做Heating试验的时候，何老师提示将Profile中的最大值放在500-600hPa附近。但是CAM中采用的是σ-P混合坐标系统，需要进行坐标转换。之所以采用这种坐标系统，是因为底层为了描述好地形的作用采用σ坐标系统，而高层则采用P坐标系统。而我们通常关心的是P坐标系统下某一层面的情况，比如500hPa位势高度场等。CAM3.0的users’ guide 上提供了CAM坐标系统向P坐标系统转化的方法
p(i,j,k)= Ak P0+ Bk Ps(i,j)
其中p(i,j,k)为指定点处的气压，A，B，P0均为常数。Ps是模式当前地表气压；P0在模式源码中已被给定。AB在模式输出数据中已经存在，界面处系数分别为hyai和hybi，层面中间点为hyam和hybm。其中主要关注的U V T等变量应该使用hyam和hybm（对应下图Level Index），而通量场变量则多位于交界面（对应下图Interface Index）。引用CAM 3.0 ug中的图如下
在CAM4和CAM5下，中间点对应的气压如下表所示（假设PS=1000hPa，Hard Coded P0=1000hPa）
| CAM4 Vertical Transform | |||
| Num | byam | hybm | presure |
| 1 | 0.003544638 | 0.000000000 | 3.544638 |
| 2 | 0.007388814 | 0.000000000 | 7.3888135 |
| 3 | 0.013967214 | 0.000000000 | 13.967214 |
| 4 | 0.023944625 | 0.000000000 | 23.944625 |
| 5 | 0.037230290 | 0.000000000 | 37.23029 |
| 6 | 0.053114605 | 0.000000000 | 53.114605 |
| 7 | 0.070059150 | 0.000000000 | 70.05915 |
| 8 | 0.077912570 | 0.007526545 | 85.439115 |
| 9 | 0.076607010 | 0.023907685 | 100.514695 |
| 10 | 0.075071085 | 0.043179250 | 118.250335 |
| 11 | 0.073264150 | 0.065851245 | 139.115395 |
| 12 | 0.071138385 | 0.092523685 | 163.66207 |
| 13 | 0.068637535 | 0.123902400 | 192.539935 |
| 14 | 0.065695415 | 0.160817850 | 226.513265 |
| 15 | 0.062234155 | 0.204247000 | 266.481155 |
| 16 | 0.058162165 | 0.255339100 | 313.501265 |
| 17 | 0.053371680 | 0.315446300 | 368.81798 |
| 18 | 0.047735925 | 0.386159300 | 433.895225 |
| 19 | 0.041105755 | 0.469349500 | 510.455255 |
| 20 | 0.033305700 | 0.567218500 | 600.5242 |
| 21 | 0.024968440 | 0.671827850 | 696.79629 |
| 22 | 0.017095910 | 0.770606150 | 787.70206 |
| 23 | 0.010214710 | 0.856946050 | 867.16076 |
| 24 | 0.004803175 | 0.924845700 | 929.648875 |
| 25 | 0.001260680 | 0.969294150 | 970.55483 |
| 26 | 0.000000000 | 0.992556100 | 992.5561 |
| CAM5 Vertical Transform | |||
| Num | byam | hybm | presure |
| 1 | 0.003643466 | 0.000000000 | 3.643465694 |
| 2 | 0.007594820 | 0.000000000 | 7.594819646 |
| 3 | 0.014356632 | 0.000000000 | 14.35663225 |
| 4 | 0.024612220 | 0.000000000 | 24.61222 |
| 5 | 0.038268300 | 0.000000000 | 38.26829977 |
| 6 | 0.054595480 | 0.000000000 | 54.59547974 |
| 7 | 0.072012451 | 0.000000000 | 72.01245055 |
| 8 | 0.087821230 | 0.000000000 | 87.82123029 |
| 9 | 0.103317127 | 0.000000000 | 103.3171266 |
| 10 | 0.121547241 | 0.000000000 | 121.5472408 |
| 11 | 0.142994039 | 0.000000000 | 142.9940388 |
| 12 | 0.168225080 | 0.000000000 | 168.2250798 |
| 13 | 0.178230673 | 0.019677414 | 197.9080867 |
| 14 | 0.170324326 | 0.062504293 | 232.828619 |
| 15 | 0.161022909 | 0.112887908 | 273.9108168 |
| 16 | 0.150080286 | 0.172161616 | 322.2419024 |
| 17 | 0.137206860 | 0.241894044 | 379.1009039 |
| 18 | 0.122061938 | 0.323930636 | 445.9925741 |
| 19 | 0.104244713 | 0.420442462 | 524.6871747 |
| 20 | 0.084979154 | 0.524799541 | 609.7786948 |
| 21 | 0.066501696 | 0.624887735 | 691.3894303 |
| 22 | 0.050196789 | 0.713207692 | 763.4044811 |
| 23 | 0.037188658 | 0.783669710 | 820.8583687 |
| 24 | 0.028431948 | 0.831102818 | 859.5347665 |
| 25 | 0.022208977 | 0.864811271 | 887.0202489 |
| 26 | 0.016407382 | 0.896237165 | 912.6445469 |
| 27 | 0.011074558 | 0.925123841 | 936.1983985 |
| 28 | 0.006254954 | 0.951230526 | 957.4854795 |
| 29 | 0.001989409 | 0.974335998 | 976.3254074 |
| 30 | 0.000000000 | 0.992556095 | 992.5560951 |