Seminars

Seminars / Informal seminars / Lectures by ECMWF Staff and Invited Lecturers

Seminars contribute to our ongoing educational programme and are tailored to the interests of the ECMWF scientific community.

Informal seminars are held throughout the year on a range of topics. Seminars vary in their duration, depending on the area covered, and are given by subject specialists. As with the annual seminar, this may be an ECMWF staff member or an invited lecturer.

The following is a listing of seminars/lectures that have been given this year on topics of interest to the ECMWF scientific community.  See also our past informal seminars

2021

17 February at 14:00

Virtual

 https://ecmwf.bluejeans.com/441189499652

 

Towards operational use of the sub-miliimetre wavelength region

Speaker: Prof Patrick Eriksson (Chalmers University, new ECMWF fellow)

Abstract

The sub-mm region has now been used for limb sounding during 20 years and it will be introduced for operational weather forecasting around year 2024 by the Ice Cloud Imager (ICI). As its name hints, the objective of ICI is to improve the characterisation of ice hydrometeors.

It will essentially close the gap between existing microwave and infrared sensors in terms of sensitivity to ice masses. Also the Arctic Weather Satellite (AWS) will have sub-mm channels.

In this talk, our preparations for ICI and AWS will be summarised with focus on radiative transfer involving  hydrometeors. The efforts range from developing a first useful database of single scattering properties for the sub-mm range to perform full 3D simulations to investigate the impact of horizontal inhomogeneities. Presently the handling of oriented particles, and the polarisation signatures they create, is a main consideration. These activities are also relevant for the existing microwave radiometers, and some of these efforts are reflected in the latest version of RTTOV-SCATT.

29 January
at 10:30

Virtual

Link: https://bluejeans.com/335995869 

Atmospheric blocking in seasonal forecast: where are we now? 

Speaker: Paolo Davini (CNR, Torino)

Abstract

Proper simulation of atmospheric blocking is a tough challenge for numerical modelling, both from the weather and the climate point of view. We here investigate blocking representation in GCMs on a less studied time window, i.e. the seasonal timescale. We assess the simulation and prediction of the winter Northern Hemisphere atmospheric blocking in the ECMWF seasonal prediction systems: blocking statistics from the operational November-initialised seasonal hindcasts are evaluated in three generations of models - System3, System4 and System5 (SEAS5) - and in a series of complementary sensitivity experiments. 

Overall, we observe improvements in the climatological representation of blocking in the most recent model configurations, with reduced bias over North Pacific and Greenland. However, as seen in many GCMs, minor progress is recorded over the European sector.

Interannual variability is also underestimated and is found to be proportional to the climatological frequency, highlighting that a negative bias in blocking frequency implies an underestimation of the interannual variance. 

Predictive skill and signal-to-noise ratio remain low - also in SEAS5 - but interesting significant results are found over Western and Central Europe. Complementary experiments show that the statistics of blocking are improved following atmospheric and oceanic resolution increase. On the other hand, the implementation of stochastic parametrizations tends to displace blocking activity equatorward.

Finally, by comparing seasonal hindcasts with non-initialised climate runs (based on the same model) we highlight that the largest contributor to the chronic underestimation of blocking are persistent errors in the atmospheric model. It is also shown that the SST errors have a larger impact on blocking bias in climate runs than in seasonal runs, and that increased ocean model resolution contributes to improved blocking more effectively in climate runs.

We conclude that - although the predictive skill is still weak - seasonal forecasts can thus be considered a suitable test-bed for model development targeting blocking improvement in climate models.

26 January
at 15:30

Virtual

Link: S_Chen_14 Jan

 

Assessing Predictability and Prediction Skill of the MJO in ECMWF S2S Reforecast

Speaker: Shu-Yi Chen (Department of Atmospheric Sciences, U Washington)

Abstract

The Madden-Julian Oscillation (MJO) has been recognized as a source of predictability of the global weather on the subseasonal-to-seasonal (S2S) time scales. However, the MJO initiation and eastward propagation of its the large-scale convection and precipitation over the Indo-Pacific warm pool remain to be difficult to evaluate quantitatively in NWP and climate models. This study aims to better understand the predictability and model prediction skill of the MJO using a new Large-scale Precipitation Tracking (LPT) method developed by Kerns and Chen (2016, 2020) based on the 20-year TRMM-GPM precipitation data and the ECMWF S2S reforecast from 1998-2018.  The advantage of LPT is its explicit representation of the MJO precipitation in terms of both zonal and meridional structure and variability in time and space. The S2S reforecast reproduced the observed MJO climatology in terms of the total number of the MJO events and seasonal variability very well. However, the timing and location of the MJO precipitation, especially over the tropical Indian Ocean, is less well predicted. In addition to the MJO, general characteristics of multiscale precipitation in the S2S reforecast compared with the TRMM-GPM observation will be discussed.

LT = Lecture Theatre, LCR = Large Committee Room, MZR = Mezzanine Committee Room,
CC = Council Chamber