Retish Senan

Retish Senan
European Center For Medium Range Weather Forecasts · Research Department

Ph.D.

About

46
Publications
9,832
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1,514
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Introduction
I am a Scientist in the Earth System Predictability Section of ECMWF's Research Department. My interests include climate variability on sub-seasonal to interannual timescales and the impact of land-surface and cryosphere on seasonal predictability.​ I also focus on the attribution of seasonal climate anomalies - their forecast error and predictability, as well as improving diagnostic tools for seasonal forecast verification.
Additional affiliations
March 2012 - November 2015
University of Oslo
Position
  • Researcher
October 2007 - February 2011
Norwegian Meteorological Institute
Position
  • Researcher
May 2007 - September 2007
Atomic Energy and Alternative Energies Commission
Position
  • Engineer
Education
August 1999 - February 2004
Indian Institute of Science
Field of study
  • Ocean Modelling
August 1997 - July 1999
Indian Institute of Science
Field of study
  • Ocean Modelling
January 1995 - June 1997

Publications

Publications (46)
Preprint
Sub-seasonal to seasonal (S2S) prediction, especially the prediction of extreme hydroclimate events such as droughts and floods, is not only scientifically challenging but has substantial societal impacts. Motivated by preliminary studies, the Global Energy and Water 20 Exchanges (GEWEX)/Global Atmospheric System Study (GASS) has launched a new ini...
Article
Full-text available
Subseasonal-to-seasonal (S2S) prediction, especially the prediction of extreme hydroclimate events such as droughts and floods, is not only scientifically challenging, but also has substantial societal impacts. Motivated by preliminary studies, the Global Energy and Water Exchanges (GEWEX)/Global Atmospheric System Study (GASS) has launched a new i...
Article
Full-text available
This study examines the climatology and structure of rainfall associated with tropical cyclones (TCs) based on the atmosphere-only Coupled Model Intercomparison Project Phase 6 (CMIP6) HighResMIP runs of the PRocess-based climate sIMulation: AdVances in high resolution modelling and European climate Risk Assessment (PRIMAVERA) Project during 1979–2...
Article
Full-text available
Accurate forecasting of variations in Indian monsoon precipitation and progression on seasonal time scales remains a challenge for prediction centres. We examine prediction skill for the seasonal-mean Indian summer monsoon and its onset in the European Centre for Medium-Range Weather Forecasts (ECMWF) seasonal forecasting system 5 (SEAS5). We analy...
Article
Full-text available
Simulation of past climate is an important tool for the validation of climate models. The comparison with observed daily values allows us to assess the reliability of their projections on climatic extremes in a future climate. The frequency and amplitude of extreme events are fundamental aspects that climate simulations need to reproduce as they ha...
Article
The simulation and prediction of winter Northern Hemisphere atmospheric blocking in the seasonal prediction systems from the European Centre for Medium‐Range Weather Forecasts (ECMWF) is analysed. Blocking statistics from the operational November‐initialised seasonal hindcasts are evaluated in three generations of models ‐ System3, System4 and Syst...
Preprint
Full-text available
Sub-seasonal to seasonal (S2S) prediction, especially the prediction of extreme hydroclimate events such as droughts and floods, is not only scientifically challenging but has substantial societal impacts. Motivated by preliminary studies, the Global Energy and Water Exchanges (GEWEX)/Global Atmospheric System Study (GASS) has launched a new initia...
Article
Full-text available
Land-atmosphere interactions are often interpreted as local effects, whereby the soil state drives local atmospheric conditions, and feedbacks originate. However, non-local mechanisms can significantly modulate land-atmosphere exchanges and coupling. We make use of GCMs at different resolutions (low ∼1° and high ∼0,25°) to separate the two contribu...
Article
Full-text available
In this study, we evaluate a set of high-resolution (25–50 km horizontal grid spacing) global climate models (GCMs) from the High-Resolution Model Intercomparison Project (HighResMIP), developed as part of the EU-funded PRIMAVERA (Process-based climate simulation: Advances in high resolution modelling and European climate risk assessment) project,...
Article
Full-text available
This study investigates how teleconnections linking tropical rainfall anomalies and wintertime circulation in the northern extra-tropics are represented in historical simulations for the period 1950–2010 run by partners of the EU-funded PRIMAVERA project, following the HighResMIP protocol of CMIP6. The analysis focusses on teleconnections from the...
Article
Full-text available
Previous studies have shown that the number, intensity and structure of simulated tropical cyclones (TCs) in climate models get closer to the observations as the horizontal resolution is increased. However, the sensitivity of tropical cyclone precipitation and moisture budget to changes in resolution has received less attention. In this study, we u...
Article
Full-text available
