The model grid elevation over each station is within 100 m of the station elevation
. Differences of this magnitude translate to an estimated 1-2-mm error in PWV depending on the station elevation
Then in ArcGIS9.3, DEM map with an accuracy of 30m was inserted in equation 1 instead of each station elevation
, and precipitation map of each period was obtained.
However, when weather station elevation
was low, there was no large deviation among weather stations.
If you are familiar with the topography, it's hard to miss the obvious connection between station elevation
and altimeter setting.
Pressure Altitude/Density Altitude (PADA)--computes the following parameters: sea level pressure (SLP), altimeter setting (ALSTG), pressure altitude (PA), density altitude (DA) and the standard atmosphere based on the upper/lower station pressure and the following optional data fields: station elevation
(for ALSTG, PA, DA), 12-hour mean temperature (for SLP), temperature (for DA) and dew point for DA.
The approach first estimates the air temperature at sea level for each station where measurements are available, using an environmental lapse rate of -6.5 x [10.sup.- 3][degrees]C [m.sup.-1] and station elevation
. Spatial interpolation can then be used to interpolate sea-level temperature to each node of the DEM.
As they studied the period 2003-14, they noticed a consistent pattern of station elevation
moving upward for the years coinciding with recent declines in precipitation, streamflow, and groundwater levels.
However, no winds are forecast within 1500 feet of station elevation
(the surface) and no temperatures are forecast for the 3000-foot level or for any level within 2500 feet of station elevation
One station is at an elevation of 99 feet, and the second station elevation
is 101 feet.
No winds are forecast when a given level is within 1500 feet of the station elevation
(i.e., the ground) and temperatures are not forecast for any station within 2500 feet of the station elevation
Errors in intermediate rod readings will result in incorrect station elevations