Computations of the tropospheric radiation budget in the Caribbean and Gulf of Mexico area for clear sky conditions

The regional climate model RegCM version 4.6, developed by the European Centre for Medium-Range Weather Forecasts Reanalysis, was used to simulate the radiation budget over China. Clouds and the Earth’s Radiant Energy System (CERES) satellite data were utilized to evaluate the simulation results based on 4 radiative components: net shortwave (NSW) radiation at the surface of the earth and top of the atmosphere (TOA) under all-sky and clear-sky conditions. The performance of the model for low-value areas of NSW was superior to that for high-value areas. NSW at the surface and TOA under all-sky conditions was significantly underestimated; the spatial distribution of the bias was negative in the north and positive in the south, bounded by 25°N for the annual and seasonal averaged difference maps. Compared with the all-sky condition, the simulation effect under clear-sky conditions was significantly better, which indicates that the cloud fraction is the key factor affecting the accuracy of the simulation. In particular, the bias of the TOA NSW under the clear-sky condition was <±10 W m-2 in the eastern areas. The performance of the model was better over the eastern monsoon region in winter and autumn for surface NSW under clear-sky conditions, which may be related to different levels of air pollution during each season. Among the 3 areas, the regional average biases overall were largest (negative) over the Qinghai-Tibet alpine region and smallest over the eastern monsoon region.

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Downward longwave radiation estimates for clear-sky conditions over northeast Brazil

Revista Brasileira de Meteorologia ◽

10.1590/s0102-77862011000300010 ◽

2011 ◽

Vol 26 (3) ◽

pp. 443-450 ◽

Cited By ~ 14

Author(s):

Carlos Antonio Costa dos Santos ◽

Bernardo Barbosa da Silva ◽

Tantravahi Venkata Ramana Rao ◽

Prakki Satyamurty ◽

Antonio Ocimar Manzi

Keyword(s):

Arid Regions ◽

Longwave Radiation ◽

Radiation Budget ◽

Semiarid Region ◽

Northeast Brazil ◽

Hydrological Models ◽

Experimental Site ◽

Clear Sky ◽

Downward Longwave Radiation ◽

Sky Conditions

The main objective of this paper is to assess the performance of nine downward longwave radiation equations for clear-sky condition and develop a locally adjusted equation using the observed vapor pressure and air temperature data. The radiation and atmospheric parameters were measured during the months of October 2005 to June 2006 at a micrometeorological tower installed at the experimental site in a banana orchard in the semiarid region of Northeast Brazil. The comparative statistics for the performance of the downward longwave radiation calculation models during daytime and nighttime compared to measured data have shown that the parameterizations with more physical foundations have the best results. The locally adjusted equation and Sugita and Brutsaert model developed in 1993 showed errors less than 1.0% in comparison with measured values. Downward longwave radiation is one of the most expensive and difficult component of the radiation budget to be monitored in micrometeorological studies. Hence, the locally adjusted equation can be used to estimate downward longwave energy, needed as input to some agricultural and hydrological models, in semi-arid regions of the Northeast Brazil, where this component is not monitored.

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Estimation of Daily Mean Photosynthetically Active Radiation under All-Sky Conditions Based on Relative Sunshine Data

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-10-05018.1 ◽

2012 ◽

Vol 51 (1) ◽

pp. 150-160 ◽

Cited By ~ 22

Author(s):

Jun Qin ◽

Kun Yang ◽

Shunlin Liang ◽

Wenjun Tang

Keyword(s):

Photosynthetically Active Radiation ◽

Sunshine Duration ◽

Surface Radiation ◽

Radiation Budget ◽

Mean Bias Error ◽

Bias Error ◽

Active Radiation ◽

Clear Sky ◽

Surface Radiation Budget ◽

Sky Conditions

AbstractPhotosynthetically active radiation (PAR) is absorbed by plants to carry out photosynthesis. Its estimation is important for many applications such as ecological modeling. In this study, a broadband transmittance scheme for solar radiation at the PAR band is developed to estimate clear-sky PAR values. The influence of clouds is subsequently taken into account through sunshine-duration data. This scheme is examined without local calibration against the observed PAR values under both clear- and cloudy-sky conditions at seven widely distributed Surface Radiation Budget Network (SURFRAD) stations. The results indicate that the scheme can estimate the daily mean PAR at these seven stations under all-sky conditions with root-mean-square error and mean bias error values ranging from 6.03 to 6.83 W m−2 and from −2.86 to 1.03 W m−2, respectively. Further analyses indicate that the scheme can estimate PAR values well with globally available aerosol and ozone datasets. This suggests that the scheme can be applied to regions for which observed aerosol and ozone data are not available.

