Altimeter Data Research Articles

An eddy-borne Argo float measurement experiment in the South China Sea

Argo floats can be used to collect unique and spatiotemporally continuous eddy profiles as they are carried forward within eddies. Using satellite altimeter data, we designed and conducted an eddy-borne Argo float measurement experiment in a South China Sea (SCS) eddy generated in the southwest region of Taiwan. The Argo float was deployed at a location that was estimated to be in the eddy corridor on December 31, 2016. As a result, the Argo float continuously observed the target eddy for more than 2 months, and successfully obtained 62 valuable daily temperature (T) and salinity (S) profiles inside this eddy. From this Argo float’s movement, the smooth transition of the float speed and heading revealed that the eddy splitting identified by satellite altimeter data should be an artifact from January 14 to 18, 2017. In addition, it is found that the depth of thermocline is negative correlated with the normalized radial distance of the float to the eddy center, and the bowl-like shape of the thermocline depth can be revealed. The T-S diagram of Argo float profiles indicated that eddy water should be derived from the Kuroshio Current. The design and implementation of this experiment are a successful example of SCS eddy observation, which will undoubtedly guide oceanographers to obtain more effective eddy data. The development of an “Eddy-Argo” program designed for eddy observation is worthy of additional research in the future.

An Adaptive Optimal Interpolation Based on Analog Forecasting: Application to SSH in the Gulf of Mexico

AbstractBecause of the irregular sampling pattern of raw altimeter data, many oceanographic applications rely on information from sea surface height (SSH) products gridded on regular grids where gaps have been filled with interpolation. Today, the operational SSH products are created using the simple, but robust, optimal interpolation (OI) method. If well tuned, the OI becomes computationally cheap and provides accurate results at low resolution. However, OI is not adapted to produce high-resolution and high-frequency maps of SSH. To improve the interpolation of SSH satellite observations, a data-driven approach (i.e., constructing a dynamical forecast model from the data) was recently proposed: analog data assimilation (AnDA). AnDA adaptively chooses analog situations from a catalog of SSH scenes—originating from numerical simulations or a large database of observations—which allow the temporal propagation of physical features at different scales, while each observation is assimilated. In this article, we review the AnDA and OI algorithms and compare their skills in numerical experiments. The experiments are observing system simulation experiments (OSSE) on the Lorenz-63 system and on an SSH reconstruction problem in the Gulf of Mexico. The results show that AnDA, with no necessary tuning, produces comparable reconstructions as does OI with tuned parameters. Moreover, AnDA manages to reconstruct the signals at higher frequencies than OI. Finally, an important additional feature for any interpolation method is to be able to assess the quality of its reconstruction. This study shows that the standard deviation estimated by AnDA is flow dependent, hence more informative on the reconstruction quality, than the one estimated by OI.

TOPOGRAPHIC MAPPING OF THE MOON IN THE 21ST CENTURY: FROM HECTOMETER TO MILLIMETER SCALES

Abstract. This paper presents a review of lunar topographic mapping in the two decades of the 21st century, including descriptions of lunar exploration missions, relevant payloads and data, mapping techniques, as well as global and regional mapping products. Various lunar photogrammetric mapping techniques such as construction of geometric models of lunar orbital images, block adjustments, shape from shading, co-registration of lunar orbital image and elevation data have been developed to process lunar orbital images and generate mapping products. Global topographic products at hectometer and decameter scales have been produced from orbital images and/or laser altimeter data. Regional topographic maps of the landing sites and other sites of interest have been generated at meter-scale using the sub-meter to meter resolution orbital images. Detailed local topographic products at centimeter to millimeter scales of the landing sites and rover traverse areas have been produced using descent images acquired by the landers and stereo images acquired by the rovers. These multiple-scale topographic mapping products have been extensively used to support various science applications, as well as engineering applications such as surface operations of the rovers.

