MOTIVATION:

Ground-based remote sensing instruments provide a unique and powerful view of the thermodynamic structure and evolution of the atmospheric boundary layer. A range of different technologies has been developed over the past 40 years to observe profiles of temperature and humidity from the ground.  These methods include passive techniques, such as single- and multi-channel microwave radiometers (MWRs) and infrared spectrometers (IRS), and active approaches, such as Raman lidars (RLID), differential absorption lidars (DIALs), and radio acoustic sounding systems (RASS). All of these techniques have strengths and weaknesses, and it can be challenging to evaluate the relative differences in their information content in a consistent way. Furthermore, this leads to questions on how to combine observations from multiple instruments synergistically. Additionally, the profiles derived from many remote sensors have correlated errors between different height levels, and thus the covariance of the profile needs to be understood if the profiles are to be properly assimilated into a weather forecast model.

WHAT IS TROPOE:

To address these questions, we have developed the TROPoe retrieval software package. TROPoe is a 1-dimensional variational algorithm, based upon optimal estimation, that incorporates forward models for all of these instruments to allow an iterative solution to be determined. A climatology, usually of historical radiosondes launched near the instrumented site, is used to provide a constraint to the retrieved solution. Uncertainties from the observations, the sensitivity of the forward models, and the uncertainty in the prior are all propagated to provide a full error covariance matrix for each retrieved thermodynamic profile. Retrievals using single instrument configurations (e.g., MWR-only, IRS-only, DIAL-only) as well as multi-instrument retrievals (e.g., MWR+IRS, MWR+DIAL, IRS+RLID, MWR+IRS+DIAL) can be performed. When the same retrieval framework and prior dataset is used, the uncertainties and information content for each instrument complement can be directly compared.

THE TRAINING:

The TROPoe software has been packaged into a Docker container, which facilitates the use of the software by a wide range of users. Next to an introduction to the retrieval theory, this workshop will provide a hands-on training to users on how to apply TROPoe to provide consistent retrievals from the ground-based remote sensing observations, including how to combine data from multiple different instruments into the retrieval. The workshop will also focus on understanding the generated output, including the uncertainty and information content output produced by TROPoe. The goal is that the user can “take home” the retrieval and apply it to their observations “at home”. Lastly, the workshop will discuss how to assimilate these retrieved profiles, regardless of the actual instrument datasets used in the analysis.

APPLICATION:

PROBE scientists and FESSTVaL Early Career Investigators are invited to apply for this 2,5-day workshop in Cologne until March 4th. On March 8 we will inform you about the success of your application and finally communicate to you if the workshop will take place as planned as an in-person meeting or if we need to use an on-line format due to the COVID-19 situation. Please note: After a successful application, we require valid proof of full COVID-19 vaccination or timely recovery.

If you want to apply, click here.

ORGANIZATIONAL ASPECTS:

• Time plan:

The training school will take place twice:

- from March 28 (7 UTC) to March 30 (10 UTC), PROBE participants

- from March 30 (12 UTC) to April 1 (16 UTC), FESSTVaL participants.

Each workshop event will be open for 10 participants.

Please book your travel only in case of a positive notification on March 8. At that point, we will provide travel advice and hotel booking assistance. Up to 10 scientists from PROBE will be awarded a travel grant through a commission. More information will be available on March 8. ECIs from FESSTVaL can apply for travel reimbursement from their project funding using funds originally designated for the FESSTVaL summer school. The workshop as such is free of charge.

• Training School Instructor: David D. Turner (NOAA GSL)
• Workshop Hosts: Christine Knist (DWD), Ulrich Löhnert (University of Cologne)
• workshop location: Institute for Geophysics and Meteorology at the University of Cologne, Germany, Pohligstr. 3, 50969 Köln

TRAINING SCHOOL PREPARATION:

Please be sure to be familiar with visualizing routines for netcdf files. Please note that it is mandatory that you bring a laptop on which you can install the Docker container. Instructions on how to install Docker for any platform are here. In order to obtain basic knowledge on optimal estimation theory, we encourage you to read the article by Maahn et al.

Maahn, M., D. D. Turner, U. Löhnert, D. J. Posselt, K. Ebell, G. G. Mace, and J. M. Comstock, 2020: Optimal Estimation Retrievals and Their Uncertainties: What Every Atmospheric Scientist Should Know. Bulletin of the American Meteorological Society, E1512–E1523, https://doi.org/10.1175/BAMS-D-19-0027.1

TROPoe example applications can be found here:

Turner, D. D. and U. Löhnert, 2021: Ground-based temperature and humidity profiling: combining active and passive remote sensors, Atmos. Meas. Tech., 14, 3033–3048, https://doi.org/10.5194/amt-14-3033-2021.