Re: 飛機雲影響氣溫
※ 引述《chingi (天佑台灣)》之銘言：
: ※ 引述《s19880609 (*~so Penny~*)》之銘言：
: : 根據我查到的資料
: : 真正有飛機雲影響氣溫的實證
: : 但是我查不到任何的表格或者圖表分析氣溫的變化
: : 可以麻煩各位如果知道的話請告訴我好嗎..?
: : 謝謝囉!!
: 印象當中看過新聞報導美國的研究
: 使用的資料是2001年九月中旬的氣象資料
: 肯定了飛機影響天氣的說法
: 不過我忘記詳細的內容了
飛機雲的學術名稱叫contrail (凝結尾)
一般相信凝結尾會增加高層卷雲的雲量與出現機率
而卷雲增多對氣候的影響包括了使地面溫度升高以及日夜溫差減小
（主要是讓夜晚最低溫增高）等等
關於contrail對氣候影響的最新研究可以參考下面兩篇論文:
Minnis et al., Contrails, cirrus trends, and climate, J. Climate, 17,
1671-1685, 2004.
Abstract:
Rising global air traffic and its associated contrails have the
potential for affecting climate via radiative forcing. Current
estimates of contrail climate effects are based on coverage by linear
contrails that do not account for spreading and, therefore, represent
the minimum impact. The maximum radiative impact is estimated by
assuming that long-term trends in cirrus coverage are due entirely to
air traffic in areas where humidity is relatively constant. Surface
observations from 1971 to 1995 show that cirrus increased
significantly over the northern oceans and the United States while
decreasing over other land areas except over western Europe where
cirrus coverage was relatively constant. The surface observations are
consistent with satellite-derived trends over most areas. Land cirrus
trends are positively correlated with upper-tropospheric (300 hPa)
humidity (UTH), derived from the National Centers for Environmental
Prediction (NCEP) analyses, except over the United States and western
Europe where air traffic is heaviest. Over oceans, the cirrus trends
are negatively correlated with the NCEP relative humidity suggesting
some large uncertainties in the maritime UTH. The NCEP UTH decreased
dramatically over Europe while remaining relatively steady over the
United States, thereby permitting an assessment of the cirrus-
contrail relationship over the United States. Seasonal cirrus changes
over the United States are generally consistent with the annual cycle
of contrail coverage and frequency lending additional evidence to the
role of contrails in the observed trend. It is concluded that the
U.S. cirrus trends are most likely due to air traffic. The cirrus
increase is a factor of 1.8 greater than that expected from current
estimates of linear contrail coverage suggesting that a spreading
factor of the same magnitude can be used to estimate the maximum
effect of the contrails. From the U.S. results and using mean
contrail optical depths of 0.15 and 0.25, the maximum contrail-cirrus
global radiative forcing is estimated to be 0.006-0.025 W m(-2)
depending on the radiative forcing model. Using results from a
general circulation model simulation of contrails, the cirrus trends
over the United States are estimated to cause a tropospheric warming
of 0.2degrees-0.3degreesC decade(-1), a range that includes the
observed tropospheric temperature trend of 0.27degreesC decade(-1)
between 1975 and 1994. The magnitude of the estimated surface
temperature change and the seasonal variations of the estimated
temperature trends are also in good agreement with the corresponding
observations.
Travis et al., Regional variations in US diurnal temperature range
for the 11-14 September 2001 aircraft groundings: Evidence of jet
contrail influence on climate, J. Climate, 17, 1123-1134, 2004.
(就是chigi提到的911研究）
Abstract:
The grounding of all commercial aircraft within U. S. airspace for
the 3-day period following the 11 September 2001 terrorist attacks
provides a unique opportunity to study the potential role of jet
aircraft contrails in climate. Contrails are most similar to natural
cirrus clouds due to their high altitude and strong ability to
efficiently reduce outgoing infrared radiation. However, they
typically have a higher albedo than cirrus; thus, they are better at
reducing the surface receipt of incoming solar radiation. These
contrail characteristics potentially suppress the diurnal temperature
range (DTR) when contrail coverage is both widespread and relatively
long lasting over a specific region. During the 11-14 September 2001
grounding period natural clouds and contrails were noticeably absent
on high-resolution satellite imagery across the regions that
typically receive abundant contrail coverage. A previous analysis of
temperature data for the grounding period reported an anomalous
increase in the U.S.-averaged, 3-day DTR value. Here, the spatial
variation of the DTR anomalies as well as the separate contributions
from the maximum and minimum temperature departures are analyzed.
These analyses are undertaken to better evaluate the role of jet
contrail absence and synoptic weather patterns during the grounding
period on the DTR anomalies.
It is shown that the largest DTR increases occurred in regions where
contrail coverage is typically most prevalent during the fall season
(from satellite-based contrail observations for the 1977-79 and
2000-01 periods). These DTR increases occurred even in those areas
reporting positive departures of tropospheric humidity, which may
reduce DTR, during the grounding period. Also, there was an
asymmetric departure from the normal maximum and minimum temperatures
suggesting that daytime temperatures responded more to contrail
absence than did nighttime temperatures, which responded more to
synoptic conditions. The application of a statistical model that
"retro-predicts" contrail-favored areas (CFAs) on the basis of
upper-tropospheric meteorological conditions existing during the
grounding period, supports the role of contrail absence in the
surface temperature anomalies; especially for the western United
States. Along with previous studies comparing surface climate data
at stations beneath major flight paths with those farther away, the
regionalization of the DTR anomalies during the September 2001
"control" period implies that contrails have been helping to decrease
DTR in areas where they are most abundant, at least during the early
fall season.
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