The air mass at 2500 m amsl had its origin in the Northwest Atlantic, although it slowed down considerably as it reached the Iberian Peninsula. The air masses at 750 and 1500 m amsl recirculated over the Iberian Peninsula, looping and contacting the ground three days before the day in question. The back trajectories at 350, 500 and 650 m amsl recirculated over the Iberian Peninsula, looping several times and contacting the ground at various points along their way, indicating regional or local transport. Finally, the back trajectories at 10, 100 and 250 m amsl showed air masses originating in the Iberian Peninsula, recirculating along their path. During this day, there was no intrusion of African dust.The air mass was classified as RE. In addition, on this day, only Cannabis pollen grains were observed in Lorca, pointing to local pollen transport.Overall, the different back trajectories point to local pollen grains. The previous examples of local/regional sources in each city should be contextualised with the frequency of origin.The days with local/regional origin were three times higher than the number of days with African origin.
As pollen displacement drops exponentially with distance from the flower cannabis vertical farming , the idea of an increase inillegal Cannabis crops surrounding the sampling points is reinforced.Fig. 4 shows that Cannabis pollen grains originated in Africa on 07/23/2017. Back trajectories at 750, 1500 and 2500m amsl showed recirculation of all the air masses over North Africa. The air mass at 2500 m amsl contacted the ground over Africa during the three days preceding the day in question, and the air mass at 750 m amsl did so from 12 h to 18 h on the previous day. This explains the transport of particles from northern Africa to the Iberian Peninsula and, specifically, to the Region of Murcia.At 18 h the previous day, with back trajectories at 350, 500 and 650 mamsl, air masses originated over the Atlantic Ocean but travelled across Africa before arriving to their destination. All the air masses had approached the ground between 6 h and 18 h the previous day and slowed down when they reached the Region of Murcia. A similar situation occurred for the back trajectories at 10, 100 and 250 m amsl. All the airmasses originated over the Atlantic Ocean, but they travelled across Africa, coming into contact with the ground from 6 h to 12 h the previous day and slowing down when they reached the Region of Murcia. Although the back trajectoriesin Fig. 4 correspond to the coordinates of Cartagena, the analysis was comparable to the back trajectories of Murcia and Lorca.
Another aspect that points to the African origin of Cannabis is the detection of African down over the Iberian Peninsula and approaching the ground as they reached their destination. African dust intrusion was not reported on this day, and the air mass was classified as AN, which is evidence of local or regional Cannabis pollen grain transport. This day can be contextualised with the day before, the peak day, with an airmass classified as EU. Air masses from AN and EU are geographically incompatible with any drag bringing Cannabis pollen from Africa. Local/regional Cannabis pollen transport was also evident in Lorca on 07/24/2011 . The air mass at 2500 m amsl had its origin in the Northwest Atlantic, although it slowed down considerably as it reached the Iberian Peninsula cannabis drying racks. The air masses at 750 and 1500 m amsl recirculated over the Iberian Peninsula, looping and contacting the ground three days before the day in question. The back trajectories at 350, 500 and 650 m amsl recirculated over the Iberian Peninsula, looping several times and contacting the ground at various points along their way, indicating regional or local transport.
Finally, the back trajectories at 10, 100 and 250 m amsl showed air masses originating in the Iberian Peninsula, recirculating along their path. They touched the ground four days before and on the same day from 00 h onwards. During this day, there was no intrusion of African dust.The air mass was classified as RE. In addition, on this day, only Cannabis pollen grains were observed in Lorca, pointing to local pollen transport.Overall, the different back trajectories point to local pollen grains. The previous examples of local/regional sources in each city should be contextualised with the frequency of origin . The days with local/regional origin were three times higher than the number of days with African origin . As pollen displacement drops exponentially with distance from the flower , the idea of an increase in illegal Cannabis crops surrounding the sampling points is reinforced.Fig. 4 shows that Cannabis pollen grains originated in Africa on 07/23/2017. Back trajectories at 750, 1500 and 2500m amsl showed recirculation of all the air masses over North Africa. The air mass at 2500 m amsl contacted the ground over Africa during the three days preceding the da yin question, and the air mass at 750 m amsl did so from 12 h to 18 h on the previous day.