echarts 如何設置熱力圖點的大小

series: [{
        name: 'AQI',
        type: 'heatmap',
        coordinateSystem: 'geo',
        blurSize: 10,
        pointSize: 10, // 設置熱力圖上點的大小
        symbolSize: 200,
        itemStyle: {
            normal: {
                width: 2,
                color: 'skyblue'
            }
        },
        data: convertData([
            {name: "海門", value: 100},
            {name: "鄂爾多斯", value: 112},
            {name: "招遠", value: 112},
            {name: "廊坊", value: 193},
            {name: "菏澤", value: 194},
            {name: "合肥", value: 229},
            {name: "武漢", value: 273},
            {name: "大慶", value: 279}
        ])
    }]

　　

pointSize
這個屬性在echarts 官方文檔上並沒有找到，但是源碼中的確有pointSize的選項 
echart 實例地址
https://gallery.echartsjs.com/editor.html?c=x8IJn-BkTO