Showing papers on "Haze published in 2004"

Around the world in 17 days - hemispheric-scale transport of forest fire smoke from Russia in May 2003

Abstract: . In May 2003, severe forest fires in southeast Russia resulted in smoke plumes extending widely across the Northern Hemisphere. This study combines satellite data from a variety of platforms (Moderate Resolution Imaging Spectroradiometer (MODIS), Sea-viewing Wide Field-of-view Sensor (SeaWiFS), Earth Probe Total Ozone Mapping Spectrometer (TOMS) and Global Ozone Monitoring Experiment (GOME)) and vertical aerosol profiles derived with Raman lidar measurements with results from a Lagrangian particle dispersion model to understand the transport processes that led to the large haze plumes observed over North America and Europe. The satellite images provided a unique opportunity for validating model simulations of tropospheric transport on a truly hemispheric scale. Transport of the smoke occurred in two directions: Smoke travelling northwestwards towards Scandinavia was lifted over the Urals and arrived over the Norwegian Sea. Smoke travelling eastwards to the Okhotsk Sea was also lifted, it then crossed the Bering Sea to Alaska from where it proceeded to Canada and was later even observed over Scandinavia and Eastern Europe on its way back to Russia. Not many events of this kind, if any, have been observed, documented and simulated with a transport model comprehensively. The total transport time was about 17 days. We compared transport model simulations using meteorological analysis data from both the European Centre for Medium-Range Weather Forecast (ECMWF) and the National Center for Environmental Prediction (NCEP) in order to find out how well this event could be simulated using these two datasets. Although differences between the two simulations are found on small scales, both agree remarkably well with each other and with the observations on large scales. On the basis of the available observations, it cannot be decided which simulation was more realistic.

Simulation of the Martian dust cycle with the GFDL Mars GCM

Abstract: [1] The Martian seasonal dust cycle is examined with a general circulation model (GCM) that treats dust as a radiatively and dynamically interactive trace species. Dust injection is parameterized as being due to convective processes (such as dust devils) and model-resolved wind stresses. Size-dependent dust settling, transport by large-scale winds and subgrid scale diffusion, and radiative heating due to the predicted dust distribution are treated. Multiyear Viking and Mars Global Surveyor air temperature data are used to quantitatively assess the simulations. Varying the three free parameters for the two dust injection schemes (rate parameters for the two schemes and a threshold for wind-stress lifting), we find that the highly repeatable northern spring and summer temperatures can be reproduced by the model if the background dust haze is supplied by either convective lifting or by stress lifting with a very low threshold and a low injection rate. Dust injection due to high-threshold, high-rate stress lifting must be added to these to generate spontaneous and variable dust storms. In order to supply the background haze, widespread and ongoing lifting is required by the model. Imaging data provide a viable candidate mechanism for convective lifting, in the form of dust devils. However, observed nonconvective lifting systems (local storms, etc.) appear insufficiently frequent and widespread to satisfy the role. On the basis of the model results and thermal and imaging data, we suggest that the background dust haze on Mars is maintained by convective processes, specifically, dust devils. Combining the convective scheme and high-threshold stress lifting, we obtain a “best fit” multiyear simulation, which produces a realistic thermal state in northern spring and summer and, for the first time, spontaneous and interannually variable global dust storms.

Antarctic oscillation and the dust weather frequency in North China

Abstract: [1] The linkage between the Antarctic Oscillation (AAO) to the dust weather frequency (DWF) in North China is addressed. Here DWF denotes the number of days of dust weather events including dust haze, blowing dust and dust storm in one year. It is found that the interannual variation of AAO plays a significant role in the dust-related atmospheric circulation during boreal spring. AAO and DWF correlate well, with positive AAO tending to decrease DWF in North China. Two possible mechanisms for the AAO-DWF coupling are identified, one is related to a meridional teleconnection pattern; the other is related to a regional circulation pattern over the Pacific Ocean.

Effects of varying aerosol regimes on low-level Arctic stratus

Abstract: [1] The effects on low-level cloud microstructures of varying aerosol regimes in the Arctic are examined using ground-based measurements obtained near Barrow, Alaska. Episodic ‘arctic haze’ events produced high cloud droplet concentrations, and small cloud droplet effective radii. By contrast, the fresh nucleation of aerosols within the Arctic produced particles high in number concentration but generally too small to be efficient cloud condensation nuclei. Comparisons with similar analyses done at lower latitudes suggest that the ‘indirect effect’ of haze aerosol on low-cloud effective radii is particularly high in the Arctic.

