Tropical Ocean And Global Atmosphere Research Articles

The North Pacific Climate Transitions of the Winters of 1976/77 and 1988/89

Abstract This paper examines characteristic changes in North Pacific sea surface temperature (SST) variability during the boreal winter (December–February) for two subperiods (1956–88 and 1977–2009) during which the 1976/77 and the 1988/89 climate transitions occurred. It is found that the Pacific decadal oscillation (PDO)-like SST variability plays a dominant role in the 1976/77 climate transition, while both the North Pacific Gyre Oscillation (NPGO)-like and PDO-like SST variability contribute to the 1988/89 climate transition. Furthermore, the leading mode changes from PDO-like SST variability during the period 1956–88 to NPGO-like SST variability during the period 1977–2009, indicative of an enhancement of NPGO-like SST variability since 1988. Changes in sea level pressure across the 1976/77 climate transition project strongly onto the Aleutian low pressure system. But sea level pressure changes across the 1988/89 climate transition project primarily onto the North Pacific Oscillation, which is associated with remote changes in the Arctic Oscillation over the polar region as well. This contributes to enhancing the NPGO-like SST variability after 1988. The authors also analyze the output from an ensemble of Tropical Ocean and Global Atmosphere (TOGA) experiments in which the observed SSTs are inserted only at grid points in the tropics between 20°S and 20°N. The results indicate that the changes in the North Pacific atmosphere in the 1976/77 climate transition are mostly due to the tropics, whereas those in the 1988/89 climate transition are not.

Spectral Retrieval of Latent Heating Profiles from TRMM PR Data. Part III: Estimating Apparent Moisture Sink Profiles over Tropical Oceans

Abstract The spectral latent heating (SLH) algorithm was developed to estimate apparent heat source (Q1) profiles for the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) in Parts I and II of this study. In this paper, the SLH algorithm is used to estimate apparent moisture sink (Q2) profiles. The procedure of Q2 retrieval is the same as that of heating retrieval except for using the Q2 profile lookup tables derived from numerical simulations of tropical cloud systems from the Tropical Ocean and Global Atmosphere (TOGA) Coupled Ocean–Atmosphere Response Experiment (COARE) utilizing a cloud-resolving model (CRM). The Q2 profiles were reconstructed from CRM-simulated parameters with the COARE table and then compared with CRM-simulated “true” Q2 profiles, which were computed directly from the water vapor equation in the model. The consistency check indicates that discrepancies between the SLH-reconstructed and CRM-simulated profiles for Q2, especially at low levels, are larger than those for Q1 and are attributable to moistening for the nonprecipitating region that SLH cannot reconstruct. Nevertheless, the SLH-reconstructed total Q2 profiles are in good agreement with the CRM-simulated ones. The SLH algorithm was applied to PR data, and the results were compared with Q2 profiles derived from the budget study. Although discrepancies between the SLH-retrieved and sounding-based profiles for Q2 for the South China Sea Monsoon Experiment (SCSMEX) are larger than those for heating, key features of the vertical profiles agree well. The SLH algorithm can also estimate differences of Q2 between the western Pacific Ocean and the Atlantic Ocean, consistent with the results from the budget study.

Research on the response of the upper layer heat structure in the Western Pacific Warm Pool to the mean Madden-Julian Oscillation

By using the long-term observed hydro-meteorological data (1985–2002) from the Tropical Atmosphere Ocean System (TAO) during the international Tropical Ocean and Global Atmosphere (TOGA) experiment, the key parameters of the Sea Surface Temperature (SST), thermocline depth, surface sensible heat flux and latent heat flux, and the pseudo wind stress in the Westen Equatorial Ocean are calculated in this paper. On the basis of the calculation, the response of upper layer heat structure in the Westen Pacific Warm Pool to the mean Madden-Julian Oscillation (MJO) and its relation to the El Nino events are analyzed. The results show that within the MJO frequency band (42–108d), the distributions of sea surface wind stress and upper ocean temperature have several spatial-temporal variation structures. Among these structures, the type-I surface pseudo wind stress field plays the role of inhibiting the eastward transport of ocean heat capacity, while the type-II strengthens the heat capacity spreading eastward. Therefore the type-II surface pseudo wind stress field is the characteristic wind field that provokes El Nino events. During calm periods (July–September) of the wind stress variations, the sensible and latent heat capacity fluxes change considerably, mostly in the region between 137°–140°E, while to the east of 150°E, the heat capacity flux changes less.

