مطالعه میدان باد لایه مرزی سیاره‌ای روی جزیره‌ قشم، ایران

نوع مقاله : پژوهشی

نویسندگان

1 دانشجوی کارشناسی ارشد، گروه علوم غیرزیستی جوی و اقیانوسی، دانشکده علوم و فنون دریایی، دانشگاه هرمزگان، بندرعباس، ایران

2 دانشیار، گروه علوم غیرزیستی جوی و اقیانوسی، دانشکده علوم و فنون دریایی، دانشگاه هرمزگان، بندرعباس، ایران

چکیده

نظر به اهمیت الگوی باد بر فعالیت‌های متعدد در جزایر و همچنین تأثیر آن بر سایر پارامترهای هواشناسی، رفتار زمانی و مکانی بلند‌مدت میدان باد تراز پایین مشاهداتی روی جزیره قشم مطالعه شد. به‌منظور حساسیت‌سنجی شبیه‌سازی‌های عددی باد تراز پایین به‌وسیله مدل WRF، پارامترسازی لایه مرزی و لایه سطحی روی جزیره قشم، در ماه منتخب از فصل گرم (جولای) و ماه منتخب از فصل سرد (ژانویه) برای سال 2015 بررسی شده‌است. نتایج شبیه‌سازی‌ها در پنج پیکربندی مختلف با سرعت باد مشاهداتی ایستگاه قشم فرودگاهی و قشم دریایی اعتبار‌سنجی شده‌است و نتایج نشان می‌دهد که در هر دو ماه طرحواره لایه مرزی ACM2 به‌علت این‌که اختلاط قائم را هم به‌صورت محلی و هم غیرمحلی در نظر می‌گیرد و در فصل گرم همرفت را بهتر از دیگر طرحواره‌ها لحاظ می‌کند در ترکیب با طرحواره لایه سطحی Pleim-Xio و پارامترسازی سطح زمین Noah شبیه‌سازی بهتری از سرعت و جهت باد تراز پایین ارائه می‌کند. پس از انتخاب پیکربندی مناسب، شبیه‌سازی میدان باد به‌مدت یک سال (2015) به‌منظور بررسی الگوی باد جزیره قشم، ساختار قائم باد لایه مرزی و تأثیر جزیره بر روی میدان باد لایه‌مرزی منطقه به انجام رسید. نتایج بیانگر آن است که سرعت باد در فصول بهار و تابستان از مقادیر بالاتری برخوردار است و زبری و پسای جزیره باعث کاهش سرعت باد، رخداد همگرایی و چرخش میدان باد بر روی تنگه هرمز می‌شود. نسیم دریا و زبری سطح در مناطق ساحلی باعث تقویت رودباد تراز پایین در حین روز و در ارتفاع‌های 180 تا 200 متر شده‌است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Study of planetary boundary layer wind field over Qeshm Island, Iran

نویسندگان [English]

  • Mona Zarghamipour 1
  • Hossein Malakooti 2
1 M.Sc. Student, Department of Marine and Atmospheric Science (non-Biologic), Faculty of Marine Science and Technology, University of Hormozgan, Bandar Abbas, Iran
2 Associate Professor, Department of Marine and Atmospheric Science (non-Biologic), Faculty of Marine Science and Technology, University of Hormozgan, Bandar Abbas, Iran
چکیده [English]

Since the wind pattern on various activities in islands as well as its effect on other meteorological parameters is important long – term temporal and spatial variations of the wind field are studied. Here, the warmest month (July) and the coldest month (January) 2015, are selected in order to test the sensitivity of low-level wind simulations of the Weather Research and Forecasting (WRF) model to the parameterizations of the boundary layer (PBL), the surface layer (SL) and the land surface (LSM) over Qeshm Island. As this work was focused on the simulation of near-surface and vertical wind profiles, the physical options related to the parameterizations of boundary layer processes (SL, PBL and LSM) that have significance influence for this purpose are validated. Although more physical options are available in the model (for cumulus convection, short and long wave radiation, microphysics and etc.), it is not feasible or necessary to include all the model configuration options in the sensitivity analysis to obtain an efficient model configuration optimization. The model grid comprised of four nested domains at horizontal resolutions of 45, 15, 5 and 1 km respectively. The innermost domain (D4) with 1 km spatial resolution covered the chosen area to simulate PBL wind field over Qeshm island region. The results of the simulations under five different configurations are validated with the observational wind speed data of Qeshm Airport and Marine Qeshm Stations. The results demonstrate that in both episodes, the ACM2 boundary layer scheme has presented the best performance in combination with the Pleim - Xio surface layer and the Noah land surface schemes because it considers vertical mixing both local and non-local in simulation of planetary boundary layer wind structure. The simulations of WRF are sensitive to warm and cold seasons as well as selected parameterizations. After selecting the appropriate configuration, the simulation of the wind field for one year was carried out to investigate the low level wind field, the vertical structure of the boundary layer wind and the impact of the land mask distribution on and around the Qeshm Island. These simulations indicate higher wind speed in spring and summer and the roughness of the island causes a low level wind convergence, then turn to the left on the Strait of Hormuz with decreasing wind speed. Monthly average of the wind direction during the daytime of reference month of each season are generally simulated to be southwesterly (January, April, July, October) and during the nights of January and July it is southerly to southeast and in April and October it is simulated southwesterly. The direction of the wind has significant variations at sunrise and sunset due to changes in regional scale forcing and baroclinicity behavior between the sea and the coast. Surface roughness in coastal areas, strait narrowing and sea breeze, enhance the low-level jet during summer and spring middays at altitudes of about 180 to 200 meters. In other words, we can say these low-level jet (Shamal winds) during summer and spring occurs as a result of the interaction of two pressure systems; the heat low pressure cell (low level cyclone) over Iran and a semi-permanent high over northwestern Saudi Arabia and it acquires some convergence because of the these factors.

کلیدواژه‌ها [English]

  • Parameterization
  • Numerical simulation
  • wind speed
  • boundary layer
  • Low-level jet
  • Qeshm Island
سازمان منطقه آزاد قشم، http://www.tourism.qeshm.ir.
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