A major regional air pollution event in the northeastern United States caused by extensive forest fires in Quebec, Canada

Abstract: [1] During early July 2002, wildfires burned ∼1 × 106 ha of forest in Quebec, Canada. The resultant smoke plume was seen in satellite images blanketing the U.S. east coast. Concurrently, extremely high CO mixing ratios were observed at the Atmospheric Investigation, Regional Modeling, Analysis and Prediction (AIRMAP) network sites in New Hampshire and at the Harvard Forest Environmental Measurement Site (HFEMS) in Massachusetts. The CO enhancements were on the order of 525–1025 ppbv above low mixing ratio conditions on surrounding days. A biomass burning source for the event was confirmed by concomitant enhancements in aerosol K+, NH4+, NO3−, and C2O42− mixing ratios at the AIRMAP sites. Additional data for aerosol K, organic carbon, and elemental carbon from the Interagency Monitoring of Protected Visual Environments network and CO data from Environmental Protection Agency sites indicated that the smoke plume impacted much of the U.S. east coast, from Maine to Virginia. CO mixing ratios and K concentrations at stations with 10-year or longer records suggested that this was the largest biomass burning plume to impact the U.S. east coast in over a decade. Furthermore, CO mixing ratios and aerosol particles with diameters <2.5 μm (PM2.5) mass and scattering coefficients from the AIRMAP network and HFEMS indicated that this event was comparable to the large anthropogenic combustion and haze events which intermittently impact rural New England. The degree of enhancement of O3, NOy, NO3−, NH4+, and SO42− in the biomass plume showed significant variation with elevation and latitude that is attributed to variations in transport and surface depositional processes.

Jovian clouds and haze

Abstract: At wavelengths from the near-ultraviolet (0.2 μm) to the infrared (5 μm) Jupiter’s appearance is dominated by contrasts produced by clouds and haze. It is important to understand the distribution and optical and physical properties of cloud and haze particles because they play a major role in the radiative heat budget, and they can tell us about atmospheric processes such as stratospheric circulation and tropospheric meteorology. The study of jovian clouds and haze also provides insight needed for interpretation of spectra of extra-solar giant planets. This chapter is concerned with the chemical and physical properties of cloud and haze particles, their vertical and horizontal distributions, their radiative properties, and their microphysical properties. These topics are entwined with the chemistry and composition of the troposphere and stratosphere, atmospheric dynamics and auroral processes that are the principal subjects of chapters in this volume by Taylor et al., Moses et al., Ingersoll et al., and Yelle et al. This chapter is divided into two main sections focusing on clouds and haze in the troposphere and stratosphere. The term “haze” will be used for a very dispersed and nearly uniform, ubiquitous layer of sub-micron particles in the upper troposphere (200 – 500 mbar) and for particles in the stratosphere (pressure less than 100 mbar). We use the term “clouds” for the more variable clouds of larger particles at deeper levels. These are further subdivided into the categories of chemical composition, physical properties, distribution, and microphysics. Both observations and theoretical treatments of each of these are given, but with emphasis on the observations since it is in that domain that most of the information resides. There is a large body of observational evidence relevant to studies of jovian clouds, with contributions from ground-based and earth-orbital telescopes over a long period of time, and major concentrated bursts from the Pioneer, Voyager, Galileo and Cassini spacecraft. In this chapter we give emphasis to research activity after 1986. The reader is encouraged to consult West et al. (1986) for a review of theory and observational results from Pioneer, Voyager and ground-based studies prior to 1986.

Haze aerosols in the atmosphere of early Earth: manna from heaven.

Abstract: An organic haze layer in the upper atmosphere of Titan plays a crucial role in the atmospheric composition and climate of that moon. Such a haze layer may also have existed on the early Earth, providing an ultraviolet shield for greenhouse gases needed to warm the planet enough for life to arise and evolve. Despite the implications of such a haze layer, little is known about the organic material produced under early Earth conditions when both CO2 and CH4 may have been abundant in the atmosphere. For the first time, we experimentally demonstrate that organic haze can be generated in different CH4/CO2 ratios. Here, we show that haze aerosols are able to form at CH4 mixing ratios of 1,000 ppmv, a level likely to be present on early Earth. In addition, we find that organic hazes will form at C/O ratios as low as 0.6, which is lower than the predicted value of unity. We also show that as the C/O ratio decreases, the organic particles produced are more oxidized and contain biologically labile compounds. After l...

