مباحث عمومی هواشناسی

[mohamad$]

شمال تهران دیروز 2.1 میلیمتر بارندگی رخ داد


بیشینه دمای دیروز

تهران 35.6
لواسان 32.7
طالقان 31.0
دماوند 30.2
آبعلی 26.6
فیروزکوه 25.6

 

[امیرکوروش]

[FONT=Vazir, times, serif]
ارتباط پوشش برف اوراسیا و شاخص AO و مونسون هند با یکدیگر :


[FONT=Vazir, times, serif]با توجه به ارتباط قوي بين پوشش برف قاره اورآسيا و شاخص AO‌ و مطالعات متعددي كه در رابطه با پوشش برف اورآسيا و موسمي هاي تابستانه هند و آسيا صورت گرفته است بارنت و همكاران ( Barnetetal ) اعتماد دارند كه نابهنجاريهاي پوشش برف برروي اورآسيا همانند انسو شرايط بازدارنده اي را در منطقه حاره اي اقيانوس بوسيله تضعيف موسمي هاي تابستاني و تشديد جريانات غربي حاره اي بوجود آورد . ( Webster – 1998 )[FONT=Vazir, times, serif]بنابراين مي توان نتيجه گرفت در شاخص هاي مثبت AO‌ كه معمولاً بادهاي غربي در شمال اقيانوس اطلس تقويت مي شود و شرايط مرطوب و گرمتر از نرمال را در روي اروپاي شمالي بدنبال دارد ( Hodge – 2000 ) بارشهاي موسمي تابستانه افزايش مي يابند . در مدلي كه توسط وبستر و همكارانش ارائه گرديده افزايش پوشش برف در اورآسيا با كاهش شدت موسمي تابستاني و كاهش پوشش برف با موسمي هاي تابستاني قوي تر همراه بوده است .[FONT=Vazir, times, serif]لذا با عنايت به اين اصل كه نوسان قطبي شمال AO‌ رقيب اصلي انسو در روند تغيير پذيري اقليمي سياره زمين به شمار مي رود .[FONT=Vazir, times, serif]مي توان رابطة قوي بين شاخص AO و بارش هاي تابستانه منطقه را توجيه نمود . شديد ترين بارش هاي تابستانه معمولاً در شرايطي كه فازهاي سرد انسو ( لانينا ) با فازهاي مثبت قوي AO‌ توام باشد ، بروز مي نمايد . و معمولاً تابستانهاي خشك در فازهاي ال نينو توام با فازهاي منفي AO مشاهده مي گردد .[FONT=Vazir, times, serif]در فصل پاييز كه منشأ بارشها با تابستان متفاوت است و در واقع فصل شروع بارشهاي اساسي منطقه از طريق كم فشارهاي همراه بادهاي غربي مي باشد بيشترين ارتباط بين سريهاي زماني بارش و شاخص هاي اساسي انسو وجود دارد .[FONT=Vazir, times, serif]همبستگي با دو شاخص SOI ( نوسان جنوبي ) و MEI ( چند متغيره انسو ) به تريتب 459/0- و 382/0 ميباشد . با توجه به آزمون همبستگي ها و مقادير P-Value اين همبستگي در سطح 01/0 معني دار مي باشد .[FONT=Vazir, times, serif]ميزان همبستگي با ساير شاخص هاي ارتباط از دور نظير NAO و NINO3-4 نيز قابل ملاحظه بوده و همبستگي هاي معني داري بين بارش پاييز و شاخص هاي ماهيانه الگوهاي آمريكاي شمالي ، آرام ( PNA ) جت اطلس شرقي
( EA JET ) و نوسان قطبي – اورآسيا ( POL / Eur ) وجود دارد .[FONT=Vazir, times, serif]



