太陽是否會驅動臭氧並改變氣候？
Is the Sun driving ozone and changing the climate?
2015年，尋找線索的工作仍在繼續……
氣候科學的核心謎團是太陽。來自 140 萬公里寬的火球的直接能量保持著驚人的恆定。輻射傾瀉在我們身上，但瓦特的無休止的相同不會導致地球溫度的波動。太陽正在發生其他事情。一方面，來自太陽的總光能幾乎保持不變，但光的類型發生了變化 — — 光譜發生變化 — — 在周期的某一點出現更短的波長，在周期的相反部分出現更長的波長。這些都有不同的效果。較短的波長（紫外線）會在平流層中產生臭氧並穿透海洋。更長的波長則不然。但太陽也發出帶電粒子並驅動巨大的波動磁場，這兩者都會影響地球的大氣層。
但總日照量（TSI）的微小變化可能仍然為我們提供了有關太陽發生的其他事情的線索。David Evans 的缺口延遲理論認為，TSI 是一個領先指標，在太陽 TSI 達到峰值後，地球溫度大約在 11 年左右（或一個太陽週期）後達到峰值。但其機制是什麼呢？斯蒂芬·王爾德有一個理論。開啟你的大腦，並遵循這一潛在影響鏈：
太陽 — →紫外線或帶電粒子 — →臭氧 — →極地急流 — →雲層 — →表面溫度。
斯蒂芬·王爾德在2010年 提出了這個假設的第一個版本。討論這些細節已經是很久以前的事了。
斯蒂芬·王爾德假說摘要
本質上：太陽通過紫外線或帶電粒子的變化影響臭氧層。當太陽更活躍時，赤道上方的臭氧較多，兩極上方的臭氧較少，反之亦然。臭氧的增加使平流層或中間層變暖，從而使對流層頂降低。因此，對流層頂的高度存在太陽引起的拉鋸效應，導致氣候帶向赤道移動，然後遠離赤道，移動急流並將其從“緯向”急流變為“經向”急流。當經緯時，急流在更遠的北部和南部循環流動，導致氣候帶邊界處的氣團混合線更長，從而產生更多的雲。雲層將陽光反射回太空，決定了氣候系統被近乎恆定的太陽輻射加熱的程度。
圖 1：當太陽不太活躍時，兩極的臭氧較多，但赤道的臭氧較少。對流層頂上方的臭氧減少會導致平流層變暖減少，從而使對流層頂上升，從而將氣候帶推向赤道。這導致急流更加偏向子午線，從而形成更多的雲。雲層反射陽光，因此使地球變暖的太陽輻射減少。
活躍的太陽會增加平流層中的臭氧：
“太陽紫外光譜輻照度的變化直接改變平流層上層臭氧的產生速率（例如Brasseur，1993），因此可以合理地預期太陽週期中臭氧量的變化。1979 年以來的全球衛星臭氧記錄顯示，低緯度地區臭氧總量存在年代際振盪，振幅最大（約 2%）（Hood 和 McCormack，1992 年；Chandra 和 McPeters，1994 年；Hood，1997 年）。
圖 2：當太陽更加活躍時，兩極的臭氧較少，但赤道上空的臭氧較多。對流層頂上方更多的臭氧會導致更多的平流層變暖，迫使對流層頂下降，從而使氣候帶遠離赤道。這使得急流更加呈緯向，因此形成的雲更少。雲層反射陽光，因此更多的太陽輻射使地球變暖。
新研究報告缺少驅動因素 — — 高能電子
2014 年 10 月，Andersson 等人發表的一篇論文建議採取另一層行動，同樣是針對臭氧層。高能電子沉澱（EEP）被描述為日地連接中缺失的驅動因素，它極大地影響了臭氧 — — 但在兩極之上，而不是赤道。中間層中的 EEP 優先沿著磁場線指向兩極，因為電子是帶電粒子，這解釋了為什麼效應在兩極最強。當太陽活躍時，高能電子雨優先減少兩極上方的臭氧，在中間層。
在兩極，規則因奇點而變得緊張
在北極和南極，磁力線會聚，地球將大氣拖動到一個點周圍，對流層頂較低，逆溫現像很常見。當低壓區域位於行星的自轉極時，就會發生極渦。這導致空氣從大氣層的高層螺旋下降，就像水流入下水道一樣。（極地渦旋不應與兩極周圍的環極急流相混淆，媒體中經常將其同名。）
所有這些顯著的作用意味著，在兩極之上，即使是高中間層也會影響對流層頂的高度。在極地渦旋中，下降的氣流將空氣從中間層向下吸引，直接穿過平流層到達對流層頂。
平流層中臭氧層的存在是對流層頂形成逆溫的原因。該臭氧層直接被入射的太陽輻射加熱。它比從地表上升的空氣更溫暖，因此它有效地抑制了對流。
臭氧變化影響平流層的溫度，進而影響對流層頂的高度。來自Zangl 和 Hoinka的第 14 頁：
“例如，假設給定了表面溫度和對流層溫度梯度，並且平流層的溫度發生變化。然後，寒冷的平流層將與高對流層頂（對流層頂壓力低）相關，而溫暖的平流層將對應於低對流層頂（對流層頂壓力高）。”
如果對流層頂上升或下降，就會引起赤道和兩極之間對流層頂高度梯度的變化。這反過來又導致急流向北或向南移動，因為它推動了對流層頂下方的氣候帶。較低的對流層頂限制了空氣在其下方水平自由流動的可用空間。因此，當太陽不太活躍時（正如安德森等人的論文所暗示的那樣），兩極上方的對流層頂降低，將對流層氣候區的空氣擠壓向赤道。我們已經看到，自大約2000 年以來，隨著太陽活動水平在從活躍的太陽週期23 過渡到不太活躍的太陽週期24 的過程中太陽活動水平下降，這種情況以急流經緯性增加的形式發生。