Usefulness of Single Column Model Diagnosis through Short-Term Predictions

Abstract Single column models (SCMs) provide an economical framework for developing and diagnosing representations of diabatic processes in weather and climate models. Their economy is achieved at the price of ignoring interactions with the circulation dynamics and with neighboring columns. It has recently been emphasized that this decoupling can lead to spurious error growth in SCM integrations that can totally obscure the error growth due to errors in the column physics that one hopes to isolate through such integrations. This paper suggests one way around this “existential crisis” of single column modeling. The basic idea is to focus on short-term SCM forecast errors, at ranges of 6 h or less, before a grossly unrealistic model state develops and before complex diabatic interactions render a clear diagnosis impossible. To illustrate, a short-term forecast error diagnosis of the NCAR SCM is presented for tropical conditions observed during the Tropical Ocean and Global Atmosphere (TOGA) Coupled Ocean–At...

Corrections of Humidity Measurement Errors from the Vaisala RS80 Radiosonde—Application to TOGA COARE Data

A series of laboratory tests have been conducted on several different batches of Vaisala RS80 radiosondes to understand and develop methods to correct six humidity measurement errors, including chemical contamination, temperature dependence, basic calibration model, ground check, sensor aging, and sensor arm heating. The contamination and temperature-dependence (TD) errors dominate total errors. The chemical contamination error produces a dry bias, and is due to the occupation of binding sites in the sensor polymer by nonwater molecules emitted from the sonde packaging material. The magnitude of the dry bias depends on sensor polymer type (RS80-A and RS80-H), age of the sonde, relative humidity (RH), and temperature, and it exists throughout the troposphere. The contamination error generally increases with age and RH, and is larger for the RS80-H than the RS80-A. It is ∼2% and ∼10% at saturation for 1-yr-old RS80-A and RS80-H sondes, respectively. The TD error for the RS80-A results from an approximation of a linear function of temperature to the actual nonlinear temperature dependence of the sensor, and also introduces a dry bias. The TD error mainly exists at temperatures below −20°C, increases substantially with decreasing temperatures below −30°C, and is much larger for the RS80-A than the RS80-H. The RS80-A's TD correction (CTA) dominates the total correction at temperatures below −40°C and has a correction factor [CTA = (RH) (CTA_factor)] of 0.15, 0.75, and 2.3 at −40°, −60°, and −80°C, respectively. The correction methods are applied to 8129 Vaisala RS80 soundings collected during the Tropical Ocean and Global Atmosphere (TOGA) Coupled Ocean–Atmosphere Response Experiment (COARE) and are applicable to RS80 radiosonde data from other field experiments and historical and operational radiosonde datasets. The methods are validated by examining various summary plots of the TOGA COARE data and comparing them with other independent data. The corrections greatly improve the accuracy of the TOGA COARE radiosonde dataset. These correction methods have their own uncertainties and may not correct all errors in Vaisala RS80 humidity data. Analyses of these uncertainties are presented in the paper.

Retrieved Vertical Profiles of Latent Heat Release Using TRMM Rainfall Products for February 1998**

