Cirrus Cloud Top-of-the-Atmosphere Net Daytime Forcing in the Alaskan Subarctic from Ground-Based MPLNET Monitoring

Abstract

Cirrus cloud daytime top-of-the-atmosphere radiative forcing (TOA CRF) is estimated for a two-year NASA Micro-Pulse Lidar Network (532 nm; MPLNET) dataset collected at Fairbanks, Alaska. Two-year averaged daytime TOA CRF is estimated at between -1.08 and 0.78 W·m-2 (-0.49 to 1.10 W·m-2 in 2017, and -1.67 to 0.47 W·m-2 in 2018). This subarctic study completes a now trilogy of MPLNET ground-based cloud forcing investigations, following midlatitude and tropical studies by Campbell et al. (2016; C16) at Greenbelt, Maryland and Lolli et al. (2017) at Singapore. C16 hypothesize a global meridional daytime TOA CRF gradient that begins positive at the equator (2.20 – 2.59 W·m-2 over land and -0.46 – 0.42 W·m-2 over ocean at Singapore), becomes neutral in the midlatitudes (0.03 – 0.27 W·m-2 over land in Maryland) and turns negative moving poleward. This study does not completely confirm C16, as values are not found as exclusively negative. Evidence in historical reanalysis data suggests that daytime cirrus forcing in and around the subarctic likely once was exclusively negative. Increasing tropopause heights, inducing higher and colder cirrus, have likely increased regional forcing over the last forty years. We hypothesize that subarctic inter-annual cloud variability is likely a considerable influence on global cirrus cloud forcing sensitivity, given the irregularity of polar versus midlatitude synoptic weather intrusions. This study and hypothesis lays basis for an extrapolation of these MPLNET experiments to satellite-based lidar cirrus cloud datasets.

Reliability Evaluation of the Joint Observation of Cloud Top Height by FY-4A and HIMAWARI-8

“…At present, a variety of methods is used to detect cloud top height, forming a groundbased and space-based detection network, which can obtain global cloud top height data more comprehensively [13][14][15][16][17][18]. Among them, ground-based measurement is very important for continuous measurement of cloud top height, especially for thin cirrus clouds [19], but ground-based observation can only observe at fixed points, and the spatial resolution is low. Meteorological satellites can realize global cloud observation due to their large observation range, and satellite remote sensing provides observations over the ocean and Remote Sens.…”

Is the Air Too Polluted for Outdoor Activities? Check by Using Your Photovoltaic System as an Air-Quality Monitoring Device

“…The processing speed is very high. In a previous study by Campbell et al [ 38 ], more than 15,000 iterations were computed in seconds. During the retrieval process, the multiple scattering is assumed negligible, and each atmospheric layer is assumed uniform in the vertical and horizontal directions.…”

Experimental assessment of a micro-pulse lidar system in comparison with reference lidar measurements for aerosol optical properties retrieval

“…5). Therefore, the VLDR for the P-MPL system was also experimentally evaluated in comparison with that derived from Polly lidar measurements, for instance, similarly to the approach shown by Córdoba-Jabonero et al (2013). This experimental polarization correction is based on real measurements as an alternative (see Sect.…”

“…As a result, a constant offset, (= δ V Polly − δ V MPL ), can be assumed between δ V MPL and δ V Polly , obtaining = −0.0040 ± 0.0016. This offset can represent a correction to account for any slight mismatch in the transmitter and detector polarization planes and any impurity of the laser polarization state (Sassen, 2005), as also found in Córdoba-Jabonero et al (2013) by characterizing the VLDR of a relatively older version (MPL-4) of the polarized MPL systems. Therefore, the P-MPL VLDR must also be corrected by that offset using the expression:…”

“…Both MPL and P-MPL observations have been widely performed for continuous monitoring of aerosols and clouds. In particular, MPL/P-MPL measurements were used for atmospheric boundary layer (ABL) height retrievals (Lewis et al, 2013;Toledo et al, 2014Toledo et al, , 2017, detection and characterization of both cirrus clouds (Campbell et al, 2016;Lewis et al, 2016;Córdoba-Jabonero et al, 2017;Lolli et al, 2017;Campbell et al, 2021) and polar stratospheric clouds (PSCs) (Campbell and Sassen, 2008;Córdoba-Jabonero et al, 2013), depolarization-based characterization of the optical properties of different aerosol mixtures (Sicard et al, 2016;Córdoba-Jabonero et al, 2016, 2018, aerosol mass concentration estimation either in synergy with airborne measurements (Córdoba-Jabonero et al, 2016) or in comparison with forecast model simulations (Córdoba-Jabonero et al, 2019), determination of the precipitation intensity (Lolli et al, 2018(Lolli et al, , 2020 and cloud thermodynamic phase (Lewis et al, 2020), and assessment of the radiative effect of aerosols and cirrus clouds (Campbell et al, 2016;Lolli et al, 2017;Córdoba-Jabonero et al, 2020Campbell et al, 2021;, among other things. These studies demonstrated good MPL performance in aerosol and cloud research.…”