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Climatic features of the Mediterranean Sea detected by the analysis of the longwave radiative bulk formulae

Annales Geophysicae ◽

10.1007/s00585-000-1482-z ◽

2000 ◽

Vol 18 (11) ◽

pp. 1482-1487 ◽

Cited By ~ 4

Author(s):

M. E. Schiano ◽

M. Borghini ◽

S. Castellari ◽

C. Luttazzi

Keyword(s):

Mediterranean Sea ◽

Longwave Radiation ◽

Radiation Budget ◽

Clear Sky ◽

Radiative Processes ◽

Direct Measurements ◽

Climatic Regime ◽

The Mediterranean ◽

Sky Conditions ◽

Climatic Features

Abstract. Some important climatic features of the Mediterranean Sea stand out from an analysis of the systematic discrepancies between direct measurements of longwave radiation budget and predictions obtained by the most widely used bulk formulae. In particular, under clear-sky conditions the results show that the surface values of both air temperature and humidity over the Mediterranean Sea are larger than those expected over an open ocean with the same amount of net longwave radiation. Furthermore, the twofold climatic regime of the Mediterranean region strongly affects the downwelling clear-sky radiation. This study suggests that a single bulk formula with constant numerical coefficients is unable to reproduce the fluxes at the surface for all the seasons.Key words: Meteorology and Atmospheric dynamics (radiative processes) – Oceanography: general (marginal and semienclosed seas; marine meteorology)

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Efficient downscaling of satellite oceanographic data with convolutional neural networks

SIGSPATIAL Special ◽

10.1145/3447994.3448011 ◽

2021 ◽

Vol 12 (3) ◽

pp. 46-47

Author(s):

Nikita Saxena

Keyword(s):

Neural Networks ◽

Deep Learning ◽

Convolutional Neural Networks ◽

Super Resolution ◽

Sea Surface ◽

Clear Sky ◽

Oceanographic Data ◽

Computationally Expensive ◽

Sky Conditions ◽

Data Inference

Space-borne satellite radiometers measure Sea Surface Temperature (SST), which is pivotal to studies of air-sea interactions and ocean features. Under clear sky conditions, high resolution measurements are obtainable. But under cloudy conditions, data analysis is constrained to the available low resolution measurements. We assess the efficiency of Deep Learning (DL) architectures, particularly Convolutional Neural Networks (CNN) to downscale oceanographic data from low spatial resolution (SR) to high SR. With a focus on SST Fields of Bay of Bengal, this study proves that Very Deep Super Resolution CNN can successfully reconstruct SST observations from 15 km SR to 5km SR, and 5km SR to 1km SR. This outcome calls attention to the significance of DL models explicitly trained for the reconstruction of high SR SST fields by using low SR data. Inference on DL models can act as a substitute to the existing computationally expensive downscaling technique: Dynamical Downsampling. The complete code is available on this Github Repository.

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Geolocators reveal migration routes, stopover sites, and nonbreeding dispersion in a population of Cerulean Warblers

Animal Migration ◽

10.1515/ami-2020-0003 ◽

2020 ◽

Vol 7 (1) ◽

pp. 19-26

Author(s):

Clayton D Delancey ◽

Kamal Islam ◽

Gunnar R Kramer ◽

Garrett J MacDonald ◽

Alexander R Sharp ◽

...

Keyword(s):

Gulf Of Mexico ◽

Spring Migration ◽

Autumn Migration ◽

Migration Routes ◽

Neotropical Migrant ◽

Wood Warblers ◽

Before And After ◽

The Caribbean ◽

Declining Species ◽

Cerulean Warblers

AbstractCerulean Warblers (Setophaga cerulea) are among the fastest declining Nearctic-Neotropical migrant wood-warblers (Parulidae) in North America. Despite ongoing conservation efforts, little is known about their non-breeding distribution. In June 2016-2018, we deployed geolocators (n = 30) on adult male Cerulean Warblers in Indiana, USA, to track annual movements of individuals. Recovered geolocators (n = 4) showed that Cerulean Warblers occurred broadly throughout northern South America. Autumn migration lasted 44-71 days (n = 4), whereas spring migration lasted 37-41 days (n = 3). The average migration distance was 5268 km. During autumn migration, Cerulean Warblers made 1-4 stopovers (i.e., ≥2 days; n = 4) and 1-2 stopovers during spring migration (n = 3). When crossing the Gulf of Mexico during autumn migration, two birds stopped over after crossing, but not beforehand. Two others navigated through the Caribbean rather than crossing the Gulf of Mexico. During spring migration, one individual stopped after crossing, one individual stopped before crossing, and one individual stopped before and after crossing the Gulf of Mexico. No birds migrated through the Caribbean Islands during spring migration. These results represent novel information describing annual movements of individual Cerulean Warblers and will inform conservation efforts for this declining species.

