Guidelines for EARLINET-ACTRIS associated stations to access QA services

ACTRIS Centre for Aerosol Remote Sensing C . A . R . S . 22 December 2025 1 / 8 Guidelines for EARLINET-ACTRIS associated stations to access QA services Emitter CARS & ARES Version 01, rev. 01 Revision 01 ACTRIS Centre for Aerosol Remote Sensing C . A . R . S . 22 December 2025 2 / 8 Table of contents APPLICABILITY OF THE DOCUMENT ................................................................................................................. 3 ACRONYMS ...................................................................................................................................................... 3 REFERENCE DOCUMENTS ................................................................................................................................. 3 1 INTRODUCTION ....................................................................................................................................... 4 2 GENERAL CONSIDERATIONS .................................................................................................................... 5 3 ACCEPTANCE OF THE EARLINET-ACTRIS ASSOCIATED STATIONS .............................................................. 6 3.1 ROLES AND RESPONSIBILITIES ........................................................................................................................ 6 3.2 ACCEPTANCE STEP-BY-STEP .......................................................................................................................... 6 3.2.1 Step1 Acceptance .............................................................................................................................. 6 3.2.2 Step2 Annual performance evaluation ............................................................................................. 6 4 PRINCIPLES FOR THE EVALUATION OF EARLINET-ACTRIS ASSOCIATED STATIONS' PERFORMANCES ........ 8 4.1 REQUIREMENTS FOR A POSITIVE ANNUAL EVALUATION OF PERFORMANCES ............................................................ 8 4.2 IMPLICATIONS OF A FAILED EVALUATION ......................................................................................................... 8 ACTRIS Centre for Aerosol Remote Sensing C . A . R . S . 22 December 2025 3 / 8 Applicability of the document These guidelines apply to the EARLINET stations which are not integrated in ACTRIS and intends to access ACTRIS aerosol remote sensing QA services. Acronyms • ACTRIS - Aerosol, Clouds and Trace gases Research InfraStructure • ACTRIS GA – ACTRIS General Assembly • ARES – Aerosol Remote Sensing unit of the ACTRIS Data Centre • ARS – Aerosol Remote Sensing • CARPORT – CARS workflow management portal • CARS - Centre for Aerosol Remote Sensing • CLU – Cloud Remote Sensing unit of the ACTRIS Data Centre • CCRES - Centre for Cloud Remote Sensing • DC – Data Centre • MP – Mobile Platform • NF - National Facility • NRT – Near-real time (less than 3 days from the measurements) • OP – Observational Platform • PI – Principal Investigator • RI Comm – Research Infrastructure Committee • RRT – Real-real time (less than 3 hours form the measurement) • SCC – Single Calculus Chain Reference documents [1]. Documentation on technical concepts and requirements for ACTRIS Observational Platforms [2]. ACTRIS NF Labelling Plan [3]. Descriptions of the workflows between ACTRIS components [4]. ACTRIS Data Management Plan [5]. CARS implementation plan [6]. ACTRIS vocabulary [7]. Technical requirements for ACTRIS Aerosol Remote Sensing Observational Platforms [8]. Measurement Guidelines for aerosol high-power lidars [9]. Standard Operation Procedure for aerosol high-power lidars [10]. Quality Assurance Procedure for aerosol high-power lidars ACTRIS Centre for Aerosol Remote Sensing C . A . R . S . 22 December 2025 4 / 8 1 Introduction Aerosol remote sensing instruments as considered by ACTRIS are: a) aerosol high-power lidars; b) automatic sun/sky/lunar photometers; c) automatic low-power lidars and ceilometers. Aerosol high-power lidars are operated by ACTRIS National Facilities either as part of the Observational Platforms (at fixed site, in synergy with collocated automatic sun/sky/lunar photometers), or onboard of Mobile Platforms (movable, along with other instruments). Aerosol high-power lidars can also be operated by other lidar stations or lidar networks, e.g. EARLINET. Although not all of the EARLINET stations are officially part of ACTRIS, they can benefit