مطالعه پیچک‌های میان مقیاس تحت تاثیر جریان‌های ساحلی در خلیج فارس و نقش آن در اقلیم منطقه
محورهای موضوعی : اقلیم شناسیامین رئیسی 1 , حسام الدین مهرفر 2 , عباسعلی علی اکبری بیدختی 3 , مسعود ترابی آزاد 4 , کامران لاری 5 , محمد جعفر ناظم السادات 6 , مجتبی عظام 7
1 - گروه فیزیک دریا، دانشکده منابع طبیعی و محیط زیست، دانشگاه آزاد اسلامی، واحد علوم و تحقیقات، تهران، ایران
2 - گروه فیزیک دریا، دانشکده منابع طبیعی و محیط زیست، دانشگاه آزاد اسلامی، واحد علوم و تحقیقات، تهران، ایران
صندوق پستی 693-69135 ، 0912194897 ، hmehrfar@gmail.com
3 - استاد، موسسه ژئوفیزیک، دانشگاه تهران، تهران، ایران
4 - دانشیار، دانشکده علوم و فنون دریایی، دانشگاه آزاد اسلامی، واحد تهران شمال، تهران، ایران
5 - دانشیار، دانشکده علوم و فنون دریایی، دانشگاه آزاد اسلامی، واحد تهران شمال، تهران، ایران
6 - استاد، دانشکده مهندسی آب، مرکز علوم جوی و اقیانوسی، دانشگاه شیراز، شیراز، ایران
7 - استادیار، دانشکده منابع طبیعی و محیط زیست، دانشگاه آزاد اسلامی، واحد علوم و تحقیقات، تهران، ایران
کلید واژه: خلیج فارس, شبیه سازی عددی, پیچک‌های میان مقیاس, جریان‌های ساحلی, ارتفاع سطح دریا,
چکیده مقاله :
نقش پیچک های میان مقیاس و جریان های ساحلی در مطالعات اقیانوسی واقلیمی از اهمیت زیادی برخوردار است. بدین منظور، داده‌های میدان ارتفاع سطح دریا، به مدت 5 سال (2010 تا 2014) از سری داده‌های مرجع آویسو استخراج شدندو پیچک‌های میان مقیاس براساس روشی مبتنی بر ارتفاع سطح دریا و به کمک نرم افزار Arc GiSمورد شناسایی و ردیابی قرار گرفتند. همچنین جریان های ساحلی به منظور تأثیرگذاری بر تشکیل پیچک های میان مقیاس با مدل عددی کوهرنس شبیه سازی شدند.نتایج تحقیق، میانگین سالانه 78 پیچک با حداقل طول عمر یک هفته را نشان داد که غالبا چرخندی (59.1%) هستند و اثرخنک‌کنندگی و کاهش دما را در جو منطقه دارند. بیشترین محدوده فعالیت پیچک‌ها در بخش‌های ورودی خلیج فارس از سمت تنگه هرمز و شمال‌غربی خلیج فارس است. قوی ترین پیچک ها در تابستان مشاهده شدند که مطابق با نتایج شبیه سازی، بیشترین شدت جریان ها نیز در ماه های جون تا آگوست می باشد.
The role of meso-scale eddies and coastal currents is of great importance in ocean and climate studies. In this regard, data related to the sea level height were extracted from the AVISO reference data series since 2010 to 2014, and meso-scale eddies were identified and tracked based on the sea level height and using ArcGiS software. Moreover, coastal currents were simulated by numerical COHERENS model to influence the formation of meso-scale eddies. The results showed an annual average of 78 meso-scale eddies with a minimum life span of one week, which are often cyclical (59.1%) and decrease the temperature of the region atmosphere. The largest activity area of meso-scale eddies is in the inlet of the Persian Gulf from the Strait of Hormuz and northwest of the Persian Gulf. The strongest eddies are observed in the summer, and in line with the simulation results, the currents with the highest intensities occur from June to August.
- افشار، ساناز و ترابی آزاد، مسعود (1394): جریان‌های ساحلی ناشی از اختلاف چگالی و جزرو مد در مناطق شمالی خلیج‌فارس، پایان‌نامه کارشناسی ارشد، دانشگاه آزاد واحد تهران شمال.
