双坐标画图，一边是柱状图，一边是折线图
首先利用plotyy函数，指定画图类型，然后分别对line和bar属性进行调整
code：
[hAxes,hBar,hLine]=plotyy([1:12],pm25_wh',[1:12],pbl_wh,'bar','plot');
set(hAxes,'Xlim',[0.5 12.5],'FontSize',font,'FontName','Times New Roman','FontWeight','bold');
set(hAxes(1),'Ylim',[0 160],'YTick',[0:50:160]);set(hAxes(2),'Ylim',[0 1200],'YTick',[0:300:1200]);
set(hLine(1),'Color',[1 0.8 0],'LineWidth',6)
set(hLine(2),'Color',[0.42 0.65 0.80],'LineWidth',6)
set(hBar(1),'FaceColor',[1 0.8 0]);set(hBar(2),'FaceColor',[0.42 0.65 0.80]);
ylabel(hAxes(1),'PM_2_._5 Concentrations ({\mu}g m^{-3})')
% ylabel(hAxes(2),'PBLH (m)');box off
xlabel(hAxes(1),'Month');box off
l1=legend('PM_2_._5-08:00','PM_2_._5-20:00','PBLH-08:00','PBLH-20:00');
set(l1,'box','off','orientation','vertical','Location','northeast','Fontname', 'Times New Roman','FontWeight','bold','FontSize',font-4)