Regional climate effects of Arctic Haze

Abstract: [1] The direct climate effect of aerosols has been studied within a regional atmospheric model of the Arctic. The mean springtime effect on the near surface temperature has been estimated and showed to be within ±1 K. However, the aerosol effect varies strongly regionally depending on the surface albedo, atmospheric humidity, and cloud condition of the region. The interannual variability of the aerosol effect is very pronounced (for the near surface temperature in the order of 2 K) and is connected with the strong varying year-specific atmospheric conditions. Due to the high horizontal resolution of the model, it was possible to assess the influence both on the large-scale as well as on the meso-scale atmospheric circulation. Through the aerosol-radiation-circulation feedback, the scattering and absorption of radiation by aerosol cause pressure pattern changes which have the potential to modify Arctic teleconnection patterns like the Barents Sea Oscillation.

Research Paper Haze Aerosols in the Atmosphere of Early Earth: Manna from Heaven

Abstract: An organic haze layer in the upper atmosphere of Titan plays a crucial role in the atmospheric composition and climate of that moon. Such a haze layer may also have existed on the early Earth, providing an ultraviolet shield for greenhouse gases needed to warm the planet enough for life to arise and evolve. Despite the implications of such a haze layer, little is known about the organic material produced under early Earth conditions when both CO2 and CH4 may have been abundant in the atmosphere. For the first time, we experimentally demonstrate that organic haze can be generated in different CH4/CO2 ratios. Here, we show that haze aerosols are able to form at CH4 mixing ratios of 1,000 ppmv, a level likely to be present on early Earth. In addition, we find that organic hazes will form at C/O ratios as low as 0.6, which is lower than the predicted value of unity. We also show that as the C/O ratio decreases, the organic particles produced are more oxidized and contain biologically labile compounds. After life arose, the haze may thus have provided food for biota. Key Words: Early Earth—Hydrocarbon aerosols—Atmospheric C/O ratio. Astrobiology 4, 409‐419.

Smoke over haze: Aircraft observations of chemical and optical properties and the effects on heating rates and stability

Abstract: [1] Airborne observations made on 8 July 2002 over five locations in Virginia and Maryland revealed the presence of two discrete layers of air pollution, one of a smoke plume between ∼2 and 3 km above mean sea level advected from Quebec forest fires and another, underlying plume from fossil fuel combustion. Within the smoke layer, large increases were observed in submicrometer particle numbers, scattering, and absorption as well as ozone (O3) and CO (but not SO2) mixing ratios. The single-scattering albedos (ω0) in the layer between ∼2 and 3 km (mean value at 550 nm = 0.93 ± 0.02) were consistently smaller than those below (mean value at 550 nm = 0.95 ± 0.01). Aerosol optical depth in the lower 3 km of the atmosphere was determined at each of the five locations, and the value at 550 nm varied between 0.42 ± 0.06 and 1.53 ± 0.21. Calculations of clear-sky aerosol direct radiative forcing by the smoke plume using an atmospheric radiative transfer code indicated that the forcing at the top of the atmosphere was small relative to the forcing at the surface. Thus atmospheric absorption of solar radiation was nearly equal to the attenuation at the surface. The net effect was to cool the surface and heat the air aloft. A morning subsidence inversion positioned the smoke in a dense enough layer above the planetary boundary layer that solar heating of the layer maintained the temperature inversion through the afternoon. This created a positive feedback loop that prevented vertical mixing and dilution of the smoke plume, thereby increasing the regional radiative impact.