2- ترابی آزاد، مسعود،بنا زاده ماهانی، محمدرضا و علی‌اکبری بیدختی، عباسعلی (1380): چرخابه‌ها در خلیج‌فارس، فصلنامه علوم و تکنولوژی محیط‌زیست، دوره3، شماره3، صص 17-32.
3- ثابت عهد، عبدالرضا، لاری، کامران، سلطانی فرد، محمدجعفر و رئیسی، امین (1390): مطالعه تأثیر پیچک‌های میان‌مقیاس بر توزیع گرادیان دما و شوری در خلیج‌فارس و تنگه هرمز، سیزدهمین همایش صنایع دریایی.
4- زارعی، زهرا، صدیق مروستی، صفورا و ترابی آزاد، مسعود (1386): مطالعه پیچک‌هایمیان‌مقیاسخلیج‌فارس با استفاده از تصاویر ماهواره‌ای، سیزدهمین کنفرانس ژئوفیزیک ایران.
5- زاهدی، رفیعه و ترابی آزاد، مسعود (1381): نقش تغییر اقلیم بر جریان‌هایخلیج‌فارس، فصلنامه علوم و تکنولوژی محیط‌زیست، دوره4، شماره4، صص 43-52.
6- Alessi, C. A. Hunt, H.D.Abd Bower, A.S. (1999): Hydrographic Data From The U.S. Naval Oceanographic Office: Persian Gulf, Southern Red Sea And Arabian Sea, Woods Hole Oceanography Institution, Technical Report WHOI-99–02.
7- Arakawa, A. And Suarez M.J. (1983): Vertical Differencing Of The Primitive Equations In Sigma Coordinates, Monthly Weather Review, Vol. 111, Pp. 34–45.
8- Beron-Vera FJ, Wang Y, Olascoaga MJ, Goni GJ, Haller G. (2013): Objective Detection Of Oceanic Eddies And The Agulhas Leakage. Journal OfPhysical Oceanography, Vol. 43(7), Pp. 1426-1438.
9- Bidokhti, A.A. And Ezam, M. (2009): The Structure Of The PG Outflow Subjected To Density Variations, Ocean Science, Vol. 5, Pp. 51-12.
10- Bower, A.S., Hunt, H.D. And Price, J.F. (2000): Character And Dynamics Of The Red Sea And Persian Gulf Outflows, Journal Of Geophysical Research Atmospheres, Vol. 105, Pp. 6387-6414.
11- Bruce JG, Kindle JC, Kantha LH, Kerling JL, Bailey JF. (1998): Recent Observations And Modeling In The Arabian Sea Laccadive High Region. Journal OfGeophysical Research, Oceans. Vol. 103(C4). Pp. 7593-7600
12- Busireddy NKR, Osuri KK, Sivareddy S, Venkatesan R. (2018): An Observational Analysis Of The Evolution Of A Mesoscale Anti-Cyclonic Eddy Over The Northern Bay Of Bengal During May–July 2014. Ocean Dynamics. Vol. 68(11), Pp. 1431-1441.
13- Chao, S-Y. Kao, T.W. And Al-Hajri, K.R. (1992): A Numerical Investigation Of Circulation In The Arabian Gulf. Journal OfGeophysical Research Atmospheres, Vol. 97(C7), Pp. 11219–11236.
14- Chelton, D.B. Schlax, M.G. And Samelson, R.M. (2011): Global Observations Of Nonlinear Meso-Scale Eddies, Progress In Oceanography, Vol. 91, Pp. 167-216.
15- Cyriac A, Ghoshal T, Shaileshbhai PR, Chakraborty A. (2016): Variability Of Sensible Heat Flux Over The Bay Of Bengal And Its Connection To Indian Ocean Dipole Events. Ocean Science Journal. Vol. 51(1), Pp. 97-107.
16- Dandapat S, Chakraborty A. (2016): Mesoscale Eddies In The Western Bay Of Bengal As Observed From Satellite Altimetry In 1993–2014: Statistical Characteristics, Variability And Three-dimensional Properties. IEEE Journal OfSelected Topics In Applied Earth Observations And Remote Sensing. Vol. 9(11), Pp. 5044-5054.
17- Ezam, M., Bidokhti, A.A. And Javid, A.H., (2010): Numerical Simulations Of Spreading Of The Persian Gulf Outflow Into The Oman Sea, Ocean Sciences, Vol. 6, Pp. 887-900.
