Radiosondes 6 Single tropopause tropopause 6 Atmospheric temperature 4 Climatology 4 Double tropopause 4 Extratropical tropopause layer 4 Rawinsonde 4 South America 4 Stratosphere 4 Tropopause climatology 4 Troposphere 4 Upper atmosphere 4 climatology 4 extratropical environment 4 jet stream 4 stratosphere 4 subtropical region 4 Air stations 2 Clouds 2 Coupling 2 Diabatic heating 2 EOF analysis 2 Empirical orthogonal function 2 Fourier analysis 2 Fourier transform 2 Height anomaly 2 Lapse rate 2 Mandatory levels 2 Middle atmosphere 2