Refine your search
Collections
Co-Authors
Journals
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z All
Johny, C. J.
- Impact of Assimilation of Megha-Tropiques ROSA Radio Occultation Refractivity by Observing System Simulation Experiment
Abstract Views :189 |
PDF Views:85
Authors
C. J. Johny
1,
V. S. Prasad
1
Affiliations
1 National Centre for Medium Range Weather Forecasting, Noida 201 309, IN
1 National Centre for Medium Range Weather Forecasting, Noida 201 309, IN
Source
Current Science, Vol 106, No 9 (2014), Pagination: 1297-1305Abstract
Numerical weather prediction models are assimilating more Global Positioning System Radio Occultation (GPSRO) observations into their operational model in recent times as a result of significant positive impact with use of GPSRO data in assimilation system. The Megha-Tropiques satellite mission is aimed to provide large number of observations over the tropical region and carries payload ROSA for providing GPSRO observations. At present, the quality of processed GPSRO retrievals from Megha-Tropiques ROSA is not satisfactory. In order to assess the impact of assimilation of good-quality ROSA observations, an observing system simulation system experiment (OSSE) was conducted using NCMRWF T574 model. The experiment was conducted for a period of 15 days during September 2012 and refractivity operator was used for assimilation. Results show significant improvement in forecast skill for forecasts beyond 72 h with OSSE data.Keywords
Assimilation System, Forecast Skill, Numerical Models, Weather Prediction.Full Text
- Global Retrospective Analysis Using NGFS for the Period 2000-2011
Abstract Views :217 |
PDF Views:86
Authors
Affiliations
1 National Centre for Medium Range Weather Forecasting, A-50 Secto-62, Institutional Area, Noida 201 309, IN
1 National Centre for Medium Range Weather Forecasting, A-50 Secto-62, Institutional Area, Noida 201 309, IN
Source
Current Science, Vol 112, No 02 (2017), Pagination: 370-377Abstract
The National Centre for Medium Range Weather Forecasting (NCMRWF) conducted its first global data retrospective analysis (reanalysis) for the period 1 January 2000-31 March 2011 using its GFS based system (NGFS). This reanalysis is called NGFS-R and the main objectives of this effort are to address issues for studying decadal variability of the Indian summer monsoon, high-resolution global analysis fields to study the Indian monsoon and to provide short-term mean fields for its seasonal/long-term forecasts by ensemble methods. NGFS-R has been conducted with the T574L64 version of the Global Data Assimilation and Forecasting System of NCMRWF that is operational as of May 2015, and using CFS-reanalysis data dump. With this effort, a high-resolution global data analysis at 6 h intervals is made available for about 16 years (2000-2015) for various uses and applications.Keywords
Global Data Assimilation and Forecasting, Monsoon Season, Numerical Weather Prediction Models, Retrospective Analysis.Full Text
- Quality and Impact of GPSRO Observations from Megha-Tropique Satellite on NGFS Model
Abstract Views :262 |
PDF Views:77
Authors
C. J. Johny
1,
V. S. Prasad
1
Affiliations
1 National Centre for Medium Range Weather Forecasting, Ministry of Earth Sciences, A-50, Sector-62, Noida 201 309, IN
1 National Centre for Medium Range Weather Forecasting, Ministry of Earth Sciences, A-50, Sector-62, Noida 201 309, IN
Source
Current Science, Vol 114, No 05 (2018), Pagination: 1083-1088Abstract
Megha-Tropique satellite mission launched in 2011 was aimed at providing more observations in the tropical region. In the initial phase of the mission, it was found that the quality of global positioning system radio occultation (GPSRO) observations was not satisfactory. The Indian Space Research Organisation (ISRO) took remedial measures in this regard by modifying the data processing algorithm and releasing the new version of data. In 2012, an observing system simulation experiment (OSSE) was done at National Centre for Medium Range Weather Forecasting (NCMRWF) using simulated data at Megha- Tropiques ROSA observation location with Global Forecast System (GFS) based model. As an extension of the previous study, the quality of new version of GPSRO bending angle observations and impact of assimilation of these observations in NCMRWF GFS (NGFS) model were studied. It was found that with the use of a new data processing algorithm, quality of bending angle observations improved and comparable with other GPSRO missions in the pressure range between 500 hpa and 200 hpa. Impact study shows that the new observations improved forecasts in the middle and upper levels in the tropics.Keywords
Assimilation, Bending Angle, GPSRO, Megha-Tropiques, NGFS.Full Text
References
- Gettelman, A. and Birner, T., Insights into tropical tropopause layer processes using global models. J. Geophys. Res., 2007, 112, D23104.
