Investigation of Low Frequency Atmospheric Oscillations Based on Satellite Data

大气低频振荡(LFO)是一种具有一到两个月时间尺度的现象，引起了世界各地研究人员的兴趣。许多工作都集中在最初发现这种效应的热带地区。这一研究项目将侧重于高纬度地区，特别是该小组首次研究低频振荡的平流层。这项研究包括四个部分：1)对于平流层中上层的红外SSU数据，将计算出与MSU微波分析(90毫巴温度)类似的全球相关图。2)利用位势高度场和SSU资料研究LFO的垂直结构和从对流层到平流层上层的传播。滞后相关霍夫莫勒研究将被用来研究波包行为。热带-高纬度连接将通过热带微波数据与高纬度/海拔位势高度和SSU场之间的相关性进行评估。3)用Eliassen-Palm通量散度计算研究LFO的能量传播及其对平均流的影响。E矢量公式将用于基本气流纬向不对称性较强的地区。将与模型预测进行比较。4)牛津大学将使用最近重新处理的中层辐射数据场来寻找平流层顶上方是否存在LFO。这项研究很重要，因为它寻找高层大气中的过程与地球表面附近的气候之间的关系。这种关系应该会增强我们对气候的理解，以及我们预测气候变化的能力。

Low frequency oscillations (LFO) of the atmosphere, a phenomenon with one-to two-month time scales, have captured the interest of researchers worldwide. Much work has been concentrated on the tropics where the effects were initially discovered. This research project will focus on higher latitudes and, in particular, the stratosphere where this group has been the first to study LFO. The research has four components: 1) Global correlation maps similar to those obtained with MSU microwave analyses (90 mb temperatures) will be calculated for infrared SSU data in the middle and upper stratosphere. 2) LFO vertical structure and propagation from the troposphere to the upper stratosphere will be studied with coherencies (in- and out-of phase correlations by wavenumber) using geopotential height fields and SSU data. Lag-correlation Hovmoller studies will be used to investigate wavepacket behavior. Tropics-higher latitude connections will be assessed with correlations between tropical microwave data and higher latitude/altitude geopotential height and SSU fields. 3) LFO energy propagation and effect on the mean flow will be investigated with Eliassen-Palm flux divergence calculations. An E-vector formulation will be used in regions of strong basic flow zonal asymmetry. Comparison will be made with model predictions. 4) Recently reprocessed mesospheric radiance data fields will be used at Oxford University to search for the existence of LFO above the stratopause. This research is important because it seeks relationships between processes in the high atmosphere and climate as manifested near the surface of the earth. Such relationships should enhance our understanding of climate and our ability to predict its variations.