Future changes in tropical cyclone properties are an important component of climate change impacts and risk for many tropical and midlatitude countries. In this study we assess the performance of a multimodel ensemble of climate models, at resolutions ranging from 250 to 25 km. We use a common experimental design including both atmosphere‐only and...
Article
Full-text available
Finer grids in global climate models could lead to an improvement in the simulation of precipitation extremes. We assess the influence on model performance of increasing spatial resolution by evaluating pairs of high‐ and low‐resolution forced atmospheric simulations from six global climate models (generally the latest CMIP6 version) on a common 1°...
Article
Full-text available
Past studies have concluded that climate models of previous generations tended to underestimate the large warming trend that has been observed in summer over western Europe in the last few decades. The causes of this systematic error are still not clear. Here, we investigate this issue with a new generation of climate models and systematically expl...
Article
Full-text available
A multi-model, multi-resolution set of simulations over the period 1950-2014 using a common forcing protocol from CMIP6 HighResMIP have been completed by six modelling groups. Analysis of tropical cyclone performance using two different tracking algorithms suggests that enhanced resolution towards 25 km typically leads to more frequent and stronger...
Article
Full-text available
The Tibetan Plateau (TP) region, often referred to as the Third Pole, is the world's highest plateau and exerts a considerable influence on regional and global climate. The state of the snowpack over the TP is a major research focus due to its great impact on the headwaters of a dozen major Asian rivers. While many studies have attempted to validat...
Article
Full-text available
This study undertakes a multi-model comparison with the aim to describe and quantify systematic changes of the global energy and water budgets when the horizontal resolution of atmospheric models is increased and to identify common factors of these changes among models. To do so, we analyse an ensemble of twelve atmosphere-only and six coupled GCMs...
Article
Full-text available
The Tibetan Plateau (TP) region, often referred to as the Third Pole and, is the world highest plateau and exerts a considerable influence on regional and global climate. The state of the snowpack over the TP is a major research focus due to its great impacts on the headwaters of a dozen major Asian rivers. While many studies have attempted to vali...
Article
Full-text available
This paper presents atmosphere-only and coupled climate model configurations of the European Centre for Medium-Range Weather Forecasts Integrated Forecasting System (ECMWF-IFS) for different combinations of ocean and atmosphere resolution. These configurations are used to perform multi-decadal ensemble experiments following the protocols of the Hig...
Article
Full-text available
This paper presents atmosphere-only and coupled climate model configurations of the European Centre for Medium-Range Weather Forecasts Integrated Forecast System (ECMWF-IFS) for different combinations of ocean and atmosphere resolution. These configurations are used to perform multi-decadal ensemble experiments following the protocols of the High R...
Article
Full-text available
We show how factorial regression can be used to analyse numerical model experiments, testing the effect of different model settings. We analysed results from a coupled atmosphere–ocean model to explore how the different choices in the experimental set-up influence the seasonal predictions. These choices included a representation of the sea ice and...
Article
Full-text available
The springtime snowpack over the Himalayan-Tibetan Plateau (HTP) region and Eurasia has long been suggested to be an influential factor on the onset of the Indian summer monsoon. To assess the impact of realistic initialization of springtime snow over HTP on the onset of the Indian summer monsoon, we examine a suite of coupled ocean-atmosphere 4-mo...
Article
Full-text available
The winter 2009/2010 was remarkably cold and snowy over North America and across Eurasia, from Europe to the Far East, coinciding with a pronounced negative phase of the North Atlantic Oscillation (NAO). While previous studies have investigated the origin and persistence of this anomalously negative NAO phase, we have re-assessed the role that the...
Article
Full-text available
We demonstrate how factorial regression can be used to analyse numerical model experiments, testing the effect of different model settings. We analysed results from a coupled atmosphere-ocean model to explore how the different choices in the experimental set-up influence the seasonal predictions. These choices included a representation of the sea-i...
Article
The NORINDIA project sheds light on how climate change could affect monsoons, droughts, and glaciers in northern India.
Data
As in Fig. 4, but for the November 15 start date, for (a) sea level pressure and (b) 200-hPa wind speed at the 30-day lead time. Only values significant at the 95 % confidence level are shown. Units are hPa and m/s, respectively.
Data
As in Fig. 5, but for the November 15 start date. Indices are shown for Series 1 (blue crosses and circled cross for ensemble-mean), Series 2 (same in red), ERAINT (orange circles), and for the ensemble-mean VAREPS forecasts
