Convective Precipitation and Heating Structures Observed By the Smart-Radar During Dynamo
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The Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign is the US component of an international experiment in late 2011/early 2012 in the Indian Ocean, the Cooperative Indian Ocean Experiment on Intraseasonal Variability (CINDY2011). The overarching goal of DYNAMO is to expedite understanding of processes key to MJO initiation over the Indian Ocean and to improve simulation and prediction of the MJO. The field campaign will include multiple radars, atmospheric sounding sites, a research aircraft, multiple research vessels, and oceanic measurements. The three main hypotheses of DYNAMO are: 1) Deep convection can be organized into an MJO convective envelope only when the moist layer has become sufficiently deep over a region of the MJO scale; the pace at which this moistening occurs determines the duration of the pre-onset state, 2) Specific convective populations at different stages are essential to MJO initiation, and 3) The barrier layer, wind- and shear-driven mixing, shallow thermocline, and mixing-layer entrainment all play essential roles in MJO initiation in the Indian Ocean by controlling the upper-ocean heat content and SST, and thereby surface flux feedback In this award, the investigator will deploy a SMART-R C-band radar on Addu Atoll for the duration of the 6-month Extended Operations Period of DYNAMO. The radar will provide continuous measurements of reflectivity and radial velocity of precipitating convection, and serve as the "workhorse" radar of DYNAMO, allowing other radars to have more flexibility in scanning strategies. The research team will also develop baseline products to assess properties of the precipitating clouds and their organization, including: reflectivity PDFs with height, echo-top heights, convective-stratiform classification, rain maps, and rain/snow water content estimates. Divergence and latent heating profiles calculated from radial velocity and reflectivity measurements will also be developed and used to determine the balance between low-level and upper level heating in precipitating convection. The broader impacts of the work include the involvement of a large number of students in field observations and data analysis, possible outreach activities on Addu Atoll, and enhanced international collaborations. A successful DYNAMO campaign would lead to improved understanding of tropical convection, the predictability of the MJO, and downstream effects of the MJO on weather in the United States and other areas.