Three-Dimensional Structure and Interannual Variability of the Kuroshio Loop Current in the Northeastern South China Sea

AbstractBased on long-term mooring-array and satellite observations, three-dimensional structure and interannual variability of the Kuroshio Loop Current (KLC) in the northeastern South China Sea (SCS) were investigated. The 3-yr moored data between 2014 and 2017 revealed that the KLC mainly occurred in winter and it exhibited significant interannual variability with moderate, weak, and strong strengths in the winters of 2014/15, 2015/16, and 2016/17, respectively. Spatially, the KLC structure was initially confined to the upper 500 m near the Luzon Strait, but it became more barotropic, with kinetic energy transferring from the baroclinic mode to the barotropic mode when it extended into the SCS interior. Through analyzing the historical altimeter data between 1993 and 2019, it is found that the KLC event in 2016/17 winter is the strongest one since 1993. Moored-data-based energetics analysis suggested that the growth of this KLC event was primarily fed by the strong wind work associated with the strengthened northeast monsoon in that La Niña–year winter. By examining all of the historical KLC events, it is found that the strength of KLC is significantly modulated by El Niño–Southern Oscillation, being stronger in La Niña and weaker in El Niño years. This interannual modulation could be explained by the strengthened (weakened) northeast monsoon associated with the anomalous atmospheric cyclone (anticyclone) in the western North Pacific during La Niña (El Niño) years, which inputs more (less) energy and negative vorticity southwest of Taiwan that is favorable (unfavorable) for the development of KLC.

GNSS assessment of sentinel-3A ECMWF tropospheric delays over inland waters

Over land and inland waters satellite radar altimetry is being used in numerous applications including polar mass change, ice topography, river and lake heights and soil moisture. To achieve high accuracy altimetric range measurements, geophysical corrections are applied including the Zenith Total Delay (ZTD) which varies spatially, temporally and with altitude. Over oceans, the wet tropospheric component of the ZTD is usually derived from onboard radiometers. However, over land, the radiometer return is saturated and the zenith wet and dry tropospheric delays are derived separately as output of a meteorological model such as that processed by the European Centre for Medium-Range Weather Forecasts (ECMWF). Using Global Navigation Satellite System (GNSS) stations located near Sentinel-3A ground tracks and correcting for any height difference the ECMWF model is compared to the ZTD estimated from GNSS data, quantifying the likely error for inland water and land applications. We found that, globally, there is a median bias of −3 mm between the ECMWF model and GNSS values with median absolute deviation (MAD) of 7.3 mm but with clear spatial and temporal variations. Spatially, ZTD differences are greatest within the tropics with MAD values exceeding 11 mm, over double that of points within the Arctic Circle (<5 mm). Temporally, the ECMWF model differs from GNSS values more during summer months. Northern Hemisphere summer (June–August) has an approximately 60% larger MAD than December-February with the summer MAD approximately 20% smaller in the Southern Hemisphere. Assessment of the tropospheric error is quantified for the largest river catchments for application to inland water heights. The close proximity of altimetric data, GNSS receiver and inland water gauges on the Amazon and Orange rivers and Lake Ontario confirms the preference for GNSS derived ZTD. Overall, the altimetric community can be reassured that the tropospheric contribution to the error budget for inland water applications is less generally than 20 mm at 1 σ in all major catchments.

A global sea state dataset from spaceborne synthetic aperture radar wave mode data

This dataset consists of integral sea state parameters of significant wave height (SWH) and mean wave period (zero-upcrossing mean wave period, MWP) data derived from the advanced synthetic aperture radar (ASAR) onboard the ENVISAT satellite over its full life cycle (2002–2012) covering the global ocean. Both parameters are calibrated and validated against buoy data. A cross-validation between the ASAR SWH and radar altimeter (RA) data is also performed to ensure that the SAR-derived wave height data are of the same quality as the RA data. These data are stored in the standard NetCDF format, which are produced for each ASAR wave mode Level1B data provided by the European Space Agency. This is the first time that a full sea state product in terms of both the SWH and MWP has been derived from spaceborne SAR data over the global ocean for a decadal temporal scale.

PHOTOGRAMMETRIC PROCESSING OF OSIRIS-REX IMAGES OF ASTEROID (101955) BENNU

Abstract. The principal objective of the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) mission is to retrieve a sample of the asteroid (101955) Bennu and return it to Earth. OSIRIS-REx arrived at Bennu in December 2018. Images of the asteroid by the OSIRIS-REx Camera Suite (OCAMS) were photogrammetrically controlled to produce a global basemap and site-specific image mosaics essential to the selection of a primary and backup sample site, which were announced in December 2019. In the control process, OCAMS images were registered to shape models created from OSIRIS-REx Laser Altimeter (OLA) data and from the process of stereophotoclinometry. This paper summarizes the photogrammetric control to date of images collected at Bennu. We briefly review the mission and the OCAMS imaging sensors. We then describe the photogrammetric control process for the global mapping campaign and targeted reconnaissance surveys of candidate sample sites. Finally, we discuss ongoing and future work.