رودبادها نقش مهمي را در حركات اتمسفري بازي مي كنند . معمولاً با افزايش فعاليتهاي همرفتي در مناطق حاره اي اقيانوس آرام طي حوادث ال نينو اين انرژي بوسيله حمل گرما و رطوبت به اتمسفر فوقاني منتقل مي شود . طي يك سري واكنش هاي جوي پيچيده شامل مكانيسم هاي پسخوراند اين انرژي به سمت قطبين منتقل مي گردد نتيجه اين تغييرات در رودباد جنب حاره اي ( STJ‌ ) و رود بار جبهه قطبي ( PFJ ) منعكس مي گردد . اين تغييرات در رودبادها بطور فزاينده اي الگوهاي هوائي در نيمكرة شمالي را تغيير مي دهد .[FONT=Vazir, times, serif]افزايش فعاليتهاي رعد و برقي در طي حوادث ال نينو كه باعث نفوذ رطوبت و گرما تا 50000 فوت بداخل جو فوقاني مي شود عامل مهمي در افزايش سرعت و تغيير موقعيت امواج رودباد مي باشد اين تغييرات در طي فازهاي مختلف انسو نه تنها برروي الگوهاي هوا در امريكاي شمالي و جنوبي بلكه در نقاط دورتري چون افريقا و خاورميانه تاثير
مي گذارد . ( USA Today – 2000 )[FONT=Vazir, times, serif]اسميت و همكاران به دو شاخه شدن رودباد بر روي بخش اقيانوس آرام جنوبي اشاره نموده ، تقويت رودباد جنب حاره اي و تضعيف رودباد جبهه قطبي طي فازهاي گرم و شرايط متضاد آن طي فازهاي سرد را مورد تاكيد قرار مي دهند . ( Smith – 1996 )[FONT=Vazir, times, serif] [FONT=Vazir, times, serif]

