IEEE Geoscience and Remote Sensing Magazine - June 2022 - 56

maxima are observed, and, before transplanting, dual minima
are seen. Moreover, the coefficient of determination is
observed as 95% for the rice yield prediction for all selected
states. The correlation coefficient is observed as 0.95, with an
RMSE equal to 0.28.
META-ANALYSIS
To analyze the research status of the scatterometer, a search
of abstracts was performed on the Scopus database using
related terms, such as 1) Seasat, 2) ESCAT, 3) ASCAT,
4) NSCAT, 5) QuikSCAT " AND " SeaWinds, 6) SeaWinds
" AND " ADEOS, 7) OSCAT, 8) HY-2A " OR " HY-2B " OR "
HY-2C " OR " HY-2D, 9) RapidSCAT, 10) SCATSAT, and 11)
CFOSAT. It is noted that, to avoid multiple entries, different
versions of ASCAT were classified into one class, and the
same procedure was followed in the HY-2 series. All of these
terms were cross-verified with respect to their relevance to
scatterometer applications, and irrelevant publications were
eliminated. Moreover, the Scopus-indexed publications
from conferences, book chapters, and journals were considered.
The final prepared database was divided into four
categories with respect to the concerned organization, i.e.,
100
150
200
50
(a)
20
40
60
80
(b)
10
20
30
40
(c)
OSCAT
SCATSAT-1
20
40
60
(d)
FIGURE 7. A stacked bar graph of publications of different versions of scatterometers developed by different agencies: (a) NASA (Seasat,
NSCAT, QuikSCAT, SeaWinds, and RapidSCAT), (b) the ESA (the ESCAT and ASCAT series), (c) the ISRO (OSCAT and SCATSAT-1), and (d) the
CNSA/CNES (the HY-2 series and CFOSAT).
56
IEEE GEOSCIENCE AND REMOTE SENSING MAGAZINE JUNE 2022
HY-2 Series
CFOSAT
ESCAT ASCAT
1) NASA (Seasat, NSCAT, QuikSCAT, SeaWinds, and RapidSCAT),
2) the ESA (the ESCAT and ASCAT series), (c) the
ISRO (OSCAT and SCATSAT-1), and (d) CNSA/CNES (HY-2
series/CFOSAT), as shown in Figure 7. The main purpose
of performing this analysis was to reveal quantitatively the
research status of scatterometers for different applications,
such as oceanography, the cryosphere, and agriculture (including
soil moisture and hydrology).
With the launch of SASS as a proof-of-concept experiment,
numerous research and development activities
have been conducted to explore the potential of scatterometer
ocean circulation models, air-sea flux studies,
numerical weather forecasting, and many varied applications
for at least two decades [3]. With the launch of
the ESA's C-band-based and NASA's Ku-band-based scatterometers,
various land cover applications, such as soil
moisture estimation [200], vegetation monitoring [201],
flood detection [19], snow cover monitoring [8], and sea
ice estimation [133], have also been explored other than
oceanography. The application range is further enhanced
by the ISRO's scatterometers in rice crop monitoring [16],
LAI estimation [30], and jute crop monitoring [7]. The
Seasat NSCAT QuikSCAT SeaWinds RapidSCAT
Number of Publications
Number of Publications
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
Number of Publications
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
Number of Publications
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
IEEE Geoscience and Remote Sensing Magazine - June 2022

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