The recent characteristics of Asian dust and haze events in Seoul, Korea

Abstract: The study on the characteristics of aerosol in Seoul during springtime from 1998 to 2003 is performed by the size-resolved number concentrations of aerosol. Asian dust events occur in spring most frequently, but it has been often observed in wintertime since 1999. Since 2000, the number of Asian dust days has been increasing, and the intensity has been more severe until 2002. However, there were only 3 dust days in Seoul during the spring of 2003, since the synoptic cyclone was relatively not intense enough to rise and transport dust to Korean peninsula, and the air stream was usually tiled to north of Korean peninsula. In addition, the precipitation was relatively plentiful and the air temperature was cold enough not to keep dry soil condition. Haze is the suspended particles in the air, reducing visibility by scattering light, and it is often a mixture of aerosols and photochemical smog. Dry particles with diameters of the order of 0.1 µm, are small enough to scatter short wavelengths of light. Haze occurs well in winter and spring, and severe haze is observed in the afternoon. The occurrence frequency of haze has been decreasing since 2000 except in May of 2003. During Asian dust events from 1998 to 2003, the number concentration of aerosol with diameters from 0.3 µm to 0.5 µm decreases notably, but that larger than 1 µm increases rapidly. On the other hand, for the haze events the number concentration from 0.3 µm to 0.5 µm increases notably, but that larger than 1 µm decreases.

Trends in atmospheric haze induced by peat fires in Sumatra Island, Indonesia and El Niño phenomenon from 1973 to 2003

Abstract: [1] Visibility was used as a long-term indicator of atmospheric haze caused by peat fires on the peat land area of the island of Sumatra, Indonesia. Visibility and the anomalies of sea surface temperature in the Nino 3.4 region from 1973 to 2003 were analyzed. A significant linear relationship existed between the visibility and time, and the two signals shared two periodic components of 45 months (3.7 yr) and 61 months (5.1 yr), corresponding with the El Nino-Southern Oscillation (ENSO) variability. Visibility decrease occurred about 3 months earlier than peak ENSO, suggesting fires initiated during the ENSO onset stage. The study demonstrated the connection of inter-annual climate variability, biomass burning, and air quality in the region. The study could facilitate the prediction of change in fire occurrence and air quality from ENSO monitoring data.

Closure study on optical and microphysical properties of a mixed urban and Arctic haze air mass observed with Raman lidar and Sun photometer

Abstract: [1] We present a comprehensive optical and microphysical characterization of an intense haze event observed over Leipzig (51.3°N, 12.4°E), Germany, in April 2002. This event was characterized by unusually high optical depths. The haze consisted of a mixture of urban and Arctic haze aerosols which were advected from the Arctic regions across eastern Europe and Scandinavia. For the first time a closure study on such an event could be carried out on the basis of combined observations with Raman lidar and Sun photometer. This study also served as a performance test of the inversion algorithms that are used for retrieving microphysical particle properties from the optical data sets. A comparison of parameters derived in this study to respective quantities determined in the Arctic regions showed that Arctic-haze-like material dominated the optical and microphysical particle properties, although a significant amount of this haze must have consisted of urban aerosols. The urban aerosols from eastern Europe had properties rather similar to those characteristic for the well-aged particles of Arctic haze. The major part of the haze was confined to heights below 3 km. Optical depth was 0.4-0.5 at 532 nm on 8 April 2002. The particle backscatter-to-extinction (lidar) ratio varied between 35 and 75 sr at 355 and 532 nm. The Angstrom exponent of particle extinction in the wavelength range from 355 to 532 nm was 1.8-2.8. The inversion of the lidar optical data resulted in particle effective radii around 0.19 ± 0.04 μm, volume concentrations of 16-33 μm 3 cm -3 , surface area concentrations of 270-510 μm 2 cm -3 , and a single-scattering albedo around 0.97 ± 0.06 at 532 nm. Particle size distributions showed a rather pronounced monomodal structure in the accumulation mode, which is characteristic for well-aged particles. The particle properties derived from the two instruments agreed well for intensive parameters, i.e., Angstrom exponents, lidar ratio, effective radius, and single-scattering albedo. Extensive parameters, i.e., total particle surface area and particle volume concentration, showed similar values.