[FONT=Vazir, times, serif]در سال 93-1992 مسيرهاي رودبادي و سيلكوني غير معمول بروي امريكاي شمالي گزارش شده
است . ( Murphre – 1998 )[FONT=Vazir, times, serif]در رويداد ال نينوي بسيار قوي سال 83-1982 تغييرات مهمي درالگوي رودباد در نيمكرة شمالي بوقوع پيوست . تغيير مسير اين رودباد عامل اصلي نابهنجاريهاي بارش ( تا بيش از 200 درصد ) در بسياري از نقاط بوده
است . ( Strahler – 1987 )[FONT=Vazir, times, serif]جهت آزمون اين فرضيه كه مسير رودباد در شرايط انسو تغيير مي نمايد نقشه هاي جهت و سرعت بادها در سطوح 500 ، 300 و 200 هكتوپاسكال نيمكرة شمالي طي فازهاي گرم ، سرد و شرايط عادي و همچنين روديدادهاي شاخص ال نينو تهيه گرديد . براساس آنكه مسير رودبادها معمولاً حداكثر هستة سرعت باد را تعقيب مي كند .
(Cunningham–2001) در سطوح 200 و 300 هكتوپاسكال مسيرهاي اصلي رودباد جنب حاره اي و برروي سطح 500 هكتوپاسكالي مسير رودباد جبهه قطبي ترسيم و نقشه هاي مربوطه تهيه گرديد . علاوه برآن منطقه جبهه اي رودباد جبهه قطبي براساس تجربيات موجود ( FAS – 1996 ) روي نقشه اايزوترم 500هكتوپاسكال ترسيم گرديد . با توجه به تفسير نقشه هاي تهيه شده نتايج مقايسه مسيرهاي رودباد به شرح زير مي باشد .[FONT=Vazir, times, serif]در فصل تابستان با توجه به حاكميت رودباد جنب حاره اي ( STJ‌ ) تفاوت هاي مشهودي در مسير متوسط اين رودباد طي فازهاي گرم و سرد مشاهده مي شود . مسير رودباد طي فازهاي گرم حدود 10 درجه در شرق اقيانوس اطلس به سمت جنوب نسبت به شرايط غير انسو و فازهاي سرد تغيير نشان مي دهد . مسير متوسط آن از روي خاورميانه و ايران ، منطقه مركزي و جنوبي هيماليا مي باشد در حالي كه طي فازهاي سرد اين رودباد با تعقيب مسيري شمالي تر از جنوب درياي خزر و شمال هيماليا عبور مي كند .[FONT=Vazir, times, serif]در فصل پاييز تفاوت در مسير رودباد طي فازهاي مختلف انسو به حداكثر خود مي رسد در نقشه هاي سطح 300 هكتوپاسكال در فازهاي گرم هسته سرعت خاورميانه اين رودباد بروي جنوب شرق ايران تا درياي سرخ كشيده شده و مسير اصلي آن از روي شمال خليج فارس ، تنگه هرمز و جنوب منطقه است در فازهاي سرد هسته سرعت مركزي به سمت مرزهاي شمالي منطقه هدايت شده و از آنجا به سمت شرق آسيا مي وزد . در شرايط غير انسو مسير رودباد در شرايط بينابين فازهاي سرد و گرم بوده و از سرعت هسته سرعت مركزي كاسته مي شود . ( نقشه هاي شماره 3 و 4 )
در حوادث گرم قوي ضمن افزايش سرعت رودباد به جنوبي ترين موقعيت خود نسبت به ساير فازها هدايت مي شود .براي مثال در حادثه پاييزي 1997 سرعت هسته مركزي به 32 متر در ثانيه بالغ گرديد .[FONT=Vazir, times, serif]رودباد جبهه قطبي ( PFJ‌ ) طي فازهاي گرم بطور متوسط از مدار 45 درجة شمالي اقيانوس اطلس ، جنوب انگليس ، شمال فرانسه به سمت شمال سيبري و جنوب آسيا جريان دارد . در حاليكه طي فازهاي سرد از عرض 50 درجة شمالي به سمت شمال انگلستان ، جنوب اسكانديناوي و سپس مستقيماً به سمت شرق مي وزد . موقعيت متوسط اين رودباد حدوداً 10 درجه شمالي تر از موقعيت فازگرم آن بوده و علاوه بر آن حركات نصف النهاري آن به نحوقابل ملاحظه اي كمتر وبيشتر بصورت مداري مي وزد .مسير اين رودباد در شرايط عادي از 5/47 درجه عرض شمالي آغاز گشته و از مركز انگليس و جنوب اسكانديناوي در مسير بين فازهاي گرم و سرد جريان مي يابد .[FONT=Vazir, times, serif]بررسي منطقه جبهه اي اين رودباد از روي نقشه هاي حرارتي سطح 500 هكتوپاسكال بيانگر آن است كه طي رويدادهاي ال نينو اين منطقه بطور متوسط از روي مديترانه شمالي به سمت شمال كشور و مستقيماً به سمت شرق جريان دارد . در حاليكه طي فازهاي سرد موقعيت آن به سمت عرضهاي شمالي تر منتقل مي گردد و تقريباً مشابه شرايط عادي
مي باشد .در دو حادثه لانينا بسيار قوي ( 1998 ، 1999 ) همراه خشكسالي ، موقعيت متوسط منطقه جبهه اي به شمالي ترين حد خود منتقل گرديده است .

 

[abtinT]

لحظه سر ریز شدن دریچه اطمینان سد منجیل​

 

[Amir Mohsen]

Climate & Conflict: Warmer World May be More Violent

• Published: August 1st, 2013 , Last Updated: August 1st, 2013

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By Andrew Freedman
Follow @afreedma
Global warming may be ratcheting up the odds for violence at the local, regional, and international scales, from inner-city America to the arid plains of Africa, according to a comprehensive new study published Thursday.
The study, published in the journal Science, concludes that climate events from heat waves to droughts and floods have strong links to violent conflicts, helping to explain patterns of crime, civil wars, and even the collapse of some ancient civilizations. The study draws on a broad body of evidence from fields as disparate as archaeology and political science that show a causal and often substantial connection between climate and those events.

