Nino Years Research Articles

How well do climate models simulate atmospheric teleconnctions over the North Pacific and East Asia associated with ENSO?

During the El Nino and La Nina mature phase, atmospheric teleconnections over the North Pacific and East Asia vary considerably on sub-seasonal time scales, and are strongly phase-locked to the sub-seasonal evolution. In this study, we investigate how well climate models that participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) simulate the sub-seasonal evolution of teleconnections over the North Pacific and East Asia associated with El Nino-Southern Oscillation (ENSO). In the observations, there is a prominent anticyclone anomaly over the Kuroshio extension region (i.e. Kuroshio anticyclone), which significantly affects East Asian climate in the early winter (November–December) of El Nino years. However, in January, the Kuroshio anticyclone suddenly disappears, and a cyclonic flow dominates over the North Pacific. It is found here that the CMIP5 models simulate the overall extratropical teleconnection patterns, but they fail to reproduce some of these sub-seasonally-varying features in atmospheric circulation. For example, the models tend to simulate a weaker Kuroshio anticyclone in the early winter during El Nino phases, and fail to capture the abrupt decay of the Kuroshio anticyclone in the late winter. We demonstrate here that these systematic errors in ENSO teleconnection can be explained by systematic errors in tropical precipitation associated with ENSO. That is, negative precipitation anomalies over the western North Pacific (WNP) are too weak in the models compared to that in the observations, and their amplitude tends to be strengthened from December to the following January, while they are weakened in the observations. In addition, analyses on the inter-model diversity strongly support that relative magnitudes of WNP and central Pacific precipitation anomalies are critical for determining sub-seasonal evolution of ENSO teleconnections over the North Pacific and East Asia.

Interannual to decadal variation of spring sea level anomaly in the western South China Sea

Satellite observations of sea level anomalies (SLA) from January 1993 to December 2012 are used to investigate the interannual to decadal changes of the boreal spring high SLA in the western South China Sea (SCS) using the Empirical Orthogonal Function (EOF) method. We find that the SLA variability has two dominant modes. The Sea Level Changing Mode (SLCM) occurs mainly during La Nina years, with high SLA extension from west of Luzon to the eastern coast of Vietnam along the central basin of the SCS, and is likely induced by the increment of the ocean heat content. The Anticyclonic Eddy Mode (AEM) occurs mainly during El Nino years and appears to be triggered by the negative wind curl anomalies within the central SCS. In addition, the spring high SLA in the western SCS experienced a quasi-decadal change during 1993–2012; in other words, the AEM predominated during 1993–1998 and 2002–2005, while the La Nina-related SLCM prevailed during 1999–2001 and 2006–2012. Moreover, we suggest that the accelerated sea level rise in the SCS during 2005–2012 makes the SLCM the leading mode over the past two decades.

Intra-seasonal and Inter-annual variability of Bowen Ratio over rain-shadow region of North peninsular India

Intra-seasonal and inter-annual variability of Bowen Ratio (BR) have been studied over the rain-shadow region of north peninsular India during summer monsoon season. Daily grid point data of latent heat flux (LHF), sensible heat flux (SHF) from NCEP/NCAR Reanalysis for the period 1970–2014 have been used to compute daily area-mean BR. Daily grid point rainfall data at a resolution of 0.25° × 0.25° from APHRODITE’s Water Resources for the available period 1970–2007 have been used to study the association between rainfall and BR. The study revealed that BR rapidly decreases from 4.1 to 0.29 in the month of June and then remains nearly constant at the same value (≤0.1) in the rest of the season. High values of BR in the first half of June are indicative of intense thermals and convective clouds with higher bases. Low values of BR from July to September period are indicative of weak thermals and convective clouds with lower bases. Intra-seasonal and inter-annual variability of BR is found to be inversely related to precipitation over the region. BR analysis indicates that the land surface characteristics of the study region during July–September are similar to that over oceanic regions as far as intensity of thermals and associated cloud microphysical properties are concerned. Similar variation of BR is found in El Nino and La Nina years. During June, an increasing trend is observed in SHF and BR and decreasing trend in LHF from 1976 to 2014. Increasing trend in the SHF is statistically significant.

