https://cddis.nasa.gov/archive/gnss/products/troposphere/zpd/
ftp://cddis.gsfc.nasa.gov/gnss/products/troposphere/zpd/（Anonymous ftp service will be discontinued on October 31, 2020.）
ftp://gssc.esa.int/gnss/products/troposphere_zpd/
%以下内容取自igs官网
IGS associate analysis centers generate troposphere products from ground-based GNSS data. These products include five-minute estimates of zenith path delay (ZPD) and north and east troposphere gradient components. Data are available in daily files by site for over 350 GNSS stations in the IGS network. Measurements of surface pressure and temperature at GNSS sites allow the extraction of precipitable water vapor from the total zenith path delay. Final troposphere estimates for over 350 stations in the IGS network. The troposphere products utilize the IGS final satellite, orbit, and EOP products and are therefore available approximately three weeks following the observation day. Troposphere products are available in a standard, IGS format.
Since the inception of the troposphere product, three analysis groups (GFZ, JPL, and currently USNO) have generated the IGS combination solution each using different methodologies. Therefore, the resulting file types have changed through the years. The current product consists of files containing daily ZPD estimates for selected sites in the IGS network. The original product consisted of one file per site per GPS week.
%以下内容取自文献：Sung H. Byun, Yoaz E. Bar-Sever. A new type of troposphere zenith path delay product of the international GNSS service. 2009, 83(3-4):1-7.
– Software: GIPSY – Fixed orbits and clocks: IGS Final Combined – Earth orientation: IGS Final Combined – Transmit antenna phase center map: IGS Convention – Receiver antenna phase center map: IGS Convention – Elevation angle cutoff: 7◦ – Mapping function (hydrostatic and wet): Niell (1996) – A priori: Hydrostatic delay based on altitude (2.3 m at sea level), and 0.1 m for the wet delay – Data time span: 24 h – Data rate: 5 min – Estimated parameters: clock (white noise), station position (constant), wet zenith delay (random walk with variance of 3 cm/h), atmospheric gradients (random walk with variance of 0.3 cm/h), phase biases (white noise)(Bar-Sever et al. 1998) – Temporal resolution of zenith delay estimates: 5 min
%以下内容取自观测文件
头文件说明：
+TROP/DESCRIPTION *_________KEYWORD_____________ __VALUE(S)_______________________________________ ELEVATION CUTOFF ANGLE 7 SAMPLING INTERVAL 300 SAMPLING TROP 300 TROP MAPPING FUNCTION WET GMF
ftp://gssc.esa.int/gnss/products/2108/
ftp://cddis.gsfc.nasa.gov/gnss/products/troposphere/sub/
头文件说明：
%=TRO 0.01 COD 20:157:84478 IGS 20:153:00000 20:154:00000 P MIX *------------------------------------------------------------------------------- +FILE/REFERENCE *INFO_TYPE_________ INFO________________________________________________________ DESCRIPTION CODE, Astronomical Institute, University of Bern OUTPUT CODE IGS 3-day solution CONTACT code@aiub.unibe.ch SOFTWARE Bernese GNSS Software Version 5.3 HARDWARE UBELIX: Linux, x86_64 INPUT CODE IGS 1-day solutions -FILE/REFERENCE *------------------------------------------------------------------------------- +TROP/DESCRIPTION *_________KEYWORD_____________ __VALUE(S)_______________________________________ ELEVATION CUTOFF ANGLE 3 SAMPLING INTERVAL 180 SAMPLING TROP 7200 TROP MAPPING FUNCTION WET_VMF
ftp://gssc.esa.int/gnss/products/2108/
ftp://cddis.gsfc.nasa.gov/gnss/products/troposphere/sub/
头文件说明：
*-------------------------------------------------------------------------------
+FILE/REFERENCE
*INFO_TYPE_________ INFO________________________________________________________
DESCRIPTION CODE, Astronomical Institute, University of Bern
OUTPUT CODE IGS 1-day solution
CONTACT code@aiub.unibe.ch
SOFTWARE Bernese GNSS Software Version 5.3
HARDWARE UBELIX: Linux, x86_64
-FILE/REFERENCE
*-------------------------------------------------------------------------------
+TROP/DESCRIPTION
*_________KEYWORD_____________ __VALUE(S)_______________________________________
ELEVATION CUTOFF ANGLE 3
SAMPLING INTERVAL 180
SAMPLING TROP 7200
TROP MAPPING FUNCTION WET_VMF
ftp://gssc.esa.int/gnss/products/2108/
ftp://cddis.gsfc.nasa.gov/gnss/products/troposphere/sub/
头文件说明：
+FILE/REFERENCE
DESCRIPTION Jet Propulsion Laboratory
OUTPUT Daily trop estimates
CONTACT Christina Selle; 335-flinn@jpl.nasa.gov
-FILE/REFERENCE
+TROP/DESCRIPTION
*_________KEYWORD_____________ __VALUE(S)______________________
SAMPLING INTERVAL 30
TROP MAPPING FUNCTION GPT2
ELEVATION CUTOFF ANGLE 7.000000
SAMPLING TROP 30
