Statistical Characterization of Zonal and Meridional Ocean Wind Stress

Abstract Four years of ocean vector wind data are used to evaluate statistics of wind stress over the ocean. Raw swath wind stresses derived from the Quick Scatterometer (QuikSCAT) are compared with five different global gridded wind products, including products based on scatterometer observations, meteorological analysis winds from the European Centre for Medium-Range Weather Forecasts, and reanalysis winds from the National Centers for Environmental Prediction. Buoy winds from a limited number of sites in the Pacific Ocean are also considered. Probability density functions (PDFs) computed for latitudinal bands show that mean wind stresses for the six global products are largely in agreement, while variances differ substantially, by a factor of 2 or more, with swath wind stresses indicating highest variances for meridional winds and for zonal winds outside the Tropics. Higher moments of the PDFs also differ. Kurtoses are large for all wind products, implying that PDFs are not Gaussian. None of the available gridded products fully captures the range of extreme wind events seen in the raw swath data. Frequency spectra for the five gridded products agree with frequency spectra from swath data at low frequencies, but spectral slopes differ at higher frequencies, particularly for frequencies greater than 100 cycles per year (cpy), which are poorly resolved by a single scatterometer. In the frequency range between 10 and 90 cpy that is resolved by the scatterometer, spectra derived from swath data are flatter than spectra from gridded products and are judged to be flatter than ω−2/3 at all latitudes.

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Validation of the Aura High Resolution Dynamics Limb Sounder geopotential heights

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-7-1001-2014 ◽

2014 ◽

Vol 7 (2) ◽

pp. 1001-1025

Author(s):

L. L. Smith ◽

J. C. Gille

Keyword(s):

High Resolution ◽

System Model ◽

Weather Forecasts ◽

Atmospheric Research ◽

Earth Observing System ◽

Medium Range ◽

High Bias ◽

Environmental Prediction ◽

The Tropics ◽

Data Screening

Abstract. Global satellite observations from the EOS Aura spacecraft's High Resolution Dynamics Limb Sounder (HIRDLS) of temperature and geopotential height (GPH) are discussed. The accuracy, resolution and precision of the HIRDLS version 7 algorithms are assessed and data screening recommendations are made. Comparisons with GPH from observations, reanalyses and models including European Center for Medium-Range Weather Forecasts Interim Reanalysis (ERA-Interim), National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis, Goddard Earth Observing System Model (GEOS) version 5, and EOS Aura Microwave Limb Sounder (MLS) illustrate the HIRDLS GPH have a precision ranging from 2 m to 30 m and an accuracy of ±100 m. Comparisons indicate HIRDLS GPH may have a slight low bias in the tropics and a slight high bias at high latitudes. Geostrophic winds computed with HIRDLS GPH qualitatively agree with winds from other data sources including ERA-Interim, NCEP and GEOS-5.

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Validation of the Aura High Resolution Dynamics Limb Sounder geopotential heights

Atmospheric Measurement Techniques ◽

10.5194/amt-7-2775-2014 ◽

2014 ◽

Vol 7 (8) ◽

pp. 2775-2785 ◽

Cited By ~ 1

Author(s):

L. L. Smith ◽

J. C. Gille

Keyword(s):

High Resolution ◽

High Latitudes ◽

Weather Forecasts ◽

Atmospheric Research ◽

Earth Observing System ◽

Medium Range ◽

High Bias ◽

Environmental Prediction ◽

The Tropics ◽

Data Screening

Abstract. The geopotential height (GPH) product created from global observations by the High Resolution Dynamics Limb Sounder (HIRDLS) instrument on NASA's Earth Observing System (EOS) Aura spacecraft is discussed. The accuracy, resolution and precision of the HIRDLS version 7 algorithms are assessed and data screening recommendations are made. Comparisons with GPH from observations, reanalyses and models including European Centre for Medium-Range Weather Forecasts Interim Reanalysis (ERA-Interim), and National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis illustrate the HIRDLS GPHs have a precision ranging from 2 to 30 m and an accuracy of ±100 m up to 1 hPa. Comparisons indicate HIRDLS GPH may have a slight low bias in the tropics and a slight high bias at high latitudes. Geostrophic winds computed with HIRDLS GPH qualitatively agree with winds from other data sources including ERA-Interim.

