The interaction of tropical convection with its environment - new observational insights
Abstract
The faithful representation of tropical convection in weather and climate models remains one of most difficult tasks in atmospheric science. This is so, because the complex interactions of small-, meso- and large-scale processes that occur in convection need to be parametrised in those models.
Since the 1990s, the operational and research radar network around Darwin has been instrumental in significantly improving our understanding of the scale interactions in tropical convection. The use of the data produced by these systems has accelerated over the past decade and has led to the generation of a unique, 16-year long data set for atmospheric convection research. We will summarise some key findings of recent research using this new data set in conjunction with large-scale information. We show that convective heating in an area is entirely dominated by the fraction of the area that experiences convection. Following in the footsteps of field studies in the 70's and 80's we identify archetypal convective states and study the relationship to their environment. We show that the most intense convection is associated with large clouds that occur in a dry and often descending atmosphere, while the largest area-average rain results from a moderate number of moderate size clouds embedded in a humid and ascending atmosphere. Combining cloud-structure information with radar-based estimates of vertical velocity, enables us for the first time to estimate convective mass-fluxes over long periods of time and large areas. We use this information to estimate the vertical structure of entrainment and detrainment and its relationship to the convective environment. Finally, we briefly highlight how the inspiration drawn from the observations can be used to design a new approach to cumulus parametrisation. In doing so we connect detailed process research based on observations with the models used in weather climate prediction.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A34A..08J
- Keywords:
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- 3314 Convective processes;
- ATMOSPHERIC PROCESSES