Space and Earth Observation Centre
Seminar Abstracts

Some abstracts of the Space and Earth Observation Centre Seminar Series in reverse chronological order.

Definition of Falling Snowflake Density and How This Is Related to Radar Observations

Irregular structure and different sizes of snowflakes present in Nature are challenging for microphysical parametrization and thereby also introduce uncertainty in remote sensing retrievals. Nowadays surface-based data are gathered mostly by automatic optical imagers.
A typical limitation of automatic observations, however, is that only a subset of needed parameters is directly measured and the observations are limited by the viewing projection. Thus the remaining degrees of freedom are rather numerous. Various definitions of density may yield significantly different results. I will present a comparison of density definitions based on observations relative to the microphysical properties of falling snow particles and link the differences to uncertainties in parametrization.

PECASUS – a Tailored Space Weather Service for Civil Aviation

Sporadic and massive eruptions of very high-energy matter and radiation from the Sun can have a pronounced impact on the aeronautical ability to aviate, navigate and communicate. In extreme cases, these eruptions pose a safety risk to passenger health. Periods of extreme solar activity are generally referred to as space weather. The exposure of the aviation community to space weather has increased since the opening of the northern polar routes at the end of the 20th century and ICAO (International Civil Aviation Organization) has acted to incorporate safety from space weather effects into its aviation regulations.
FMI is leading a European multi-national consortium, called PECASUS that has been established in response to the ICAO call issued in May 2017 for global space weather services. ICAO’s call has gained wide attention among space weather service providers, because it specifies the wanted products and requirements for the service Reliability, Availability and Maintainability on a very detailed level. Nine parties have expressed their interest to offer ICAO either global or regional space weather services. The proposed concepts were audited in February 2018. PECASUS passed the audit successfully. FMI’s previous experience in maintaining 24/7 space weather services and close collaboration with the Finnish aviation authorities according to a well-established Quality Management System have been valuable assets in PECASUS planning work.
I will start the presentation with an introduction to space weather phenomena and discuss some of the main challenges in forecasting them. I will then give a brief review on the data sources and processing methods to be used in PECASUS and continue with descriptions on the planned operation concepts, staff and user training programmes, and product verification. Finally I will try to envisage the impact of PECASUS to FMI’s future in space weather research and operations.

Space Laboratory Overview and Current Activities

In this talk I will present the space laboratory (located in the P-floor) and give an overview of the current and past missions that we are involved. The history of the FMI's space instrumentation starts already from the 1980's and FMI has been involved in more than 40 space instruments. In recent years we have manufactured, calibrated and delivered atmospheric instruments for different Mars rovers and landers, and about these missions I will talk in more detail. To test and calibrate these instruments we have developed our own equipment to simulate the Martian atmospheric conditions and the work is still ongoing.

Likelihood-Informed Dimension Reduction for Atmospheric Remote Sensing

In this talk, we consider ground based Fourier transform infrared spectrometer (FTIR, part of TCCON network) solar absorption measurements from Sodankylä station, to invert trace gas density profiles ranging from 0 to 40 km. We use Bayesian framework with Optimal Estimation and adaptive MCMC to characterise the full posterior distribution of the solution and the related uncertainties. Using likelihood-informed subspace (LIS) dimension reduction approach, we identify the the low dimensional subspace of the parameter space that contains most of the measurement’s information, and implement computational dimension-reduced methods to solve the inverse problem in determination of atmospheric methane (CH₄) density profiles. The results of inversions are validated by comparing them against direct measurements from co-located AirCore Atmospheric Sampling System balloon experiments.