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Measurements of Directional Wave Spectra and Wind Stress from a Wave Glider Autonomous Surface Vehicle

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-17-0091.1 ◽

2018 ◽

Vol 35 (2) ◽

pp. 347-363 ◽

Cited By ~ 17

Author(s):

Jim Thomson ◽

James B. Girton ◽

Rajesh Jha ◽

Andrew Trapani

Keyword(s):

Wind Stress ◽

Reference Data ◽

Full Range ◽

Bulk Wave ◽

Frequency Spectra ◽

Low Frequencies ◽

Wind Speeds ◽

Autonomous Surface Vehicle ◽

Ultrasonic Anemometer ◽

Wave Glider

AbstractMethods for measuring waves and winds from a Wave Glider autonomous surface vehicle (ASV) are described and evaluated. The wave method utilizes the frequency spectra of orbital velocities measured by GPS, and the wind stress method utilizes the frequency spectra of turbulent wind fluctuations measured by an ultrasonic anemometer. Both methods evaluate contaminations from vehicle motion. The methods were evaluated with 68 days of data over a full range of open ocean conditions, in which wave heights varied from 1 to 8 m and wind speeds varied from 1 to 17 m s−1. Reference data were collected using additional sensors on board the vehicle. For the waves method, several additional datasets are included that use independently moored Datawell Waverider buoys as reference data. Bulk wave parameters are determined within 5% error with biases of less than 5%. Wind stress is determined within 4% error with 1% bias. Wave directional spectra also compare well, although the Wave Glider results have more spread at low frequencies.

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Subseasonal midlatitude prediction skill following Quasi-Biennial Oscillation and Madden–Julian Oscillation activity

Weather and Climate Dynamics ◽

10.5194/wcd-1-247-2020 ◽

2020 ◽

Vol 1 (1) ◽

pp. 247-259

Author(s):

Kirsten J. Mayer ◽

Elizabeth A. Barnes

Keyword(s):

Northern Hemisphere ◽

Rossby Waves ◽

Prediction Skill ◽

Lead Times ◽

Madden Julian Oscillation ◽

Quasi Biennial Oscillation ◽

Weather Forecasts ◽

The Pacific ◽

Environmental Prediction ◽

Biennial Oscillation

Abstract. The Madden–Julian Oscillation (MJO) is known to force extratropical weather days to weeks following an MJO event through excitation of stationary Rossby waves, also referred to as tropical–extratropical teleconnections. Prior research has demonstrated that this tropically forced midlatitude response leads to increased prediction skill on subseasonal to seasonal (S2S) timescales. Furthermore, the Quasi-Biennial Oscillation (QBO) has been shown to possibly alter these teleconnections through modulation of the MJO itself and the atmospheric basic state upon which the Rossby waves propagate. This implies that the MJO–QBO relationship may affect midlatitude circulation prediction skill on S2S timescales. In this study, we quantify midlatitude circulation sensitivity and prediction skill following active MJOs and QBOs across the Northern Hemisphere on S2S timescales through an examination of the 500 hPa geopotential height field. First, a comparison of the spatial distribution of Northern Hemisphere sensitivity to the MJO during different QBO phases is performed for European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim reanalysis and ECMWF and the National Centers for Environmental Prediction (NCEP) hindcasts. Secondly, differences in prediction skill in ECMWF and NCEP hindcasts are quantified following MJO–QBO activity. In both hindcast systems, we find that regions across the Pacific, North America, and the Atlantic demonstrate an enhanced MJO impact on prediction skill during strong QBO periods with lead times of 1–4 weeks compared to MJO events during neutral QBO periods.

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Variance of the Equatorial Atmospheric Circulations in the Reanalysis

Journal of Marine Science and Engineering ◽

10.3390/jmse9121386 ◽

2021 ◽

Vol 9 (12) ◽

pp. 1386

Author(s):

Emmanuel OlaOluwa Eresanya ◽

Yuping Guan

Keyword(s):

