m −2 over land in Maryland), and turns negative moving poleward.m −2 over ocean at Singapore), becomes neutral in the midlatitudes (0.03–0.27 W.hypothesize a global meridional daytime TOA CRF gradient that begins as positive at the equator (2.20–2.59 W This subarctic study completes a now trilogy of MPLNET ground-based cloud forcing investigations, following midlatitude and tropical studies by Campbell et al. Two-year-averaged daytime TOA CRF is estimated to be between −1.08 and 0.78 W Sample-relative net average TOA CRF distributions vs log 10(COD) for the (a) annual 2017 (solid lines) and 2018 (dashed lines) daytime samples as a function of their 20- (blue) and 30-sr (red) estimates and for the 20 (b) summer and (c) winter periods.Ĭirrus cloud daytime top-of-the-atmosphere radiative forcing (TOA CRF) is estimated for a 2-yr NASA Micro-Pulse Lidar Network (532 nm MPLNET) dataset collected at Fairbanks, Alaska. m −2), and (g)–(i) absolute normalized net TOA CRF solved at Fairbanks.Interannual values are solved after daily data point smoothing is done with a low-bandpass filter.įor (left) the bulk 2-yr sample and for individual years (center) 2017 and (right) 2018, (a)–(c) the MPLNET-derived daytime cirrus cloud sample-relative frequency, (d)–(f) sample-relative average net TOA CRF (W Thirty-nine-year (1980–2018) seasonal 2.0-PVU (summer and winter) height anomalies and trend analyses solved over the Arctic domain (70°–90°N) from ERA5 datasets. Sample-relative daytime cirrus cloud occurrence histograms derived from continuous NASA MPLNET observations at Fairbanks during (top) 2017 and (bottom) 2018 as a function of COD (30-sr solutions only see insets for bulk percentages) vs CTT (a),(d) annually (b),(e) from May to October and (c),(f) from November to March. (2015), from June 2006 to May 2017 centered near Fairbanks (white star) (a) annually, (b) from May to October, and (c) from November to March. Any reuse without express permission from the copyright owner is prohibited.Cirrus cloud absolute occurrence rate frequencies at 2.5° × 2.5° resolution estimated from NASA CALIOP level 2 cloud-layer products, and thus subcategorized on the basis of definitions outlined in Campbell et al. Published on 1 February 2016.Įxcept where otherwise noted, images are subject to copyright. Meanwhile, the researchers call for more modeling studies to explore its potential effects. Still, cirrus cloud thinning is a very new idea, and it is uncertain whether the technique is even feasible. This would keep precipitation up in regions that are prone to drought. The team found that unlike other radiation management techniques, cirrus cloud thinning could potentially alleviate the disruption of the water cycle while keeping global temperatures down. This would allow more longwave radiation to escape from the atmosphere into space. In the real world, scientists would thin out cirrus clouds by using aircraft to seed the cloud formation regions-where the icy wisps form-with small particles to reduce the clouds’ thickness and lifetime. The researchers used a global climate model to simulate the effects of cirrus cloud thinning. examined the effects of so-called cirrus cloud thinning to find out if the technique could avoid some of the problems that might accompany other radiation management approaches, including suppression of the water cycle. Understanding how climate engineering techniques might affect the water cycle is important for evaluating their potential usefulness. Evidence suggests that climate change is already affecting the global water cycle low-latitude and midlatitude land regions could see increased droughts in the future, whereas global precipitation will increase overall. Along those same lines, a newer approach proposes disrupting the formation of cirrus clouds-the thin, wispy clouds found above 20,000 feet-to let out more longwave radiation that would otherwise remain trapped in the atmosphere.Įarlier climate model studies found that radiation management can suppress the water cycle, reducing rainfall and causing droughts in vulnerable regions throughout the world. Some proposed projects involve reflecting incoming solar radiation back into space, keeping it from warming the atmosphere. Sign up now Source: Geophysical Research LettersĪs climate change progresses, researchers are exploring climate engineering methods to slow it down or lessen its extent.