Convective available potential energy

About: Convective available potential energy is a research topic. Over the lifetime, 936 publications have been published within this topic receiving 43773 citations. The topic is also known as: CAPE.

Neural Networks: Cloud Parameterizations

Abstract: The role of clouds in the climate system is very complex and is the subject of much interest and research. Clouds interact nonlinearly with radiative, dynamical, chemical, and hydrological processes in the atmosphere on a wide range of temporal and spatial scales. Clouds play a fundamental role in controlling the amount of solar and infrared radiation available to the climate system. The radiative properties of clouds make them a key component in the energy balance of the Earth. In particular, clouds are involved in both heating and cooling in the determination of the Earth’s temperature. On average, roughly 50% of the Earth is covered by clouds. They contribute to the planet’s albedo by reflecting some incident sunlight (shortwave radiation) back to space (they also absorb some). However, they also partially block the escape of infrared radiation from below; that is, they exert a greenhouse effect on Earth. (Clouds are the primary contributors to the greenhouse effect.) They also emit some longwave radiation. Clouds also play an essential role in controlling the amount of moisture available to the climate system. Through precipitation, clouds serve as a conduit for the transfer of heat from the oceans to the atmosphere. They are also important in many chemical processes such as the absorption of water-soluble chemicals and pollutants in cloud droplets and their elimination by precipitation. See [Tre92] for further discussion.

Analysis of atmospheric stability using AIRS data

Abstract: An optimal cloud-clearing method using collocated MODIS clear pixels is applied to AIRS partly cloudy radiance. Temperature and humidity profiles with 100 layers are retrieved from cloud-free and cloud-cleared AIRS radiance. Using these retrieved profiles, atmospheric environment parameters (include Convective Available Potential Energy, CAPE; Convective Inhibition, CIN) and instability indices (include K index, Lifted Index, Showalter Index) are calculated and compared with that calculated from AIRS and ATOVS operational products and ECMWF analysis fields. These different datasets have different spatial resolution (both in vertical and in horizontal) and spectral resolution. Results show that spatial resolution have obviously influence to the calculations, the lower spatial resolution is likely to have some small energy region lost or reduce the calculation precision. And the profiles derived from partly cloudy area are more meaningful to weather events. The CAPE values of typhoon rain region show differences to that of trough region.

Clouds, Noncloudy Latent Heat Convection, Entrainment, and Horizontal Averaging

Abstract: Crucial observations describing the mechanisms active in the convective planetary boundary layer are reviewed. Attention is drawn to the observed transport of heat and moisture upward against vertical stratifications stable to cloud-free convection. Occasional saturated parcels carry air of a different composition through regions well below cloud base. These parcels do not form sustained or easily visible cloud and are observed to penetrate even where no sustained cloud forms higher up. This mechanism is likely to be of major importance. The possibility of erosion into the warm overlying air at the top of the convective layer due to a negative heat flux is discussed. One must conclude from the observations discussed here that it does not actually occur. Despite claims to the contrary, the air above appears to enter the convecting layer only when the convection has effectively reached its temperature. When stratus cloud is present, mixtures with the overlying unsaturated air often have the same density as the cloudy air below. Both these phenomena illustrate the inadequacy of conceptual thinking based on averaged horizontal uniformity in the fluid, without recognizing that convective transport is a process where isolated thermal elements in the fluid carry practically all of the quantitiesmore » such as heat and moisture from one level to another. Gradient turbulent diffusion usually has no role to play and is not a satisfactory concept in describing the planetary boundary layer. 30 refs.« less

Convective Storm Initiation and Organization

Abstract: The conditions necessary for the development of deep moist convection are discussed. This material is followed by an overview of the ways in which convective storms may be organized, with emphasis on the environmental characteristics favoring the various organizational modes.