First results of diurnal variation of radar echo area observed at Vientiane, Lao PDR, in the middle of Indochina are reported. Radar echo intensity data from April to October 2008 is analyzed. The monthly averaged diurnal cycles of radar echo area have a peak in the late afternoon in April and midnight in July. The echo area per one echo at the time of the maximum total echo area in the diurnal cycle in April (@600 km 2 ) is smaller than that in July (@1,200 km 2 ). The phases of diurnal cycle

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... f echo area in 6 banded regions oriented from southwest to northeast are compared to examine spatial di¤erences of diurnal cycles. It is found that the phase of each band delays from southwestern to northeastern banded regions. The propagation speed of phase of echo area diurnal cycle is estimated as about 14 m s À1 .