Search Results
drivers of climate change that are significantly influenced by human activities. The overall radiative forcing of anthropogenic aerosols is negative and can offset a large portion of the global warming caused by greenhouse gases. The effects of anthropogenic aerosols on regional climate, especially over monsoon regions, have been investigated in many studies. For example, it was found that anthropogenic aerosols could weaken the East Asian summer monsoon ( Zhang et al. 2012 ) and the South Asian
drivers of climate change that are significantly influenced by human activities. The overall radiative forcing of anthropogenic aerosols is negative and can offset a large portion of the global warming caused by greenhouse gases. The effects of anthropogenic aerosols on regional climate, especially over monsoon regions, have been investigated in many studies. For example, it was found that anthropogenic aerosols could weaken the East Asian summer monsoon ( Zhang et al. 2012 ) and the South Asian
1. Introduction Field observations in recent decades have revealed an abundance of anthropogenic aerosols, particularly absorbing aerosols, over South Asia and its surrounding ocean during the dry season ( Ramanathan et al. 2001 ). Modeling studies and observation-based analyses have indicated that the radiative effects of these aerosols can interrupt not just localized meteorological features but also large-scale climate features such as monsoons. Using prescribed direct radiative forcing
1. Introduction Field observations in recent decades have revealed an abundance of anthropogenic aerosols, particularly absorbing aerosols, over South Asia and its surrounding ocean during the dry season ( Ramanathan et al. 2001 ). Modeling studies and observation-based analyses have indicated that the radiative effects of these aerosols can interrupt not just localized meteorological features but also large-scale climate features such as monsoons. Using prescribed direct radiative forcing
mechanisms as natural precipitation. If the quantities of water involved are similar to natural precipitation amounts, then similar mesoscale weather effects will result. Preliminary screening of the various types of human activity that add water to the environment identified three types that add water in amounts comparable to natural precipitation in the forecast area. As a result, it was hypothesized that the observed warm bias was a result of neglecting these sources of anthropogenic moisture, which
mechanisms as natural precipitation. If the quantities of water involved are similar to natural precipitation amounts, then similar mesoscale weather effects will result. Preliminary screening of the various types of human activity that add water to the environment identified three types that add water in amounts comparable to natural precipitation in the forecast area. As a result, it was hypothesized that the observed warm bias was a result of neglecting these sources of anthropogenic moisture, which
.1016/j.atmosenv.2012.12.039 . 10.1016/j.atmosenv.2012.12.039 Jiang , Y. , X. Q. Yang , and X. Liu , 2015 : Seasonality in anthropogenic aerosol effects on East Asian climate simulated with CAM5 . J. Geophys. Res. , 120 , 10 837 – 10 861 , https://doi.org/10.1002/2015JD023451 . 10.1002/2015JD023451 Kjellsson , J. , 2015 : Weakening of the global atmospheric circulation with global warming . Climate Dyn. , 45 , 975 – 988 , https://doi.org/10.1007/s00382-014-2337-8 . 10.1007/s00382
.1016/j.atmosenv.2012.12.039 . 10.1016/j.atmosenv.2012.12.039 Jiang , Y. , X. Q. Yang , and X. Liu , 2015 : Seasonality in anthropogenic aerosol effects on East Asian climate simulated with CAM5 . J. Geophys. Res. , 120 , 10 837 – 10 861 , https://doi.org/10.1002/2015JD023451 . 10.1002/2015JD023451 Kjellsson , J. , 2015 : Weakening of the global atmospheric circulation with global warming . Climate Dyn. , 45 , 975 – 988 , https://doi.org/10.1007/s00382-014-2337-8 . 10.1007/s00382
potential anthropogenic effects (e.g., due to nearby industrial or urban areas). 2. The chi-square and the balls-in-boxes tests Here, a “wet day” is defined as any day, say, the i th day in the sequence, for which the daily rainfall amount h i ≥ h t , where h t is a selected threshold. We wish to test against the null hypothesis that wet days arrive on any day of the week with equal probability . Let n k indicate the number of wet days occurring on the k th day of the week and n = ∑ 1 7 n
potential anthropogenic effects (e.g., due to nearby industrial or urban areas). 2. The chi-square and the balls-in-boxes tests Here, a “wet day” is defined as any day, say, the i th day in the sequence, for which the daily rainfall amount h i ≥ h t , where h t is a selected threshold. We wish to test against the null hypothesis that wet days arrive on any day of the week with equal probability . Let n k indicate the number of wet days occurring on the k th day of the week and n = ∑ 1 7 n