This paper represents the first attempt to use Tropical Rainfall Measuring Mission (TRMM) rainfall information to estimate the four-dimensional latent heating structure over the global Tropics for one month (February 1998). The mean latent heating profiles over six oceanic regions [Tropical Ocean and Global Atmosphere (TOGA) Coupled Ocean–Atmosphere Response Experiment (COARE) Intensive Flux Array (IFA), central Pacific, South Pacific Convergence Zone (SPCZ), east Pacific, Indian Ocean, and Atlantic Ocean] and three continental regions (South America, central Africa, and Australia) are estimated and studied. The heating profiles obtained from the results of diagnostic budget studies over a broad range of geographic locations are used to provide comparisons and indirect validation for the heating algorithm–estimated heating profiles. Three different latent heating algorithms, the Goddard Space Flight Center convective–stratiform heating (CSH), the Goddard profiling (GPROF) heating, and the hydrometeor heating (HH) algorithms are used and their results are intercompared. The horizontal distribution or patterns of latent heat release from the three different heating retrieval methods are very similar. They all can identify the areas of major convective activity [i.e., a well-defined Intertropical Convergence Zone (ITCZ) in the Pacific, a distinct SPCZ] in the global Tropics. The magnitudes of their estimated latent heating release are also in good agreement with each other and with those determined from diagnostic budget studies. However, the major difference among these three heating retrieval algorithms is the altitude of the maximum heating level. The CSH algorithm–estimated heating profiles only show one maximum heating level, and the level varies among convective activity from various geographic locations. These features are in good agreement with diagnostic budget studies. A broader maximum of heating, often with two embedded peaks, is generally derived from applications of the GPROF heating and HH algorithms, and the response of the heating profiles to convective activity is less pronounced. Also, GPROF and HH generally yield heating profiles with a maximum at somewhat lower altitudes than CSH. The impact of different TRMM Microwave Imager (TMI) and precipitation radar (PR) rainfall information on latent heating structures was also examined. The rainfall estimated from the PR is smaller than that estimated from the TMI in the Pacific (TOGA COARE IFA, central Pacific, SPCZ, and east Pacific) and Indian Oceans, causing weaker latent heat release in the CSH algorithm–estimated heating. In addition, the larger stratiform amounts derived from the PR over South America and Australia consequently lead to higher maximum heating levels. Sensitivity tests addressing the appropriate selection of latent heating profiles from the CSH lookup table were performed.

The Energetics of Asian Summer Monsoon

— In this paper, we examine the large-scale balances of kinetic energy, vorticity, angular momentum, heat and moisture over the Asian summer monsoon region. The five year (1986–1990) uninitialized daily analyses for the summer season comprising June, July and August (JJA), produced at the European Centre for Medium Range Weather Forecasts (ECMWF) under the aegis of Tropical Ocean and Global Atmosphere (TOGA) have been considered to carry out the study.¶The following features characterize the Asian summer monsoon domain. It acts as the source of kinetic energy as well as vorticity, and sink of heat and moisture. Kinetic energy and vorticity are produced in the monsoon region and transported horizontally. On the contrary, heat and moisture are transported into the monsoon region. The zonal and meridional components of adiabatic generation of kinetic energy contribute to the production of kinetic energy over the Arabian Sea and Bay of Bengal, respectively. The horizontal advection of relative vorticity is balanced by sub-grid scale generation. The angular momentum generated due to pressure torque (east-west pressure gradient) is balanced by the flux convergence of omega momentum. Further, the angular momentum budget delineates that flux convergence of relative momentum is necessary to maintain the surface westerlies against the friction. The horizontal convergence of heat and moisture facilitates enhancement of diabatic heating, and also leads to the formation of diabatic heat sources, which are crucial to sustain the summer monsoon circulation.

Prediction of sea level anomalies using ocean circulation model forced by scatterometer wind and validation using TOPEX/Poseidon data

Uncertainties in the surface wind field have long been recognized as a major limitation in the interpretation of results obtained by oceanic circulation models. It is especially true in the tropical oceans, where the response to wind forcing is very strong on short time scales. The purpose of this paper is to show that these uncertainties can be greatly reduced by using spaceborne wind sensors that provide accurate measurements on a global basis. Surface winds over the global oceans have been measured by scatterometry since the launch of the European Remote Sensing Satellite (ERS-1) in August 1991 by the European Space Agency, Noordwijk, The Netherlands, and is currently provided by ERS-2, launched in April 1995. The ground-track wind vectors are processed to compute mean weekly surface winds onto a 1/spl deg/ square grid at the Institut Francais de Recherche pour l'Exploitation de la Mer (IFREMER), Plouzane, France. These winds are validated by comparison with the buoy array in the tropical Pacific ocean, showing good agreement. In order to further evaluate this wind field, the three-dimensional (3D) ocean model OPA7 developed at Laboratoire d'Oceanographie Dynamique et de Climatologie, Paris, France, is forced over the tropical oceans by the ERS-derived wind stress fields and by fields from the atmospheric model Arpege/Climat. Selected ocean parameters are defined in order to validate the ocean model results with measurements of the tropical ocean and global atmosphere (TOGA) buoys in the Pacific ocean. The ability of the model to describe the short scale (a few weeks to a few years) oceanic variability is greatly enhanced when the satellite-derived surface forcing is used. Further comparison of the ocean model results with the TOPEX-Poseidon altimeter measurements is presented.

