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.

General climatic controls and topoclimatic variations in Central and High Asia

Abstract: Basic features of current spatial and seasonal climate variations in Central and High Asia are presented. Large-scale circulation modes were inferred from NCAR/CDAS General Circulation Model (GCM) data and interpreted with particular emphasis on the Asian Monsoon circulation. Using spatial high-resolution estimates of radiation, temperature and precipitation covering Central and High Asia in a regular grid network with a grid-cell spacing of 1 km2, topoclimatic variations are investigated and discussed with respect to their major barometric and topographic controls. In general, weather patterns of Central and High Asia are determined by tropical monsoon as well as extratropical circulation modes. Associated synoptic conditions and processes, in particular the alternation of tropical and polar air masses, lead to distinct large-scale variations valid for all climatic parameters in all seasons. The regional analysis and discussion of climatic gradients and environmental lapse rates stress the significant role of Asia's marked orography and its influence on advective processes, flow currents and topoclimatic settings. Preliminary estimations of the annual water balance, however, are still afflicted with major uncertainties owing to methodical limits in the spatial estimation of precipitation rates and widely lacking evapotranspiration records, particularly in the Tibetan Plateau and adjacent high mountain systems. Given the importance of the mountainous water resources for the affected economies, further regional investigations on the water cycle and its components are vital future tasks for climate research.

Atmospheric rivers induced heavy precipitation and flooding in the western U.S. simulated by the WRF regional climate model

Abstract: [1] A 20-year regional climate simulated by the Weather Research and Forecasting model has been analyzed to study the influence of the atmospheric rivers and land surface conditions on heavy precipitation and flooding in the western U.S. The simulation realistically captured the mean and extreme precipitation, and the precipitation/temperature anomalies of all the atmospheric river events between 1980–1999. Contrasting the 1986 President Day and 1997 New Year Day events, differences in atmospheric stability have an influence on the spatial distribution of precipitation. Although both cases yielded similar precipitation, the 1997 case produced more runoff. Antecedent soil moisture, rainfall versus snowfall, and existing snowpack all seem to play a role, leading to a higher runoff to precipitation ratio for the 1997 case. This study underscores the importance of the atmospheric rivers and land surface conditions for predicting heavy precipitation and floods in the current and future climate of the western U.S.

Climate response of direct radiative forcing of anthropogenic black carbon

Abstract: The equilibrium climate effect of direct radiative forcing of anthropogenic black carbon (BC) is examined by 100-year simulations in the Goddard Institute for Space Studies General Circulation Model II-prime coupled to a mixed-layer ocean model. Anthropogenic BC is predicted to raise globally and annually averaged equilibrium surface air temperature by 0.20 K if BC is assumed to be externally mixed. The predicted increase is significantly greater in the Northern Hemisphere (0.29 K) than in the Southern Hemisphere (0.11 K). If BC is assumed to be internally mixed with the present day level of sulfate aerosol, the predicted annual mean surface temperature increase rises to 0.37 K globally, 0.54 K for the Northern Hemisphere, and 0.20 K for the Southern Hemisphere. The climate sensitivity of BC direct radiative forcing is calculated to be 0.6 K W (sup -1) square meters, which is about 70% of that of CO2, independent of the assumption of BC mixing state. The largest surface temperature response occurs over the northern high latitudes during winter and early spring. In the tropics and midlatitudes, the largest temperature increase is predicted to occur in the upper troposphere. Direct radiative forcing of anthropogenic BC is also predicted to lead to a change of precipitation patterns in the tropics; precipitation is predicted to increase between 0 and 20 N and decrease between 0 and 20 S, shifting the intertropical convergence zone northward. If BC is assumed to be internally mixed with sulfate instead of externally mixed, the change in precipitation pattern is enhanced. The change in precipitation pattern is not predicted to alter the global burden of BC significantly because the change occurs predominantly in regions removed from BC sources.

Gridded North American monthly snow depth and snow water equivalent for GCM evaluation

Abstract: Evaluation of snow cover in GCMs has been hampered by a lack of reliable gridded estimates of snow water equivalent (SWE) at continental scales In order to address this gap, a snow depth analysis scheme developed by Brasnett (1999) and employed operationally at the Canadian Meteorological Centre (CMC), was applied to generate a 03° latitude/longitude grid of monthly mean snow depth and corresponding estimated water equivalent for North America to evaluate GCM snow cover simulations for the Atmospheric Model Intercomparison Project II (AMIP II) for the period 1979–96 Approximately 8000 snow depth observations per day were obtained from US cooperative stations and Canadian climate stations for input to the analysis The first‐guess field used a simple snow accumulation, aging and melt model driven by 6‐hourly values of air temperature and precipitation from the European Centre for Medium‐range Weather Forecasting (ECMWF) ERA‐15 Reanalysis with extensions from the Tropical Ocean Global Atmosphe