A Sudanese woman and children are pictured in Fanga Suk in East Jebel Marra, South Darfur.
Credit: United Nations Photo by Olivier Chassot.
The report, which took a sweeping view of 60 previously published studies on climate and conflict, found that the size of climate’s influence on conflict is larger than most previous studies had estimated, although the authors cautioned that climate is not necessarily the biggest factor driving violence in most situations.
Written by researchers at Princeton University and the University of California at Berkeley, the study found that when the climate deviates far from average conditions, the risk of many types of conflict increases.
“The central finding of the study is the link — the very strong link — we find between adverse climate and more violence, more human conflict,” said co-author Edward Miguel, of U.C. Berkeley, in an interview. “We establish that link looking at a much broader set of studies than others have before.”
To put it more technically, the study found that for each one standard deviation change in the climate toward warmer average temperatures or more extreme rainfall, the median estimate of the frequency of intergroup conflict — i.e. civil war — rises by 14 percent, while the frequency of interpersonal conflict increases by 4 percent.
“For a sense of scale, this kind of temperature change is roughly equal to warming an African country by 0.6°F for an entire year, or warming a U.S. county by 5°F for a given month. These are moderate changes, but they have a sizable impact on societies,” said study co-author Marshall Burke of U.C. Berkeley, in a press release.
Given that climate projections show that many parts of the world are expected to at least double that amount of warming by 2050, the findings strongly suggest that barring other mitigating factors, a warmer world will also be a more violent one.
Zambian peacekeepers from the United Nations Mission in Sudan (UNMIS) patrol streets lined with looted items awaiting collection in Abyei, the main town of the disputed Abyei area on the border of Sudan and newly independent South Sudan.
Credit: United Nations Photo by Stuart Price.
There are numerous recent conflicts that studies have linked to climate extremes, including the Arab Spring that began two years ago, genocide in Darfur, and the ongoing Syrian civil war.
In the case of Syria, for example, a major drought and sharp spike in food prices, along with reduced access to water and power supplies preceded the uprising against the regime of president Bashar Al-Assad, and similar climate-related food price spikes played out in Egypt and Tunisia prior to the ouster of longtime governments in those countries.
Lack of consistent access to water may contribute to more conflicts in the future, with increasingly strained water resources in coming decades due to burgeoning populations and drought. Climate studies show that drought is projected to increase in frequency and severity in some parts of the world that are experiencing high rates of population growth, such as the Middle East and parts of Africa.
The research is the first to reexamine the available evidence on climate and conflict, which has at times been a contentious subject within the scientific community.
The results dramatically depart from prior research that said the relationship between global warming and conflict is contradictory and inconclusive. The Cal-Berkeley team found that all 27 studies dealing with modern societies found a relationship between higher temperatures and greater violence.
Experts in the field who were not involved in the study said its findings are groundbreaking.
“I think it’s a path-breaking study that lays to rest a lot of the earlier, slightly misinformed, debate and confusion,” said Marc Levy, deputy director of the International Earth Science Information Network at Columbia University.
Levy said the study shows that climate is clearly a driver of violence, but not the main driver in most cases, given the many other contributing factors to conflict, from ethnic rivalries to economic development and political repression. He said previous studies that had looked at individual conflicts and individual climate factors resulted in a “cacophony” of seemingly disparate results.
These four maps illustrate the increased potential for future drought worldwide over the decades indicated, based on current projections of future greenhouse gas emissions. The maps use a common measure, the Palmer Drought Severity Index, which assigns positive numbers when conditions are unusually wet for a particular region, and negative numbers when conditions are unusually dry.
Click image to enlarge. Credit: NCAR.
“It’s really, really difficult to find a smoking gun, to find a climate stress in a conflict and say definitively that in the absence of climate stress this conflict wouldn’t have occurred,” he said in an interview.
Levy said the study demonstrates where the social and physical science communities are headed on the climate and conflict nexus, with more researchers becoming convinced that the evidence is far stronger than it was just a few years ago.
“Many more people are falling into the camp that the evidence is definitive,” Levy said.
Thomas Homer-Dixon, a professor at the University of Waterloo in Canada, said the study presents a compelling case for a robust link between climatic stress and violence, while being careful to acknowledge that climate change is but one of many factors that can increase the likelihood of violence.
“The paper’s conclusions are dramatic in terms of their implications for policy and for humankind more generally, but they’re not sensationally stated,” Homer-Dixon said in an email conversation. “The paper is well-caveated, with clear acknowledgments of areas where future research is necessary.