18- Faghmous JH, Frenger I, Yao Y, Warmka R, Lindell A, Kumar V. (2015): A Daily Global Mesoscale Ocean Eddy Dataset From Satellite Altimetry, Scientific Data. 2:150028.
19- Frenger I, Gruber N, Knutti R, Münnich M. (2013): Imprint OfSouthern Ocean Eddies On Winds, Clouds And Rainfall. Nature Geoscience. Vol. 6(8), 608.
20- Gopalan AKS, Krishna VV, Ali MM, Sharma R. (2000): Detection OfBay Of Bengal Eddies From TOPEX And In Situ Observations. Journal OfMarine Research. Vol. 58(5), Pp.721-734.
21- Goni G.J., Trinanes J.A. (2003): Ocean Thermal Structure Monitoring Could Aid In The Intensity Forecast Of Tropical Cyclones. Eos, Transactions American Geophysical Union. Vol. 84(51), Pp. 573-578.
22- Hong X, Chang SW, Raman S, Shay LK, Hodur R. (2000): The Interaction Between Hurricane Opal (1995) And A Warm Core Ring In The Gulf OfMexico. Monthly Weather Review. Vol. 128(5). Pp. 1347-1365.
23- Hosseinibalam, F., Hassanzadeh, S. And Rezaei - Latifi, A. (2011): Three-Dimensional Numerical Modeling Of Thermohaline And Wind-Driven Circulations In The Persian Gulf. Applied Mathematical Modelling, Vol. 35, Pp. 5884–5902.
24- Johns, W.E. Yao, F. And Olson, D.B. (2003): Observations Of Seasonal Exchange Through The Straits Of Hormuz And The Inferred Heat And Freshwater Budgets Of The Persian Gulf, Journal Of Geophysical Research Atmospheres, Vol. 108, Pp. 3391-3391.
25- Kampf, J. And Sadrinasab, M. (2006): The Circulation Of The Persian Gulf: A Numerical Study, Ocean Sciences, Vol. 2(1), Pp. 27–41.
26- Kumar BP, Vialard J, Lengaigne M, Murty VSN, Mcphaden MJ. (2012): Tropflux: Air-Sea Fluxes For The Global Tropical Oceans—Description And Evaluation. Climate Dynamics. Vol. 38(7-8), Pp. 1521-1543
27- Luyten P.J. Deleesnijder,E. . Ozer, J. Ruddick, K.G. (1996) :Presentation Of A Family Of Turbulence Closure Models For Stratified Shallow Water Flows And Preliminary Application To The Rhine Outflow Region, Continental Shelf Research, Vol. 16, Pp.101–130
28- Mainelli M, Demaria M, Shay L.K, Goni G. (2008): Application Of Oceanic Heat Content Estimation To Operational Forecasting Of Recent Atlantic Category 5 Hurricanes. Weather AndForecasting. Vol. 23(1), Pp. 3-16
29- Mellor G.L. And Yamada T. (1982): Development Of A Turbulence Closure Model For Geophysical Fluid Problems”, Reviews Of Geophysics And Space Physics, Vol. 20(4), Pp. 851–875.
30- Mohandesi, M., Bidokhti, A.A., Khaniki, A.K., Hasanzadeh, I. &Torabi Azad, M. (2016): Astudy Of The Performances Of Different Turbulence Schemes In Numerical Simulation Of Hydrodynamics Of A Semi-Closed Sea (Persian Gulf). Marine Geodesy, 39(2):141-64.
31- Noori, R. Abbasi, M.R. Aamowski, J.F. And Dehghani, M. (2017): A Simple Mathematical Model To Predict Sea Surface Temperature Over The Northwest Indian Ocean, Estuarine, Coastal And Shelf Science,Vol. 197, Pp. 236-243.
