The warming over the Tibetan Plateau(TP) is very significant during last 30 years,but the thermal forcing has been weakened.The thermal weakening is attributed mainly to the enhancement of the TOA(top of atmosphere) o...The warming over the Tibetan Plateau(TP) is very significant during last 30 years,but the thermal forcing has been weakened.The thermal weakening is attributed mainly to the enhancement of the TOA(top of atmosphere) outgoing radiation.This enhancement is opposite to the greenhouse-gas-induced weakening of the global mean TOA outgoing radiation and is also unable to be explained by the observed decrease of total cloud cover.This study presents the importance of cloud height change and the warming over the TP in modulating the TOA radiation budget and thus the thermal forcing during spring and summer.On the basis of surface observations and satellite radiation data,we found that both the TOA outgoing shortwave radiation and longwave radiation were enhanced during this period.The former enhancement is due mainly to the increase of low-level cloud cover,which has a strong reflection to shortwave radiation,especially in summer.The latter enhancement is caused mainly by the planetary warming,and it is further enhanced by the decrease of total cloud cover in spring,as clouds extinguish outgoing longwave radiation emitted from the land surface.Therefore,the radiative cooling enhancement and thus the thermal weakening over the TP is a response of the earth-atmosphere system to the unique change of cloud cover configuration and the rapid warming of the land surface.However,these trends in cloud cover and TOA outgoing radiation are not well represented in four reanalyses.展开更多
The Atmospheric Ultraviolet Radiance Integrated Code （AURIC） is a software package developed by Computa- tional Physics, Inc. （CPI） under the sponsorship of the Air Force Phillips Laboratory/Geophysics Directorate...The Atmospheric Ultraviolet Radiance Integrated Code （AURIC） is a software package developed by Computa- tional Physics, Inc. （CPI） under the sponsorship of the Air Force Phillips Laboratory/Geophysics Directorate （PL/GP） （cur- rently the Air Force Research Laboratory） for middle and upper atmospheric radiance modeling from the far ultraviolet to the near infrared. The AURIC has been considered as a general model for the radiative transfer simulation of airglow. Based on the theory of MODerate resolution atmospheric TRANsmission （MODTRAN）, the AURIC extends calculation to altitudes above 100 km and the wavelength down to 80 nm. A package of AURIC vl.2 was released in 2002, which can be used for sin- gle-point simulation from 1947 to 1999. It means that the model is not suitable for atmospheric simulation of large datasets or for atmospheric parameters retrieval from amount of satellite measurements. In this paper, AURIC vl.2 is upgraded to AURIC-2012 based on MATLAB with improvements for modules of the Geomagnetic Parameter （GEOPARM）, Atmosphere neutral composition （ATOMS）, and Ionospheric electron density （IONOS）. The improved AURIC can be used for global au- tomatic airglow simulation and also for automatic retrieval of atmospheric compositions from satellite global observations, such as O/N2 and electron density etc. Besides, the model supplies possibilities for further improvement of airglow radiative mechanism and for substitution of other modules. Based on the AURIC-2012, Limb Column Emission Intensity （L-CEI） and Volume Emission Rate （VER） are calculated. For validation, the results were compared with measurements of the Global Ul- traviolet Imager （GUVI） and TIMED Doppler Interferometer （TIDI）, respectively. The averaged relative errors of L-CEI and VER at peak altitude are both within 20%. Finally, L-CEI varying with latitude, altitude, solar activity, and geomagnetic activ- ity is simulated, and the distribution characteristics of the simulation and their influencing factors are analyzed subsequently.展开更多
基金supported by the Strategic Priority Research Program(B) of the Chinese Academy of Sciences(Grant No.XDB03030300)Global Change Program of Ministry of Science and Technology of China(Grant No.2010CB951703)the National Natural Science Foundation of China(Grant Nos.41190083,41325019)
文摘The warming over the Tibetan Plateau(TP) is very significant during last 30 years,but the thermal forcing has been weakened.The thermal weakening is attributed mainly to the enhancement of the TOA(top of atmosphere) outgoing radiation.This enhancement is opposite to the greenhouse-gas-induced weakening of the global mean TOA outgoing radiation and is also unable to be explained by the observed decrease of total cloud cover.This study presents the importance of cloud height change and the warming over the TP in modulating the TOA radiation budget and thus the thermal forcing during spring and summer.On the basis of surface observations and satellite radiation data,we found that both the TOA outgoing shortwave radiation and longwave radiation were enhanced during this period.The former enhancement is due mainly to the increase of low-level cloud cover,which has a strong reflection to shortwave radiation,especially in summer.The latter enhancement is caused mainly by the planetary warming,and it is further enhanced by the decrease of total cloud cover in spring,as clouds extinguish outgoing longwave radiation emitted from the land surface.Therefore,the radiative cooling enhancement and thus the thermal weakening over the TP is a response of the earth-atmosphere system to the unique change of cloud cover configuration and the rapid warming of the land surface.However,these trends in cloud cover and TOA outgoing radiation are not well represented in four reanalyses.
基金funded by the Strategic Pilot Projects in Space Science of Chinese Academy of Sciences(Grant No.XDA04060202)
文摘The Atmospheric Ultraviolet Radiance Integrated Code （AURIC） is a software package developed by Computa- tional Physics, Inc. （CPI） under the sponsorship of the Air Force Phillips Laboratory/Geophysics Directorate （PL/GP） （cur- rently the Air Force Research Laboratory） for middle and upper atmospheric radiance modeling from the far ultraviolet to the near infrared. The AURIC has been considered as a general model for the radiative transfer simulation of airglow. Based on the theory of MODerate resolution atmospheric TRANsmission （MODTRAN）, the AURIC extends calculation to altitudes above 100 km and the wavelength down to 80 nm. A package of AURIC vl.2 was released in 2002, which can be used for sin- gle-point simulation from 1947 to 1999. It means that the model is not suitable for atmospheric simulation of large datasets or for atmospheric parameters retrieval from amount of satellite measurements. In this paper, AURIC vl.2 is upgraded to AURIC-2012 based on MATLAB with improvements for modules of the Geomagnetic Parameter （GEOPARM）, Atmosphere neutral composition （ATOMS）, and Ionospheric electron density （IONOS）. The improved AURIC can be used for global au- tomatic airglow simulation and also for automatic retrieval of atmospheric compositions from satellite global observations, such as O/N2 and electron density etc. Besides, the model supplies possibilities for further improvement of airglow radiative mechanism and for substitution of other modules. Based on the AURIC-2012, Limb Column Emission Intensity （L-CEI） and Volume Emission Rate （VER） are calculated. For validation, the results were compared with measurements of the Global Ul- traviolet Imager （GUVI） and TIMED Doppler Interferometer （TIDI）, respectively. The averaged relative errors of L-CEI and VER at peak altitude are both within 20%. Finally, L-CEI varying with latitude, altitude, solar activity, and geomagnetic activ- ity is simulated, and the distribution characteristics of the simulation and their influencing factors are analyzed subsequently.