世界被劃分為多個永久氣候區，由於地球自轉，這些氣候區沿著緯線排列。這些區域可以向極地或赤道移動，以響應地球能量預算的變化。在 20 世紀末變暖期間觀察到了向極地移動，眾所周知，這些區域在小冰河時期向赤道移動。
圖 3：急流可以是緯向的（左）或經向的（右）。
來源。
急流是氣候帶之間快速移動的高空氣流河流，由不同類型氣團之間的溫度、濕度和密度差異驅動：
- 氣候帶向赤道方向的轉變為噴流提供了更多的空間來向北和向南循環，從而產生了更多的子午線噴流（噴流的南北部分）。
- 這些區域向極地的移動將噴流推向極地，迫使它們更緊密地遵循緯線，即更多的緯向噴流（東西向部分）。
- 這種變化也與北極濤動有關，其中正相位導致氣候帶被拉向極地，噴流採用更偏向（更直）的模式。負相位會產生相反的結果。由於極地平流層的冷卻（通過極渦下降的中層臭氧減少）以及隨之而來的極地對流層頂的抬升，更頻繁的正相位與更活躍的太陽相關。更頻繁或更明顯的負相位（在第23 和第24 週期之間的極低太陽極小期期間觀察到創紀錄的程度）與由於極地平流層變暖而導致的太陽不太活躍有關（更多的中層臭氧通過極地渦旋下降） ）。
徘徊的噴氣機意味著更多的雲
圖 4：Jetstream 顯示大量經向流。
來源。
更多的經向急流軌跡在世界各地的氣候帶之間流動，導致氣候帶邊界處的氣團混合線更長。來自不同氣候帶不同地點的空氣混合，由於溫度和密度不同，會導致對流不穩定，從而增加雲的形成。
最後，雲反射太陽輻射（即調節反照率），從而影響流入氣候系統的熱量。值得注意的是，進入海洋的太陽能比例受到影響，最終是海洋決定了大氣溫度（參見此處）。
因此，隨著太陽活動水平在數十年和數百年中的變化（例如在中世紀溫暖期、小冰河期和當前溫暖期期間），通過噴流的緯度移動，全球雲量會出現來回變化。溪流軌跡和永久氣候區。
還提出，隨著時間的推移，較高中間層水平的變化占主導地位，因為如上所述，較高水平的影響通過極地渦旋內的下降空氣柱逐漸過濾到較低水平。這將觀察到的兩極臭氧空洞大小的變化與太陽原因聯繫起來，而不是與人類排放的氟氯化碳聯繫起來。當太陽活躍時，臭氧空洞會擴大，而現在，隨著太陽不活躍，臭氧空洞會縮小。
對安德森“高能電子”論文的進一步思考
安德森等人的新論文建立在臭氧具有影響力和放大太陽因素的潛在機制這一假設之上。它將高能電子沉澱 (EEP) 添加到紫外線光譜變化中，這是向前邁出的重要一步。
安德森等人將其描述為具有短期區域影響，對全球或長期氣候變化沒有影響。但是，如果這種影響在單個太陽週期的高峰和低谷之間顯著，那麼它在太陽變化的千年周期中肯定也會很顯著 — — 例如從中世紀溫暖期到小冰河期及以上觀察到的結果迄今為止。
過去一千年對氣候變化的觀察表明，情況必定如此。在中世紀溫暖時期，格陵蘭島有農業，蘇格蘭西部群島也很繁榮，人口比今天多得多，這意味著當時有更多的極地氣候帶和緯向急流。相比之下，小冰河時期的船舶記錄顯示當時的大西洋風暴更大，並且當時的低氣壓軌跡更靠近赤道中緯度（低氣壓通常沿著急流的軌跡）。
炒作食品
斯蒂芬·王爾德的假設是缺口延遲理論的一種可能機制，其中 TSI 在一個太陽黑子週期（約 11 年）延遲後驅動表面溫度，這可能解釋了過去幾百年的大部分溫度變化。如果驅動臭氧產生和破壞的極紫外線，以及安德森等人發現的高能電子沉澱的影響，都落後於整體TSI（可見光和正常紫外線）的趨勢一個太陽黑子週期，就會發生這種情況- 也就是說，半個完整太陽週期（約 22 年）。
（快速提醒：ND理論中一個太陽黑子週期的延遲克服了由於TSI等在1986年左右達到頂峰並且表面溫度不斷上升到1997年左右，太陽無法驅動溫度的反對意見。延遲可以解釋這一點：1986 + 11 = 1997 年。這一延遲還意味著2004 年左右TSI 的整體下降預示著大約一個太陽黑子附近的地表溫度將在2017 年左右下降：2004 + 13 = 2017 年。碳危機的信徒最近“暫停”了承認可能會成為一個“高原”。）
參考
ME Andersson 等人“高能電子沉澱影響日地連接中缺失的驅動因素影響中層臭氧”在此進行了討論。
Zangl 和 Hoinka (2001) 《極地對流層頂》，美國氣象學會，第 14 卷，第 3117 頁
也可以看看：
Evans, David MW“缺口延遲太陽理論”，sciencespeak.com/climate- nd-solar.html，2014 年。