32- Noori R. Fuqiang, T. Ronny, B. Abbasi, M.R. Vesalinaseh, M.R. Modabberi, A. Soltani, A. Klove, B. (2019): Recent And Future Trends In Sea Surface Temperature Across The Persian Gulf And Gulf Of Oman, PLOS ONE, Pp. 1-19
33- Oropeza F, Raga GB. (2015): Rapid Deepening Of Tropical Cyclones In The Northeastern Tropical Pacific: The Relationship With Oceanic Eddies. Atmosfera. Vol. 28(1), Pp. 27-42
34- Patnaik KVKRK, Maneesha K, Sadhuram Y, Prasad KVSR, Ramana Murty TV, Brahmananda Rao V. (2014): East India Coastal Current Induced Eddies And Their Interaction With Tropical Storms Over Bay Of Bengal, Journal Of Operational Oceanography, Vol. 7(1), Pp. 58-68
35- Pous S. Lazure P. And Xavier,C. (2015): A Model Of The General Circulation In The Persian Gulf And In The Strait Of Hormuz: Intraseasonal To Interannual Variability”,Continental Shelf Research, Vol. 94, Pp. 55-70.
36- Prasanna Kumar S, Muraleedharan PM, Prasad TG, Gauns M, Ramaiah N, De Souza SN. (2002): Why Is The Bay Of Bengal Less Productive During Summer Monsoon Compared To The Arabian Sea.Geophysical Research Letters. Vol. 29(24). Pp. 88-81
37- Reynolds, R.M. (1993): Physical Oceanography Of The Gulf, Strait OfHormuz, And The Gulf Of Oman—Results From The Mt Mitchell Expedition, Marine Pollution Bulletin, Vol. 27, Pp.35 – 59.
38- Thoppil, P.G. And Hogan, P.J. (2010): A Modeling Study Of Circulation And Eddies In The Persian Gulf, Journal Of Physical Oceanography, Vol. 40(9), Pp. 2122–2134
39- Yao, F. And Johns, W. E. (2010): A HYCOM Modelling Study Of The Persian Gulf: 2: Formation And Export Of Persian Gulf Water, Journal Of Geophysical Research Atmospheres, 115. C11018. 1-23
39- Yao, F. And Johns, W.E. (2010): A HYCOM Modeling Study Of The Persian Gulf: 1. Model Configurations And Surface Circulation, Journal Of Geophysical Research Atmospheres, Vol. 115, C11017. Pp. 1-17.
_||_- افشار، ساناز و ترابی آزاد، مسعود (1394): جریان‌های ساحلی ناشی از اختلاف چگالی و جزرو مد در مناطق شمالی خلیج‌فارس، پایان‌نامه کارشناسی ارشد، دانشگاه آزاد واحد تهران شمال.
2- ترابی آزاد، مسعود،بنا زاده ماهانی، محمدرضا و علی‌اکبری بیدختی، عباسعلی (1380): چرخابه‌ها در خلیج‌فارس، فصلنامه علوم و تکنولوژی محیط‌زیست، دوره3، شماره3، صص 17-32.
3- ثابت عهد، عبدالرضا، لاری، کامران، سلطانی فرد، محمدجعفر و رئیسی، امین (1390): مطالعه تأثیر پیچک‌های میان‌مقیاس بر توزیع گرادیان دما و شوری در خلیج‌فارس و تنگه هرمز، سیزدهمین همایش صنایع دریایی.
4- زارعی، زهرا، صدیق مروستی، صفورا و ترابی آزاد، مسعود (1386): مطالعه پیچک‌هایمیان‌مقیاسخلیج‌فارس با استفاده از تصاویر ماهواره‌ای، سیزدهمین کنفرانس ژئوفیزیک ایران.
5- زاهدی، رفیعه و ترابی آزاد، مسعود (1381): نقش تغییر اقلیم بر جریان‌هایخلیج‌فارس، فصلنامه علوم و تکنولوژی محیط‌زیست، دوره4، شماره4، صص 43-52.
6- Alessi, C. A. Hunt, H.D.Abd Bower, A.S. (1999): Hydrographic Data From The U.S. Naval Oceanographic Office: Persian Gulf, Southern Red Sea And Arabian Sea, Woods Hole Oceanography Institution, Technical Report WHOI-99–02.
7- Arakawa, A. And Suarez M.J. (1983): Vertical Differencing Of The Primitive Equations In Sigma Coordinates, Monthly Weather Review, Vol. 111, Pp. 34–45.
8- Beron-Vera FJ, Wang Y, Olascoaga MJ, Goni GJ, Haller G. (2013): Objective Detection Of Oceanic Eddies And The Agulhas Leakage. Journal OfPhysical Oceanography, Vol. 43(7), Pp. 1426-1438.