Imprint of the ENSO on rainfall and latent heating variability over the Southern South China Sea from TRMM observations

Analyses of the Tropical Rainfall Measuring Mission (TRMM) datasets revealed a prominent interannual variation in the convective-stratiform rainfall and latent heating over the southern South China Sea (SCS) during the winter monsoon between 1998 and 2010. Although the height of maximum latent heating remained nearly constant at around 7 km in all of the years, the year-to-year changes in the magnitudes of maximum latent heating over the region were noticeable. The interannual variations of the convective- stratiform rainfall and latent heating over the southern SCS were highly anti-correlated with the Nino-3 index, with more (less) rainfall and latent heating during La Nina (El Nino) years. Analysis of the large-scale environment revealed that years of active rainfall and latent heating corresponded to years of large deep convergence and relative humidity at 600 hPa. The moisture budget diagnosis indicated that the interannual variation of humidity at 600 hPa was largely modulated by the vertical moisture advection. The year-to-year changes in rainfall over the southern SCS were mainly caused by the interannual variations of the dynamic component associated with anomalous upward motions in the middle troposphere, while the interannual variations of the thermodynamic component associated with changes in surface specific humidity played a minor role. Larger latent heating over the southern SCS during La Nina years may possibly further enhance the local Hadley circulation over the SCS in the wintertime.

Vegetation dynamics in Qinling-Daba Mountains in relation to climate factors between 2000 and 2014

Using the Moderate Resolution Imaging Spectroradiometer-normalized difference vegetation index (NDVI) dataset, we investigated the patterns of spatiotemporal variation in vegetation coverage and its associated driving forces in the Qinling-Daba (Qinba) Mountains in 2000–2014. The Sen and Mann–Kendall models and partial correlation analysis were used to analyze the data, followed by calculation of the Hurst index to analyze future trends in vegetation coverage. The results of the study showed that (1) NDVI of the study area exhibited a significant increase in 2000–2014 (linear tendency, 2.8%/10a). During this period, a stable increase was detected before 2010 (linear tendency, 4.32%/10a), followed by a sharp decline after 2010 (linear tendency,–6.59%/10a). (2) Spatially, vegetation cover showed a “high in the middle and a low in the surroundings” pattern. High values of vegetation coverage were mainly found in the Qinba Mountains of Shaanxi Province. (3) The area with improved vegetation coverage was larger than the degraded area, being 81.32% and 18.68%, respectively, during the study period. Piecewise analysis revealed that 71.61% of the total study area showed a decreasing trend in vegetation coverage in 2010–2014. (4) Reverse characteristics of vegetation coverage change were stronger than the same characteristics on the Qinba Mountains. About 46.89% of the entire study area is predicted to decrease in the future, while 34.44% of the total area will follow a continuously increasing trend. (5) The change of vegetation coverage was mainly attributed to the deficit in precipitation. Moreover, vegetation coverage during La Nina years was higher than that during El Nino years. (6) Human activities can induce ambiguous effects on vegetation coverage: both positive effects (through implementation of ecological restoration projects) and negative effects (through urbanization) were observed.

Impact des saisons, des années El Nino/La Nina et des précipitations sur la morbi-mortalité des accidents vasculaires cérébraux à Kinshasa

The significant impact of seasonality and climate change on stroke-related morbidity and mortality is well established, however, some findings on this issue are conflicting. The objective was to determine the impact of gender, age, season, year of admission, temperature, rainfall and El Nino phenomenon on ischemic and hemorrhagic strokes and fatal cases of stroke. The study was carried out at the teaching hospital of Kinshasa, DRC, between January 1998 and December 2004. Rainy and dry seasons, elevated temperatures, indices of rainfalls El Nino years 1998, 2002 and 2004, but La Nina years 1999-2000 and neutral/normal years 2001 and 2003 were defined. Among 470 incident strokes, 34.5% of victims (n=162) died. Traditional seasons (small dry season, small rainy season, great dry season, great rainy season) and temperatures did not significantly (P>0.005) impact on stroke incidence. However, there was a positive association between the decrease in rainfall, El Nino, and incident ischemic strokes, but a significant positive association between the increase in rainfall, La Nina, and incident hemorrhagic strokes. Using logistic regression analysis, age ≥ 60 years (OR: 1.7, 95% CI: 1.2-2.5; P=0.018) and El Nino years (OR: 2, 95% CI: 1.2-3.3; P=0.009) were identified as the independent predictors of fatal strokes. Early warning systems should be developed to predict the impact of seasons and climate variability on stroke morbidity and mortality.

