Updates from the 2022 CEDAR Workshop in Austin, TX



The workshop “Advances in atmosphere vertical coupling and its relationship with ionosphere-thermosphere oscillatory phenomena (TAD/TID/MSTIDs)” was organized by Arecibo Observatory scientists Dr. Pedrina Terra, Dr. Christiano Brum, and Dr. Sukanta Sau in collaboration with Dr. Dustin Hickey from NRL. The workshop reunited about 50 people during its 2 hours of duration. A total of 10 short talks focusing on state-of-the-art investigations of the atmospheric processes that enable or indicate coupling and energy transfer within the atmosphere layers, including TAD, TIDs, and MSTIDs phenomena were presented. The talks showcased some of the latest advances in the vertical coupling of the atmosphere and their relationship with the ionosphere-thermosphere oscillatory phenomena (TAD/TIDs/MSTIDs), its low, medium, and high latitude sources, and its physical mechanisms of excitation. Long-standing challenges of space weather research as the formation, progression, and global impacts of traveling ionospheric/atmospheric disturbances (TADs/TIDs) were discussed.

Dr. Pedrina Terra presented the talk titled: “A multi-instrumental diagnosis of the Hurricane Maria Category IV signatures over the Caribbean sector” on 21 June, 2022. During her presentation, Dr. Terra showed wave signatures observed in the upper atmosphere and IT system related to the Extreme Weather System (EWS) hurricane Maria during its approach to the Caribbean. Remarkably, those signatures covered a broad zone, extending ~1000 km around Maria's center, and were detected even by optical narrowed field instruments (such as photometers and Fabry Perot interferometer) at Arecibo Observatory. Dr. Terra's work also presented wave oscillations observed by an all-sky imager, VLF receivers, and a digisonde along Maria's trajectory. The altitude-dependent signatures showed by Dr. Terra were detected during different intensity levels of the EWS Maria, highlighting the potential and importance of pursuing long-term observations at Arecibo Observatory and its Remote Optical Facility (ROF) in Culebra.

Dr. Terra emphasized that AO and ROF are unique US territory facilities in the Northeast Caribbean and a "hot spot" to monitor the upper atmosphere response to the EWS traveling towards the Caribbean and the US. The strategic location, summed to the variety of instruments at AO and ROF, allows the scientific community to coordinate multi-instrumental observations to enhance the knowledge of how tropospheric forcing impacts the upper layers of Earth's atmosphere.

Dr. Shikha Raizada presented the talk in the session “Low- and Mid-Latitude Ionosphere-Thermosphere-Mesosphere (ITM) Physics” held on 24 July 2022. Her presentation was titled: “Significance of a low-latitude and tropical site like Arecibo for Mesosphere-thermosphere-ionosphere investigations”. Dr. Raizada noted that it is important to show the valuable contributions from AO, and the advances that are possible due to the ongoing investigations by the AO team. She presented AO Calcium resonance lidar data (shown in the figure 1) and investigated the factors that could influence the uplift of the Sporadic E layer and were not seen in the co-located neutral sodium lidar data. The uplift allowed us to infer the vertical ion velocity to be close to ~ 3 m/sec, which can occur due to electric fields in the range 0.7 mV/m. This inference comes from the lack of any such uplift in the simultaneous sodium data, which points to the absence of sufficient vertical winds that could also possibly uplift the neutrals/ions.

Dr. Raizada showed the significance of coordinated observations that provide new insights into coupling mechanisms. She demonstrated that calcium ion data obtained using resonance lidar acts as a proxy for the Sporadic E layer (Es), and the resolution obtained with this instrument is unmatched. She presented evidence of E and F region coupling, and also highlighted the significance of the location of AO, including: (a) AO is geomagnetically a mid latitude, while geographical a low-latitude location. This makes it a very interesting location for both ion-neutral coupling investigations as well as a site influenced by tropical/latent heat convection at lower altitudes; (b) its close proximity to the edge of Equatorial Ionization Anomaly (EIA), as well as conjugate point of South Atlantic Magnetic Anomaly further makes this location significant to explore the coupling processes via geomagnetic fields lines; and c) provides a bridge between equatorial and mid/high latitudes for both neutral and plasma dynamics coupling effects.

Figure 1: Temporal and altitudinal variation of Calcium resonance lidar data from AO showing Kelvin-Helmholz strictures during pre-midnight sector followed by uplift of Es layer during pre-dawn hours.

Dr. Sukanta Sau gave the presentation “Retrieval of rotational temperatures using the Arecibo Observatory Ebert-Fastie spectrometer and their comparison with multiple instruments and theoretical calculation” on 21 June, 2022. Dr. Sau described the one-meter Ebert-Fastie Spectrometer (EFS) that was routinely operated in the Arecibo Observatory to record the OH(6,2) Meinel band emission lines. The team utilized the P1 lines of OH (6,2) Meinel band to estimate rotational temperatures in the MLT region using data from February 2005 to April 2005, and found that the temperatures were consistent with what is in the literature. Dr. Sau presented preliminary results that show that the EFS temperatures are found to be higher than the K-Lidar temperature by ~ 10.49 K. In addition, combining the EFS and the vertical profiles of K-Lidar temperature, the temporal variation of the peak emission altitude of OH(6,2) Meinel band over Arecibo was retrieved and compared with theoretical values.

Dr. Sau noted that the CEDAR meeting is well attended by researchers who work in the different branches of space and atmospheric sciences. In general, the largest number of attendees come from different institutes within the U.S.A. while a good number of international researchers also attend this meeting.

“It provides a very good opportunity to showcase and discuss our research with peers from the same field. Since the number of attendees are typically close to 200, it allows more room for interaction and networking opportunities in comparison to larger meetings,” says Dr. Sau. “In addition, early career scientists are allowed to judge undergraduate student posters which is a great opportunity to enhance the mentoring capabilities.”

Article written by Dr. Tracy Becker - AO Collaborator / SwRI Research Scientist Contact: tbecker@swri.edu
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Keywords: education, atmospheric