The central mystery in climate science is the Sun. The direct energy from the 1.4 million-kilometer-wide flaming ball stays remarkably constant. The radiation pours down on us but the relentless sameness of the watts can’t be causing of the swings in temperature on Earth. Something else is going on with the Sun. For one thing, the total light energy coming off the Sun stays almost the same but the type of light changes — the spectrum shifts — with more shorter wavelengths at one point in the cycle and longer wavelengths at the opposite part of the cycle. These have different effects. Shorter wavelengths (UV) generate ozone in the stratosphere and penetrate the ocean. Longer wavelengths don’t. But the Sun is also sending out charged particles and driving a massive fluctuating magnetic field, both of which affect Earth’s atmosphere.
But the tiny changes in total sunlight (TSI) may still be leaving us clues about other things going on with the Sun. David Evans’ notch-delay theory is that TSI is a leading indicator, and after solar TSI peaks, the temperatures on Earth follows with a peak roughly 11 years or so later (or one solar cycle). But what’s the mechanism? Stephen Wilde has a theory. Plug in your brain, and follow this chain of potential influence:
The Sun — -> UV or charged particles — → ozone — -> polar jet streams — –> clouds — –> surface temperatures.
Stephen Wilde put forward the first version of this hypothesis in 2010. It is long past time to get into those details.
Summary of the Stephen Wilde Hypothesis
In essence: The Sun affects the ozone layer through changes in UV or charged particles. When the Sun is more active there is more ozone above the equator and less over the poles, and vice versa. An increase in ozone warms the stratosphere or mesosphere, which pushes the tropopause lower. There is thus a solar induced see-saw effect on the height of the tropopause, which causes the climate zones to shift towards then away from the equator, moving the jet streams and changing them from “zonal” jet streams to “meridonal” ones. When meridonal, the jet streams wander in loops further north and south, resulting in longer lines of air mass mixing at climate zone boundaries, which creates more clouds. Clouds reflect sunlight back out to space, determining how much the climate system is heated by the near-constant incoming solar radiation. Thus the Sun’s UV and charged particles modulate the solar heating of the Earth.
