ERA40 T106 Analysis Fields on Model Levels, created at NCAR

DS127.2 represents a dataset implemented and computed by NCAR's Data Support Section, and forms an essential part of efforts undertaken in late 2004, early 2005, to produce an archive of selected segments of ERA-40 on standard transformation grids. In this case, ERA-40 6-hourly upper air variables on 60 model levels were transformed from either spherical harmonics (surface geopotential, temperature, vertical velocity, vorticity, logarithm of surface pressure, divergence), or a reduced N80 Gaussian grid (specific humidity, ozone mass mixing ratio, cloud liquid water content, cloud ice water content, cloud cover), to a 320 by 160 regular Gaussian grid at T106 spectral truncation. In addition, horizontal wind components were derived from spectral vorticity and divergence and also archived on a T106 Gaussian grid. All scalar fields were transformed using routines from the ECMWF EMOS library, whereas the horizontal winds were obtained using NCAR's SPHEREPACK library.

The ERA-Interim data from ECMWF is an update to the ERA-40 project. The ERA-Interim data starts in 1989 and has a higher horizontal resolution (T255, N128 nominally 0.703125 degrees) than the ERA-40 data (T159, N80 nominally 1.125 degrees). ERA-Interim is based on a more current model than ERA-40 and uses 4DVAR (as opposed to 3DVAR in ERA-40). ECMWF will continue to run the ERA-Interim model in near real time through at least 2010, and possibly longer. This data is available in ds627.0 [https://rda.ucar.edu/datasets/ds627.0/].

DS127.2 代表由美国国家大气研究中心（NCAR）的数据支持部门实施和计算的数据集，构成了2004年底至2005年初为生产ERA-40在标准变换网格上的选定段落的存档工作的重要组成部分。在本例中，ERA-40的每6小时一次的上空气象变量，在60个模型层面上，从球谐函数（地表位势、温度、垂直速度、涡度、地表压力的对数、散度）或简化的N80高斯网格（比湿、臭氧质量混合比、云液态水含量、云冰水含量、云量）变换为一个320×160的常规高斯网格，该网格的T106光谱截断。此外，水平风分量是通过谱涡度和散度导出的，并同样存档在T106高斯网格上。所有标量场均使用欧洲中期天气预报中心（ECMWF）的EMOS库中的例程进行变换，而水平风速则通过美国国家大气研究中心（NCAR）的SPHEREPACK库获得。

欧洲中期天气预报中心（ECMWF）的ERA-Interim数据是对ERA-40项目的更新。ERA-Interim数据始于1989年，其水平分辨率（T255，N128的名义分辨率为0.703125度）高于ERA-40数据（T159，N80的名义分辨率为1.125度）。ERA-Interim基于比ERA-40更先进的模型，并使用4DVAR（与ERA-40中的3DVAR相对）。欧洲中期天气预报中心（ECMWF）将继续至少到2010年，甚至可能更长时间，在接近实时状态下运行ERA-Interim模型。此数据可通过ds627.0 [https://rda.ucar.edu/datasets/ds627.0/]获取。