علوم غیرزیستی دریا
Atefe Pourkarimian; Maryam Soyuf Jahromi; Hossein Malakooti
Abstract
The new insights into ocean-atmosphere-land synoptic studies, have led scientists to trace attractive atmospheric and oceanic phenomena. In this study, by using synoptic maps and some precipitation indices for Iran, we estimated the type and intensity of the extreme precipitation event in Dayyer Port ...
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The new insights into ocean-atmosphere-land synoptic studies, have led scientists to trace attractive atmospheric and oceanic phenomena. In this study, by using synoptic maps and some precipitation indices for Iran, we estimated the type and intensity of the extreme precipitation event in Dayyer Port synoptical station (27˚51ʹ34ʺN-51˚57ʹ52ʺ, ID: 40872) for 19March 2017. In order to identify oceanic sources of the water content for this precipitation event, air parcels were traced as lagrangian single particle trajectory by a hybrid model of HYSPLIT which is run backward interactively on the web site, during 9-days by the start of maximum rainfall, locatacted at Dayyer port station. Accordingly, we plotted pattern of the average moisture transfer paths on 800-550 hPa atmospheric levels. The field climate data (including wind speed and direction, relative humidity and precipitation) with 6-hour time steps and spatial resolution of 2.5˚×2.5˚(longitude and latitude), entered into the model from the reanalysis global data archive of the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR). Consequently, by assessment of the meteorological maps and data and by using a precipitation index of R10mm, we found that this precipitation event (19th March 2017) defined as a heavy precipitation day. Finally, the simulation outputs clearly showed that the water contents of this rainfall system (19th March 2017) originates from two source locations of the north area of Indian Ocean (Arabian Sea), and also the east part of Atlantic Ocean. In addition, the results illustrated that during the occurrence of this precipitation event, an extra-tropical cyclone was active on the studied area.
Hossein Malakooti
Abstract
Domain design, different starting times and applying internal fixed and moving domains within the coarser simulation domain can play important roles in the results of numerical models in order prediction of tropical cyclones. In this study, Gonu Tropical Cyclone (2007) that it was formed in Arabian Sea ...
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Domain design, different starting times and applying internal fixed and moving domains within the coarser simulation domain can play important roles in the results of numerical models in order prediction of tropical cyclones. In this study, Gonu Tropical Cyclone (2007) that it was formed in Arabian Sea and AHW model have been selected to demonstrate this sensitivity. The simulation results in domain design sensitivity showed, the domain that was extended more to the east direction and was included a lower coverage of the Persian Gulf had more accuracy in predicting of track and the best performance and also had an acceptable performance in predicting of hurricane intensity at the time to reach the coast of Oman and Iran. Then, internal fixed and moving domains to separate within this domain is considered and the results showed that despite some improvement in simulated intensity error, there was a reduction of simulated cyclone track. Generally, the results showed that internal fixed domain rather than internal moving domain has the better performance in selected cases. Thereafter, different starting times were tested and the results showed that the simulation starting time, 48 to 60 hours before maximum intensity of storm or in other words, when the central pressure of system shows about 1000 hp has the better performance in simulation of cyclone track and intensity. Finally, the final conditions are tested for Phet tropical cyclone (2010) that was formed in the same area. The results of this testing were satisfactory.