“What does it all mean? The world will be a very violent place by mid-century if climate change continues as projected. Climate change will increase the likelihood that large zones of the world will see central institutions disintegrate and evolve into a form of chronic security anarchy — think Somalia, Yemen, western Pakistan, eastern Congo, etc.”
Not everyone is convinced by the new research, however. “I struggle to see how the authors can claim a remarkable convergence of quantitative evidence when one-third of their civil conflict models produce a climate effect statistically indistinguishable from zero, and several other models disagree on the direction of a possible climate effect,” said Halvard Buhaug, research director at the Peace Research Institute in Oslo whose work has cast doubt on ties between climate extremes and conflict.
“Surprisingly, the authors provide no examples of real conflicts that plausibly were affected by climate extremes that could serve to validate their conclusion. For these and other reasons, this study fails to provide new insight into how and under what conditions climate might affect violent conflict,” he said in an email conversation.
The new study is what is known as a “meta analysis,” and it took the data from numerous prior studies and examined them collectively using state of the art statistical methods that were unavailable to researchers until relatively recently, thereby drawing conclusions from a far larger dataset than the individual studies themselves.
In total, the research contains the results of a comprehensive review of the available data put forward by 60 prior studies of climate from 190 researchers in various disciplines, including data on violence dating from 10,000 B.C.E. to the present day, extending across all regions of the globe. Reflecting the growth of research on this topic in recent years, 78 percent of the studies were published since 2009.
The study incorporated findings from research on domestic violence, street crime, rioting, civil war, all the way to the collapse of entire civilizations.
To compare all the datasets from individual studies, the researchers first standardized the information using a measure of normal climate variability, known as the standard deviation unit. Miguel likened this process to “converting weather variables into a common currency.”
Next, in order to reduce the margin of error, the researchers pooled the standardized data together in a way that is similar to how a political pollster might average a group of polls to accurately predict the outcome of a presidential election, rather than relying on just one or two polls to get a snapshot of the race. These methods allowed the researchers to analyze separate data sets that would otherwise make for “apples to oranges” comparisons.
A deserted drought-stricken village in Mauritania seen in 2011.
Credit: United Nations Photo by John Isaac.
Among climate change-related factors, the study found that temperature has a larger effect on violence, particularly intergroup violence, than precipitation, although both clearly influence the odds of violence.
In order to prevent such a bleak future, researchers and policymakers face a daunting task, since knowing that climate change affects violence is not enough to create better early warning systems or develop violence-prevention strategies.
“We can’t just stick with the status quo,” Miguel said. “Our study suggests that if we stick with the status quo we’re going to have a lot more violence.”
To devise successful strategies that reduce the risk of future violence, scientists need to determine the causal pathways through which climate influences conflict. For example, it could be through economic factors, with a drought reducing farmers’ income and, at the same time, increasing food prices that further stress society. Policymakers also need to put in place tools to anticipate and prevent conflict.
“We’re in the same position that medical researchers were in during the 1930s: they could find clear statistical evidence that smoking tobacco was a proximate cause of lung cancer, but they couldn’t explain why until many years later. In the same way, we can show that climatic events cause conflict, but we can’t yet say exactly why,” said lead author Solomon Hsiang of Princeton University (now at U.C. Berkeley), in a press release.
The evidence regarding the link between climate change and conflict is solid enough to have motivated the U.S. national security establishment, spurring research projects at the CIA, the Defense Advanced Research Projects Agency, and other agencies.
The 2010 Quadrennial Defense Review, and the 2010 National Security Strategy identified climate change as a threat to U.S. national security, in part, because of its potential to foment political instability in strategically important regions, such as the Middle East.
A CIA-funded study published in 2012 found that climate extremes, such as droughts and heat waves, are already exacerbating tensions in parts of the world.
A promising avenue for early warning systems may be through the use of big data. Those approaches would combine various social indicators, such as the average income of a country, with environmental monitoring data, such as satellite imagery showing vegetation health, to detect areas at higher risk of climate change-related violence.
Some of those efforts are already underway. A Pentagon-sponsored research group that Columbia’s Levy is advising is trying to combine social media data mining with remote sensing data from satellites and other tools to identify potential pressures on social stability in the so-called “megacities” of the world, with populations of greater than 10 million.
“I think we’re still in the early days of being able to take all these potential technologies and turn them into reliable, actionable early warning systems,” Levy said. “We’re much, much closer than we were five years ago.”
​