MULTI-MODAL DEEP LEARNING WITH SENTINEL-3 OBSERVATIONS FOR THE DETECTION OF OCEANIC INTERNAL WAVES

Abstract. The observation of waves that propagate along density interfaces inside the ocean poses a significant challenge, as their visible surface signatures are much lower compared to their internal amplitudes. However, monitoring internal waves is important as they redistribute large amounts of energy, play a role in mixing and vertical heat transfer, and modify water and nutrient transports. Although satellite observations would allow global monitoring of internal waves at constant time intervals, their automatic detection is challenging: In optical images, internal waves are hardly visible and can be obscured by clouds, whereas radar data have limitations in coastal regions and their spatial coverage is not perfect. Furthermore, the occurrence of internal waves can be confused with other ocean phenomena. In this work, we present an automated detection framework for internal waves based on multiple data sources in order to compensate for the shortcoming of single data sources. In our application, we use Ocean and Land Color Imager and Synthetic Aperture Radar Altimeter data. Our contributions are (1) we develop a multi-modal deep neural network SONet with multi-streams and late fusion, which performs a classification on the basis of training with both modalities, and (2) we establish a method to deal with missing modalities. Experiments in the Amazon Shelf region show SONet achieves adequate results when both modalities are available, but also when only a single modality is available. By exploiting correlations between the modalities, SONet classifies OLCI images off the SRAL ground track better than uni-modal network ONet, which describes a great advantage of our multi-modal network.

Random Movement of Mesoscale Eddies in the Global Ocean

AbstractIn this study we track and analyze eddy movement in the global ocean using 20 years of altimeter data and show that, in addition to the well-known westward propagation and slight polarity-based meridional deflections, mesoscale eddies also move randomly in all directions at all latitudes as a result of eddy–eddy interaction. The speed of this random eddy movement decreases with latitude and equals the baroclinic Rossby wave speed at about 25° of latitude. The tracked eddies are on average isotropic at mid- and high latitudes, but become noticeably more elongated in the zonal direction at low latitudes. Our analyses suggest a critical latitude of approximately 25° that separates the global ocean into a low-latitude anisotropic wavelike regime and a high-latitude isotropic turbulence regime. One important consequence of random eddy movement is that it results in lateral diffusion of eddy energy. The associated eddy energy diffusivity, estimated using two different methods, is found to be a function of latitude. The zonal-mean eddy energy diffusivity varies from over 1500 m2 s−1 at low latitudes to around 500 m2 s−1 at high latitudes, but significantly larger values are found in the eddy energy hotspots at all latitudes, in excess of 5000 m2 s−1. Results from this study have important implications for recently developed energetically consistent mesoscale eddy parameterization schemes which require solving the eddy energy budget.

Significant wave height retrieval from Sentinel-1 SAR imagery by convolutional neural network

Significant wave height (SWH) is an important wave parameter that is related to near-shore activities and research on the phenomenon near the air-sea interface. Here, we proposed a new method for retrieving SWH from C-band Sentinel-1 synthetic aperture radar (SAR) interferometric wide mode data based on convolutional neural network (CNN), which can directly establish the empirical relationship between normalized radar cross section and SWH. We collected 1597 Sentinel-1 SAR images matched with in situ buoys and conducted homogeneity tests for each of the matched sub-images, producing ~ 3330 matchups with 2028 of them being VV-polarization. After training, the VV-polarization data extracted by 0.5 threshold for homogeneity test perform better, and the comparison between these results and in situ buoy measurements in validation data indicates a SWH root mean square error of 0.32 m, a 23.58% scatter index and a 0.90 correlation coefficient. And the SWH from CNN-based method is also validated with radar altimeter data and Wavewatch3 data. These results demonstrate that the proposed CNN method is suitable for retrieving SWH from Sentinel-1 SAR imagery with some constraints on the matched dataset.

