| Texto completo | |
| Autor(es): |
Cordeiro, Luan P.
;
Gouveia, Diego A.
;
Barbosa, Henrique M. J.
Número total de Autores: 3
|
| Tipo de documento: | Artigo Científico |
| Fonte: | JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES; v. 130, n. 21, p. 20-pg., 2025-11-05. |
| Resumo | |
Cirrus clouds strongly influence Earth's radiation balance, yet their optical properties and formation pathways add uncertainty to climate models. Satellites offer a global view of cirrus but have key limitations: passive sensors struggle to detect thin layers, and active instruments in polar orbits miss the diurnal cycle. Long-term records of ground-based lidar measurements can help fill this important observational gap. Here, we analyzed of lidar data gathered near Manaus, Brazil (July 2011-December 2017), to characterize the cirrus clouds over the Amazon rainforest. An automated routine set cloud boundaries, and multiple-scattering-corrected retrievals yielded cloud optical depth (COD) and the lidar ratio. Cirrus were found to occur with a frequency of 73.1%. Thin layers (-0.30) are the most prevalent with a 48.4% relative frequency, followed by opaque (; 26.4%) and subvisual (; 25.2%). The mean base and top altitudes were and , and the lidar ratio averaged . Thinner clouds clustered near the tropopause, while higher tops tracked the tropopause variability. A clear diurnal cycle shows a noon minimum frequency of occurrence and a late-afternoon maximum, strongest for opaque cirrus and consistent with convective-anvil outflow. Optical properties such as COD, lidar ratio, and geometric properties follow a well-defined daily rhythm. Seasonally, cirrus are more frequent in the wet season (81.8%) than in the dry (56.7%). Bases, tops, and thickness are likewise larger in the wet season, whereas lidar ratios peak in the dry season. This long-term record benchmarks satellite retrievals, sharpens radiative impact calculations, and clarifies cirrus formation over tropical forests. (AU) | |
| Processo FAPESP: | 13/50510-5 - Pesquisa colaborativa Brasil-EUA: modificações causadas pela poluição antrópica na química da atmosfera e na microfísica de partículas da floresta tropical durante as campanhas intensivas do GoAmazon |
| Beneficiário: | Henrique de Melo Jorge Barbosa |
| Modalidade de apoio: | Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Regular |