 

[Amir Mohsen]

پیش بینی جدید هواشناسی ایتالیا برای ماه آگوست:

http://www.isac.cnr.it/dinamica/projects/forecast_dpc/MONTHLY/month_201308.pdf

 

[Amir Mohsen]

[h=2]Lightning Storm in Oregon Credit: Steve Lenz/Steve Lenz Photography
Photographer Steve Lenz captured this incredible lightning photo in northeast Oregon, outside the city of Milton-Freewater. The region is characterized by rolling hills, and treeless agriculture, he said. Lenz snapped this electrifying shot during a storm on July 20, 2012.

"I was out in the middle of this storm with lightning crashing all around (a few miles away) and excitedly taking photos," Lenz told LiveScience in an email. "This photo is the last one I got when my shutter broke. My heart sank. I put my equipment away and got in my car and then realized the lightning had gotten dangerously close. So I was somehow relieved my shutter had broken or I might have been in trouble."

Lenz used a Canon 5D mark1 camera and a Sigma 150-500 lens to capture the magnificent scene.

"I set the camera on a tripod and aimed it towards the windmills where there was a high concentration of lightning strikes," he said. "I set it at F5, ISO 100 and left the shutter open for about 30 seconds at a time hoping to catch strikes​

 

[Fooladi]

درود دوستان
میگرن شدیدی دارم و فعلا نمی تونم مطالب مفیدتون رو مطالعه کنم اما این همبستگی ها رو می ذارم

تاثیر NAO برآنومالی تراز ۵۰۰ میلی بار. با مثبت شدن شاخص بخشهای مثبت هم افزایش ارتفاع خواهند داشت و بخش های منفی کاهش ارتفاع

پاییز:


زمستان:


بهار:


تابستان:




اما تاثیر NAO بربارش. با مثبت شدن شاخص بخشهای مثبت هم افزایش بارش خواهند داشت و بخش های منفی کاهش بارش

پاییز:


زمستان:


بهار:


تابستان:

 

[Fooladi]

ببینیم طبق آمار با گرمتر شدن زمین بارش ها در کجاها دچار تغییر شدند:

اول بارش اول پاییز تا آخر بهار رو بررسی کردم
متاسفانه وضعیت رو می بینید:





تغییرات بارش تابستانه:

 

[felan123]

خلاصه بعد این همه تخصوصی نگاه کردن
پاییز و زمستون خوبی داریم یا نه ؟؟؟؟؟

 

[Amir Mohsen]

Ecosystems Face Unprecedented ‘Climate Change Velocity’

• Published: August 1st, 2013

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By Brian Kahn
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Over the next century, plants and animals on land might be in for a wild and ultimately devastating ride. Warming temperatures, changing precipitation patterns, and extreme weather and climate events are likely to increase at a rate and magnitude not seen in more than 65 million years, according to a new study published Thursday in the journal Science.
Couple that with other human-related ecosystem disruptions, from highways to deforestation to pollution, and some species could find themselves pushed to the top of the mountain or the tip of a continent with no suitable habitat left in which to move.

A view of the Brazilian Amazon rainforest and a field that's been clearcut. Rising temperatures and land use changes will pose an unprecedented challenge to ecosystems across the globe.
Credit: CIAT International Center for Tropical Agriculture/Flickr
Global average surface temperatures have risen about twice as fast over land during the past century as they have over the ocean, a trend likely to continue into the next century. Based on the current emissions trajectory, temperatures are projected to rise by as much as 9°F over much of the Earth’s land, the study found. The last time the Earth warmed that much was around 55 million years ago. Only the cooling that caused the extinction of the dinosaurs tops the magnitude of change over the past 65 million years.
“The key difference is the rate of change,” said co-author Noah Diffenbaugh, a climate scientist and Senior Fellow at the Woods Institute for the Environment at Stanford University, in an interview. “The combination of rate and magnitude over the next century is unprecedented. In the context of the geological record of the last 65 million years, this (change in the 21st century) is likely to be an order of magnitude, or two or three orders, more rapid.”
When Earth warmed 55 million years ago, it did so over 10,000 years. The projected change over the next century provides a small window in which life on Earth, including humans, will need to adapt to a similar change in temperatures.
Average temperature change only tells part of the story, though. “One key aspect of this review is that extremes really are where a lot of the impact is felt,” Diffenbaugh said. “It’s not that another degree of global warming will impact ecosystems, it’s that those ecosystems will encounter extremes much more frequently.”
And those extremes can have profound impacts on ecosystems around the world. For example, in the Amazon, rainfall decreased by 3.2 percent each year from 1970 to 1998. That led to increased wildfires and tree die-offs throughout the region.
To cope with the changes, ecosystems will either need to adapt to the new normal or migrate to a more suitable habitat. Certain species are already responding. Shrubland has expanded throughout the Arctic in response to warmer conditions. In the Northeast U.S., certain plants bloomed 11 days earlier on average from 2000 to 2009 compared to 161 years ago, according to historical records.