9- Bidokhti, A.A. And Ezam, M. (2009): The Structure Of The PG Outflow Subjected To Density Variations, Ocean Science, Vol. 5, Pp. 51-12.
10- Bower, A.S., Hunt, H.D. And Price, J.F. (2000): Character And Dynamics Of The Red Sea And Persian Gulf Outflows, Journal Of Geophysical Research Atmospheres, Vol. 105, Pp. 6387-6414.
11- Bruce JG, Kindle JC, Kantha LH, Kerling JL, Bailey JF. (1998): Recent Observations And Modeling In The Arabian Sea Laccadive High Region. Journal OfGeophysical Research, Oceans. Vol. 103(C4). Pp. 7593-7600
12- Busireddy NKR, Osuri KK, Sivareddy S, Venkatesan R. (2018): An Observational Analysis Of The Evolution Of A Mesoscale Anti-Cyclonic Eddy Over The Northern Bay Of Bengal During May–July 2014. Ocean Dynamics. Vol. 68(11), Pp. 1431-1441.
13- Chao, S-Y. Kao, T.W. And Al-Hajri, K.R. (1992): A Numerical Investigation Of Circulation In The Arabian Gulf. Journal OfGeophysical Research Atmospheres, Vol. 97(C7), Pp. 11219–11236.
14- Chelton, D.B. Schlax, M.G. And Samelson, R.M. (2011): Global Observations Of Nonlinear Meso-Scale Eddies, Progress In Oceanography, Vol. 91, Pp. 167-216.
15- Cyriac A, Ghoshal T, Shaileshbhai PR, Chakraborty A. (2016): Variability Of Sensible Heat Flux Over The Bay Of Bengal And Its Connection To Indian Ocean Dipole Events. Ocean Science Journal. Vol. 51(1), Pp. 97-107.
16- Dandapat S, Chakraborty A. (2016): Mesoscale Eddies In The Western Bay Of Bengal As Observed From Satellite Altimetry In 1993–2014: Statistical Characteristics, Variability And Three-dimensional Properties. IEEE Journal OfSelected Topics In Applied Earth Observations And Remote Sensing. Vol. 9(11), Pp. 5044-5054.
17- Ezam, M., Bidokhti, A.A. And Javid, A.H., (2010): Numerical Simulations Of Spreading Of The Persian Gulf Outflow Into The Oman Sea, Ocean Sciences, Vol. 6, Pp. 887-900.
18- Faghmous JH, Frenger I, Yao Y, Warmka R, Lindell A, Kumar V. (2015): A Daily Global Mesoscale Ocean Eddy Dataset From Satellite Altimetry, Scientific Data. 2:150028.
19- Frenger I, Gruber N, Knutti R, Münnich M. (2013): Imprint OfSouthern Ocean Eddies On Winds, Clouds And Rainfall. Nature Geoscience. Vol. 6(8), 608.
20- Gopalan AKS, Krishna VV, Ali MM, Sharma R. (2000): Detection OfBay Of Bengal Eddies From TOPEX And In Situ Observations. Journal OfMarine Research. Vol. 58(5), Pp.721-734.
21- Goni G.J., Trinanes J.A. (2003): Ocean Thermal Structure Monitoring Could Aid In The Intensity Forecast Of Tropical Cyclones. Eos, Transactions American Geophysical Union. Vol. 84(51), Pp. 573-578.
22- Hong X, Chang SW, Raman S, Shay LK, Hodur R. (2000): The Interaction Between Hurricane Opal (1995) And A Warm Core Ring In The Gulf OfMexico. Monthly Weather Review. Vol. 128(5). Pp. 1347-1365.
23- Hosseinibalam, F., Hassanzadeh, S. And Rezaei - Latifi, A. (2011): Three-Dimensional Numerical Modeling Of Thermohaline And Wind-Driven Circulations In The Persian Gulf. Applied Mathematical Modelling, Vol. 35, Pp. 5884–5902.
24- Johns, W.E. Yao, F. And Olson, D.B. (2003): Observations Of Seasonal Exchange Through The Straits Of Hormuz And The Inferred Heat And Freshwater Budgets Of The Persian Gulf, Journal Of Geophysical Research Atmospheres, Vol. 108, Pp. 3391-3391.
