Using Commercial Aircraft Meteorological Data to Assess the Heat Budget of the Convective Boundary Layer Over the Santiago Valley in Central Chile

Abstract

The World Meteorological Organization Aircraft Meteorological Data Relay (AMDAR) programme refers to meteorological data gathered by commercial aircraft and made available to weather services. It has become a major source of upper-air observations whose assimilation into global models has greatly improved their performance. Near busy airports, AMDAR data generate semi-continuous vertical profiles of temperature and winds, which have been utilized to produce climatologies of atmospheric-boundary-layer (ABL) heights and general characterizations of specific cases. We analyze 2017–2019 AMDAR data for Santiago airport, located in the centre of a $$40\times 100$$ 40 × 100 km$$^2$$ 2 subtropical semi-arid valley in central Chile, at the foothills of the Andes. Profiles derived from AMDAR data are characterized and validated against occasional radiosondes launched in the valley and compared with routine operational radiosondes and with reanalysis data. The cold-season climatology of AMDAR temperatures reveals a deep nocturnal inversion reaching up to 700 m above ground level (a.g.l.) and daytime warming extending up to 1000 m a.g.l. Convective-boundary-layer (CBL) heights are estimated based on AMDAR profiles and the daytime heat budget of the CBL is assessed. The CBL warming variability is well explained by the surface sensible heat flux estimated with sonic anemometer measurements at one site, provided advection of the cool coastal ABL existing to the west is included. However, the CBL warming accounts for just half of the mean daytime warming of the lower troposphere, suggesting that rather intense climatological diurnal subsidence affects the dynamics of the daytime valley ABL. Possible sources of this subsidence are discussed.

New Observations of the Meteorological Conditions Associated with Particulate Matter Air Pollution Episodes in Santiago, Chile

“…Point 12 shows the location of the Santiago International Airport (SCEL) base operation site for the commercial airplanes providing the AMDAR vertical profiles of winds and temperature. Detailed description of the AMDAR data for Santiago, their validation and their use to estimate boundary layer heights based on Richardson number computation is presented in [22]. In particular, the comparison of AMDAR profiles with 33 morning radiosondes in Santiago showed almost perfect correlations for temperature and root mean squared deviations smaller than 1 °C in the vertical column below 4000 m AGL, while for winds above 1000 m AGL, correlation coefficients were larger than 0.7, and root mean squared deviations were smaller than 2 m s −1 .…”

“…AMDAR data are routinely assimilated into global weather forecast models, and their positive impact in model results at the synoptic and larger scales is well documented [23,24]. However, at the ABL scale, where urban air pollution takes place, AMDAR basic data provide valuable information (e.g., boundary layer height, valley-scale stability) that is lost in their assimilation into the relatively low-resolution global models, as has been demonstrated for the Santiago case [22]. AMDAR data have been used to describe ABL climatology at the large [25] and local scales [26], but to our knowledge, their use in support of air pollution analyses is limited, despite their great potential.…”

“…Additionally, in 2017, the South American LATAM airline joined the World Meteorological Organization's Aircraft Meteorological Data Relay (AMDAR) program aimed at communicating to weather services the meteorological data gathered by commercial airplanes during routine operations [21]. As a consequence, an almost continuous monitoring of vertical profiles of temperature and winds in the Santiago valley has been accomplished based on the data collected by airplanes landing and taking off at the international airport located in the center of the valley [22]. AMDAR data are routinely assimilated into global weather forecast models, and their positive impact in model results at the synoptic and larger scales is well documented [23,24].…”

Meteorological export and deposition fluxes of Black Carbon on glaciers of the central Chilean Andes

“…Local observational data of wind speed and direction at surface level in the Santiago area is extracted from the Chilean automated meteorological and air quality monitoring network (Ministerio del Medio Ambiente, 2015), which will be abbreviated as SINCA in the continuation of this work, and the Chilean weather service stations (Dirección Meteorológica de Chile, 2019), referred to as DMC thereafter. Wind vertical profiles at hourly frequency in Santiago, for the years 2017 to 2019, are extracted from the Aircraft Meteorological Data Relay (AMDAR) data available for the Santiago airport, as presented and analyzed in Muñoz et al (2022).…”

Midday Boundary-Layer Collapse in the Altiplano Desert: The Combined Effect of Advection and Subsidence

“…This locally driven ABL evolution is canonical and it can be disrupted by non-local phenomena, such as advection and subsidence that are associated by meso-or synoptic scales, and are influenced by complex topographies. Muñoz et al (2022) analyzed the ABL dynamics in the semi-arid valley of central Chile using meteorological data gathered at a local airport, radiosondes and reanalysis data. They found that the ABL warming is not only explained by the surface fluxes but also by an intense diurnal subsidence.…”