Introduction

This comparison effort tries to find an answer to the question concerning the choice of the mean gravity for the height transformation. It is studied how and to which extent the choice of the gravity model changes the obtained ellipsoidal height. Thereby, geopotential heights (g_n = 9.80665 m/s^2) in a numerical weather model are assumed to be given at [0, 10, 20, 50, 100, 200, 500, 1000, 2000, 5000, 10000, 20000, 50000, 100000] meters. The task was to transform these heights to ellipsoidal heights (assuming a constant geoid undulation of N=20 m). At all grid points (pairs) with geodetic latitude/longitude [-90,-89,..,89,90] /[0,1,…,359,360]. For this study it was assumed that geodetic latitude/longitude is identical to the one used in the numerical weather models.

Submissions

In total the following 8 contributions were submitted (all data and documents are password protected):

  1. GFZ: description, data
  2. GRGS: description, data
  3. NICT: description, data
  4. UNB-A: description, data
  5. UNB-B: description, data
  6. UNB-C: description, data
  7. UNB-D: description, data
  8. UNB-E: description, data
  9. VUT: description, data

Results

RMS w.r.t. a median map for each solution over all heights

RMS w.r.t. an average map for each height over all solutions

(Map plots can be accessed by clicking on the “o” symbols)

0 m 10 m 20 m 50 m 100 m 200 m 500 m 1000 m 2000 m 5000 m 10000 m 20000 m 50000 m 100000 m
o o o o o o o o o o o o o o

Mean RMS w.r.t. a median map as a function of latitude

Absolute differences w.r.t. an averge map at each height layer

(Map plots can be accessed by clicking on the “o” symbols)

0 m 10 m 20 m 50 m 100 m 200 m 500 m 1000 m 2000 m 5000 m 10000 m 20000 m 50000 m 100000 m
GFZ o o o o o o o o o o o o o o
GRGS o o o o o o o o o o o o o o
NICT o o o o o o o o o o o o o o
UNB-A o o o o o o o o o o o o o o
UNB-B o o o o o o o o o o o o o o
UNB-C o o o o o o o o o o o o o o
UNB-D o o o o o o o o o o o o o o
UNB-E o o o o o o o o o o o o o o
VUT o o o o o o o o o o o o o o