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Nocturnal convective cloud formation under clear-sky conditions at the eastern Andes of south Ecuador

Journal of Geophysical Research Atmospheres ◽

10.1029/2010jd014146 ◽

2010 ◽

Vol 115 (D24) ◽

Cited By ~ 11

Author(s):

K. Trachte ◽

R. Rollenbeck ◽

J. Bendix

Keyword(s):

Convective Cloud ◽

Cloud Formation ◽

Clear Sky ◽

Sky Conditions

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Nonlinear analysis of the occurrence of hurricanes in the Gulf of Mexico and the Caribbean Sea

Nonlinear Processes in Geophysics ◽

10.5194/npg-25-291-2018 ◽

2018 ◽

Vol 25 (2) ◽

pp. 291-300 ◽

Cited By ~ 1

Author(s):

Berenice Rojo-Garibaldi ◽

David Alberto Salas-de-León ◽

María Adela Monreal-Gómez ◽

Norma Leticia Sánchez-Santillán ◽

David Salas-Monreal

Keyword(s):

Time Series ◽

Gulf Of Mexico ◽

Nonlinear Analysis ◽

Chaotic Behavior ◽

Caribbean Sea ◽

Historical Record ◽

Nonlinear Analyses ◽

The North ◽

The Caribbean ◽

The Individual

Abstract. Hurricanes are complex systems that carry large amounts of energy. Their impact often produces natural disasters involving the loss of human lives and materials, such as infrastructure, valued at billions of US dollars. However, not everything about hurricanes is negative, as hurricanes are the main source of rainwater for the regions where they develop. This study shows a nonlinear analysis of the time series of the occurrence of hurricanes in the Gulf of Mexico and the Caribbean Sea obtained from 1749 to 2012. The construction of the hurricane time series was carried out based on the hurricane database of the North Atlantic basin hurricane database (HURDAT) and the published historical information. The hurricane time series provides a unique historical record on information about ocean–atmosphere interactions. The Lyapunov exponent indicated that the system presented chaotic dynamics, and the spectral analysis and nonlinear analyses of the time series of the hurricanes showed chaotic edge behavior. One possible explanation for this chaotic edge is the individual chaotic behavior of hurricanes, either by category or individually regardless of their category and their behavior on a regular basis.

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Intra-Day DNI Forecasting Under Clear Sky Conditions Using ANFIS

IFAC Proceedings Volumes ◽

10.3182/20140824-6-za-1003.02087 ◽

2014 ◽

Vol 47 (3) ◽

pp. 10361-10366 ◽

Cited By ~ 2

Author(s):

Rémi Chauvin ◽

Julien Nou ◽

Stéphane Thil ◽

Stéphane Grieu

Keyword(s):

Clear Sky ◽

Sky Conditions

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A Blended Sea Ice Concentration Product from AMSR2 and VIIRS

Remote Sensing ◽

10.3390/rs13152982 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2982

Author(s):

Richard Dworak ◽

Yinghui Liu ◽

Jeffrey Key ◽

Walter N. Meier

Keyword(s):

Sea Ice ◽

Spatial Resolution ◽

Infrared Imaging ◽

High Spatial Resolution ◽

Sea Ice Concentration ◽

Clear Sky ◽

Ice Concentration ◽

Best Linear Unbiased ◽

The Individual ◽

Sky Conditions

An effective blended Sea-Ice Concentration (SIC) product has been developed that utilizes ice concentrations from passive microwave and visible/infrared satellite instruments, specifically the Advanced Microwave Scanning Radiometer-2 (AMSR2) and the Visible Infrared Imaging Radiometer Suite (VIIRS). The blending takes advantage of the all-sky capability of the AMSR2 sensor and the high spatial resolution of VIIRS, though it utilizes only the clear sky characteristics of VIIRS. After both VIIRS and AMSR2 images are remapped to a 1 km EASE-Grid version 2, a Best Linear Unbiased Estimator (BLUE) method is used to combine the AMSR2 and VIIRS SIC for a blended product at 1 km resolution under clear-sky conditions. Under cloudy-sky conditions the AMSR2 SIC with bias correction is used. For validation, high spatial resolution Landsat data are collocated with VIIRS and AMSR2 from 1 February 2017 to 31 October 2019. Bias, standard deviation, and root mean squared errors are calculated for the SICs of VIIRS, AMSR2, and the blended field. The blended SIC outperforms the individual VIIRS and AMSR2 SICs. The higher spatial resolution VIIRS data provide beneficial information to improve upon AMSR2 SIC under clear-sky conditions, especially during the summer melt season, as the AMSR2 SIC has a consistent negative bias near and above the melting point.

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