Sea level anomaly measurements from satellite coastal altimetry and tide gauges at the entrance of the Gulf of California

The Sea Level Anomalies (SLA) obtained from tide gauges and coastal altimetry are compared in four locations around the entrance area of the Gulf of California, Mexico to validate the coastal altimetry data in our region. We perform two analyses using SLA data from X-TRACK coastal altimetry product (1 Hz along track) for the missions Topex/Poseidon (TP), Jason 1–2-3 (Ja), Geosat Follow-On (GFO) and Envisat (EN). The first compares SLA from X-TRACK with the SLA obtained from tide gauge subtracting 31 tidal components. In the second comparison, we start from the total water level envelope for altimetry data, which results from adding the Sea Level Anomalies, tides and atmospheric corrections. A harmonic analysis is performed to subtract only the most relevant tidal constituents in our region. We obtain 18 tidal constituents based on the harmonic analysis of the four tide gauges (16 with amplitudes > 1 cm and including the LDA2 and MM constituent). However, the number of tidal constituents that can be removed from the altimetric data varies due to their tidal alias periods which, in turn depend on their repetition periods and orbits. Therefore, we extract only 18/16/11 constituents for TP-Ja/GFO/EN respectively. The same number of constituents are removed from the tide gauges for comparison. The results show greater similarity between the SLA time series of altimeters and tide gauges for the second analysis, obtaining higher correlations (R > 0.6) and smaller root mean square differences (Rmse < 11 cm) for the TP-Ja and GFO missions and less than 18 cm for the EN mission. The tidal constituents inside the gulf undergo significant changes in amplitude and phase over short distances. Because of this, large differences can be found between the SLA time series of tide gauges when comparing with altimetry points located at distances 40–80 km away. However, when comparing points located less than 30 km away the comparisons are acceptable with differences attributable to the coastal dynamics, and therefore we consider them to be properly validated.

Influence of Novaya Zemlya Bora on Sea Waves: Satellite Measurements and Numerical Modeling

This paper investigates for the first time sea waves during Novaya Zemlya bora—a downslope windstorm on the western coast of the archipelago during eastern winds—using a statistical and case-study approach. Statistical analysis of altimeter data off the western coast of Novaya Zemlya during bora shows that, despite strong wind forcing, the frequency of hazard wave heights was low due to the limited fetch. This result was confirmed by the high-resolution numerical simulations of two severe bora episodes. However, the influence of bora on sea waves in some cases was significant: bora increased wave height at a distance from shore greater than 200 km and wave height anomaly was up to 2–3 m. The influence of the wind input parametrization choice during bora is great in the coastal region; however, parametrizations with fetch-limited modifications and strong-wind adopted aerodynamic drag coefficient do not improve the modeling results in the open sea where altimeter data are available.

A New Method of De-Aliasing Large-Scale High-Frequency Barotropic Signals in the Mediterranean Sea

With the development of satellite observation technology, higher resolution and shorter return cycle have also placed higher demands on satellite data processing. The non-tide high-frequency barotropic oscillation in the marginal sea produces large aliasing errors in satellite altimeter observations. In previous studies, the satellite altimeter aliasing correction generally relied on a few bottom pressure data or the model data. Here, we employed the high-frequency tide gauge data to extract the altimeter non-tide aliasing correction in the west Mediterranean Sea. The spatial average method and EOF analysis method were adopted to track the high-frequency oscillation signals from 15 tide gauge records (TGs), and then were used to correct the aliasing errors in the Jason-1 and Envisat observations. The results showed that the EOF analysis method is better than the spatial average method in the altimeter data correction. After EOF correction, 90% of correlation (COR) between TG and sea level of Jason-1 has increased ~5%, and ~3% increase for the Envisat sea level; for the spatial average correction method, only ~70% of Jason-1 and Envisat data at the TGs location has about 2% increase in correlation. The EOF correction reduced the average percentage of error variance (PEL) by ~30%, while the spatial average correction increased the average percentage of PEL by ~20%. After correction by the EOF method, the altimeter observations are more consistent with the distribution of strong currents and eddies in the west Mediterranean Sea. The results prove that the proposed EOF method is more effective and accurate for the non-tide aliasing correction.

A sea-level monopole in the equatorial Indian Ocean

In this study, we show the relationship between sea-level anomalies (SLA) and upper-ocean parameters in the Equatorial Indian Ocean (EIO). This work also focuses on the variability of SLA obtained from satellite altimeter data in different spatial and temporal scales and its relationship with computed ocean heat content (OHC), dynamic height (DH), and thermocline depth (20 °C isotherm: D20) during 1993–2015. SLA showed low Pearson’s correlation coefficient (CC) with upper-ocean parameters over central EIO resembling a “Monopole” pattern. The Array for Real-time Geostrophic Oceanography (ARGO) in situ profile data in the central EIO also confirmed this. SLA over this monopole showed low correlations with all parameters as compared with eastern and western EIO. These findings show a clear signature of a persisting sea-level monopole in the central EIO. Oscillating SLA over western and eastern EIO during summer and winter monsoon months is found to be responsible for locking this monopole in the central EIO. Both SLA and OHC increased in EIO during 2006–2015 compared with 1993–2005. The month of January showed different east–west trends at different times. This trend during 1993–2015 is neutral, but it shifted from negative during 1993–2005 to positive during 2006–2015.

