JOANNE : Joint dropsonde Observations of the Atmosphere in tropical North atlaNtic meso-scale Environments

Abstract

Abstract. As part of the EUREC4A field campaign which took place over the tropical North Atlantic during January–February 2020, 1216 dropsondes from the HALO and WP-3D aircraft were deployed through 26 flights to characterize the thermodynamic and dynamic environment of clouds in the trade-wind regions. We present JOANNE (Joint dropsonde Observations of the Atmosphere in tropical North atlaNtic meso-scale Environments), the dataset that contains these dropsonde measurements and the products derived from them. Along with the raw measurement profiles and basic post-processing of pressure, temperature, relative humidity and horizontal winds, the dataset also includes a homogenized and gridded data set with 10 m vertical spacing. The gridded data are used as a basis for deriving diagnostics of the area-averaged meso-scale circulation properties such as divergence, vorticity, vertical velocity and gradient terms, making use of sondes dropped at regular intervals along a circular flight path. 85 such circles, ~222 km in diameter, were flown during EUREC4A. We describe the sampling strategy for dropsonde measurements during EUREC4A, the quality control for the data, the methods of estimation of additional products from the measurements and the different post-processed levels of the dataset. The dataset is publicly available (https://doi.org/10.25326/221) as is the software used to create it (https://doi.org/10.5281/zenodo.4746313).

EUREC<sup>4</sup>A's HALO

“…The snapshots were chosen to capture the cloud scene roughly 3 h after take-off. Like the snapshots, the actual movies (Schulz et al, 2021) meso-scans of the Advanced Baseline Imager (ABI) on-board the GOES-16 satellite (GOES-R Calibration Working Group and GOES-R Series Program, 2017), when these are available. During daytime reflectance (channel 2; 0.64 µm) and during nighttime brightness temperature (channel 13; 10.35 µm) are used.…”

“…4) provides aircraft location and attitude data for all HALO flights, in addition to atmospheric measurements. A subset of the BAHAMAS data, consisting of aircraft altitude, heading, 135 latitude, longitude, roll angle, pitch angle and true air speed with a time resolution of 10 Hz, has been created (Klingebiel, 2021). Figure 1…”

“…The quality of the original brightness temperature measurements was evaluated by comparing them with synthetic ones simulated from dropsonde profiles provided in the JOANNE data set considering the suggested humidity correction (George et al, 2021). Systematic differences which can arise from insufficient pre-flight calibration are corrected using a linear relation between recorded and synthetic brightness temperatures, which is estimated for each flight and radiometer channel.…”

“…Definition of flight segments. The total number of these segments identified from all flights has been provided in the right-most column George et al, 2021)…”

“…This system provides aircraft attitude and location data, together with in-situ observations of atmospheric quantities at aircraft level (Sec. 3.1).JOANNEDropsonde observations(George et al, 2021) provide in-situ profiles of temperature, humidity, pressure, and wind along the sonde trajectory.…”