Table 1.
Properties of the Datasets.
| Name | Level | Coverage/time range | Time Res. | Horizontal Res. Grid pts/degrees/distance | Data history | Variables | Special Notes |
|---|---|---|---|---|---|---|---|
| Interpolated station data | |||||||
| CRU325 | Station | Global1901–2011 | Monthly | 720 × 3600.5°lat × lon | Average of daily values | Tmax, Vap, Tm | Triangulated linear interpolation, Tmax, Tm from observed mean and diurnal range, Vap from mix of observed and ‘synthetic’ values. |
| CRU401 | Station | Global1901–2011 | Monthly | 720 × 3600.5°lat × lon | Average of daily values | Tmax, Vap, Tm | Angular distance weighting, Tmax, Tm from observed mean and diurnal range, Vap from mix of observed and ‘synthetic’ values. |
| NCD | Station | CONUS 1900–2011 | Monthly | Varies, single value per CD | Average of forecast daily maximum | Tmax | Station data merged within each CD, subject to various geographic and sampling adjustments |
| Reanalyses | |||||||
| NARR | 2 m | Regional1979–2011 | 3-hourly | 349 × 2770.3°32 km | 2D field | T, RH | rcm2rgrid used to interpolate to rectangular grid. T from operational forecast system but not 2 m values; 2 m RH from assimilated 3-D fields. |
| MERRA2 | 2 m | Global1980–2011 | 1-hourly | 576 × 3610.625° × 0.5°70 × 55 km | Instantaneous 2D Collections, instl1_2d_asm_Nx: Single-Level Diagnostics | T, q, surface pressure | Derived from assimilation of radiosonde and other data, but not 2 m land station observations of T or Vap. |
| ERA-20C | 2 m | Global1900–2010 | 6-hourly, monthly for ensemble values | 320 × 1601.125°125 km | ERA 20th Century atmospheric ‘final’ surface analysis | T, Td | Also has 10 ensemble members. Model-created data from surface: pressure and oceanic winds observations |
| 20CRv2 | sig995 | Global1900–2011 | 6-hourly | 180 × 912.0°220 km | Regular Gridded Data, monolevel, ensemble mean | T, RH | Also has 56 ensemble members. Model-created data as only surface pressure data observations input. |
| NNRA 1 | sig995 | Global1950–2011 | 6-hourly | 144 × 732.5°275 km | 3D field | T, RH | Both variables are class ‘B’: direct observation input with ‘strong’ model influence |
| CFSR | sig995 | Global1979–2010 | 6-hourly | 720 × 3610.5°55 km | High Resolution 3D Analysis Pressure Level Data (pgbhnl), | T, RH | NCO used to concatenate files into single file for each year. Does not assimilate surface station values. |
| NDRA2 | 1000 hPa | Global1979–2011 | 6-hourly | 144 × 732.5°~275 km | Pressure level data | T, RH | Variables similar to NNRA1 |
| ERA-I | 2 m | Global1980–2011 | 6-hourly | 480 × 2410.75°80 km | Instantaneous, temporally varying, surface level analysis | T, Td | Direct assimilation of 2 m station T and Vap plus other data. |
Abbreviations: T = air temperature, RH = relative humidity, q = specific humidity, Td = dew point T, Tmax = daily maximum T, Vap = water vapor pressure, CD = NOAA US climate divisions.