied for the same period; their association with UVB is investigated. The radiative amplification factor value between UVB and ozone is 0.62. The correlation coefficient between UVB and a cloudiness index [equal to one minus the (number of sun hours divided by the number of theoretical sun hours)] is −0.57. A time series model describing the UVB series is shown. It is useful in estimating the UVB values, even on days when radiation values are not available. It provides accurate performance, can be used any day of the year, and has no main restrictions for its application. Thus, this kind of model can be a ...

Diurnal and seasonal variation of the surface ozone in Spain

Abstract In this study we present the diurnal and monthly variations in the surface ozone concentrations of five Spanish remote stations belonging to the EMEP network. In two of the stations, a maximum in the afternoon is presented because of the turbulent mixing producing appreciable downward ozone flux. In other two stations no maxima are produced. In one of them this result is due to the strong westerly winds that dominate the air flow and the low solar insolation. In the other station the reason are two phenomena: the mountain induced flow regime that produce high concentrations during the night and the photochemical production that results in high concentrations during the afternoon. Four of the five considered stations show the typical natural spring maximum. This maximum extends into summer in two of the stations. In one of the stations the maximum is reached in summer and it is due to the proximity of the station to strong nitrogen oxide emission areas.

The Temperature Component of the Common-Sense Index in Northwestern Iberian Peninsula

The use of indices has been, traditionally, one of the main tools to identify climatic changes. In this paper we use the temperature component of the Common Sense Climate Index of Hansen et al. (1998) to study regional climate change in the northwestern Iberian Peninsula, an area strongly affected by the North Atlantic Oscillation. 850, 500 and 200 hPa pressure levels from NCEP-NCAR reanalysis have been used, together with indices of the El Nino- Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO). The temperature component of the Common- Sense Climate Index was calculated as well as its three components (seasonal mean temperatures, degree days and frequency of extreme temperatures). Results show a noticeable temperature change in the 1980s and 1990s, and a close relationship between the index and the North Atlantic Oscillation index.

On the origin of the elevated ozone concentration in Spain

Abstract The objective of this work is to study the influence of three mechanisms in the high surface concentration of the Spanish EMEP stations. These mechanisms are: Photochemical production from organic compounds and nitrogen oxides, exchange of air between the Planetary Boundary Layer and the free troposphere and the advection of ozone. To do this we have designed a new method that use multivariate analysis and the average ozone concentrations, NOx concentrations, lenght of the air mass trajectories reaching the stations and emissions of NOx. Results suggest that high surface ozone concentrations are controled by photochemical production if the source is close to the station. If the distance from the source to the station rises, the influence of the NOx emissions become more important.

Geographical sources of surface ozone concentrations in Spain

Abstract Geographical sources of surface ozone in five Spanish EMEP stations are studied using the air mass trajectories that arrive at the stations together with the CPFs (Conditional Probability Functions). Results show that regions with strong NOx emissions placed far away the stations are the main sources of ozone in Spain. So, the center of Europe and the middle Mediterranean area are the two main geographical sources of surface ozone in Spain.

Project EUROMET: Meteorological Computer-Assisted Learning in Europe

This paper presents the EUROMET project to the international meteorological community. EUROMET is an effort to develop a multimedia, network-based service to support meteorological education and training throughout Europe.