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Paolo Andrezorri – Constraining aerosol representations through interactions with clouds in the ECMWF’s Integrated Forecasting System
December 17 @ 16:00 - 17:00
CESOC continues the seminar series “My Research” this Winter term 2024/25 with a series of talks given by scientists from University of Bonn, University of Cologne and Research Centre Jülich.
This semester, we are excited to announce that the seminar series will be in a hybrid format and hosted by the different CESOC partners and it will also be streamed online (via zoom). The seminars will take place on Tuesdays on a bi-weekly basis at 16:00 hr.
on Tuesday, 17 Dec. 2024 at 16:00 (CST)
Paolo Andreozzi
a Step-UP fellow at ECMWF and Institute of Climate and Energy Systems (ICE), Troposphere (ICE-3), Forschungszentrum Jülich, talking on their work
“Constraining aerosol representations through interactions with clouds in the ECMWF’s Integrated Forecasting System”
It is open to any interested person within the CESOC research disciplines (any Earth system sciences, mathematics or computer science).
Please contact info[@]cesoc.net, if you would like to participate.
Full Schedule is available here!
Abstract:
Aerosol-cloud-radiation interactions (ACI) determine microphysical properties of clouds, and particularly their reflectivity, to which the Earth’s climate is known to be very sensitive. Therefore, ACI have been for long time included in most climate models. However, the representation of ACI in models is still very uncertain. On the one hand, this limits the capacity of climate models to provide precise predictions. On the other hand, ACI have mostly been neglected in non-critical applications such as numerical weather prediction (NWP) settings. This seminar will show some results of the ongoing investigation to calculate the number of droplets (Nd) in liquid-phase clouds online from global aerosol fields in the ECMWF Integrated Forecasting System (IFS), i.e. the first indirect radiative effect of aerosols (also known as Twomey effect). Our new ACI scheme uses a lookup table, produced from offline cloud parcel model simulations, to estimate the number of aerosol particles activated into cloud droplets. This approach allows, among others, the effect of large sea salt to suppress the activation of sulphate aerosols to be included. Finally, such representation of ACI can be constrained against available satellite and station-based observations. This setup can be deployed in different configurations of the IFS, spanning from the NWP medium range (10-15 days) to seasonal forecasts to climate projections, either with a climatological or prognostic representation of aerosols. We will illustrate that ACI can effectively improve realism of cloud properties, by substantially reducing shortwave radiative flux biases in subtropical stratocumulus regimes. At the same time, ACI can also degrade forecasts in regions where the underlying aerosols are represented less correctly. We will show how we can exploit ACI to better understand underlying errors in the representation of aerosol species and inform associated removal and transport processes.