Preliminary marine gravity field from HY-2A/GM altimeter data

HY-2A (Haiyang-2A), launched in 2011, is the first ocean dynamic environment satellite of China and is equipped with a radar altimeter as one of the primary payloads. HY-2A shifted the drift orbit in March 2016 and has been accumulating geodetic mission (GM) data for more than three years with 168-day cycle. In this paper, we present the preliminary gravity field inverted by the HY-2A/GM data from March 2016 to December 2017 near Taiwan (21°–26°N, 119°–123°E). The gravity anomaly is computed by Inverse Vening Meinesz (IVM) formula with a one-dimensional FFT method during remove-restore procedure with the EGM2008 gravity model as the reference field. For comparison, CryoSat-2 altimeter data are used to inverse the gravity field near Taiwan Island by the same method. Comparing with the gravity field derived from CryoSat-2, a good agreement between the two data sets is found. The global ocean gravity models and National Geophysical Data Center (NGDC) shipboard gravity data also are used to assess the performance of HY-2A/GM data. The evaluations show that HY-2A and CryoSat-2 are at the same level in terms of gravity field recovery and the HY-2A/GM altimeter-derived gravity field has an accuracy of 2.922 mGal. Therefore, we can believe that HY-2A will be a new reliable data source for marine gravity field inversion and has the potentiality to improve the accuracy and resolution of the global marine gravity field.

Wind-forced equatorial wave dynamics of the Pacific Ocean during 2014/2015 and 2015/2016 El Niño events

The equatorial wave dynamics of interannual sea level variations between 2014/2015 and 2015/2016 El Nino events are compared using the Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics Climate Ocean Model (LICOM) forced by the National Centers for Environmental Prediction (NCEP) reanalysis Ⅰ wind stress and heat flux during 2000-2015. In addition, the LICOM can reproduce the interannual variability of sea surface temperature anomalies (SSTA) and sea level anomalies (SLA) along the equator over the Pacific Ocean in comparison with the Hadley center and altimetric data well. We extracted the equatorial wave coefficients of LICOM simulation to get the contribution to SLA by multiplying the meridional wave structure. During 2014/2015 El Nino event, upwelling equatorial Kelvin waves from the western boundary in April 2014 reach the eastern Pacific Ocean, which weakened SLA in the eastern Pacific Ocean. However, no upwelling equatorial Kelvin waves from the western boundary of the Pacific Ocean could reach the eastern boundary during the 2015/2016 El Nino event. Linear wave model results also demonstrate that upwelling equatorial Kelvin waves in both 2014/2015 and 2015/2016 from the western boundary can reach the eastern boundary. However, the contribution from stronger westerly anomalies forced downwelling equatorial Kelvin waves overwhelmed that from the upwelling equatorial Kelvin waves from the western boundary in 2015. Therefore, the western boundary reflection and weak westerly wind burst inhibited the growth of the 2014/2015 El Nino event. The disclosed equatorial wave dynamics are important to the simulation and prediction of ENSO events in future studies.

Development and validation in a 2D-GIS environment of a 3D shadow cast vector-based model on arbitrarily orientated and tilted surfaces

This paper presents a systematic GIS-based methodology to obtain the shadow cast profile of a group of buildings on arbitrarily orientated and tilted surfaces. The model is integrated in the widely-employed 2D-GIS environment. Given its scalability, the methodology can be easily applied from a local level up to a district, city or even regional level. This work is of interest for a wide range of applications such as for instance in Solar Resource Assessments (SRA) in urban environments.The starting point is to use cadastral cartography and LiDAR altimetric data to obtain a 3D vector-based model of the buildings using high robust mode estimators. Once the geometry of the buildings is defined, analytical models are applied to calculate the shadow cast profile on any arbitrarily orientated and tilted surface of the surroundings.The model has been implemented in the R programming language. An extensive validation has been carried out for several buildings of Valencia (Spain) using CAD elevation views of the buildings and the SketchUp’s shadow tool. The error of the vector-based city model is lower than 1% in all LiDAR datasets. The maximum error of the overall methodology, including both height and shadow models, is lower than 2%.