25- Kampf, J. And Sadrinasab, M. (2006): The Circulation Of The Persian Gulf: A Numerical Study, Ocean Sciences, Vol. 2(1), Pp. 27–41.
26- Kumar BP, Vialard J, Lengaigne M, Murty VSN, Mcphaden MJ. (2012): Tropflux: Air-Sea Fluxes For The Global Tropical Oceans—Description And Evaluation. Climate Dynamics. Vol. 38(7-8), Pp. 1521-1543
27- Luyten P.J. Deleesnijder,E. . Ozer, J. Ruddick, K.G. (1996) :Presentation Of A Family Of Turbulence Closure Models For Stratified Shallow Water Flows And Preliminary Application To The Rhine Outflow Region, Continental Shelf Research, Vol. 16, Pp.101–130
28- Mainelli M, Demaria M, Shay L.K, Goni G. (2008): Application Of Oceanic Heat Content Estimation To Operational Forecasting Of Recent Atlantic Category 5 Hurricanes. Weather AndForecasting. Vol. 23(1), Pp. 3-16
29- Mellor G.L. And Yamada T. (1982): Development Of A Turbulence Closure Model For Geophysical Fluid Problems”, Reviews Of Geophysics And Space Physics, Vol. 20(4), Pp. 851–875.
30- Mohandesi, M., Bidokhti, A.A., Khaniki, A.K., Hasanzadeh, I. &Torabi Azad, M. (2016): Astudy Of The Performances Of Different Turbulence Schemes In Numerical Simulation Of Hydrodynamics Of A Semi-Closed Sea (Persian Gulf). Marine Geodesy, 39(2):141-64.
31- Noori, R. Abbasi, M.R. Aamowski, J.F. And Dehghani, M. (2017): A Simple Mathematical Model To Predict Sea Surface Temperature Over The Northwest Indian Ocean, Estuarine, Coastal And Shelf Science,Vol. 197, Pp. 236-243.
32- Noori R. Fuqiang, T. Ronny, B. Abbasi, M.R. Vesalinaseh, M.R. Modabberi, A. Soltani, A. Klove, B. (2019): Recent And Future Trends In Sea Surface Temperature Across The Persian Gulf And Gulf Of Oman, PLOS ONE, Pp. 1-19
33- Oropeza F, Raga GB. (2015): Rapid Deepening Of Tropical Cyclones In The Northeastern Tropical Pacific: The Relationship With Oceanic Eddies. Atmosfera. Vol. 28(1), Pp. 27-42
34- Patnaik KVKRK, Maneesha K, Sadhuram Y, Prasad KVSR, Ramana Murty TV, Brahmananda Rao V. (2014): East India Coastal Current Induced Eddies And Their Interaction With Tropical Storms Over Bay Of Bengal, Journal Of Operational Oceanography, Vol. 7(1), Pp. 58-68
35- Pous S. Lazure P. And Xavier,C. (2015): A Model Of The General Circulation In The Persian Gulf And In The Strait Of Hormuz: Intraseasonal To Interannual Variability”,Continental Shelf Research, Vol. 94, Pp. 55-70.
36- Prasanna Kumar S, Muraleedharan PM, Prasad TG, Gauns M, Ramaiah N, De Souza SN. (2002): Why Is The Bay Of Bengal Less Productive During Summer Monsoon Compared To The Arabian Sea.Geophysical Research Letters. Vol. 29(24). Pp. 88-81
37- Reynolds, R.M. (1993): Physical Oceanography Of The Gulf, Strait OfHormuz, And The Gulf Of Oman—Results From The Mt Mitchell Expedition, Marine Pollution Bulletin, Vol. 27, Pp.35 – 59.
38- Thoppil, P.G. And Hogan, P.J. (2010): A Modeling Study Of Circulation And Eddies In The Persian Gulf, Journal Of Physical Oceanography, Vol. 40(9), Pp. 2122–2134
39- Yao, F. And Johns, W. E. (2010): A HYCOM Modelling Study Of The Persian Gulf: 2: Formation And Export Of Persian Gulf Water, Journal Of Geophysical Research Atmospheres, 115. C11018. 1-23
39- Yao, F. And Johns, W.E. (2010): A HYCOM Modeling Study Of The Persian Gulf: 1. Model Configurations And Surface Circulation, Journal Of Geophysical Research Atmospheres, Vol. 115, C11017. Pp. 1-17.