Article
Full-text available
The influence of the snowpack on wintertime atmospheric teleconnections has received renewed attention in recent years, partially for its potential impact on seasonal predictability. Many observational and model studies have indicated that the autumn Eurasian snow cover in particular, influences circulation patterns over the North Pacific and North...
Article
Climatological winds over the equatorial Indian Ocean (EqlO) are westerly most of the year. Twice a year, in April-May ("spring") and October-December ("fall"), strong, sustained westerly winds generate eastward equatorial jets in the ocean. There are several unresolved issues related to the equatorial jets. They accelerate rapidly to speeds over l...
Article
Full-text available
The autumn and early winter atmospheric response to the record-low Arctic sea ice extent at the end of summer 2007 is examined in ensemble hindcasts with prescribed sea ice extent, made with the European Centre for Medium-Range Weather Forecasts state-of-the-art coupled ocean–atmosphere seasonal forecast model. Robust, warm anomalies over the Pacif...
Article
Full-text available
Current seasonal forecast models involve simple schemes for representing sea ice, such as imposing climatological values. The spread of ensemble forecasts may in principle be biased due to common boundary conditions prescribed in the high latitudes. The degree of sensitivity in the 2-metre temperature, associated with seasonal time scales and the s...
Article
Current seasonal forecast models involve simple schemes for representing sea ice, such as imposing climatological values. The spread of ensemble forecasts may in principle be biased due to common boundary conditions prescribed in the high latitudes. The degree of sensitivity in the 2-metre temperature, associated with seasonal time scales and the s...
Article
Sea-ice has a memory of several months and influences the atmosphere by modifying exchange of heat, moisture and momentum at the ocean-atmosphere interface, and by changing the albedo in summer. Thus, being a slowly evolving component of the Earth's climate, sea-ice could be very important for seasonal weather forecasting, especially in the polar r...
Article
Most coupled ocean-atmosphere models used for seasonal forecasting prescribe climatological conditions for sea-ice, which may imply that the predictions are biased and have too weak spread. In the coupled operational seasonal forecast model at ECMWF (IFS/HOPE), the sea-ice normally is relaxed towards climatology after the first month. We present re...
Article
Exploring the relationship between the Arctic sea-ice and mid-latitude storm frequency
Article
Full-text available
New satellite and in situ observations show large intraseasonal (10-60 day) variability of surface winds and upper-ocean current in the equatorial Indian Ocean, particularly in the east. An ocean model forced by the Quick Scatterometer (QuikSCAT) wind stress is used to study the dynamics of the intraseasonal zonal current. The model has realistic u...
Article
Full-text available
The National Institute of Oceanography, Goa, deployed moorings with several subsurface current meters at 0°, 93°E (in February 2000) and 0°, 83°E (in December 2000) in the eastern Indian Ocean. Observed meridional current at all depths has a 10- to 20-day (or biweekly) variability that is distinct from longer period (20- to 60-day) subseasonal vari...
Thesis
Full-text available
Climatological winds over the equatorial Indian Ocean (EqlO) are westerly most of the year. Twice a year, in April-May ("spring") and October-December ("fall"), strong, sustained westerly winds generate eastward equatorial jets in the ocean. There are several unresolved issues related to the equatorial jets. They accelerate rapidly to speeds over l...
Article
Full-text available
[1] The zonal wind in the equatorial Indian Ocean (EqIO) is westerly almost throughout the year. It has a strong semiannual cycle and drives the spring and fall Wyrtki jets. In addition, high resolution daily satellite winds show “westerly wind bursts” lasting 10–40 days, associated with atmospheric convection in the eastern EqIO. These bursts have...
Article
Full-text available
The space-time evolution of the ocean and atmosphere associated with 1998–2000 monsoon intraseasonal oscillations (ISO) in the Indian Ocean and west Pacific is studied using validated sea surface temperature (SST) and surface wind speed from the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager, and satellite outgoing longwave radiation....
Article
Full-text available
Observed upper ocean currents south of Sri Lanka exhibit large, irregular fluctuations with periods of days to weeks. An ocean model driven by daily surface winds is able to reproduce the observed fluctuations. We find from model experiments that low frequency (30–50 day) intraseasonal variability (ISV) arises when Rossby waves radiated from the ea...

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Projects

Projects (3)
Archived project
Project
PRIMAVERA is a European Union H2020 project that aims to develop a new generation of advanced and well-evaluated high-resolution global climate models, capable of simulating and predicting regional climate with unprecedented fidelity, for the benefit of governments, business and society in general. https://www.primavera-h2020.eu/