An influence of solar spectral variations on radiative forcing of climate
An influence of solar spectral variations on radiative forcing of climate
复制标题
DOI：
10.1038/nature09426
复制
发表时间：
2010-10-07
期刊：
影响因子：
64.8
通讯作者：
Harder, Jerald W.
中科院分区：
文献类型：
--
作者：
Haigh, Joanna D.;Winning, Ann R.;Harder, Jerald W.
大气的热结构和组成基本上由入射的太阳辐照度决定。紫外线波长的辐射使大气分子离解，引发化学反应链-特别是产生平流层臭氧的化学反应链-并为中层大气提供主要的加热源，而可见光和近红外波长的辐射主要到达并加热低层大气和地球表面。因此，太阳辐射的光谱组成对于确定大气结构和地表温度至关重要，因此大气对太阳辐照度变化的响应取决于光谱（2）。自2004年4月以来，由太阳辐射和气候实验卫星（3）上的光谱辐照度监测仪（SIM）每天对0.2 μ m至2.4 μ m之间的太阳光谱进行测量，发现（4）在太阳活动周期的这个下降阶段，紫外线的下降比我们以前预测的要大四到六倍。认识这一减少部分地通过增加可见光波长的辐射在太阳总输出中得到补偿。在这里，我们表明，这些光谱的变化似乎已经导致了显着下降，从2004年至2007年在平流层臭氧低于海拔45公里，与此海拔以上的增加。我们的研究结果，模拟与辐射光化学模型，是一致的同期测量的臭氧从Aura-MLS卫星，虽然短的时间内精确归因于太阳的影响是困难的。我们还表明，使用SIM数据，地面气候的太阳辐射强迫与太阳活动的相位。目前还没有足够的观测证据来验证SIM观测到的光谱变化，或充分表征其他太阳周期，但我们的研究结果提出了太阳变化对整个大气温度的影响可能与目前的预期相反的可能性。
The thermal structure and composition of the atmosphere is determined fundamentally by the incoming solar irradiance. Radiation at ultraviolet wavelengths dissociates atmospheric molecules, initiating chains of chemical reactions-specifically those producing stratospheric ozone-and providing the major source of heating for the middle atmosphere, while radiation at visible and near-infrared wavelengths mainly reaches and warms the lower atmosphere and the Earth's surface(1). Thus the spectral composition of solar radiation is crucial in determining atmospheric structure, as well as surface temperature, and it follows that the response of the atmosphere to variations in solar irradiance depends on the spectrum(2). Daily measurements of the solar spectrum between 0.2 mu m and 2.4 mu m, made by the Spectral Irradiance Monitor (SIM) instrument on the Solar Radiation and Climate Experiment (SORCE) satellite(3) since April 2004, have revealed(4) that over this declining phase of the solar cycle there was a four to six times larger decline in ultraviolet than would have been predicted on the basis of our previous understanding. This reduction was partially compensated in the total solar output by an increase in radiation at visible wavelengths. Here we show that these spectral changes appear to have led to a significant decline from 2004 to 2007 in stratospheric ozone below an altitude of 45 km, with an increase above this altitude. Our results, simulated with a radiative-photochemical model, are consistent with contemporaneous measurements of ozone from the Aura-MLS satellite, although the short time period makes precise attribution to solar effects difficult. We also show, using the SIM data, that solar radiative forcing of surface climate is out of phase with solar activity. Currently there is insufficient observational evidence to validate the spectral variations observed by SIM, or to fully characterize other solar cycles, but our findings raise the possibility that the effects of solar variability on temperature throughout the atmosphere may be contrary to current expectations.