Field Campaigns

KLAsh: Rapid Response to Volcanic Eruption

Increased volcanic activity over the past decade is thought to have contributed significantly to the recent global warming 'hiatus'. Thus, it is important to improve our understanding of the microphysical and optical properties of even small volcanic plumes as well as their associated climate impacts. On February 13th, 2014, the Mt. Kelud volcano, located near 4°S on the island of Java (Indonesia), injected volcanic gases and ash into the tropical stratosphere. An overpass of the CALIPSO lidar during the active phase of the eruption showed volcanic materials reaching 26 km with the main volcanic cloud near 18-19 km. CALIPSO tracked the dispersion of the Kelud plume throughout the tropical lower stratosphere (~20°N-20°) and showed the persistence of small ash particles a month after the eruption. This is significant because the climate impact of ash is neglected in most climate models.

In May 2014, a team of NASA and University of Wyoming scientists mounted a 2-week balloon field campaign to Darwin (Australia) to characterize the optical properties, sulfate fraction and particle sizes of the stratospheric plume from Mt. Kelud, while it remained relatively fresh. They conducted 4 launches of backscatter sondes with red and blue channels under small balloons, and a single launch of two optical particle counters, one with an inlet heated to 200°C, under a large balloon, to characterize aerosol size and volatility. Preliminary results from the campaign indicated 2 layers between 18 and 21 km and suggested the persistence of ash particles in the lower layer of the Kelud plume 3 months after the eruption.

BATAL-2014: Balloon characterization of the Asian Tropopause Aerosol Layer

Satellite observations have recently shown that the Summer Asian Monsoon leads to the formation of an aerosol layer in the upper troposphere extending from the Eastern Mediterranean Sea to Western China. Firstly discovered by analyzing data from the CALIPSO space-borne lidar and recently confirmed by past SAGE-II limb observations, this Asian Tropopause Aerosol Layer (ATAL) seems to be the main source of aerosols in the tropical upper troposphere during volcanic quiescent periods. Analysis of long-term satellite observations suggests the emergence of this feature since the beginning 2000's, representing a new source of radiative forcing for the Asian Region which could potentially alters the earth energy balance.

A balloon field campaign was mounted to characterize the aerosol optical properties and size distribution of the Asian Tropopause Aerosol Layer (ATAL). The objective of this mission was to better understand the role of convection over the Indian sub-continent in the formation of the ATAL. A 10-day field experiment between 15-27 August 2014, based in Gadanki (13.4°N,71.2°E, India) at the National Atmospheric Research Laboratory (NARL), has deployed 7 flights of a two-wavelength aerosol backscatter sonde and one Optical Particle Counter configured for light weather balloons.

The balloon campaign was supported by intensive ground-based lidar and radar measurements. In addition, a similar balloon field campaign took place from Kunming (China). Altogether, those deployments represent the most significant effort to date in order to better understand the nature, origin and formation of the ATAL throughout Asia.

SWOP - A Sounding water vapor, ozone and particle campaign

A sounding water vapor, ozone and particle (SWOP) campaign has been conducted every year at Kunming (25°N, 102.6°E, China) or Lhasa (30°N, 91°E, China) during the Asian summer monsoon (ASM) since 2009, with an aim to investigate the tropopause transition layer within the ASM anticyclone. A combined measurement of water vapor by frost-point hygromemeter (CFH or FPH) and particle by two-wavelength aerosol backscatter sonde (COBALD) can provide the detailed information about cirrus and aerosol layer. Totally, there are 21 combined soundings (3 cases in August 2010, 18 cases in August 2013) from Lhasa, and 22 soundings (12 cases in August 2012, 10 cases in August 2014). These balloon-borne soundings will provide in-situ observation of aerosol and related measurements in order to better understand the nature, origin and formation of the ATAL throughout Asia.

StratoClim

Stratospheric and upper tropospheric processes for better climate predictions

• improve the understanding of the microphysical, chemical and dynamical processes that determine the composition of the UTS, such as the formation, loss and redistribution of aerosol, ozone and water vapour, and how these processes will be affected by climate change;
• implement these processes and fully include the interactive feedback from UTS ozone and aerosol on surface climate in CCMs and ESMs

Through StratoClim new measurements will be obtained in key regions:

• in a tropical campaign with a high altitude research aircraft carrying an innovative and comprehensive payload,
• by a new tropical station for unprecedented ground and sonde measurements, and
• through newly developed satellite data products.

The improved climate models will be used to make more robust and accurate predictions of surface climate and stratospheric ozone, both with a view to the protection of life on Earth. Socioeconomic implications will be assessed and policy relevant information will be communicated to policy makers and the public through a dedicated office for communication, stakeholder contact and international co-operation.

Stratéole-2

Strat (stratospheric) éole (winds) in the tropics

• Dynamics in the TTL through better representation of temperature across the TTL and thus gravity, Rossby, and Kelvin wave structure.
• Transport of water vapor and other trace gases across the TTL.
• The prevalence of sub visible cirrus and large aerosol above the TTL, and frequency of overshooting convection or other episodic stratospheric aerosol perturbations.

The Engineering Flight campaign was completed from November 2019 - February 2020 with the goal to flight test all instruments, gondolas, and balloon configurations. Eight balloons were released between mid-November and mid-December 2019, five for remote measurements, drifting at 20 km, and three for in situ measurements, drifting at 18 km. The balloon flight lifetimes ranged from 57 to 108 days, with most completing 1.5 circumnavigations of the Earth between 10°S and 10°N. The campaign was successful in flight certifying the instruments, with suitable improvements, and the flight operations.

The first Science Campaign is planned for November 2021 - February 2022 and will release up to 20 balloons. A second Science Campaign, with a similar number of balloons, is planned for 2024-2025 to capture the opposite phase of the quasi-biennial oscillation.