Figure 1: When the Sun is less active there is more ozone at the poles but less over the equator. Less ozone above the tropopause causes less stratospheric warming, allowing the tropopause up, which pushes the climate zones towards the equator. This causes the jet streams to be more meridonal, so more clouds are formed. Clouds reflect sunlight, so less solar radiation warms the Earth.
An active Sun increases ozone in the stratosphere:
“Changes in solar ultraviolet spectral irradiance directly modify the production rate of ozone in the upper stratosphere (e.g. Brasseur, 1993), and hence it is reasonable to expect a solar cycle variation in ozone amount. The global satellite ozone records since 1979 show evidence for a decadal oscillation of total ozone with maximum amplitude (~2%) at low latitudes (Hood and McCormack, 1992; Chandra and McPeters, 1994; Hood, 1997).
Figure 2: When the Sun is more active there is less ozone at the poles but more over the equator. More ozone above the tropopause causes more stratospheric warming, forcing the tropopause down, which pushes the climate zones away from the equator. This causes the jet streams to be more zonal, so fewer clouds are formed. Clouds reflect sunlight, so more solar radiation warms the Earth.
New research reports a missing driver — energetic electrons
In October 2014 a paper by Andersson et al suggests another layer of action, again on ozone. Described as the missing driver in the Sun-Earth connection, energetic electron precipitation (EEP) dramatically affects ozone — but above the poles, not the equator. The EEP in the mesosphere is directed preferentially towards the poles along the magnetic field lines because the electrons are charged particles, which explains why the effect is strongest at the poles.When the Sun is active the energetic electron rain decreases ozone preferentially above the poles and in the mesosphere.
At the poles, the rules get strained through a singularity
At the north and south poles the magnetic field lines converge, the Earth drags the atmosphere around a single point, the tropopause is lower, and temperature inversions are common. Polar vortices occur when an area of low pressure sits at the rotation pole of a planet. This causes air to spiral down from higher in the atmosphere, like water going down a drain. (Polar vortices should not be confused with the circumpolar jet around the poles, which is often given the same name in the media.)
All this remarkable action means that above the poles even the high mesosphere affects the height of the tropopause. In the polar vortices the descending flow draws air down from the mesosphere, right through the stratosphere to the tropopause.
The presence of a layer of ozone in the stratosphere is the cause of the temperature inversion that forms at the tropopause. That layer of ozone is warmed directly by incoming solar radiation. It is warmer than the rising air coming up from the surface below, so it effectively puts a lid on convection.
Ozone variations affect the temperature of the stratosphere, which in turn affects the height of the tropopause. From page 14 of Zangl and Hoinka:
“Suppose, for example, that the surface temperature and the tropospheric temperature gradient are given and that the temperature of the stratosphere varies. Then, a cold stratosphere will be associated with a high tropopause (low tropopause pressure), and a warm stratosphere will correspond to a low tropopause (high tropopause pressure).”
If the tropopause rises or falls, it causes a change in the gradient of tropopause height between equator and poles. This in turn causes the jet streams to shift north or south, because it pushes around the climate zones beneath the tropopause. A lower tropopause restricts the available space for free movement of air horizontally beneath it. So a lowering of the tropopause above the poles when the Sun is less active (as implied in the Andersson et al paper) squeezes the air in the tropospheric climate zones towards the equator. We have seen that happen in the form of increased jet stream meridionality since about 2000, as the level of solar activity declined in the transition from active solar cycle 23 to much less active solar cycle 24. That is the reason for the observation of more frequent and intense incursions of polar air across middle latitudes in recent years.
The world is divided up into permanent climate zones, which align along the lines of latitude due to the Earth’s rotation. These zones can move poleward or equatorward, in response to changes in the Earth’s energy budget. Poleward shifting was observed during the late 20th century warming, and it is well know that the zones shifted equatorward during the Little Ice Age.
Figure 3: A Jetstream can be more zonal (left) or meridonal (right).
The jet streams are high-level rivers of fast moving air threading between the climate zones, and are driven by temperature, humidity and density differentials between the different types of air mass:
- An equatorward shift of the climate zones gives the jets more room to loop north and south, and that gives more meridonal jets (the north-south components of the jets).