1. Introduction The annual discharge of anthropogenic aerosols into the atmosphere is considerable, but the effects of those aerosols on weather and climate remain very uncertain ( IPCC 2007 ). Aerosols can absorb and reflect solar radiation, thereby reducing the surface temperature and planetary boundary layer height, but they also act as cloud condensation nuclei (CCN) or ice nuclei, affecting cloud microphysics and subsequent precipitation rates, and increasing cloud coverage, albedo, and
1. Introduction The annual discharge of anthropogenic aerosols into the atmosphere is considerable, but the effects of those aerosols on weather and climate remain very uncertain ( IPCC 2007 ). Aerosols can absorb and reflect solar radiation, thereby reducing the surface temperature and planetary boundary layer height, but they also act as cloud condensation nuclei (CCN) or ice nuclei, affecting cloud microphysics and subsequent precipitation rates, and increasing cloud coverage, albedo, and
of research and policies aimed to “alleviate known causes of people’s vulnerability to harm, to pay attention to the distribution of risks and benefits, and to reflect on social factors that promote or discourage learning” ( Jasanoff 2007 ). In addition to mitigation, a comprehensive climate policy would require adopting adaptation strategies, not simply because of the now inevitable effects of the anthropogenic forcing, but also because of the growing risks of declining baselines of resilience
of research and policies aimed to “alleviate known causes of people’s vulnerability to harm, to pay attention to the distribution of risks and benefits, and to reflect on social factors that promote or discourage learning” ( Jasanoff 2007 ). In addition to mitigation, a comprehensive climate policy would require adopting adaptation strategies, not simply because of the now inevitable effects of the anthropogenic forcing, but also because of the growing risks of declining baselines of resilience
since humans first began to modify the face of the land through agriculture and other activities; we are comparing a potential vegetation state (no human disturbance) to the present-day condition. Not all impacts resulting from these changes would be captured by a time series of the most recent 130 years. These two factors suggest that our experiments place an upper bound on the potential impact of the biophysical effects of anthropogenic land cover change. Thus, if land cover change was the major
since humans first began to modify the face of the land through agriculture and other activities; we are comparing a potential vegetation state (no human disturbance) to the present-day condition. Not all impacts resulting from these changes would be captured by a time series of the most recent 130 years. These two factors suggest that our experiments place an upper bound on the potential impact of the biophysical effects of anthropogenic land cover change. Thus, if land cover change was the major
stronger (weaker) TCs tend to be controlled more by upper-level (lower-level) steering flow. Our results further indicate that the changes of TC tracks (including interbasin trend and latitudinal shift) make a much larger contribution to the slowing trend compared with the weakening of tropical circulation, which is related to anthropogenic warming. Note that the effects of interbasin trend and latitudinal shift are not independent of each other; they are largely coincident with each other, and hard to
stronger (weaker) TCs tend to be controlled more by upper-level (lower-level) steering flow. Our results further indicate that the changes of TC tracks (including interbasin trend and latitudinal shift) make a much larger contribution to the slowing trend compared with the weakening of tropical circulation, which is related to anthropogenic warming. Note that the effects of interbasin trend and latitudinal shift are not independent of each other; they are largely coincident with each other, and hard to
1. Introduction Anthropogenic aerosol is thought to play an important role in driving climate change, but its role is so complex that uncertainty in estimates of radiative forcing of climate change is dominated by uncertainty associated with forcing by anthropogenic aerosol ( Forster et al. 2007 ). This complexity arises because anthropogenic aerosol alters the planetary energy balance through a variety of mechanisms operating across a wide range of spatial scales: direct effects ( Haywood and
1. Introduction Anthropogenic aerosol is thought to play an important role in driving climate change, but its role is so complex that uncertainty in estimates of radiative forcing of climate change is dominated by uncertainty associated with forcing by anthropogenic aerosol ( Forster et al. 2007 ). This complexity arises because anthropogenic aerosol alters the planetary energy balance through a variety of mechanisms operating across a wide range of spatial scales: direct effects ( Haywood and