ENSO impacts on temperature over South Korea

The climatic impact of the two phases (warm/cold) of ENSO phenomena on monthly temperature patterns over South Korea is examined based on the composite and harmonic analysis. The core regions, namely the north-east region and the south-west region, were identified with a high-level spatial coherence and temporal consistency, which represent the geographical extent and magnitude of the response of the ENSO forcing to the temperature patterns. For the both regions, the temperature anomalies in El Nino year are below normal for summer through fall of the ENSO year and above normal for winter through spring of the following year. The spatial coherence rates of each region are 0.95, 0.97 and the temporal consistency rates are 0.70/0.70 (cold/warm) and 0.70/0.80 (cold/warm), respectively. On the other hand, in case of the cold events, the temperature anomalies for the both regions are above normal for summer through fall of the episode year and below normal for winter through spring of the following year. The spatial coherence rates of each region are 0.98, 0.99 and the temporal consistency rates are 1.00/0.78 (warm/cold) and 0.89/0.78 (warm/cold), respectively. According to the comparative analyses for both extreme episodes in two core regions, the El Nino/La Nina–temperature relationships show reverse patterns of sign, negative–positive and positive–negative temperature anomalies, respectively. Based on the results of annual cycle analysis, Mann–Whitney U test and cross-correlation analysis, the cold–warm anomalies during the warm event years are more remarkable and significant than the warm–cold departures during the cold event years. Consequently, the climatic teleconnective pattern between the extreme phase of SO and mid-latitude temperature is identified over South Korea.

Wintertime precipitation variability over the Arabian Peninsula and its relationship with ENSO in the CAM4 simulations

The climate variability on Earth is strongly influenced by the changes in the Sea Surface Temperature (SST) anomalies in the tropical oceans. More specifically, the inter-annual climate variability in the tropics as well as extra-tropical areas has large impact due to the anomalous SSTs in the tropical Pacific coupled with the El Nino Southern Oscillation (ENSO) through atmospheric teleconnections. However, the effect of ENSO on Middle Eastern region, specifically the Arabian Peninsula (AP) is marginally explored in previous studies. Hence, this study explicitly focuses on the assessment of ENSO variability and its winter climate teleconnections to the AP using the Community Atmospheric Model Version 4.0 (CAM4) simulations and Reanalysis datasets. ENSO teleconnections are also evaluated based on two sensitivity experiments (ENSO-related and ENSO-unrelated) using the CAM4 model. It is observed that during El Nino years the peninsular region receives more rainfall through enhanced moisture transport associated with anomalous westerly winds from adjoining Seas. The Rossby wave energy propagation in the atmosphere underlies important teleconnections involving ENSO. It is also noticed that there exist a distinct change in the phase of the Rossby wave pattern during El Nino and La Nina years which further causes the shift in the position of the jet stream over the Middle East.

Ekman Pumping and Mixed Layer Depth Variability over the Indo-Pacific Oceans during the El Nino and IOD Events

The following study addresses the variability of Mixed Layer Depth (MLD) and Ekman pumping (W EK ) during the extreme El Nino and Indian Ocean Dipole (IOD) over the Indo-Pacific regions. Monthly anomalies considering the climatology of the period of 1980 through 2011 show that during the El Nino years, Ekman suction (positive Ekman pumping) is replaced with Ekman pumping (negative Ekman pumping) in the tropical eastern Pacific Ocean (88˚W-90˚W and 13˚S-15˚S) resulting in positive MLD anomalies, and the strong Ekman pumping may be the source for the deepened thermocline during El Nino. In the La Nina events shallow MLD exits in the tropical eastern Pacific Ocean, due to positive Ekman pumping. During the positive IOD (PIOD) events in the south eastern Indian Ocean (97˚E-100˚E and 2˚S-5˚S) MLD becomes shallow and positive Ekman pumping anomalies occur. During the negative IOD (NIOD) years opposite signs take place. Composite events of El Nino are compared with those of IOD, showing more Ekman pumping anomalies during IOD events as against less deviation in SST.