from CARS and ARES support if they are providing data to the ACTRIS Data Centre and follow the protocols issued by CARS and ARES. In the following, these lidar stations will be referred as "EARLINET-ACTRIS associated stations". In order to be accepted as EARLINET-ACTRIS associated stations, lidar stations must join EARLINET and must undergo the technical acceptance process described in this document. ➢ General considerations related to the status of the EARLINET-ACTRIS associated stations are presented in Section 2. ➢ Specific roles and responsibilities, conditions to be met and actions to be pursued for the acceptance of EARLINET-ACTRIS associated stations are described in Section 3. ➢ Principles for the evaluation of EARLINET-ACTRIS associated stations' performances are described in 4. ➢ The methodology for calculating the data coverage for EARLINET-ACTRIS associated stations is presented in Error! Reference source not found.. ➢ The simplified workflow of the aerosol remote sensing measurements is shown in Error! Reference source not found.. ACTRIS Centre for Aerosol Remote Sensing C . A . R . S . 22 December 2025 5 / 8 2 General considerations The main responsibility of CARS and ARES is to provide operation support to ACTRIS ARS National Facilities. This operation support extends from the calibration of instruments to the fully quality assured data products, which are calculated from a single instrument and/or from synergy of multiple instruments. In order to extend the geographical coverage of the aerosol remote sensing variables made available through the ACTRIS Data Centre, CARS and ARES also provides services for the calibration of lidars and photometers operated by the EARLINET-ACTRIS associated and AERONET stations, and for the related data flow, up to the capacity limit. In the following we will refer strictly to the EARLINET-ACTRIS associated stations, i.e. operated by EARLINET members. In order to receive support from ACTRIS, EARLINET stations must be accepted as EARLINET-ACTRIS associated stations. The acceptance process is run by CARS and ARES and it is based on several criteria, such as fulfillment of the technical requirements, implementation of ACTRIS QA/QC procedures and the data flow, and regular submission of operational data to the ACTRIS Data Centre. The process includes: a) a technical evaluation for granting the acceptance; b) annual evaluation of performances. Data provided to the ACTRIS Data Centre by the EARLINET-ACTRIS associated stations are tagged as: • "ACTRIS associated data" if not all the technical requirements for the lidar are met but the associated SOPs and QAPs issued by CARS are followed, and the data is submitted to the ACTRIS Data Centre according to the measurement guidelines; • "ACTRIS compliant data" if all technical requirements for the lidar are met, the associated SOPs and QAPs issued by CARS are followed, and the data is submitted to the ACTRIS Data Centre according to the measurement guidelines. The acceptance process for the EARLINET-ACTRIS associated stations is schematically presented below: Figure 1 Steps and actions of the ACTRIS acceptance process: responsibilities and interactions. The performances of the EARLINET-ACTRIS associated stations are annually evaluated according to the specific criteria, starting with the acceptance. The status of ACTRIS-associated lidar station can be withdrawn if the facility is negatively evaluated for two consecutive years. ACTRIS Centre for Aerosol Remote Sensing C . A . R . S . 22 December 2025 6 / 8 3 Acceptance of the EARLINET-ACTRIS associated stations 3.1 Roles and responsibilities Station PI – coordinates the activities related to the EARLINET-ACTRIS associated station; contact person for CARS and ARES; fills in the necessary information in CARPORT, the CARS workflow management portal (https://carport.inoe.ro/) CARS – provides support for the QA/QC of the measurements performed by the EARLINET-ACTRIS associated station; evaluates the compliance with the technical requirements in the various steps of the operations ARES – provides support for the data processing and the QA/QC of the data products derived from the measurements performed by the EARLINET-ACTRIS associated station; evaluates the compliance with the measurement guidelines in the various steps of the operations EARLINET Council – recommends lidar stations to be accepted as EARLINET-ACTRIS associated stations; analyses the result of the annual evaluation of performances of the