Quasi-2-Day Signals Observed in the Warm Pool Region during TOGA/COARE IOP

During Tropical Ocean and Global Atmosphere (TOGA)/Coupled Ocean and Atmosphere Research Experiment (COARE) Intensive Observing Period (IOP), upward-looking acoustic Doppler current profilers (ADCP) and current meters were moored at two equatorial sites (147°E and 154°E) and two off-equatorial sites (2°N and 2°S, 156°E) in the warm pool region of the western equatorial Pacific. Using current data obtained by these moorings, we have shown that there is a dominant signal with a period of about 2 days from the end of November to the middle of December in 1992, except at the equatorial site on 147°E (Ueki et al., 1998). The energy of this quasi-2-day signal for the meridional current is larger than that for the zonal one and the signal has a high coherence between two off-equatorial sites. In this paper, using band-passed time series of the meridional curerent, we investigated characters of the quasi-2-day signal and attempted to interpret this signal as an equatorially trapped wave. Complex empirical orthogonal function (CEOF) analysis reveals two different phase propagating features between the equatorial and off-equatorial site. One is an upward propagating signal, which is dominant near the surface at two off-equatorial sites, and the other is a downward propagating signal, which is dominant near 200 m at the equatorial site. If one interprets the quasi-2-day signal as an equatorially trapped wave, it is suggested that it cannot be explained as a single wave but can be described as the superimposition of several wave signals. The main part of these signals consists of two signals, one caused by a meteorological forcing and another by another factor in the ocean field.

Intercomparisons of ECMWF ERA and TOGA data with observations for the 1993 Great Flood

The 1993 summer rainfall over the Midwestern United States caused major flooding in the Upper Mississippi and Lower Missouri River basins. In this paper, a monthly comparative study of the analysis products from the European Centre for Medium‐Range Weather Forecasts (ECMWF) with observations is conducted for the period September 1992 to August 1993. The model products include the ECMWF analysis for the Tropical Ocean and Global Atmosphere (TOGA) project and ECMWF reanalysis (ERA) project. Overall, the large‐scale hydrological components (precipitation, evaporation, precipitable water, surface temperature, and relative humidity) appear partially improved from TOGA to ERA. Some internal inconsistencies exist in the assimilation of the ERA data from October 1992 to March 1993, in association with the dramatic prevalence of large‐scale moisture divergence at 0000 UT. The separation of moisture flux into meridional and zonal components indicates that the correct description of the meridional moisture flow is of crucial importance for simulation of anomalously wet conditions. While the spatially averaged monthly fields in ERA and TOGA are reasonable (in particular, the models maintain very good mean flow), the fine‐scale extremes are less accurate. The models do not reproduce observed mesoscale convective complexes due to limitations on resolution and the parameterization of precipitation processes. The new soil hydrology and boundary layer schemes of ERA work better in warm months but with no consistent improvement over TOGA. The terrestrial water budget in ERA is unrealistic, with accumulated model runoff being largely deviated from the observed streamflow. In addition to modeling internal water balance, the lack of the routing procedure and the low spatial resolution of surface hydrology are the other major reasons for this imbalance.

Further Studies of a Prefrontal Convective Rainband During TAMEX IOP 13: Part I:Reflectivity History and Cell Evolution

Radar measurements obtained from both conventional and Doppler radars were used to study the life cycle of a prefrontal convective rainband during TAMEX IOP 13 on 25 June 1987.The conventional radar data were available at 20-min intervals, while Doppler data were available at 7-min intervals. Additionally, surface observations at 30-min intervals taken from nine stations over the west coast and the Taiwan Strait were also used for analysis to determine the approximate positions of the Mei-Yu front and the leading edge of the rainband(gust front). Results show that a prefrontal convective rainband formed in the vicinity of the Mei-Yu front when the system was located far north of the island. As the rainband moved slowly down the central west coast, it began to move away from the front as gust fronts were formed by cells at the leading edge of the system. The convective cells generated low-level cold outflows in the warm sector to the southeast of the front. Part of these cold outflows moved toward the southeast, interacting with the strong moisture-rich southwest monsoon flow to form a gust front. At the same time, the southwestern portion of the front, located 50-60 km west of the coast, continued to lift moist air, generating anew cell along the front. This new cell then traveled to the east at a more rapid speed following the prevailing westerly flow at low levels. It eventually merged with the main(old)cell, thereby prolonging the lifetime of the rainband. The analysis in this study, as a whole, further supports the conceptual model of this rainband reported in the study by Lin et al.(1992) using two volumes of dual-Doppler data obtained from CP-4 and TOGA(Tropical Ocean and Global Atmosphere).