Global Climate ◽

Coupled Model ◽

Department Of Energy ◽

Atmospheric Circulations ◽

Fifth Generation ◽

The Pacific ◽

Ensemble Mean ◽

Intercomparison Project ◽

Environmental Prediction ◽

The Tropics

The structure of the equatorial atmospheric circulation, as defined by the zonal mass streamfunction (ZMS), computed using the new fifth-generation ECMWF reanalysis for the global climate and weather (ERA-5) and the National Centers for Environmental Prediction NCEP–US Department of Energy reanalysis (NCEP-2) reanalysis products, is investigated and compared with Coupled Model Intercomparison Project Phase 6 (CMIP 6) ensemble mean. The equatorial atmospheric circulations majorly involve three components: the Indian Ocean cell (IOC), the Pacific Walker cell (POC) and the Atlantic Ocean cell (AOC). The IOC, POC and AOC average monthly or seasonal cycle peaks around March, June and February, respectively. ERA-5 has a higher IOC intensity from February to August, whereas NCEP-2 has a greater IOC intensity from September to December; NCEP-2 indicates greater POC intensity from January to May, whereas ERA-5 shows higher POC intensity from June to October. For the AOC, ERA-5 specifies greater intensity from March to August and NCEP-2 has a higher intensity from September to December. The equatorial atmospheric circulations cells vary in the reanalysis products, the IOC is weak and wider (weaker and smaller) in the ERA-5 (NCEP-2), the POC is more robust and wider (feebler and teensier) in NCEP-2 (ERA-5) and the AOC is weaker and wider (stronger and smaller) in ERA-5 (NCEP-2). ERA-5 revealed a farther westward POC and AOC compared to NCEP-2. In the CMIP 6 model ensemble mean (MME), the equatorial atmospheric circulations mean state indicated generally weaker cells, with the IOC smaller and the POC greater swinging eastward and westward, respectively, while the AOC is more westward. These changes in equatorial circulation correspond to changes in dynamically related heating in the tropics.

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Monthly Climatologies of Oceanic Friction Velocity Cubed

Journal of Climate ◽

10.1175/jcli3863.1 ◽

2006 ◽

Vol 19 (21) ◽

pp. 5700-5708 ◽

Cited By ~ 8

Author(s):

Barry A. Klinger ◽

Bohua Huang ◽

Ben Kirtman ◽

Paul Schopf ◽

Jiande Wang

Keyword(s):

Wind Speed ◽

Wind Stress ◽

Friction Velocity ◽

Turbulent Energy ◽

Data Set ◽

Wind Influence ◽

Satellite Microwave ◽

Environmental Prediction ◽

Satellite Microwave Measurements ◽

The Tropics

Abstract Different measures of wind influence the ocean in different ways. In particular, the time-averaged mixed layer turbulent energy production rate is proportional to 〈u3*〉, where u* is the “oceanic friction velocity” that is based on wind stress. Estimating 〈u3*〉 from monthly averages of wind stress or wind speed may introduce large biases due to the day-to-day variability of the direction and magnitude of the wind. The authors create monthly climatologies of 〈u3*〉 from daily wind stress measurements obtained from the Goddard Satellite-based Surface Turbulent Fluxes version 2 (GSSTF2; based on satellite microwave measurements), the Quick Scatterometer (QuikSCAT; based on satellite scatterometry measurements), and the National Centers for Environmental Prediction (NCEP) reanalysis wind. The differences among zonal averages of these climatologies and of a similar climatology based on the da Silva version of the Comprehensive Ocean–Atmosphere Data Set (COADS) have a complex dependence on latitude. These differences are typically 10%–30% of the climatological values. The GSSTF2 data confirm that 〈u3*〉 is much larger than estimates from monthly averaged wind stress or wind speed, especially outside the Tropics.

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Systematics, Biogeography, and Morphological Character Evolution of the Hemiepiphytic Subfamily Monsteroideae (Araceae)

Annals of the Missouri Botanical Garden ◽

10.3417/2018269 ◽

2019 ◽

Vol 104 (1) ◽

pp. 33-48 ◽

Cited By ~ 4

Author(s):

Alejandro Zuluaga ◽

Martin Llano ◽

Ken Cameron

Keyword(s):

