| The Whole Atmosphere Community Climate Model(WACCM) is employed in the numerical simulation study on which the climate responses to ultraviolet irradiation forcing. Via setting sensitive experiments, the impact of UV variability on middle atmosphere can be detected and analyzed.Firstly, the most important and directly impact of UV on atmosphere is the ozone photochemical process in stratosphere. From the analysis of model simulation results, it is sensitive to UV irradiation variability for ozone distribution in atmosphere. While UV irradiation enhanced, because of the different photochemical mechanism, the ozone content increases at altitude from 10 to 30 km and decreases at altitude above 30 km over low-middle latitudes. Furthermore, when UV irradiation is enhanced, the temperature will increase at all atmosphere below mesosphere. The warm temperature emergence above 35 km and achieved max temperature increasing at stratopause. It accords with the zone concentration location in atmosphere, which indicates the work of ozone heating mechanism. Although it is on the contrary for ozone and temperature when the UV irradiation is rebated.Secondly, by through ozone heating mechanism, leading to enlarge the temperature gradient between the equator and polar modules the zonal wind specially in stratosphere and upper troposphere over middle high latitudes when UV forcing enhanced. With the zonal wind propagating polewards and downwards, a pattern of Arctic Oscillation will take place in the northern hemisphere winter. At the same time the Asia temperature increases. There are also some different features found through the contrast experiment and the observation data from The European Centre for Medium-Range Weather Forecasts. It is maybe resulted from that observation data not long enough. Another is that because some unclear mechanism UV irradiation impact on climate. Comprehensive research work is needed to be done in future.With UV forcing changed, global average temperature has a little change. But it is significant for the response of the East Asia. Based on previous research and simulation results in this paper, we get to know that UV enhanced in winter will indirectly affect the climate at high latitude in the northern hemisphere. The UV irradiation variability modules sea level pressure to form an AO-like which leading to affect surface temperature in the low latitudes. So as to probe into the indirect influence of ultraviolet, a statistical analysis of the NCEP/NCAR reanalysis data and Met Office Had ISST over the period 1948-2013 is conducted to explore the influence of the winter AO on East Asian surface air temperature. Some results show that the positive phase of the winter AO is characterized by weaken East Asia deep through as well as Siberian high, low-level southerly wind field, and weaken East Asian winter monsoon resulting in temperature rise in the East Asian winter monsoon region. The contrary is the case in the negative phase of the winter AO.In the high latitudes, Atmospheric variability in winter is very big. With probing deeply into the relationship between monthly winter AO and East Asian surface air temperature, it is founded that the impact of AO in January and February can last 2 months or longer, respectively. And that impact will almost disappear in June. As we all known, the disturbance of atmosphere is short time scale. The effect of winter AO on monthly scale is not consistent. AO can only last no more than two months after calculating the self-correlation of it. Though a large amount of ocean heat content, sea change is slow and persistent. Ocean can store abnormal information of atmosphere, and then acting on atmosphere. We think about that ocean is an important factor in the course of AO affecting East Asian surface air temperature. For the positive phase of AO, the sea surface temperature(SST) in Western Pacific and East Asian surface temperature are simultaneously anomalous highness. With analysis of 1000 hPa wind vectors, it leads to SST anomalies in Western Pacific that anomalous northeast trades. At the same time Western Pacific get the information through the anomalous trades. It makes that Western Pacific sea surface temperature could carry the AO signals for more than 4 month.The regional average of sea surface temperature in Western Pacific has significant positive correlation that can last less than 4 months with East Asian surface air temperature. With the effect of Western Pacific on East Asia happened, the AO signals are passed continuously into East Asia. From the above, the effect of SST in Western Pacific is of vital importance for the lasting impact of Arctic Oscillation on the East Asian surface. The reason that the lasting impact of winter Arctic Oscillation on the East Asian is more likely to be air-sea interaction. Finally, it comes true that the lasting indirect influence of UV to East Asia climate. |
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