- Huang, C. Y., Kuo, Y. H., Chen, S. Y., Rao, A. S. K. A. V. P. and Wang, C. J., The assimilation of GPS radio occultation data and its impact on rainfall prediction along the west coast of India during monsoon 2002. Pure Appl. Geophys., 2007, 164(8), 1577–1591.
- Jakowsk, N., Wilken, V. and Mayer, C., Space weather monitoring by GPS measurements on board CHAMP. Space Weather, 2007, 5, S08006.
- Schmidt, T., de la Torre, A. and Wickert, J., Global gravity wave activity in the tropopause region from CHAMP radio occultation data. Geophys. Res. Lett., 2008, 35, L16807.
- Wickert, J. et al., GPS radio occultation: results from CHAMP, GRACE and FORMOSAT-3/COSMIC. Terr. Atmos. Ocean. Sci., 2009, 20(1), 35–50.
- Pavelyev, A. G., Liou, Y. A., Wickert, J., Pavelyev, A. A. and Igarashi, K., New applications and advances of the GPS radio occultation technology as recovered by analysis of the FORMOSAT3/COSMIC and CHAMP database. In New Horizons in Occultation Research – Studies in Atmosphere and Climate (eds Steiner, A. et al.), Springer Berlin Heidelberg, 2009, pp. 163–176.
- Jin, S., Occhipinti, G. and Jin, R., GNSS ionospheric seismology: recent observation evidences and characteristics. Earth Sci. Rev., 2015, 147, 54–64.
- Steiner, A. K. et al., Quantification of structural uncertainty in climate data records from GPS radio occultation. Atmos. Chem. Phys. Discuss., 2013, 12, 26963–26994.
- Harnisch, F., Healy, S. B., Bauer, P. and English, S. J., Scaling of GNSS radio occultation impact with observation number using an ensemble of data assimilations. Mon. Weather Rev., 2013, 141, 4395–4413; doi:10.1029/2008GL035873.
- Healy, S. B. and Thepaut, J. N., Assimilation experiments with CHAMP GPS radio occultation measurements. Q. J. R. Meteorol. Soc., 2006, 132, 605–623.
- Aparicio, J. and Deblonde, G., Impact of the assimilation of CHAMP refractivity profiles in environment Canada global forecasts. Mon. Weather Rev., 2008, 136, 257–275.
- Poli, P., Healy, S., Rabier, F. and Pailleux, J., Preliminary assessment of the scalability of GPS radio occultations impact in numerical weather prediction. Geophys. Res. Lett., 2008, 35(23), L23 811.
- Cucurull, L., Improvement in the use of an operational constellation of GPS radio occultation receivers in weather forecasting. Weather Forecast., 2010, 25, 749–767.
- Cucurull, L., Kuo, Y. H., Barker, D. and Rizvi, S. R. H., Assessing the impact of simulated COSMIC GPS radio occultation data on weather analysis over the Antarctic: A case study. Mon. Weather Rev., 2006, 134, 3283–3296.
- Auligne, T., McNally, A. and Dee, D., Adaptive bias correction for satellite data in a numerical weather prediction system. Q. J. R. Meteorol. Soc., 2007, 133, 631–642.
- Cardinali, C. and Healy, S., Impact of GPS radio occultation measurements in the ECMWF system using adjoint-based diagnostics. Q. J. R. Meteorol. Soc., 2014, 140, 2315–2320.
- Cucurull, L. and Derber, J. C., Operational implementation of COSMIC observations into NCEP’s global data assimilation system. Weather Forecast., 2007, 23, 702–711.
- Johny, C. J. and Prasad, V. S., Impact of assimilation of MeghaTropiques ROSA radio occultation refractivity by observing system simulation experiment. Curr. Sci., 2014, 106(9), 1297–1305.
- Sokolovskiy, S., Effect of super-refraction on inversions of radio occultation signals in the lower troposphere. Radio Sci., 2003, 38, 1058; doi:10.1029/2002ES002728.
- Cucurull, L., Derber, J. C. and Purser, R. J., A bending angle forward operator for global positioning system radio occultation measurements. J. Geophys. Res. Atmos., 2013, 118, 14–28; 2012JD017782.
- Prasad, V. S., Saji, M., Gupta, M. D., Rajagopal, E. N. and Dutta, S. K., Implementation of upgraded global forecasting systems (T382L64 and T574L64) at NCMRWF. Technical Report. 2011, NCMR/TR/5/2011.
- Hu, M., Shao, H., Stark, D. and Newman, K., Gridpoint Statistical Interpolation (GSI; Version 3.3 User’s Guide). Developmental Testbed Centre, NCAR, NOAA, USA, 2014; http://www.dtcenter.org/com-GSI/users/index.php