Project 13 (TWP2): Reconstruction of SIRTA data

Project lead: Marjolaine Chiriaco

Engineer : Julio Lopez

Project Start/End : 01/11/2014 – 31/10/2015

Description of work:

Many observations are available for the study of natural variability and climate feedbacks, and for better understanding the processes of interaction between atmosphere, land and interfaces at different spatial and temporal scales. Nevertheless, two major difficulties slow down the research: (a) the disparity of observations, and (b) the weak magnitude of the signals that one seeks to highlight and the complex connections between processes at the local scale and anomalies at climate scale.

We work on a synthesis of regionally observed multi-variables from SIRTA observatory. Quality controls must be applied, as well as an estimation of uncertainties and representativeness, an harmonization and standardization of the datasets, in order to facilitate use by a wide user community. In addition to studying the trends and climate variability, these developments will provide datasets to evaluate the models and their parameterization, and to better understand the processes and couplings. This work is underway SIRTA: all the observations collected since the early 2000s are synthesized into a single file after a major cleaning job, homogenization, quality control, application of the same algorithms, time averaging ...

In the case of obtaining a LABEX position in support of these activities, the continuation of this work will be:

  • automating and perpetuating the work already undertaken, including the updating of month after month data stream.
  • Further processes on some variables already in the dataset: lidar profiles, meteorology, radiative fluxes, in ground moisture.
  • Adding new variables: GPS water vapoor, regional meteorology, extraction of satellite products, radiosounding profiles
  • Producting documentation and a webpage
  • Distributing the dataset

Supervision team: The work will be conducted at IPSL under the main supervision of Marjolaine Chiriaco and Martial Haeffelin

Preliminary results:

The list of tasks that were performed by Julio Lopez so far is:

  • The SIRTA-ReOBS work started in 2011: it needs to be re-organized. Actually, the expertise on data evolves over years, the number of variables increases: then, the production codes have evolved one by one following various procedures and tools. The system was not coherent anymore and presented a great heterogeneity of tools and methods. This made it difficult to maintain, evolve and operate. To solve problems and to better integrate SIRTA treatment processes in the creation of SIRTA-ReOBS file, a processing chain has been designed and will be implemented in the coming months. It technical internal document has been produced that describe it (attached file).
  • A web page including documentation, illustrations, and description of the content has been developed: http://sirta.ipsl.polytechnique.fr/sirta.old/reobs.html. It will soon include an ftp to access the data. Also, an article is in preparation, that describes the SIRTA-ReOBS approach and work.
  • Variables:
    • An important work has been done on the improvement of the meteorology at 2 m, with a new quality control which led to numerous corrections;
    • SIRTA lidar profiles are now included following the same approach than the one used for the CALIPSO-GOCCP lidar products;
    • The solar zenithal angle is now included;
    • A cleaning data work has been performed on the radiative fluxes variable, and a best-estimated of the global SW flux has been produced.
  • Work in progress (Julio Lopez is still working on SIRTA-ReOBS for a few months, supported by another contract), i.e. short-term: correction of some parameters like the wind direction, continuing the new treatment processes, adding water vapor from GPS, adding the regional meteorological variables from Météo-france, correcting the latent heat flux.