- A poleward shift of the zones pushes the jets poleward, forcing them to more closely following the lines of latitude, that is, more zonal jets (the east-west components).
- Such shifts are also associated with the Arctic Oscillation, wherein a positive phase results in the climate zones being pulled poleward and the jets adopting a more zonal (straighter) pattern. A negative phase results in the opposite. A more frequent positive phase is associated with a more active Sun due to cooling of the polar stratosphere (less mesospheric ozone descending through the polar vortex) and consequent lifting of the polar tropopause. A more frequent or more pronounced negative phase (as observed to a record extent during the very low solar minimum between cycles 23 and 24) is associated with a less active Sun due to warming of the polar stratosphere (more mesospheric ozone descending through the polar vortex).
Wandering jets means more clouds
Figure 4: Jetstream showing a lot of meridonal flow.
More meridonal jet stream tracks flowing around the world between the climate zones result in longer lines of air mass mixing at climate zone boundaries. Mixing of air from different locations within different climate zones causes convective instability due to differing temperatures and densities, which increases cloud formation.
Finally, clouds reflect solar radiation (that is, modulate the albedo), thus affecting the amount of heat flowing into the climate system. Significantly, the proportion of solar energy entering the oceans is affected and ultimately it is the oceans that determine atmospheric temperatures (see here).
Thus there is a back and forth in global cloudiness as the Sun’s activity level changes over the decades and centuries — such as during the period covering the Medieval Warm Period, the Little Ice Age, and the current warm period — through latitudinal shifting of the jet stream tracks and permanent climate zones.
It is also proposed that, over time, the changes at the higher mesospheric level dominate because the higher level effect gradually filters down to lower levels through the descending column of air within the polar vortices as described above. This links observed changes in the size of the ozone holes at the poles to solar causation rather than to human emissions of CFCs. The ozone holes grew when the Sun was active and are now shrinking with the less active Sun.
Further thoughts on the Andersson “energetic electron” paper
The new paper by Andersson et al builds on the hypothesis that ozone is influential and a potential mechanism to amplify solar factors. It adds energetic electron precipitation (EEP) to spectral changes in UV, which is a significant step forward.
Andersson et al describe it as having a short term regional effect, with no implications for global or long term climate change. But if the effect is significant between the peak and trough of a single solar cycle, then surely it is also going to be significant over the millennial cycle of solar variation — such as that observed from the Medieval Warm Period through the Little Ice Age and up to date.
Observations of climate changes across the last thousand years suggest that it must be so. In the Medieval Warm Period, Greenland had agriculture and the Western Isles of Scotland were prosperous with a much larger population than today — which implies more poleward climate zones and zonal jets at that time. In contrast, ships logs from the Little Ice Age show much greater Atlantic storminess and more equatorward mid latitude depression tracks at that time (depressions generally follow the tracks of the jet streams).
Food for speculation
Stephen Wilde’s hypothesis is a possible mechanism for the notch-delay theory, in which the TSI drives surface temperatures after a delay of one sunspot cycle (~11 years) and which potentially explains most of the temperature variations over the last few hundred years. This would occur if the extreme ultraviolet that drives ozone creation and destruction, and the effects of the energetic electron precipitation found by Andersson et al, both lag the trends in bulk TSI (visible light and normal UV) by one sunspot cycle — that is, by half a full solar cycle (~22 years).
(Quick reminder: The delay of one sunspot cycle in the ND theory overcomes the objection that because TSI and so on peaked around 1986 and surface temperatures kept rising to about 1997, the Sun cannot be driving temperature. The delay can explain this: 1986 + 11 = 1997. The delay also means that the fall off in bulk TSI around 2004 presages a fall in surface temperatures around about one sunspot later, around 2017: 2004 + 13 = 2017. The “pause” the believers of the carbon crisis have lately admitted to may turn out to be a “plateau”.)
REFERENCES
M.E. Andersson et al “Missing driver in the Sun–Earth connection from energetic electron precipitation impacts mesospheric ozone” Discussed here.
Zangl and Hoinka (2001) The Tropopause in the Polar Regions, American Meteorological Society, vol 14, page 3117
See also:
Evans, David M.W. “The Notch-Delay Solar Theory”, sciencespeak.com/climate-nd-solar.html, 2014.
