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GPS derived Integrated water vapour

This dataset contains Integrated Water Vapor (IWV) estimates derived from GPS receivers that comprise the GAGAN TEC network. These receivers have been installed at airports at various locations in India. The Zenith Tropospheric Delay was estimated from the GPS observations using the GAMIT software. Further, IWV was estimated from the ZTD values using surface temperature and pressure from ERA-I reanalysis as additional inputs. The GAGAN-IWV estimates for 1 year – March 2013 to February 2014 – have currently been made available.

 

Data Access

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Data Version

  • Version 1.0 (beta)

Data Sources

  • GPS receivers from GAGAN TEC Network

Processing Steps

  • GAMIT software used to derive Zenith Tropspheric Delay (ZTD)
  • Integrated Water Vapor (IWV) derived using procedure described in Bevis et. al. (1992)

References

  • M. Bevis, S. Businger, T. A. Herring, C. Rocken, R. A. Anthes, and R. H. Ware, “GPS Meteorology: Remote sensing of atmospheric water vapor using global positioning system,” J. Geophys. Res., vol. 97, pp. 15, 787-15, 801, 1992.
  • Herring, T. A., R. W. King, and S. C. McClusky. "Introduction to Gamit/Globk." Massachusetts Institute of Technology, Cambridge (2008).
  • Acharya, R., M. R. Sivaraman, K. Bandyopadhyay, N. Nagori, S. Sunda, and S. Regar (2007), Ionospheric studies for the implementation of GAGAN, Ind. J. Radio Space Phys., 36 (5), 394–404.
  • Sunda, S., R. Sridharan, B. M. Vyas, P. V. Khekale, K. S. Parikh, A. S. Ganeshan, C. R. Sudhir, S. V. Satish, and M. S. Bagiya (2015), Satellite-based augmentation systems: A novel and cost-effective tool for ionospheric and space weather studies, Space Weather, 13, doi:10.1002/2014SW001103.

Derivation Techniques and Algorithm

  • Described in the report titled “Demonstration of GNSS-based short-range forecasting of rainfall”

Limitations

  • The IWV estimates constitute a conical average of variable shape and orientation depending on the location of available GPS satellites.

Known problems with data

  • No known issues at this time.

File Naming Convention

  • ASCII files:
  • Currently, the data for 1 year is provided in the file gagan_iwv_v1.txt

MetaData

Sr. No Core Metadata Elements Definition
1 Metadata language English
2 Metadata Contact MOSDAC
3 Metadata date November, 2017
4 Data Lineage or Quality GPS-derived Integrated Water Vapor.
5 Title GPS-derived Integrated Water Vapor (Indian region)
6 Abstract This dataset contains Integrated Water Vapor (IWV) estimates derived from GPS receivers that comprise the GAGAN TEC network. These receivers have been installed at airports at various locations in India. The Zenith Tropospheric Delay was estimated from the GPS observations using the GAMIT software. Further, IWV was estimated from the ZTD values using surface temperature and pressure from ERA-I reanalysis as additional inputs. The GAGAN-IWV estimates for 1 year – March 2013 to February 2014 – have currently been made available.
7 Dataset Contact Kaushik Gopalan, GRD/AOSG/EPSA, Space Applications Centre (ISRO), Ahmedabad, 380015, kaushikg@sac.isro.gov.in
8 Update Frequency 1 year of GPS-derived IWV is now available. Further data will be added intermittently in caches of 1 year each.
9 Access Rights or Restriction Open Access
10 Spatial Resolution Point data
11 Language English
12 Topic Category GNSS meteorology
13 Keywords GNSS meteorology, GPS meteorology, Integrated Water Vapor
14 Date or period March 2013 to February 2014
15 Responsible Party Kaushik Gopalan,GRD/AOGG/ EPSA, Space Applications Centre (ISRO), Ahmedabad-380015, India
16 Organization Space Applications Centre (ISRO), Ahmedabad, India
16a Org. role Geophysical parameters from satellite altimeter in the coastal region.
16b Individual name Kaushik Gopalan, GRD/AOSG/EPSA, SAC (ISRO), Ahmedabad-380015, India. Ph: +91 79 2691 6110. Email: kaushikg@sac.isro.gov.in
16c Position Scientist/Engineer, GRD/AOSG/EPSA, SAC (ISRO), Ahmedabad-380015
16d Vertical Extent (minimumValue, maximumValue, unitOfMeasure, vertical datum) NA
17 Geographic Extent Indian Landmass
18 Geographic name, geographic Identifier Indian Landmass
19 Bounding box lat_min: 0N, lat_max: 30N, lon_min: 60E, lon_max: 100E
20 Temporal Extent March 2013 to February 2014
21 Access Rights or Restrictions Open Access
22 Distribution Information Online download of data files in ASCII format
23 Processing Level Level 2 (Data product derived from raw GPS data)
24 Reference System Datum: WGS84