Airborne Characterization of the Chemical, Optical, and Meteorological Properties, and Origins of a Combined Ozone-Haze Episode over the Eastern United States

Abstract: Airborne observations of trace gases, particle size distributions, and particle optical properties were made during a constant altitude transect from New Hampshire to Maryland on 14 August 2002, the final day of a multiday haze and ozone (O3) episode over the Mid-Atlantic and northeastern United States. These observations, together with chemical, meteorological, and dynamical analyses, suggest that a simple two-reservoir model, composed of the lower free troposphere (LFT), where photochemical processes are accelerated and removal via deposition does not occur, and the planetary boundary layer (PBL), where most precursor species are injected, may realistically represent the physics and chemistry of severe, multiday haze and O 3 episodes over the Mid

Estimating the direct radiative forcing due to haze from the 1997 forest fires in Indonesia

Abstract: [1] The El Nino event of 1997–1998 caused a severe reduction of rainfall in Indonesia that promoted the spread of forest fires, leading to a pervasive haze in the region Here we use fire coverage data from the 1997 World Fire Atlas with a review of other available data and literature to estimate the distribution of particulate emissions from August to November 1997 and the particle size and radiative properties Our preferred estimate of the total particulate emissions is approximately 41 Tg The emissions have been used to drive an atmospheric model to simulate the distribution of the haze and its direct radiative effect, with and without allowing for the effects of the smoke on the atmospheric evolution Model diagnostics of the aerosol and its radiative impact are compared with measurements and output from other models Large decreases in the incident solar flux at the surface are obtained in the region The simulated global mean shortwave radiative forcing at the top of the atmosphere, averaged over the 4 months, is −032 Wm−2 The accuracy of this calculation is discussed, and the importance of the Indonesian fires in particular and of biomass burning in general is assessed

Apparatus and methods for enabling robust separation between signals of interest and noise

Abstract: Disclosed are methods and apparatus for analyzing the Haze data provided by an optical inspection tool. The Haze data is analyzed so as to detect defects associated with the specimen surface (202). In general, the Haze data is first conditioned so that background noise which corresponds to low frequency variation on the specimen is separated or removed from the Haze data prior to analysis of such Haze data (204). In a specific embodiment, low frequency variations in the specimen surface are characterized, in effect, as an optical surface upon which an incident beam is directed (204). In one example, the Haze data that corresponds to the specimen surface is characterized with a polynomial equation, such as a Zernike equation. In other words, a polynomial equation is fit to the low frequency or background noise of the Haze data (204). The Haze data that conforms to this resulting polynomial equation is then subtracted from the original Haze data to result in residual data (206), where slow variations in surface roughness are subtracted out, leaving possible defect information in the residual Haze data. This residual Haze data may then be analyzed to determine whether the specimen contains a defect (208).

Seasonal change in Titan's haze 1992--2002 from Hubble Space Telescope observations

Abstract: [1] Images from the Hubble Space Telescope (HST) document the seasonal migration of haze in Titan's atmosphere. Image profiles show darkening of the north relative to the south at 439 nm (blue) but no change at 619 nm. The limb profile at 889 nm has inverted, becoming north-bright, a variation consistent with haze transport towards the winter hemisphere by winds. The complex altitude-time variation of the north-south haze differences are indicated in resolved spectra acquired with the Space Telescope Imaging Spectrograph (STIS): the continuum slope of a north/south ratio spectrum changes sign, becoming red, between 2000 and 2002, although the 889 nm band had already reversed by 2000, suggesting the haze distribution changes most rapidly at high altitudes.

Variation of mass scattering efficiencies in IMPROVE.

Abstract: The Interagency Monitoring of Protected Visual Environments (IMPROVE) equation used to assess compliance under the U.S. Environmental Protection Agency (EPA) Haze Rule assumes that dry mass scattering efficiencies for aerosol chemical components are constant. However, examination of aerosol size distributions and chemical composition during the Big Bend Regional Aerosol and Visibility Observational Study and the Southeastern Aerosol and Visibility Study suggests that volume and mass scattering efficiencies vary directly with increasing particle light scattering and aerosol mass concentration. This is consistent with the observation that particle distributions were shifted to larger sizes under more polluted conditions and appears to be related to aging of the aerosol during transport to remote locations.

