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مباحث عمومی هواشناسی
- شروع کننده موضوع Amir Mohsen
- تاریخ شروع
- وضعیت
Amir Mohsen
متخصص بخش هواشناسی
خواهش میکنم بهروز جان
راستش بصورت نمودار میله ای نمی تونم ولی به شکل تاثیر بر روی نقشه ایران به صورت درصد افزایش و یا کاهش آنومالی بارش در ماههای مختلف سال واسم امکان پذیره:خجالت2:
Amir Mohsen
متخصص بخش هواشناسی
امیر کوروش عزیز
این پدیده ای رو که گفتید یعنی پوشش برف آسیای میانه در ماه اکتبر با شاخصی به اسم SAI Index یا SNOW ADVANCED INDEX می سنجند که فکر کنم یک شاخص نوظهوری هست که از 2 تا سال پیش در امریکا مورد توجه قرار گرفته .
با توجه به مقالاتی که در این زمینه خوندم هرچه میزان پوشش برف در منطقه آسیای میانه و سیبری در ماه اکتبر بیشتر باشه، میشه به وقوع زمستانهایی با سرمای سخت در عرضهای میانه جغرافیایی نیمکره شمالی امیدوار شد.
Amir Mohsen
متخصص بخش هواشناسی
Snow Advance Index: A New Tool for Predicting Winter’s Severity
Judah Cohen, PhD
November 14, 2011
[h=4]Snow Advance Index: A New Tool for Predicting Winter’s Severity Researchers at AER have developed a new Snow Advance Index that could greatly improve the accuracy of winter seasonal forecasts. Based on research and testing, this index for the first time can accurately predict the severity of the upcoming winter. What makes this discovery so significant is that advances in seasonal forecasting have remained elusive, and for much of the United States seasonal forecasts are no more accurate today then they were decades ago.
[h=4]Benefit to industry and government Because weather impacts so many industries, this research and the inclusion of the Snow Advance Index in seasonal forecasts have direct benefit for businesses and government agencies that use long-range forecasts to optimize their operations and financial results and mitigate risk. Demonstrating this need, a recent report issued by the National Academy of Sciences on climate prediction concluded that more accurate climate forecasts would provide great benefit to society and would improve decision making from the agriculture to the energy sector.
[h=4]Why has accurate seasonal forecasting been so difficult? Significant improvements have been made in short term weather forecasting. People rely on the nightly broadcast of the seven day weather forecast, which is more often correct than not.
In contrast, making accurate seasonal forecasts continues to frustrate the large government forecast centers. Despite the use of ever more sophisticated climate models, the only demonstrable skill is that associated with the El Niño/Southern Oscillation (ENSO). Yet the temperature forecast accuracy related to ENSO is limited to western North America; and climate model forecasts for the Eastern US, Europe and East Asia remain no better than using past history or even a coin flip as a forecast tool.
[h=4]Predicting the North Atlantic Oscillation or Arctic Oscillation (N/AO) The scientific community acknowledges that a different climate phenomenon is strongly related to the weather in the Eastern US and Europe. It’s known as the North Atlantic Oscillation or Arctic Oscillation (N/AO) and is explained below.
Until now, the N/AO has been considered unpredictable; but this new Snow Advance Index developed at AER can, for the first time, predict the N/AO with a high degree of accuracy. Even more importantly, the Snow Advance Index predicts with unprecedented accuracy winter temperatures and thus the severity of winter weather in the Eastern US, Europe and East Asia. This is discussed below and shown in the Figure.
[h=4]How the N/AO impacts temperatures in Eastern US, Europe and East Asia The N/AO can be thought of as a winter severity index.
- When the N/AO index is high, winters in the Eastern US, Europe and East Asia are milder or less severe.
- In contrast, when the N/AO index is low, winters in the Eastern US, Europe and East Asia are more severe with increased bouts of cold weather and snowstorms.
- When there is more Eurasian snow cover in October, the following winter N/AO is low and there is an increased frequency of severe weather in the mid-latitudes.
- When there is less Eurasian snow cover in October, the following winter N/AO is high and there is a decrease in the frequency of severe weather in the mid-latitudes.
- When snow cover advances rapidly across Eurasia in October, this is an indication that the upcoming winter will be more severe for the Eastern US, Europe and East Asia.
- When snow cover advances slowly across Eurasia in October this is an indication that the upcoming winter will be milder for the Eastern US, Europe and East Asia.
This new Snow Advance Index will be used for the first time in the AER winter forecast for the winter season of 2011-2012.
[h=4]The link between the N/AO and Winter Severity The N/AO can be thought of as an index of high latitude blocking.
- When the N/AO is high, high latitude blocking is much less frequent. The Jet Stream flows quickly from west to east carrying weather systems along quickly and acts as a divide between cold air to the north and warm air to the south. The Eastern US, Europe and East Asia, which lie in the mid-latitudes, experience long stretches of mild weather, as they remain cut off from cold, Arctic air masses.
- When the N/AO is low, high latitude blocking is more frequent. The flow of air in the atmosphere is impeded or becomes blocked and the Jet Stream is diverted from its normal trajectory and meanders north and south around the high latitude blocking. Mixing of air masses occurs with warm air flowing north into the Arctic and cold air flowing south into the midlatitudes. The Eastern US, Europe and East Asia, which lie in the mid-latitudes experience more severe winter weather, as Arctic air masses repeatedly drive southward. Furthermore, the mixing of warm and cold air masses fuel storms and with more abundant cold air, the precipitation from these storms often falls as snow.
