Precipitation

About: Precipitation is a research topic. Over the lifetime, 32861 publications have been published within this topic receiving 990496 citations. The topic is also known as: rain & rainfall.

Global and regional increase of precipitation extremes under global warming.

Abstract: Simon Michael Papalexiou1,2 and Alberto Montanari3 2 1Department of Civil, Geological and Environmental Engineering, University of 3 Saskatchewan, Canada 4 2Global Institute for Water Security 5 3University of Bologna, DICAM, Bologna, Italy 6 7 Global warming is expected to change the regime of extreme precipitation. Physical laws 8 translate increasing atmospheric heat into increasing atmospheric water content that 9 drives precipitation changes. Within the literature, general agreement is that extreme 10 precipitation is changing, yet different assessment methods, datasets, and study periods, 11 may result in different patterns and rates of change. Here we perform a global analysis of 12 8730 daily precipitation records focusing on the 1964-2013 period when the global 13 warming accelerates. We introduce a novel analysis of the N largest extremes in records 14 having N complete years within the study period. Based on these extremes, which 15 represent more accurately heavy precipitation than annual maxima, we form time series of 16 their annual frequency and mean annual magnitude. The analysis offers new insights and 17 reveals: (1) global and zonal increasing trends in the frequency of extremes that are highly 18 unlikely under the assumption of stationarity, and (2) magnitude changes that are not as 19 evident. Frequency changes reveal a coherent spatial pattern with increasing trends being 20 detected in large parts of Eurasia, North Australia, and the Midwestern United States. 21 Globally, over the last decade of the studied period we find 7% more extreme events than 22 the expected number. Finally, we report that changes in magnitude are not in general 23 correlated with changes in frequency. 24

Modeling the Ice-Age Climate

Abstract: Using the boundary conditions of seasurface temperature, ice sheet topography, and surface albedo assembled by CLIMAP for 18,000 B.P., the global ice-age July climate has been simulated with a two-level dynamical atmospheric model. Compared with the simulation for present July climate, the ice age is substantially cooler and drier over the unglaciated continental areas, with the maximum zonal westerlies in the Northern Hemisphere displaced southward in the vicinity of the ice sheets. The simulated changes of surface air temperature agree reasonably well with the estimates available from the analysis of fossil pollen and periglacial data, and are consistent with the simulated changes of other climatic variables. These results are generally supported by independent investigations with simpler models. In spite of this qualified success, further analysis of both simulated and verification data is needed to establish the details of ice-age climate, especially the precipitation regimes, and to document the role of eddy fluxes in maintaining the heat, momentum, and moisture balances of the ice-age general circulation. New paleoclimatic data bases for both July and January of 18,000 B.P. are being assembled by CLIMAP and will be used in new simulations of the seasonal ice-age climate.

Influence of the Global Warming on Tropical Cyclone Climatology: An Experiment with the JMA Global Model

Abstract: The influence of the global warming on tropical cyclones has been examined using a high resolution AGCM. Two ten-year integrations were performed with the JMA global model at T106 horizontal resolution. For the control experiment, the observed SST for the period 1979-1988 is prescribed, while for the doubling CO2 (2 × CO2) experiment, SST anomaly due to the global warming estimated from a coupled model transient CO2 experiment (Tokioka et al. 1995) is added to the SST used in the control experiment. The results of experiments show that a significant reduction in the frequency of tropical cyclones is possible in response to the greenhouse gas-induced global warming. The most significant decrease is indicated over the North Pacific. On the other hand, a considerable increase in tropical cyclone frequency is indicated for the North Atlantic. As for the maximum intensity of tropical cyclones, no significant change has been noted. It has been found that the regional change in tropical cyclone frequency is closely related to the distribution of the SST anomaly, and the change in convective activity associated with it. The results of the experiment indicate that the change in tropical cyclogenesis is strongly controlled by dynamical factors associated with the change in SST distribution, rather than the thermodynamical factors associated with the change in absolute value of local SST. On the other hand, for the decrease in the global total number of tropical cyclones on doubling CO2, a weakening of tropical circulation associated with the stabilization of the atmosphere (the increase in dry static stability), seems to be responsible. It is found that the rate of increase in the tropical precipitation due to the global warming is much less than the rate of increase in the atmospheric moisture. With this little increase in precipitation (convective heating), a considerable increase in the dry static stability of the atmosphere leads to a weakening of the tropical circulation.

Environmental and climatic implications of late Quaternary lake-level fluctuations in Africa

Abstract: Widespread water balance shifts in closed basin lakes reveal major glacial–interglacial variations in rainfall and streamflow. Markedly arid conditions characterising intertropical Africa during the last glacial maximum were followed by an early Holocene lacustral phase in which annual precipitation between 24 °N and 8 °S exceeded 150% of the 1931–60 mean.