Synoptic aspects of wet and dry conditions in central Australia: observations and GCM simulations for 1 × CO2 and 2 × CO2 conditions

Synoptic climatological patterns that produce anomalous wet conditions in central Australia during the period from September to April have been studied. The analysis was done by using observed daily rainfall data at a number of stations, wind and mean sea level pressure from the European Centre for Medium Range Weather Forecasts (ECMWF), Tropical Ocean and Global Atmosphere (TOGA) data from 1985 to 1991, and the CSIRO 9-level (CSIR09) global climate model (GCM) simulated data for 1 × CO2 and 2 × CO2 experiments. On the basis of rainfall values above 99.5 percentile in observed and simulated data, wet days have been selected to study the synoptic-scale weather systems that produce anomalous wet events in central Australia. As the vast majority of days in central Australia are dry, the same number of days with no rainfall for both observed and simulated conditions have been selected randomly. The observed synoptic climatological patterns have been compared with the results of the control simulation of CSIRO9. A comparison between CSIRO9 simulated synoptic patterns and observed synoptic patterns reveals that the model fairly well captures the synoptic climatological characteristics which produce anomalous wet and contrasting dry weather conditions during the period from September to April. Under enhanced greenhouse experiments, the main features of the synoptic patterns are intensified both for wet and dry conditions, which result in an increase in extreme weather conditions, an increase in rainfall intensity, a spatial expansion of the heavy rainfall region during wet days, and an expansion of the dry area during dry days. During anomalous wet conditions, the low pressure area is intensified, monsoonal winds and southeasterlies are strengthened and strong wind shear over tropical Australia is simulated. During this condition, the monsoon shear line moves poleward particularly over the Northern Territory. In contrast, during dry conditions, the anticyclonic circulation over the continent is strengthened.

Climatic crystal balls

What do anchovy and coffee prices have in common? They both are influenced by weather patterns. And so are a lot of other industries in the world of commodities. A new report from the National Research Council says it's time to protect these economic interests. The report outlines a new 15‐year global research program that would help scientists make better seasonal and interannual climate predictions. Called the Global Ocean‐Atmosphere‐Land System or GOALS, the new program would be an extension of the decade‐long international Tropical Ocean and Global Atmosphere (TOGA) program, which comes to an end this year. Besides studying the climatic effects of tropical phenomena such as the El Niño/Southern Oscillation, the program would expand these types of studies to Earth's higher latitudes and to additional physical processes, such as the effects of changes in upper ocean currents, soil moisture, vegetation, and land, snow, and sea‐ice cover, among others.

Large‐scale circulation associated with westerly wind bursts and deep convection over the western equatorial Pacific

