描述:

抬升指数(LI)是一种表示自由对流高度以上不稳定能量大小的指数。它表示一个气块 从抬升凝结高度出发，沿湿绝热线上升到500百帕(海拔5500米左右高度)处所具有的 温度被该处实际大气温度所减得到的差值。比如，某一气块沿湿绝热线上升到500百帕 时的理论值为－14°C, 而该处的实际温度为－18°C, 那么抬升指数就是-4。 当差值为负数时，表明气块比其环境温度更暖，因此将会继续上升。该差值的绝对值 越大，出现对流天气的可能性也越大。差值为正数时，表示大气层结稳定。

值得注意的是，中国气象学家定义的抬升指数和上面的定义正好相反，他们用一个气块 沿湿绝热线上升到500百帕处所具有的温度减去该处实际大气温度得到的差值定义抬升 指数(大气科学辞典，P603)。因此获得的抬升指数值和我们此处的抬升指数值符号正好 相反。

抬升指数

天气现象

>0

不可能出现雷雨天气

0－ -3

可能出现雷雨天气

-3 - -5

很可能出现雷雨天气

-5 - -7

强对流(雷雨)天气

<-7

大气极端不稳定，强对流天气

CFS:

The CFS model is different to any other operational weather forecasting model you will see on Weatheronline.
Developed at the Environmental Modelling Center at NCEP (National Centers for Environment Prediction) in the USA, the CFS became operational in August 2004.
The systems works by taking reanalysis data (NCEP Reanalysis 2) and ocean conditions from GODAS (Global Ocean data Assimilation). Both of these data sets are for the previous day, and so you should be aware that before initialisation the data is already one day old.
Four runs of the model are then made, each with slightly differing starting conditions, and from these a prediction is made.
Caution should be employed when using the forecasts made by the CFS. However, it is useful when monitored daily in assessing forecasts for the coming months, the confidence levels in these forecasts and in an assessment of how such long range models perform.
A description of the CFS is given in the following manuscript.
S. Saha, S. Nadiga, C. Thiaw, J. Wang, W. Wang, Q. Zhang, H. M. van den Dool, H.-L. Pan, S. Moorthi, D. Behringer, D. Stokes, M. Pena, S. Lord, G. White, W. Ebisuzaki, P. Peng, P. Xie , 2006 : The NCEP Climate Forecast System. Journal of Climate, Vol. 19, No. 15, pages 3483.3517.
http://cfs.ncep.noaa.gov/

NWP:

Numerical weather prediction uses current weather conditions as input into mathematical models of the atmosphere to predict the weather. Although the first efforts to accomplish this were done in the 1920s, it wasn't until the advent of the computer and computer simulation that it was feasible to do in real-time. Manipulating the huge datasets and performing the complex calculations necessary to do this on a resolution fine enough to make the results useful requires the use of some of the most powerful supercomputers in the world. A number of forecast models, both global and regional in scale, are run to help create forecasts for nations worldwide. Use of model ensemble forecasts helps to define the forecast uncertainty and extend weather forecasting farther into the future than would otherwise be possible.

Wikipedia, Numerical weather prediction, http://zh.wikipedia.org/wiki/數值天氣預報(as of Feb. 9, 2010, 20:50 UTC).