EARLINET-ACTRIS associated stations and recommends to CARS and ARES continuation or withdraw of the support 3.2 Acceptance step-by-step 3.2.1 Step1 Acceptance Conditions to be met: - The lidar station must have an EARLINET station ID - The lidar station must have an operational aerosol high-power lidar 1 - The lidar station must have an SCC lidar ID Actions to be done: 1. The EARLINET Council must inform CARS about the readiness of the lidar station to enter the acceptance process o EARLINET station ID o Name and contact of the station PI 2. The station PI must fill in the technical information about the ARS instruments 2 in CARPORT o The station PI must activate his/her CARPORT user (@ notification from CARPORT) o The station PI must fill in technical information about the ARS instruments in CARPORT and submit the application (@ notification from CARPORT) 3. CARS and ARES must approve the lidar station as EARLINET-ACTRIS associated station 3.2.2 Step2 Annual performance evaluation Conditions to be met: - The lidar station should have been initially accepted as EARLINET-ACTRIS associated stations Actions to be done: - The lidar station must operate according to the SOPs: 1 Collocated automatic sun/sky/photometer is advisable. Collocated automatic low-power lidar / ceilometer is advisable 2 Information about existing automatic sun/sky/photometer and/or automatic low-power lidar / ceilometer should be included along with the information about the aerosol high-power lidar ACTRIS Centre for Aerosol Remote Sensing C . A . R . S . 22 December 2025 7 / 8 o Operate the lidar according to the Standard Operation Procedure for aerosol highpower lidars o Maintain and update the lidar log according to the Standard Operation Procedure for aerosol high-power lidars o Use ATLAS for lidar measurements quality control - The lidar station must participate in the QA/QC activities: o Perform and submit to CARS lidar QA tests according to Quality Assurance Procedure for aerosol high-power lidars o Implement recommendations from CARS to optimize the performances of the instruments o Participate to webinars, workshops and training sessions - The lidar station must collect and submit operational data to the ACTRIS Data Centre: o Perform and submit lidar measurements according to the Measurement Guidelines for aerosol high-power lidars ACTRIS Centre for Aerosol Remote Sensing C . A . R . S . 22 December 2025 8 / 8 4 Principles for the evaluation of EARLINET-ACTRIS associated stations' performances 4.1 Requirements for a positive annual evaluation of performances The facility should submit to the ACTRIS DC data collected in accordance with ACTRIS procedures on average at least 75% of the expected coverage (either temporal coverage or expected number of samples) of the parameters of the minimum requirements concerning the periods possible for measurements. This is calculated as covered time for each parameter separately but in the end averaged over all expected parameters so that insufficient data provision on one parameter may be compensated by other parameters. The times when an instrument cannot measure due to reasons not under control of the facility are to be excluded from the calculation of any parameter for which the instrument is needed. Note: The methodology for calculating data coverage for the EARLINET-ACTRIS associated stations is described in Measurement Guidelines for aerosol high-power lidars. The instruments must participate in the QA/QC activities according to the schedule provided by CARS. If the instrument cannot participate in a given QA/QC action as scheduled, it may participate in another action during the year concerned. The special cases of instruments in hard-to-reach locations will be considered in the schedules. If an instrument does not participate in a required QA/QC activity during the year, the data produced by the instrument is to be considered non-compliant starting from the scheduled date of the activity. Note: The mandatory QA/QC activities are described in Quality Assurance Procedure for aerosol highpower lidars. 4.2 Implications of a failed evaluation A single failure in the annual compliancy evaluation will not remove the acceptance, but corrective actions need to be planned and taken together with CARS and ARES, and reported to the EARLINET Council. After two consecutive years of failing the evaluation, the situation will be examined in detail and the acceptance as EARLINET-ACTRIS associated stations may be withdrawn.