Distribution pattern of juveniles of the pink shrimps Farfantepenaeus brasiliensis (Latreille, 1817) and F. paulensis (Pérez-Farfante, 1967) on the southeastern Brazilian coast

The spatio-temporal distribution of juveniles of the pink shrimps Farfantepenaeus brasiliensis (Latreille, 1817) and Farfantepenaeus paulensis (Perez-Farfante, 1967) in the Ubatuba region (SP) was investigated. Sampling was performed in the bays of Ubatumirim (UBM), Ubatuba (UBA) and Mar Virado (MV). A total of 2,018 F. brasiliensis and F. paulensis were collected. The largest catch of juveniles of both species occurred in UBA (N = 867), followed by UBM (N = 729) and MV (N= 422). The bottom sediment in MV had the highest silt and clay content, which explains the negative correlation of the substrate with the abundance of both species. Temperature was positively correlated with the abundance of both species. Juveniles were highly abundant in shallower areas in the summer of 1998. The high rainfall in this El Nino period may have lowered the salinity in estuarine waters and led the shrimps to move to coastal areas in search of higher salinities such as in bays. With this unusually early reduction in salinity, individuals migrated to the bay before the closed season began and thus became more exposed to fishing. We confirmed that monitoring environmental variations, especially in El Nino years, is essential for understanding the distribution patterns of juveniles of both species.

Índice estandarizado de precipitación (SPI) para la caracterización de sequías meteorológicas en la cuenca del río Dagua-Colombia

The Standardized Precipitation Index (SPI) characterizes meteorological droughts of a place, by quantifying the deficit of rainfall in different time periods. Negative SPI values represents drought, while positive values indicate wet periods. The results suggest that negative SPI periods coincide with El Nino years: 82-83, 91-92 and 97-98. The 91-92 event had the largest impact on the region. These results indicate that the most severe droughts in the basin of Dagua, were presented at the quarters of Dec- Jan-Feb, Jan-Feb-Mar, Jun-Jul-Aug and Jul-Aug-Sep. The results have been obtained with geostatistical techniques, and are a basic input to formulate adaptation strategies and ensure food sovereignty of small farmers against drought.

Analysis of Long-Term Meteorological Observation for Weather and Climate Fundamental Data over the Northern Tibetan Plateau

Meteorological observation plays a critical role in climatic study, and in situ measurements are the foundation of meteorological observation, especially in the Tibetan Plateau, the surface of which is fairly complex. Several field stations in the Northern Tibetan Plateau, which features relatively homogeneous surface, were selected as the study area. A detailed description on the significance of site observation for climate prediction was given in this paper. Data from weather stations can be used to verify satellite data and provide parameters for initial mode field in the study of weather and climate changes. The field observation data in the Northern Tibetan Plateau from 2001 to 2013 is analyzed. The results show that in El Nino year, values of land surface temperature (Ts), air temperature (Ta) and wind speed are all greater than their mean values and that soil moisture values are lower than the averaged, while the opposite is the case in La Nina year. The warming rate in the Northern Tibetan Plateau is greater than that in global areas. The diurnal variations ofTsandTaare various in different seasons and underlying surfaces, with the diurnal variations greater in spring, and less in summer and autumn. Furthermore, the diurnal variation in the area with drier underlying surface is more obvious than that in area with moist surface.

Summer SST anomalies in the Indian Ocean and the seasonal timing of ENSO decay phase

ENSO affects the tropical Indian Ocean (TIO) SST in winter-spring in ENSO decay years through an ENSO-induced ‘atmospheric-bridge’ and subsequent air-sea coupling processes. The interdecadal delay of El Nino decay phase has been related to a warming change in the summer TIO since 1970s. A physical linkage between the summer SST anomalies over the TIO and the timing of ENSO decay phase is however still unclear. This study uses multi-source data to distinguish ‘later-decay’ from ‘normal-decay’ El Nino/La Nina events, and performs diagnostic analysis of the changes in various thermodynamic and dynamic processes due to later-decay ENSO for quantifying the partial contribution by each of these processes to the summer SST changes over the TIO. The results show that, at both the interannual and interdecadal timescales, the significant warmer and colder SST anomalies in the spring TIO in later-decay El Nino and La Nina years respectively can persist into summer. Most of the ENSO-induced atmospheric-bridge-related processes contribute positively to the TIO SST changes in summer due to later-decay of ENSO, as they do in spring during normal-delay ENSO year. The exceptions are the surface wind-evaporation-mechanism and sensible heat-flux anomalies in summer, which always contribute negatively to the summer SST anomalies over most parts of the TIO. The negative contributions from these two processes in summer exist no matter whether there is a weakening or strengthening surface wind due to later-decay of ENSO events. Generally, the presence of five later-decay El Nino events after the 1970s is mainly responsible for the observed interdecadal summer TIO warming in recent decades.

