- TO CHARACTERIZE THE METEOROLOGICAL CONDITIONS AND TRANSPORT MECHANISMS WHICH CAN RESULT IN A SUBCONTINENTAL CIRCULATION COVERING MOST OF SPAIN. SELECTED URBAN AND POWER PLANT PLUMES WILL BE FOLLOWED BY COSPEC USING SO2 AND NO2 AS TRACERS OF OPPORTUNITY OF THE POLLUTED AIRMASSES.
- TO DETERMINE PREFERRED PATHWAYS IN THE CONVERGENCE LEG OF THE CYCLE FOR THE POLLUTANTS EMITTED IN THE COASTAL AREAS.
- TO CHARACTERIZE WET DEPOSITION PROCESSES UNDER THE CHOSEN URBAN PLUMES FOR CONDITIONS OF EPISODE BREAK-UP BY PRECIPITATION
- TO EVALUATE THE DIRECT EFFECTS OF THE POLLUTED AIRMASS ON VEGETATION ACROSS THE PREFERRED PATHWAYS DURING DRY AND WET-TRANSPORT CONDITIONS AS AN ALTERNATE OR COMPLEMENTARY MONITORING MECHANISM.
- TO INCREASE THE KNOWLEDGE OF MESO-SCALE PROCESSES IN THE INTERPHASE ZONE BETWEEN ATLANTIC AND CONTINENTAL - MEDITERRANEAN AIR MASSES.
Results from the mesometeorological cycles of air pollution in the Iberian Peninsula (MECAPIP) project indicate that mesoscale circulations generated in Southern Europe, either by thermally driven and/or orographically aided processes can play an important role in the balance of pollutants and photooxidants over the Mediterranean area, in the midtroposphere over the whole of Europe, and probably also over the Central Atlantic. Perhaps the 2 most important consequences of the project have been: in the first place to document the nonhomogeneous structure in the concentrations of air pollutants, both horizontally and vertically, their marked diurnal and seasonal cycles and their association with orography.
In second place, this information has helped to establish the relationships between the atmospheric circulations at various scales (from local, to regional, to subcontinental), with the behaviour of polluted airmasses over the Iberian Peninsula and Western Mediterranean areas.
The most relevant processes are all time dependent, with very few near stationary conditions. The dominant period in diurnal and involves flow reversal and/or coupling decoupling cycles between upper and surface winds. Most of the observed mechanisms involve convergence at the local to regional scale, which is followed by transport of the accumulated material at the synoptic scale. Applicable atmospheric dispersion models should be able to handle recirculatory flows, including transport in different directions at varying heights and/or sloshing cycles (ie direct oscillation of the airmass with accumulation of pollutants within an airshed without significant vertical exchange). They would also require dealing with orographic and convective injection, layering mechanisms and subsidence.
A great deal of effort will be required to parameterize those mesoscale processes in order to link existing knowledge about local phenomena, which can result in the accumulation of pollutants over large reg ions, with their continuity and transport and effects at the continental and global scales.
The general conclusion is that models and procedures presently in use should be reconsidered very carefully, or used with extreme caution when applying them, or extending them, to Mediterranean like climates and conditions.
The large horizontal nonhomogeneity resulting from convective activity and the thermal circulations, and their relationship to orographic features, suggest that specific monitoring programmes should be launched to document the horizontal extent of these variations and their effects on vegetation.
THE IBERIAN PENINSULA HAS SOME UNIQUE CHARACTERISTICS IN THAT IT IS :
A) A HIGH PLATEAU BARRIER BETWEEN THE ATLANTIC AND MEDITERRANEAN (COLD VS. WARM SEAS),
B) SEMI ARID,
C) SOUTHERLY LOCATED AND
D) SUB-CONTINENTAL IN SIZE. WITH THESE CONDITIONS LOCAL AIR POLLUTION EPISODES CAN ORIGINATE VIA RECIRCULATORY FLOWS IN THE MESO-SCALE (I.E. LAND-SEA BREEZES, ETC.). AT THE SAME TIME, THE ULTIMATE TRANSPORT FATE OF THOSE AGED AIR MASSES CAN BE DOMINATED BY THE IBERIAN THERMAL LOW FROM MID TO LATE SUMMER. THIS LOW CAN FORM EVERY DAY AND FORCES A SUB-CONTINENTAL CONVERGENCE TOWARDS THE CENTRAL PLATEAU WHERE THE AIR MASSES CAN BE FURTHER AGED, CONVECTIVELY INJECTED INTO THE MID TROPOSPHERE (1-3 KM) AND LEFT READY FOR LONG RANGE TRANSPORT OUT OF THE PENINSULA.