The heat balance of the tropical tropopause, cirrus, and stratospheric dehydration
نویسندگان
چکیده
If tropical tropopause cirrus lie above convective anvils with tops above about 13km, then net radiative cooling from the cirrus can be produced that is large enough to offset significant subsidence heating, even at the lowest temperatures observed in the tropics. Cirrus clouds near the tropopause are strongly heated by radiation unless they lie above convective anvil clouds. Radiative relaxation in the tropical troposphere is slow above about 14km unless clouds are present. Radiative cooling of tropopause cirrus may be important in processes that dehydrate air before it enters the stratosphere.
منابع مشابه
Ice nucleation and dehydration in the Tropical Tropopause Layer.
Optically thin cirrus near the tropical tropopause regulate the humidity of air entering the stratosphere, which in turn has a strong influence on the Earth's radiation budget and climate. Recent high-altitude, unmanned aircraft measurements provide evidence for two distinct classes of cirrus formed in the tropical tropopause region: (i) vertically extensive cirrus with low ice number concentra...
متن کاملA new wave scheme for trajectory simulations of stratospheric water vapor
We have developed a new wave scheme particularly aiming to provide better temperature fields with realistic variability for trajectory modeling of dehydration processes in the tropical tropopause layer (TTL). The new scheme includes amplitude-phase interpolation and amplification of waves in reanalysis data. Amplification factors are based on statistical variability differences between reanalys...
متن کاملUltrathin Tropical Tropopause Clouds (UTTCs): II. Stabilization mechanisms
Mechanisms by which subvisible cirrus clouds (SVCs) might contribute to dehydration close to the tropical tropopause are not well understood. Recently Ultrathin Tropical Tropopause Clouds (UTTCs) with optical depths around 10−4 have been detected in the western Indian ocean. These clouds cover thousands of square kilometers as 200–300 m thick distinct and homogeneous layer just below the tropic...
متن کاملKeith: Inferences from the Isotopic Composition of Water Vapor
Air may cross the tropical tropopause either by gradual ascent or in localized episodes associated with convection. While observations demonstrate that water vapor mixing ratios of air entering the tropical stratosphere are consistent with the mean tropical tropopause temperature, they do not resolve key mechanistic questions, such as the relative contribution of gradual or episodic transport, ...
متن کاملAn Intercomparison of Microphysical Retrieval Algorithms for Upper- Tropospheric Ice Clouds
U pper-tropospheric ice clouds are important modulators of the Earth’s climate, cover 20% of the globe at any given time (Liou 1986), and occur ~43% of the time in long-term satellite datasets (Wylie and Menzel 1999). Ice clouds, such as cirrus, tend to ref lect less incoming solar radiation and absorb more infrared radiation than water clouds, which are typically optically thicker and occur at...
متن کامل