The change features of the west boundary bifurcation line of the North Equatorial Current in the Pacific

The equatorial Current in the North Pacific (NEC) is an upper layer westward ocean current, which flows to the west boundary of the ocean, east of the Philippines, and bifurcates into the northerly Kuroshio and the main body of the southerly Mindanao current. Thus, NEC is both the south branch of the Subtropical Circulation and the north branch of the Tropical Circulation. The junction of the two branches extends to the west boundary to connect the bifurcation points forming the bifurcation line. The position of the North Pacific Equatorial Current bifurcation line of the surface determines the exchange between and the distribution of subtropical and tropical circulations, thus affecting the local or global climate. A new identification method to track the line and the bifurcation channel was used in this study, focusing on the climatological characteristics of the western boundary of the North Equatorial Current bifurcation line. The long-term average NEC west boundary bifurcation line shifts northwards with depth. In terms of seasonal variation, the average position of the western boundary of the bifurcation line is southernmost in June and northernmost in December, while in terms of interannual variation, from spring to winter in the years when ENSO is developing, the position of the west boundary bifurcation line of NEC is relatively to the north (south) in EI Nino (La Nina) years as compared to normal years.

Interannual variability of thermal front west of Luzon Island in boreal winter

Interannual variability of thermal front west of Luzon Island during the winter of 1993–2013 is examined with the method of singular value decomposition (SVD) and a suite of satellite measurements in this paper. It is found that both the area and intensity of the thermal front west of Luzon Island show apparent interannual variability. Further study based on SVD shows that the interannual variability of the thermal front is highly associated with El Nino and Southern Oscillation (ENSO), and the correlation coefficient between Nino3.4 index and the first Principal Component (PC1) of thermal front can reach–0.65. The mechanism can be described as follows. In El Nino (La Nina) years, the East Asian winter monsoon (EAWM) is weakened (enhanced), inducing weaker (stronger) local wind stress curl (WSC) west of Luzon Island, and resulting in weakened (enhanced) Luzon cold eddy, which finally leads to the weakening (enhancement) of the thermal front.

Integrated Resource Mapping of Wave and Wind Energy

A common platform of wind and wave energy conversion should reduce upfront as well as maintenance costs relative to wave and offshore wind energy converters installed separately. For this cost reduction to happen, temporally integrated resource estimate of wind and wave at a given coordinate is desirable so that areas of high wind and wave energy convergences can be identified. In this paper, a combined energy resource potential of wave and wind modeling procedure is shown using the California coast as a case study, mapped for three distinct years: a “calm” year, an El Nino year, and a recent “normal” year allowing model analyses of a range of possible weather conditions and sea states along the coastline.

Trends and Anomalies in Extreme Climate Indices and Influence of El Niño and La Niña over Pranhita Catchment in Godavari Basin, India

AbstractHydrologic design and planning requires dealing with extremes in precipitation and temperature events caused due to climate change. Long-term trends and variability in 20 extreme climate indices (ECIs) and the influence of El Nino and La Nina over the Pranhita catchment, India are studied for the period of 1951–2013. An overall increase in daily precipitation, more intense rain, and an increase in continuous dry days are observed; however, total rain shows a negative trend. A warming trend is observed with an increase in dry days, warm days, and hot nights, and a decrease in the frequency of cool days and nights. Observed +ve trends for maximum and minimum temperatures are 0.7 and 0.8°C, respectively. El Nino years resulted in −ve anomaly and +ve anomaly was observed during La Nina years for the majority of ECIs. The association between ENSO and yearly temperature indices is found to be weak in comparison with precipitation indices. The study confirmed the multimodal nature of precipitation during...

El Niño and Indian summer monsoon rainfall relationship in retrospective seasonal prediction runs: experiments with coupled global climate models and MMEs