Shrubland has increased in recent years throughout the Arctic.
Credit: kdee64/Flickr
The idea that species will move is informing a relatively new area of research known as “climate change velocity.” The basic premise rests on looking at expected changes over the next century in relation to the present, and then anticipating how far ecosystems would need to shift each year to stay in their comfort zone.
“If you look at how rapidly species would have to move in space to keep up with climate change, over many land areas species would have to move at a rate of at least a kilometer per year in order to maintain the annual temperature that they currently experience,” Diffenbaugh said.
Some previous research has identified flat areas as where changes will happen the fastest because plants and animals will have to move greater distances to find the same conditions they’re used to. However, the new study shows that ecosystems in mountainous zones, such as the edge of South America and Africa, and high northern latitudes could have to travel the fastest and farthest to keep up with temperature change.
Species in those regions may have to move at a rate upwards of 80 miles a year in order to stay in areas with the same temperature they currently live with, according to the study. For species at the top of the mountain that are accustomed to a cooler climate, that could simply translate to nowhere to go or no path to get there.
While the high latitudes and mountains have the more eye-popping velocity of change numbers, Diffenbaugh warned that species in tropical areas, which are experiencing less of an absolute temperature change compared to the other regions, are still at risk in a warming world. That’s because species there are adapted to the relatively lower climate annual variability so even slight shifts in that range can have profound consequences.
“We’ve seen, for example in the Amazon, severe heat and severe drought have substantial impacts on forest ecosystems,” Diffenbaugh said. “There are examples of extreme events having substantial impacts on a yearly timescale.”
This past year, Australia experienced its hottest summer on record during which wildfires raged across the landscape.

The top map shows velocity of climate change estimates based on the new Science study. The bottom map shows velocity of climate change based on previous estimates. Note the two maps use different scales.
Credit: Diffenbaugh and Field, 2013
While using temperature to determine the velocity of change shows relatively clear consequences, Diffenbaugh acknowledged that the approach might oversimplify the issue. “In the paper, we review a number of other aspects of climate that can have impacts on ecosystems, including precipitation and extreme events such as heat waves, droughts, and severe storms,” he said. “The velocity question could be asked through a number of those lenses. That’s part of the active edge of this area of research.”
At the root of those future changes is the path humans take into the 21st century.
For example, the Energy Information Administration forecasts that fossil fuels will be the dominant source of energy through 2040, but allows for a number of uncertainties from economic growth to price spikes that could alter that trajectory.
Similarly, population growth, technological innovations, and policy changes could further change greenhouse gas emissions and, with it, what the future climate and its impact on ecosystems will look like.
Regardless, any warming will also take place in a world that’s increasingly fragmented by human development. Water and air pollution, urban sprawl, mining, deforestation, and other alterations to the landscape will create a steeplechase course for plants and animals to navigate in search of more hospitable climates.
How species deal with this confluence of changes in the coming century is uncertain. Terrestrial ecosystems faired well during the warming 55 million years ago, though they had much longer to adapt.
Michael Mann, a scientist at Penn State not affiliated with the study, said, “this study makes clear that we can expect unprecedented rates of warming, shifting rainfall and drought, that will challenge the adaptive capacity of life on Earth -- including human beings.”
​

 

[Amir Mohsen]

