Dear AERONET colleagues and data users,

The AERONET website recently came to a halt due to a large volume of auto-generated download requests, and thus a limit was imposed to stabilize the system. We would like to inform all data users that some scripts, especially Python ones, have the capability of generating web hits very quickly, potentially slowing down and crashing the system if run by many users. The system will now throttle an IP/host that hits the same cgi-bin more than 10 times per minute. To avoid an IP block we recommend data users to consider the following suggestions for downloads:

If you suspect your IP was blocked, please send an email to Ilya Slutsker. Please also visit the Download Tool Interface Help page to learn more about the web service parameters and data types. We appreciate your cooperation and support!

After a rigorous testing and improvement process, we are pleased to release our new MAN download tool. This interactive software can download AOD/SDA data from the shipborne Microtops II sunphotometers based on multiple criteria, either by drawing geographic bounds directly on the map, by specifying a custom date range, or by manual selection. With capability of specifying all-point, series, or daily average datasets, this tool makes it easier to explore and retrieve maritime aerosol observations. A new version is expected to release in a few months with even more features.

On 17 October 2024, the AERONET team corrected instrumental time shifts at two Australian sites: Birdsville (17 July 2018 - 25 November 2022) and Fowlers_Gap (5 June 2018 - 5 May 2021). The time shift of about 1 min was caused by the GPS malfunction. The original data had unrealistic air mass calculations at higher solar zenith angles and resulted in the Quality Assurance algorithm removing measurements, especially during low AOD periods. Consequently, climatological data at those sites contained biases. After applying the time correction to the clock readings in the raw datasets, a sig-nificant increase in Level 1.5 and Level 2.0 data took place. Datasets, display charts and climatology tables for these sites were updated on the AERONET website. All users working with Birdsville and Fowlers_Gap data are advised to download their latest versions, processed on or after 17 October 2024.

Dear colleagues, partners, and all participants in the AERONET Science and Application Exchange,

We are pleased to announce that the event page has been posted on our website under the Publications tab. It includes photo highlights from the event, along with the full program and links to some of the presentations and posters. If you would like access to all the event photos, please email Pawan Gupta and Petar Grigorov to request the Google Drive link.

We appreciate your support and look forward to more events like this in the future!

AERONET has been acquiring lunar observations from the majority of model T CIMEL sun photometers in the network for many years and producing a night-time AOD data set, which currently includes observations at 492 sites dating back as far as 2014 for some locations.

The Lunar AOD product relies on the ROLO Lunar Irradiance Model for extraterrestrial spectral irradiance, and for some time, it had been clear that some corrections needed to be made to this input to produce valid lunar AOD.

The AERONET approach to address this was by comparing Vo's (top-of-the-atmosphere signal) of high elevation lunar Langleys with solar Langleys at Mauna Loa Observatory (MLO) and Izaña calibration facilities. For a given instrument, the solar to lunar Vo ratios should match the sun/sky gain ratio of 4096. Thus, observed deviations from this nominal value could be determined as a function of lunar phase angle (LPA) and used as an empirical correction factor by which the base ROLO irradiances are modified.

The initial (provisional) lunar AOD product was based on a moderate number of such solar/lunar Vo comparisons; however, in the last several months, this comparison set was updated with the last 5 years of Langleys and adopted modified filtering thresholds. This has resulted in substantially more solar/lunar Langley pairs (N > 500 at every wavelength) from MLO and Izaña calibration sites. These data were used to generate statistically robust ROLO correction factors for each wavelength as a function of LPA.

The reprocessed dataset of lunar AOD, corrected with the updated empirical bias, has now also been extensively analyzed for all contributing sites. This analysis, which included evaluating the continuity of AOD between solar and lunar measurements during limited temporal windows, provides confidence in the robustness of the data. The absence of systematic bias and the AOD continuity during sunrise or sunset transitions further validate the accuracy of the dataset. Therefore, the decision was made to remove the current provisional status of the lunar level 1.5 data.

It's important to note that while the revised dataset of lunar AOD is a significant improvement, there are some operational aspects of the automated cloud-screening that are absent from the lunar AOD QC protocols. Additionally, there are other additional sources of uncertainty in lunar AOD which are spectrally variable which also result in larger total uncertainty of cloudless data as compared to daytime sun measurements of AOD. As a result, the lunar AOD cannot be expected to exactly match the accuracy of daytime AOD measurements. We continue with research to develop improved nighttime cloud screenings and processing to final Level 2.0 datasets.

We are happy to report that AERONET data are now visible on NASA's Worldview application. This open source code app from the Earth Observing System Data and Information System (EOSDIS) provides the capability to interactively browse over 1000 global, full-resolution satellite imagery layers and then download the underlying data. Many of the imagery layers are updated daily and are available within three hours of observation. Four of those layers represent AERONET's Aerosol Optical Depth 500nm (Near Real-Time and Daily) and Angstrom Parameter 440-870nm (Near Real-Time and Daily) data.