The relationship between the warm phase of El Nino southern oscillation (ENSO) and Indian summer monsoon rainfall is explored through seven coupled global climate models (CGCMs), which are semi-operational at APEC Climate Center (APCC). The 23-year (1983–2005) hindcast datasets of individual model ensembles derived from May initial conditions for southwest monsoon season (JJAS) are utilized to find out the simultaneous influence of El Nino–ISMR relationship in 1990s, which is observed to be weaker than present decades. The hindcast of ISMR climatology derived from seven individual models viz. APCC, NCEP, POAMA, SINT, SUT1, PNU and UHT1 appears to be reasonably simulated; in particular, about 50 % of mean departure is evident in most CGCMs. In addition, four of six El Nino years during the aforementioned period are well depicted in most of the CGCMs, while the years 1994 and 1997 are not represented well by these seven individual models. The warm SST anomaly aligned with surplus precipitation over tropical equatorial Pacific region simulated using APCC, NCEP, POAMA, SINT and SUT1 is relatively better than that simulated in PNU and UHT1 and it is closer to observation. The El Nino–ISMR teleconnection skills both monthly to seasonal scale are very poor in PNU as well as UHT1 and their RMSEs are 3.84 and 3.77 higher than APCC, NCEP, POAMA, SINT and SUT1 models. The authors developed two Multi-Model Ensembles (MMEs) that were simple composites of ensemble forecast from seven models (APCC, NCEP, POAMA, SINT, SUT1, PNU and UHT1) referred to as MME1, and from five models (APCC, NCEP, POAMA, SINT and SUT1) are referred to as MME2. Importantly, the one-month lead MME2 prediction of anomaly correlation coefficient (ACC) and its adverse impacts is reasonably better than MME1 prediction. However, there are some limitations in capturing SST forcing fields over Indian Ocean region in both MMEs. Among the seven models, SINT has the highest pattern correlation of precipitation over the Indian monsoon region.

Rainfall Variability in the Shoalhaven River Catchment and its Relation to Climatic Indices

The management of the Shoalhaven River, in southern Australia, is important for water supply and floodplain issues including flooding and acid sulphate soil management. Analysis of the spatial variation in rainfall was performed in order to assess temporal and geographical variability within this east Australian catchment and its relationship to large-scale climate drivers, such as the Southern Oscillation Index (SOI), the Interdecadal Pacific Oscillation (IPO), particularly in its negative phase, and the Atmospheric Blocking Index. A total of 141 rain gauges located within a 10-km buffer around the perimeter of the Shoalhaven catchment provided rainfall information spanning from 1885 to 2011. The highest annual mean was in 1950 (1670 mm), with other wet years in 1959 (1564 mm) and 1974 (1571 mm), and the lowest mean was in 1982 (440 mm) and 1944 (446 mm). In the calendar year of 2011 (922 mm), March accounted for 14.5 % of the annual rainfall while April, May and September accounted for less than 5 %. Interpolation between rainfall gauges indicated that the highest rainfall areas occurred in the lower catchment, adjacent to the coast, where there is a pronounced orographic effect. Although it has been implied that drought in this region is related to El Nino years, there was only a weak positive correlation between catchment rainfall and SOI which was moderately enhanced during negative phases of IPO. Seasonal influence of Atmospheric Blocking could be detected on the rain-gauge records during April–October. These findings provide insights not only for this catchment but also for other parts of southeast Australia, implying that coastal catchments may not have strong linkages to key climatic drivers as previously inferred, and management actions and planning on the basis of these climatic indices are not recommended.

Interannual variability of upper ocean stratification in Bay of Bengal: observational and modeling aspects

The annual cycle and interannual variability of stratification in Bay of Bengal (BoB) are studied using both observations and Global Ocean Data Assimilation System (GODAS) analysis during 2003–2012. Annual cycle of stratification and sea surface temperature (SST) evolve coherently, highlighting its role on modulating air-sea interaction over this climatologically important region. Spatial distribution of stratification shows strong seasonality in ARGO observations, whereas it is highly underestimated in GODAS with highest discrepancies during fall and spring. The annual cycle of sea surface salinity (SSS) in GODAS is out of phase with observations implying potential feedbacks. During La Nina years, SSS drop in fall and winter and are lesser than those reported during El Nino years. All these features are misrepresented in GODAS. As stratification modulates air-sea interaction over BoB especially during El Nino and La Nina years, such misrepresentation of ocean stratification may lead to unrealistic thermocline-SST coupling in the models. The mean stratification and its interannual variability in GODAS are weaker than observed even though interannual variability in freshwater flux (P-E) is higher in GODAS. Detailed analysis of GODAS with in situ observations reveals that upper ocean current shear (vertical) is overestimated in GODAS, leading to unrealistically strong mixing which is primarily responsible for the deeper penetration of surface warm and freshwater resulting weaker stratification. As GODAS is used to initialize the ocean component of the coupled forecasting system for seasonal prediction of Asian monsoon, proper representation of stratification is essential. This study advocates the need of accurate representation of upper ocean salinity in GODAS for improved stratification. We speculate that improved stratification and mixing in the BoB improve summer monsoon forecast.