The relationship between deep equatorial convection over the western Pacific and atmospheric circulation during November to February, 1986–1992 is studied using cross correlations between outgoing longwave radiation (OLR) and National Meteorological Center global analyses. We focus on intraseasonal convective events on the 6‐ to 30‐day timescale over two regions: just east of Borneo and over the Tropical Ocean and Global Atmosphere (TOGA) Coupled Ocean‐Atmosphere Response Experiment (COARE) domain to the northeast of New Guinea. Although comparatively little work has been done on this timescale, we show that the bulk of the intraseasonal variability in both convection and low‐level circulation over the tropical western Pacific occurs in this period range. As a comparison with these higher‐frequency events, the evolution of COARE convection on the 30‐ to 70‐day timescale is also considered. The results of the historical data analysis are compared to a case study of deep convection associated with strong surface westerly winds during November 1989. This analysis is meant to serve as a benchmark for future case studies from the Tropical Ocean‐Global Atmosphere COARE experiment and other periods. In general, 6‐ to 30‐day equatorial convection in the regions studied occurs in conjunction with low‐level equatorial westerly wind anomalies, paired anomalous cyclonic circulations straddling the equator, and a strengthening of the sea level pressure gradient along the equator. The increase in the pressure gradient appears most often tied to the simultaneous equatorward movement of high‐pressure systems originating over southeastern Asia and Australia. A surge of trades over the central Pacific also accompanies the development of convection over both study regions. Following the convective peak, the low‐level westerlies slowly decay, as the northern cyclone moves northwestward away from the equator in a track characteristic of a tropical depression. It is also observed that low‐level westerly anomalies occur frequently without deep convection. The vertical structure during convective events along the equator on the 30‐ to 70‐day timescale and over Indonesia in the 6‐ to 30‐day band is baroclinic, with easterly anomalies at upper levels overlying low‐level westerlies. At 200 mbar a strengthened meridional outflow from the OLR signal into a wave train on the equatorward side of the Asian jet is observed to develop following the convective peak, suggesting forcing of this circulation by the convection. Over the COARE domain there is evidence that 6‐ to 30‐day convection often occurs in conjunction with deep westerly flow. It is suggested that these types of events are frequently characterized by vertical propagation of westerlies from the surface to the upper troposphere, as is shown for a case study from November 1989. This westerly burst episode is shown to have many features in common with the “typical” case as defined from historical data.

The Integrated Sounding System: Description and Preliminary Observations from TOGA COARE

An Integrated Sounding System (ISS) that combines state-of-the-art remote and in situ sensors into a single transportable facility has been developed jointly by the National Center for Atmospheric Research (NCAR) and the Aeronomy Laboratory of the National Oceanic and Atmospheric Administration (NOAA/AL). The instrumentation for each ISS includes a 915-MHz wind profiler, a Radio Acoustic Sounding System (RASS), an Omega-based NAVAID sounding system, and an enhanced surface meteorological station. The general philosophy behind the ISS is that the integration of various measurement systems overcomes each system's respective limitations while taking advantage of its positive attributes. The individual observing systems within the ISS provide high-level data products to a central workstation that manages and integrates these measurements. The ISS software package performs a wide range of functions: real-time data acquisition, database support, and graphical displays; data archival and communications; and operational and posttime analysis. The first deployment of the ISS consists of six sites in the western tropical Pacific--four land-based deployments and two ship-based deployments. The sites serve the Coupled Ocean-Atmosphere Response Experiment (COARE) of the Tropical Ocean and Global Atmosphere (TOGA) program and TOGA's enhanced atmospheric monitoring effort. Examples of ISS data taken during this deployment are shown in order to demonstrate the capabilities of this new sounding system and to demonstrate the performance of these in situ and remote sensing instruments in a moist tropical environment. In particular, a strong convective outflow with a pronounced impact of the atmospheric boundary layer and heat fluxes from the ocean surface was examined with a shipboard ISS. If these strong outflows commonly occur, they may prove to be an important component of the surface energy budget of the western tropical Pacific.

Wind profiler dedicated in Indonesia

A dedication ceremony was recently held in Biak, Indonesia, to commemorate the opening of the Biak VHF wind profiler. The wind profiler, which operates at 50 MHz, was constructed by the National Oceanic and Atmospheric Administration's Aeronomy Laboratory in cooperation with the Indonesian National Institute of Aeronautics and Space (LAPAN). The Biak facility completes the NOAA'Colorado University trans‐Pacific wind‐profiler network. Other stations in the network, which is sponsored by the National Science Foundation, are Piura, Peru; Pohnpei, Federated States of Micronesia; and Christmas Island in Kirabati. The Christmas Island facility is supported by NOAA's Tropical Ocean and Global Atmosphere (TOGA) Program Project Office.

