Intercomparison of in situ water vapor balloon-borne measurements from Pico-SDLA H<sub>2</sub>O and FLASH-B in the tropical UTLS

Abstract

Abstract. In this paper we compare water vapor mixing ratio measurements from two quasi-parallel flights of the Pico-SDLA H2O and FLASH-B hygrometers. The measurements were made on 10 February 2013 and 13 March 2012, respectively, in the tropics near Bauru, Sao Paulo St., Brazil during an intense convective period. Both flights were performed as part of a French scientific project, TRO-Pico, to study the impact of the deep-convection overshoot on the water budget. Only a few instruments that permit the frequent sounding of stratospheric water vapor can be flown within a small volume weather balloons. Technical difficulties preclude the accurate measurement of stratospheric water vapor with conventional in situ techniques. The instruments described here are simple and lightweight, which permits their low-cost deployment by non-specialists aboard a small weather balloon. We obtain mixing ratio retrievals which agree above the cold-point tropopause to within 1.9 and 0.5 % for the first and second flights, respectively. This level of agreement for measured stratospheric water mixing ratio is among the best ever reported in the literature. Because both instruments show similar profiles within their combined uncertainties, we conclude that the Pico-SDLA H2O and FLASH-B datasets are mutually consistent.

Modeling the TTL at Continental Scale for a Wet Season: An Evaluation of the BRAMS Mesoscale Model Using TRO‐Pico Campaign, and Measurements From Airborne and Spaceborne Sensors

“…We also make use of temperature (see section 4) and wind (see section 6) measurements from RS92 SGP radiosondes of the TRO‐Pico campaign, and some more temperature measurements from the RS over Brazil during the FMOP. A detailed description of TRO‐Pico can be found in Ghysels et al (). Thereafter, the performance of the model in producing convective clouds, both in spatial and temporal precision is investigated, using GOES‐12 and MHS measurements (see section 4).…”

“…The measurement principle is simple: H 2 O mixing ratio is extracted from the absorbed signal applying the Beer‐Lambert law, knowing temperature and pressure. A full description of the instrument, including its uncertainties, is provided by Ghysels et al (). In the TRO‐Pico flight conditions, the measurement uncertainty for a unitary spectrum (10 ms acquisition time, not averaged) in the TTL ranges from 3.5% to 7.5%.…”

“…The precision can be improved by averaging over N unitary spectra, enhancing the signal‐to‐noise ratio by a factor of . The time schedule of the different measurements used in this study can be found in Ghysels et al () (see also Figure a). Most of the observations were made during the IOP2, while eight other profiles were taken from the FMOP.…”

“…Here we apply a composite data set of WV profiles from both Pico‐SDLA and FLASH‐B hygrometers to evaluate the modeled TTL. Ghysels et al () have shown a relative difference of H 2 O mixing ratio <1.9% between Pico‐SDLA and FLASH‐B in the TTL, based on a couple of coincident flights during the TRO‐Pico campaign. This constitutes one of the best intercomparison results of WV sensors, making it a fully consistent data set.…”

On the cross-tropopause transport of water by tropical convective overshoots: a mesoscale modelling study constrained by in situ observations during the TRO-Pico field campaign in Brazil

“…As a result, this study generates a variety of estimations for ice injection into the stratosphere and water remaining after sublimation. We use the data from a well-documented case on 13 March 2012 in Bauru, São Paulo state, Brazil, during the TRO-Pico, a small balloon campaign (Khaykin et al, 2016;Ghysels et al, 2016). On that particular day, two lightweight balloon-borne hygrometers intercepted a hydrated stratospheric air parcel emanating from two distinct overshooting plumes.…”