Remote Sensing of Dust Storms Over the Indo-Gangetic Basin

Abstract: HESHAM EL-ASKARY, RITESH GAUTAM and MENAS KAFATOS Center for Earth Observing and Space Research, School of Computational Sciences George Mason University, Fairfax, VA 22030-4444, USA Dust storms are naturally occurring events that take place in arid and semi- arid regions of the Earth, temperate, tropical and sub-tropical latitudes characterized by dry soil/sand. Arid regions around the Arabian Sea like Iran, Afghanistan, India and Pakistan usually experience a high frequency of dust storms, approximately 30 events per year. Dust storms are believed to be one of the most serious environmental hazards. In this paper, we show the usefulness of optical remote sensing data for monitoring dust storms. The Moderate Resolution Imaging Spectroradiometer (MODIS) and the Multiangle Imaging Spectro Radiometer (MISR) on board Terra/Aqua platforms can be used for the optical sensing of dust storms. The different viewing angles of MISR provide information about dust particles through their discrimination from other suspended particles. In this paper, we examine a dust event over the Indo-Gangetic basin, which occurred on June 9-10, 2003. Occasionally dust storms can travel all the way to Asia with the seasonal summer monsoons. In the summer months, dust storms have a significant impact on the amount of solar radiation reaching the surface, producing a cooling effect that can affect as far away as North America (Liepert, 2002). The Indo-Gangetic basin experiences dust storms that take place during the pre-monsoon period. These dust storms originate in the western side in the pre- monsoon period and act as a major threat to agricultural resources and people living in the Indo- Gangetic basin. Satellite observations of dust storms utilize the behavior of the dust and haze in different parts of the electromagnetic spectrum. In the optical part of the spectrum, (e.g. used by NASA Terra/Aqua MODIS), dust particles have a very high albedo and hence appear quite bright (E1-Askary

Chemical composition of Titan's haze: Are PAHs present?

Abstract: [1] Previous laboratory studies of haze aerosols analogous to those in Titan's atmosphere have shown evidence of the formation of polycyclic aromatic hydrocarbons (PAHs). If present, PAHs may provide a mechanism for both particle formation and nitrogen incorporation. We have conducted new experiments simulating Titan haze production using an Aerosol Mass Spectrometer (AMS). The AMS allows us to examine the chemical structure of the haze particles under a variety of starting conditions in real-time and without collection. Our results for particles produced from a mixture of 10% CH4 in N2 are consistent with a large fraction of aromatics, including specific m/z peaks likely due to PAHs. However, at lower concentrations of CH4 (1% and lower), the mass fraction of PAHs greatly diminishes, and an aliphatic pathway dominates. Haze containing sediments may trace the history of methane on Titan through their composition. The implications for Titan haze and for observations from the Huygens probe are discussed.

Seasonal trends in Titan's atmosphere: haze, wind, and clouds

Abstract: I present an analysis of visible and near-infrared adaptive optics images and spectra of Titan taken over 43 nights between October 1997 and January 2003 with the AEOS 3.6-m, Palomar Hale 5-m, and W.M. Keck 10-m telescopes. These observations reveal a seasonally changing stratospheric haze layer, two distinct regions of condensate clouds in the southern hemisphere, the albedo of Titan's surface, and the zonal wind field of the stratosphere. Transient convective CH4 clouds are identified near Titan's south pole, rising to 16±5 km above the surface. These clouds have been continuously present south of 70°S since at least December 2001, currently account for 0.5-1% of Titan's 2μm flux, and appear to be gradually brightening or thickening as the insolation of the south polar region increases. Above the polar clouds, an extensive but optically thin (τ≈0.05 at 2μm) cloud layer is noted near the tropopause south of 30°S. This cirrus-like structure has remained unchanged in extent and thickness since September 1999 despite seasonal changes in the underlying convective clouds and the overlying stratospheric haze. Aside from the convective CH4 clouds near the south pole, Titan's troposphere is free of aerosols with an upper limit of τ The albedo of Titan's surface at 2.0μm is derived from the radiative transfer analysis of spatially resolved spectra and images, and presented in the form of a ~600 km resolution global surface albedo map. At this resolution, the 2.0μm albedo ranges from 0.05 to 0.17, consistent with extensive exposure of clean water ice in some regions, while hydrocarbons and atmospheric sediments blanket others. The zonal wind field of Titan's stratosphere near southern summer solstice is derived from adaptive optics observations of the occultation of a binary star on 20 December 2001. Multiple refracted stellar images were detected on Titan's limb during the each successive occultation, allowing the angular deflection of the starlight at two altitudes over both hemispheres to be measured with an uncertainty of ~2 milliarcseconds. The zonal wind field derived from this measurement of the shape of Titan's limb exhibits strong but asymmetric high latitude jets, with peak wind speeds of 230±20 m s-1 at 60°N and 160±40 m s-1 at 40°S, and lower winds of 110±40 m s-1 at the equator. The direction of the wind is not constrained.