Monitoring the 1979‐1985 equatorial Pacific current transports with expendable bathythermograph data

Geostrophic transports of the major equatorial currents, including the Equatorial Undercurrent and the South Equatorial Current, have been estimated on a bimonthly basis in the central and western Pacific over the 1979‐1985 period. This was made possible by a collection of carefully checked expendable bathythermograph (XBT) data and a few hydrocast and conductivity‐temperature‐depth data. This collection considerably improved the number and quality of temperature profiles of the original Institut Français de Recherche Scientifique pour le Développement en Coopération (ORSTOM)‐Scripps Institute of Oceanography tropical Pacific XBT Ship‐of‐Opportunity Program. The temperature profiles were first grouped, independently of longitude, in regions around mean XBT tracks. Dynamic heights were then calculated relative to 400 dB through a T‐S relationship deduced from the climatological Levitus file. Geostrophic currents were calculated along the roughly south‐north oriented Fiji‐Hawaii and New Caledonia‐Japan mean XBT tracks, using a specific technique. This technique, which combines Fourier filtering in the meridional direction and in time, also ensures the continuity across the equator between geostrophic currents deduced from the first and second derivatives of the meridional pressure field. The filter coefficients in the meridional direction were determined through an adjustment of geostrophic currents to directly measured currents, using the mean of data collected along 165°E during six Tropical Ocean and Global Atmosphere (TOGA)‐ORSTOM cruises. Finally, transports of the main equatorial currents were computed in a subjective way between 20°N and 20°S, 0–400 m using monthly charts of geostrophic currents along the two mean XBT tracks. The transports in the central Pacific were compared to the transports derived from the semicontinuous direct current measurements taken during the Hawaii‐Tahiti Shuttle Experiment in 1979‐1980 and during the Line Island Profiling Project‐Pacific Equatorial Ocean Dynamics Experiment in 1982‐1983. Reasonable agreement demonstrates that it is possible to use XBT data for transport indexes of the major equatorial currents in the central and western Pacific.

TOGA Program Office established

The international project office for the Tropical Ocean and Global Atmosphere (TOGA) program—a 10‐year international study on how atmospheric and oceanographic changes in the tropics affect climate patterns worldwide—has been established at the National Oceanic and Atmospheric Administration (NOAA) Environmental Research Laboratories in Boulder, Colo. Rex J. Fleming of NOAA will head this office.Scientists from as many as 36 nations are expected to take part in the TOGA program, which will be responsible for assembling the instrumentation system for monitoring tropical ocean atmospheric and oceanic conditions. Data will be gathered from ocean buoys, satellites, research ships, balloons, and other platforms to support the research.

The U.S.‐PRC planned TOGA‐related Cooperative Research Program for the Western Pacific Region

The National Oceanic and Atmospheric Administration (NOAA), acting as the lead agency in the United States for the Tropical Ocean and Global Atmosphere (TOGA) program of the World Climate Research Program, has negotiated an agreement with its counterpart, the National Bureau of Oceanography (NBO) of the People's Republic of China (PRC) for jointly carrying out a TOGA‐related air‐sea interaction study of the western Pacific region near 165°E. This study was originated under the U.S.‐PRC Protocol on Cooperation in the Field of Marine and Fishery Science and Technology as a contribution to the TOGA Pacific program. In addition to NOAA and NBO the Academia Sinica, the State Meteorological Administration of China, and the National Science Foundation (NSF) of the United States are all active participating agencies. Participation of scientists from other agencies and from the scientific communities of both countries is welcome and encouraged in any part of the cooperative air‐sea study program.

Satellite monitoring of the ocean for global climate research

The study of climate embraces a broad range of timescales, from weeks to millions of years. This paper concentrates on the narrow spectral band ‘several weeks to several decades’ chosen for study in the World Climate Research Programme (WCRP). The programme is divided into three streams, concerned with climate variation on timescales of several weeks, several years and several decades, respectively. The aim is to discover how far it is possible to predict natural climate variation and man’s influence on climate in each of these spectral bands. It is believed that an improved understanding of, and an ability to monitor and model, the World Ocean will be critical to the success of the WCRP in each stream. International experiments are now being planned to achieve these improvements. Satellite monitoring of the ocean offers a number of advantages for these experiments, including the following: global coverage, accuracy and consistency, novel products, tracking and communication. The paper reviews specifications for monitoring the ocean in the context of the WCRP and assesses the extent to which satellite monitoring will help towards meeting these requirements. The special needs of two major projects, the World Ocean Circulation Experiment (WOCE) and the Tropical Ocean and Global Atmosphere (TOGA), are described. The prospects seem good for a new generation of ocean-observing satellites suitable for climate research in the next decade. They will be crucial to the success of the World Climate Research Programme.