Dna Sequences ◽

Pacific Islands ◽

R Package ◽

Morphological Characters ◽

Ancestral State ◽

Seed Shape ◽

Long Distance ◽

The Pacific ◽

And Migration ◽

The Tropics

The subfamily Monsteroideae (Araceae) is the third richest clade in the family, with ca. 369 described species and ca. 700 estimated. It comprises mostly hemiepiphytic or epiphytic plants restricted to the tropics, with three intercontinental disjunctions. Using a dataset representing all 12 genera in Monsteroideae (126 taxa), and five plastid and two nuclear markers, we studied the systematics and historical biogeography of the group. We found high support for the monophyly of the three major clades (Spathiphylleae sister to Heteropsis Kunth and Rhaphidophora Hassk. clades), and for six of the genera within Monsteroideae. However, we found low rates of variation in the DNA sequences used and a lack of molecular markers suitable for species-level phylogenies in the group. We also performed ancestral state reconstruction of some morphological characters traditionally used for genera delimitation. Only seed shape and size, number of seeds, number of locules, and presence of endosperm showed utility in the classification of genera in Monsteroideae. We estimated ancestral ranges using a dispersal-extinction-cladogenesis model as implemented in the R package BioGeoBEARS and found evidence for a Gondwanan origin of the clade. One tropical disjunction (Monstera Adans. sister to Amydrium Schott–Epipremnum Schott) was found to be the product of a previous Boreotropical distribution. Two other disjunctions are more recent and likely due to long-distance dispersal: Spathiphyllum Schott (with Holochlamys Engl. nested within) represents a dispersal from South America to the Pacific Islands in Southeast Asia, and Rhaphidophora represents a dispersal from Asia to Africa. Future studies based on stronger phylogenetic reconstructions and complete morphological datasets are needed to explore the details of speciation and migration within and among areas in Asia.

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Chance long-distance or human-mediated dispersal? How Acacia s.l. farnesiana attained its pan-tropical distribution

Royal Society Open Science ◽

10.1098/rsos.170105 ◽

2017 ◽

Vol 4 (4) ◽

pp. 170105 ◽

Cited By ~ 5

Author(s):

Karen L. Bell ◽

Haripriya Rangan ◽

Manuel M. Fernandes ◽

Christian A. Kull ◽

Daniel J. Murphy

Keyword(s):

The Philippines ◽

Historical Sources ◽

Long Distance ◽

Old World ◽

South Central ◽

The Pacific ◽

The Pacific Ocean ◽

Spanish Explorers ◽

The Tropics ◽

Old World Tropics

Acacia s.l. farnesiana , which originates from Mesoamerica, is the most widely distributed Acacia s.l. species across the tropics. It is assumed that the plant was transferred across the Atlantic to southern Europe by Spanish explorers, and then spread across the Old World tropics through a combination of chance long-distance and human-mediated dispersal. Our study uses genetic analysis and information from historical sources to test the relative roles of chance and human-mediated dispersal in its distribution. The results confirm the Mesoamerican origins of the plant and show three patterns of human-mediated dispersal. Samples from Spain showed greater genetic diversity than those from other Old World tropics, suggesting more instances of transatlantic introductions from the Americas to that country than to other parts of Africa and Asia. Individuals from the Philippines matched a population from South Central Mexico and were likely to have been direct, trans-Pacific introductions. Australian samples were genetically unique, indicating that the arrival of the species in the continent was independent of these European colonial activities. This suggests the possibility of pre-European human-mediated dispersal across the Pacific Ocean. These significant findings raise new questions for biogeographic studies that assume chance or transoceanic dispersal for disjunct plant distributions.

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Impact of dams and irrigation schemes in Anopheline (Diptera: Culicidae) bionomics and malaria epidemiology

Revista do Instituto de Medicina Tropical de São Paulo ◽

10.1590/s0036-46652012000400001 ◽

2012 ◽

Vol 54 (4) ◽

pp. 179-191 ◽

Cited By ~ 12

Author(s):

Jordi Sanchez-Ribas ◽

Gabriel Parra-Henao ◽

Anthony Érico Guimarães

Keyword(s):

Control Measures ◽

Successful Implementation ◽

Negative Effects ◽

Irrigation Scheme ◽

Tropical Regions ◽

Malaria Epidemiology ◽

The Pacific ◽

The Tropics ◽

And Control ◽

Anopheline Mosquitoes

Irrigation schemes and dams have posed a great concern on public health systems of several countries, mainly in the tropics. The focus of the present review is to elucidate the different ways how these human interventions may have an effect on population dynamics of anopheline mosquitoes and hence, how local malaria transmission patterns may be changed. We discuss different studies within the three main tropical and sub-tropical regions (namely Africa, Asia and the Pacific and the Americas). Factors such as pre-human impact malaria epidemiological patterns, control measures, demographic movements, human behaviour and local Anopheles bionomics would determine if the implementation of an irrigation scheme or a dam will have negative effects on human health. Some examples of successful implementation of control measures in such settings are presented. The use of Geographic Information System as a powerful tool to assist on the study and control of malaria in these scenarios is also highlighted.

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