TY - JOUR

T1 - Response of noctilucent cloud brightness to daily solar variations

AU - Dalin, P.

AU - Pertsev, N.

AU - Perminov, V.

AU - Dubietis, A.

AU - Zadorozhny, A.

AU - Zalcik, M.

AU - McEachran, I.

AU - McEwan, T.

AU - Černis, K.

AU - Grønne, J.

AU - Taustrup, T.

AU - Hansen, O.

AU - Andersen, H.

AU - Melnikov, D.

AU - Manevich, A.

AU - Romejko, V.

AU - Lifatova, D.

N1 - Publisher Copyright: © 2018 Elsevier Ltd

PY - 2018/4/1

Y1 - 2018/4/1

N2 - For the first time, long-term data sets of ground-based observations of noctilucent clouds (NLC) around the globe have been analyzed in order to investigate a response of NLC to solar UV irradiance variability on a day-to-day scale. NLC brightness has been considered versus variations of solar Lyman-alpha flux. We have found that day-to-day solar variability, whose effect is generally masked in the natural NLC variability, has a statistically significant effect when considering large statistics for more than ten years. Average increase in day-to-day solar Lyman-α flux results in average decrease in day-to-day NLC brightness that can be explained by robust physical mechanisms taking place in the summer mesosphere. Average time lags between variations of Lyman-α flux and NLC brightness are short (0–3 days), suggesting a dominant role of direct solar heating and of the dynamical mechanism compared to photodissociation of water vapor by solar Lyman-α flux. All found regularities are consistent between various ground-based NLC data sets collected at different locations around the globe and for various time intervals. Signatures of a 27-day periodicity seem to be present in the NLC brightness for individual summertime intervals; however, this oscillation cannot be unambiguously retrieved due to inevitable periods of tropospheric cloudiness.

AB - For the first time, long-term data sets of ground-based observations of noctilucent clouds (NLC) around the globe have been analyzed in order to investigate a response of NLC to solar UV irradiance variability on a day-to-day scale. NLC brightness has been considered versus variations of solar Lyman-alpha flux. We have found that day-to-day solar variability, whose effect is generally masked in the natural NLC variability, has a statistically significant effect when considering large statistics for more than ten years. Average increase in day-to-day solar Lyman-α flux results in average decrease in day-to-day NLC brightness that can be explained by robust physical mechanisms taking place in the summer mesosphere. Average time lags between variations of Lyman-α flux and NLC brightness are short (0–3 days), suggesting a dominant role of direct solar heating and of the dynamical mechanism compared to photodissociation of water vapor by solar Lyman-α flux. All found regularities are consistent between various ground-based NLC data sets collected at different locations around the globe and for various time intervals. Signatures of a 27-day periodicity seem to be present in the NLC brightness for individual summertime intervals; however, this oscillation cannot be unambiguously retrieved due to inevitable periods of tropospheric cloudiness.

KW - Noctilucent clouds

KW - Polar mesospheric clouds

KW - Solar activity

KW - Summer mesopause

KW - POLAR MESOSPHERIC CLOUDS

KW - MESOPAUSE

KW - MODEL

KW - AIM SOFIE

KW - INDUCED 27-DAY VARIATIONS

KW - ATMOSPHERIC TIDES

KW - TEMPERATURE

KW - WATER-VAPOR

KW - LUNAR TIDES

KW - MIDDLE

UR - http://www.scopus.com/inward/record.url?scp=85042264456&partnerID=8YFLogxK

U2 - 10.1016/j.jastp.2018.01.025

DO - 10.1016/j.jastp.2018.01.025

M3 - Article

AN - SCOPUS:85042264456

VL - 169

SP - 83

EP - 90

JO - Journal of Atmospheric and Solar-Terrestrial Physics

JF - Journal of Atmospheric and Solar-Terrestrial Physics

SN - 1364-6826

ER -