شهاب از بوشهر
کاربر ويژه
سلام علیکم.
جمعه ملکان بارش داره یا نه؟
دلتنگ باران ام.
جمعه ملکان بارش داره یا نه؟
دلتنگ باران ام.
Amir Mohsen
متخصص بخش هواشناسی
Snow Advance Index (SAI)
During October we look for a number of factors which help us to determine the possible general state of the atmosphere leading in to the winter months. One of these, called the Snow Advance Index, measures the rate of advance of the permanent snow cover for the winter across Russia and Asia. The faster the rate of this advance, the more likely it is that during the winter the UK will experience some spells of cold weather, owing to various feedback mechanisms within the Earth’s atmosphere, ultimately leading to an event known as a Sudden Stratospheric Warming.
During October we look for a number of factors which help us to determine the possible general state of the atmosphere leading in to the winter months. One of these, called the Snow Advance Index, measures the rate of advance of the permanent snow cover for the winter across Russia and Asia. The faster the rate of this advance, the more likely it is that during the winter the UK will experience some spells of cold weather, owing to various feedback mechanisms within the Earth’s atmosphere, ultimately leading to an event known as a Sudden Stratospheric Warming.
Amir Mohsen
متخصص بخش هواشناسی
Profile for Ludovic Brucker
Click image to view larger version.
[h=2]Research InterestsDr. Brucker's research focuses on the investigation of the Earth's polar climate evolution by interpreting air- and space-borne measurements of snow-covered polar and sub-polar regions (such as sea ice, ice sheets and terrestrial snowpacks) to provide climate-related variables for the satellite era. To that end, he works on developing algorithms to estimate snow properties from space using state-of-the-art multilayer snow evolution and emission models. Specifically, Dr. Brucker's current objectives are:
[h=2]Field Work
Click image to view larger version.
| Affiliation: | GESTAR, Universities Space Research Association |
|---|---|
| Contact: | E-mail NASA Goddard Space Flight Center Cryospheric Sciences Laboratory, Code 615 Greenbelt, MD 20771 Office Phone: 301-614-6748 Fax: 301-614-5644 |
- to advance, and validate, snow-depth-on-first- and multi-year-ice retrievals from the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) using Operation IceBridge measurements;
- to contribute to the comprehension of the relationships between microwave space-borne observations and snow physical properties using modeling approaches.
[h=2]Field Work
- 2013 Initial Investigation of the Greenland Perennial Firn Aquifer (PFA), Southeast Greenland
- 2011 Satellite Era Accumulation Traverse (SEAT), West Antartica
- 2008 International Polar Year field campaign “Variability and change in the Canadian cryosphere: a contribution to state and fate of the Cryosphere”, Schefferville, Québec, Canada
- Glaciological surveys, Chamonix, France
شهاب از بوشهر
کاربر ويژه
پس بارش نداریم.
حیف شد.
باید منتظر آبان در بوشهر باشم.
حیف شد.
باید منتظر آبان در بوشهر باشم.
http://www.sid.ir/Fa/VEWSSID/J_pdf/66913891903.pdf
تحليل سينوپتيكى بارشهاى فوق سنگين
طبق اين مقاله ، چنانچه دو رودباد استوايى و قطبى بهم نزديك بشوند آنگاه شاهد تشكيل ناوه عميق و قوى بارشى در كشور خواهيم بود
يادمه بهمن ٨٣ هم اصغرى گفت علت برف سنگين و باران سيل آسا روزهاى اخير علتش ادغام اين دو رودباد
تحليل سينوپتيكى بارشهاى فوق سنگين
طبق اين مقاله ، چنانچه دو رودباد استوايى و قطبى بهم نزديك بشوند آنگاه شاهد تشكيل ناوه عميق و قوى بارشى در كشور خواهيم بود
يادمه بهمن ٨٣ هم اصغرى گفت علت برف سنگين و باران سيل آسا روزهاى اخير علتش ادغام اين دو رودباد
در رابطه با زمستان 1374اینجا خیلی صحبت شده از پر بارشی .اما اون سال در نیمه جنوبی ونوار مرکزی بارش مخصوصا برف خوب بود در نوار شمالی بیشتر سوز و سرما حاکم بود .مثلا تو همین خراسان شهر های جنوبی مثل بیرجندوفردوس حتی نهبندان و طبس برف میبارید.اما شهرهای شمالی بجنوردو قوچان و مشهد هوا صاف بود. این جریان بارها اون سال تکرار شد. من فکر کنم پرفشار سیبری اجازه نفوذ بارشهارو به نوار شمالی نمیداد.
وضعيت ناهنجارى بارش كشور طى پاييز ١٣٩٠ ( در تاريخ اول سپتامبر 2011 )
http://axgig.com/images/68046384462811920648.jpg
پيش بينى وضعيت دماى كشور طى زمستان ١٣٩١ ( در تاريخ اول سپتامبر 2012 )
http://axgig.com/images/47322622092343219166.jpg
پيش بينى وضعيت دماى كشور طى زمستان ١٣٩١ ( در تاريخ اول دسامبر 2012 )
http://axgig.com/images/92799661308311890894.jpg
http://axgig.com/images/68046384462811920648.jpg
پيش بينى وضعيت دماى كشور طى زمستان ١٣٩١ ( در تاريخ اول سپتامبر 2012 )
http://axgig.com/images/47322622092343219166.jpg
پيش بينى وضعيت دماى كشور طى زمستان ١٣٩١ ( در تاريخ اول دسامبر 2012 )
http://axgig.com/images/92799661308311890894.jpg
- وضعیت