@Article{EberhardtSRSFAMITFL:2016:ClCoAs,
author = "Eberhardt, Isaque Daniel Rocha and Schultz, Bruno and Rizzi,
Rodrigo and Sanches, Ieda Del'Arco and Formaggio, Antonio Roberto
and Atzberger, Clement and Mello, Marcio Pupin and Immitzer,
Markus and Trabaquini, Kleber and Foschiera, William and Luiz,
Alfredo Jos{\'e} Barreto",
affiliation = "{Universidade de Bras{\'{\i}}lia (UNB)} and {Instituto Nacional
de Pesquisas Espaciais (INPE)} and {Universidade Federal de
Pelotas (UFPel)} and {Instituto Nacional de Pesquisas Espaciais
(INPE)} and {Instituto Nacional de Pesquisas Espaciais (INPE)} and
{University of Natural Resources and Life Sciences} and {The
Boeing Company} and {University of Natural Resources and Life
Sciences} and {Agricultural Research and Rural Extension Company
of Santa Catarina (Epagri)} and {Instituto Nacional de Pesquisas
Espaciais (INPE)} and {Embrapa Meio Ambiente}",
title = "Cloud cover assessment for operational crop monitoring systems in
tropical areas",
journal = "Remote Sensing",
year = "2016",
volume = "8",
number = "3",
pages = "219",
keywords = "Agriculture monitoring, Clear sky coverage, Crop classification,
MODIS.",
abstract = "The potential of optical remote sensing data to identify, map and
monitor croplands is well recognized. However, clouds strongly
limit the usefulness of optical imagery for these applications.
This paper aims at assessing cloud cover conditions over four
states in the tropical and sub-tropical Center-South region of
Brazil to guide the development of an appropriate agricultural
monitoring system based on Landsat-like imagery. Cloudiness was
assessed during overlapping four months periods to match the
typical length of crop cycles in the study area. The percentage of
clear sky occurrence was computed from the 1 km resolution MODIS
Cloud Mask product (MOD35) considering 14 years of data between
July 2000 and June 2014. Results showed high seasonality of cloud
occurrence within the crop year with strong variations across the
study area. The maximum seasonality was observed for the two
states in the northern part of the study area (i.e., the ones
closer to the Equator line), which also presented the lowest
averaged values (15%) of clear sky occurrence during the main
(summer) cropping period (November to February). In these
locations, optical data faces severe constraints for mapping
summer crops. On the other hand, relatively favorable conditions
were found in the southern part of the study region. In the South,
clear sky values of around 45% were found and no significant clear
sky seasonality was observed. Results underpin the challenges to
implement an operational crop monitoring system based solely on
optical remote sensing imagery in tropical and sub-tropical
regions, in particular if short-cycle crops have to be monitored
during the cloudy summer months. To cope with cloudiness issues,
we recommend the use of new systems with higher repetition rates
such as Sentinel-2. For local studies, Unmanned Aircraft Vehicles
(UAVs) might be used to augment the observing capability.
Multi-sensor approaches combining optical and microwave data can
be another option. In cases where wall-to-wall maps are not
mandatory, statistical sampling approaches might also be a
suitable alternative for obtaining useful crop area information.",
doi = "10.3390/rs8030219",
url = "http://dx.doi.org/10.3390/rs8030219",
issn = "2072-4292",
language = "en",
targetfile = "eberhardt_cloud.pdf",
urlaccessdate = "27 abr. 2024"
}