[h=2]Sun Finally Sets in Barrow, Alaska
[h=5]August 02, 2013; 3:17 AM
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The residents of Barrow, Alaska, will see something tonight that they have not seen since May 10, a sunset.
Ever since 2:54 a.m. on May 11, the sun has been in the sky, keeping the town in continual light. Early Saturday at 1:58 a.m. Alaska Standard Time (AKST), the sun will fall below the horizon, making it the first official sunset on summer for the town.
The reason that Barrow experiences the periods of continual light is due to their close location to the North Pole. As the Earth revolves on its axis, Barrow is turned toward the sun and remains light until the revolution of the Earth turns Barrow away from the sun.
Unfortunately, residents of Barrow will likely not be able to witness the sunset, as a storm system will spread clouds and rain showers across northern Alaska.

This summer has been unusually warm across the Last Frontier. So far this summer, Barrow and Anchorage have averaged right around 2.7 degrees above average, while Fairbanks has averaged nearly 4 degrees above average!
Although Anchorage has averaged above normal, they have yet to break any daily temperature records this summer. The persistent warmth has managed to break a different type of record for the city, however.
Over the past 16 days, Anchorage has either reached or climbed above 70 degrees. This breaks the old record of set in 2004 when the city had a stretch of 13 consecutive days of at or above 70.
This warmer weather has also contributed to the lighting of dozens of wildfires burning across Alaska over the past few weeks. According to Alaska Interagency Coordination Center, there are currently 76 active wildfires across the state.
​

 

[mehrafarin]

 

[arashz]

درود بر همه دوستان
امروز ساعت 2 بعد از ظهر از اصفهان به سمت تهران حرکت کردم دمای اصفهان 40 درجه بود که در طول مسیر و ارتفاع 2250 متری به 34 درجه کاهش پیدا کرد. بعد از نطنز میدان دید به شدت کاهش پیدا کرد و در نزدیکی قم با دمای 43 درجه به زیر 5 کیلومتر رسید! نرسیده به عوارضی قم با صحنه آتش گرفتن یک تریلی هم مواجه شدیم که این اتفاق در مسیر کسالت آور کاشان واقعا عجیب و تا حدی هیجان انگیز بود و خدا رو شکر برای راننده مشکلی پیش نیومده بود. جنوب تهران دما 40 درجه بود امیر آباد 38 و در سعادت آباد دما به 34 درجه رسید.
فعلا

Sent from my GT-I9100G using Tapatalk 2

 

[tima ir]

سلام به همه اساتید گرامی بارش باران همینک در سیستان بلوچستان و شهر چابهار .

 

[Amir Mohsen]

سلام دوستان

مطابق با نقشه های امشب احتمال وقوع بارش در نواحی شمالی خراسان رضوی و خراسان شمالی از اواسط هفته جدید به بعد وجود داره!

در ضمن نفوذ جربانات خنک و مرطوب شمالی رو نیز در پیش خواهیم داشت

 

[heaven1]

درود بر دوستان
خوشبختانه روند كاهش دما در سطح كشور همچنان ادامه داره و خصوصن اين خنكي هوا در ساعات شب ملموستر هست

 

[heaven1]

سلام دوستان

مطابق با نقشه های امشب احتمال وقوع بارش در نواحی شمالی خراسان رضوی و خراسان شمالی از اواسط هفته جدید به بعد وجود داره!

در ضمن نفوذ جربانات خنک و مرطوب شمالی رو نیز در پیش خواهیم داشت

درود امير محسن جان
پس گرماي 2 شنبه زياد دووم نمياره؟!

 

[Amir Mohsen]

درود امير محسن جان
پس گرماي 2 شنبه زياد دووم نمياره؟!

درود هادی جان

کاملا درسته و دیگه خنکی هوا روز به روز بیشتر احساس میشه

 

[heaven1]

تا 2 هفته قبل دماي مشهد ساعت 4 صبح به دماي 25 ميرسيد ولي الان در اين ساعت به اين دما رسيده! واقعن هوا فوق العاده دلپذيره تو اين ساعت

 

[heaven1]

درود هادی جان

کاملا درسته و دیگه خنکی هوا روز به روز بیشتر احساس میشه

خصوصن شب ها!