Statistical analysis of long-lived mesoscale eddies in the Lofoten basin from satellite altimetry

The paper presents a statistical analysis of long-lived detected mesoscale eddies in the Lofoten Basin (LB). An automated eddy identification and tracking method is applied to the altimeter data during the time-period 1993–2017 to detect and track anticyclonic (ACEs) and cyclonic eddies (CEs) in the LB. Our analysis found that only one percent of the eddies detected are long-lived (eddy-life > 35 days). Even though only 1%, the detected 330 long-lived mesoscale eddies (CEs, 120; ACEs, 210) account for >11,550 daily individual eddy-observations. The lifetime, occurrence, generation sites, size, intensity, and drift of these long-lived eddies are quantified. The average drift speed of long-lived eddies is found to show a pronounced seasonal variation with a maximum from October to March. Long-lived eddies in the LB are further divided into four groups based on their region of generation and dissipation. Long-lived eddies generated and dissipated outside the region of the Lofoten Vortex (group 2 eddies) are found to be the predominant type (CEs, 73.3%; ACEs, 69.5%). The eddies generated and dissipated in the region of the permanent Lofoten Vortex form the second dominant type (CEs, 14.3%; ACEs, 26.2%). Based on their lifetime, properties of the two predominant groups of eddies are examined in detail. The difference found in the temporal variability of the eddy characteristics of the two groups reflects their different genesis. The analysis revealed that the mesoscale eddies of group 2 have a longer life than eddies of group 1, and ACEs are more long-lived in comparison to CEs. The analysis also found three main areas of eddy generation in the frontal zone of the NwASC from where mesoscale eddies propagate to the north-west, forming three main corridors of trajectories. The study further provides evidence of long-lived cyclonic CEs surrounding the large quasi-permanent Lofoten Vortex (LV) and forming a shield around it. Small CEs located in two areas with centers at 69.5° N, 4° E, and 70° N, 2.5° E survive nearby the LV resisting the vortex-vortex interaction with the large and strong LV.

Observation of continental shelf wave propagating along the eastern Taiwan Strait during Typhoon Meranti 2016

This study is the first to depict typhoon-induced continental shelf wave (CSW) propagation in the eastern Taiwan Strait (TWS) during the passage of Typhoon Meranti in 2016 using tidal gauge data and along-track satellite altimeter data. The strong amplitude response of sea level oscillations (within the range of 0.30–0.54 m) as a free, barotropic CSW after Meranti, which impacted the TWS, was clearly detected in time and frequency (in bands of 64–81 h) using wavelet and cross-wavelet analyses. The measured group and phase speeds were consistent with the dispersion curves for CSW with the first-mode derived from the cross-shelf sections of the eastern TWS, with the mean speeds reaching 3 and 5.6±0.7 m/s, respectively. Coincidentally, the typhoon-induced sea level anomaly (SLA) was also captured by the satellite altimeter before this CSW entered into the TWS. Using the theoretical cross-shore CSW modes to fit the SLA data, the results indicated that the first three wave modes can interpret this CSW event appeared in the southern TWS very well, with the first mode being the dominant one.

Detection of waveguide for Rossby waves using satellite altimetry in the Antarctic Circumpolar Current

ABSTRACT The subject of this paper is the Antarctic Circumpolar Current (ACC) as the waveguide for Rossby waves. The ACC is the region where Rossby waves manifest differently in comparison to other parts of the World Ocean. The ACC is not only the waveguide for Rossby waves where wave kinetic energy is modified by jets, yet the region where Rossby waves interact with the flow. This manuscript contains a theoretical discussion of idealized Rossby wave dynamics and then computes a set of waveguide boundaries for the ACC, based on analysis of the propagation characteristics of sea surface height from satellite altimeter data. Since the linear theory of Rossby waves is not suitable within the waveguide areas, we propose a nonlinear approach that can explain the eastward propagation of Rossby waves in the ACC. We use the nonlinear theory of Rossby waves and zonal jets interaction, based on the fact that the nonlinearity in the long-wave approximation for Rossby waves exactly compensates the Doppler shift. The dispersion equation agrees well with altimetry data and provides a reasonable explanation to the propagation of the Rossby waves eastward within the ACC. We detect the northern and the southern waveguide boundaries for the ACC using altimetry and compare them to the climatological fronts in the ACC. We reveal that the Polar Front and the northern and southern branches of the Subantarctic Front are mostly located inside the waveguide in the South Ocean except the Indian sectors of the (30° to 90° E).