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    Atmospheric and hydrospheric sciences

    Diurnal cycle over a coastal area of the Maritime Continent as derived by special networked soundings over Jakarta during HARIMAU2010

    Katsumata M, Mori S, Hamada JI, Hattori M, Syamsudin F, Yamanaka MD

    diurnal cycle, maritime continent, sounding network, thermodynamic budget analyses

    Obtained diurnal composite over Jakarta during HARIMAU2010 field campaign. (a) Areal coverage of cloud, derived by satellite-borne infrared sensor; (b) surface rainfall, derived from satellite product TRMM 3B42; (c) vertical profile of areal coverage of rain, derived by ground-based C-band radar; (d) diabatic heating, derived from networked soundings; (e) diabatic drying, derived from networked soundings; (f) vertical advection of the moisture, derived from networked soundings.

    This study investigates the nature and mechanisms of the diurnal precipitation system over a coastal area of the Maritime Continent (MC) by utilizing the data from a field campaign, HARIMAU2010. During the 1-month campaign, diurnal cycles over Jakarta were well identified by special networked soundings and a C-band radar. Radar and satellites captured the convective-type heavy rains that appeared in the afternoon over the array, which were followed by stratiform-type precipitation during the night. Thermodynamic budget analyses were also performed using sounding data. The period-averaged vertical profiles of Q1 and Q2 indicate that diurnal precipitation acted as deep convection in the diabatic heating and drying. The diurnal composite of the obtained parameters revealed key processes such as (1) just before the onset of the afternoon convective rain, the lower troposphere was moistened by subarray-scale processes; (2) moistening of the troposphere continued during the convective heavy precipitation; (3) the stratiform rains during the night were partly maintained by consuming the pre-existing hydrometeor aloft; and (4) in the early morning, the clouds redeveloped over the ocean to produce precipitation as well as hydrometeor aloft. The possible physical processes promoting lower-tropospheric moistening before onset of the convective rain are also discussed.