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Evaluation of turbulent surface flux parameterizations for the stable surface layer over Halley, Antarctica

first_imgCalculated surface fluxes from seven surface layer parameterizations are verified against 45 months of observations from Halley, Antarctica, with a temporal resolution of 1 h. The surface layer parameterizations aretaken from widely used numerical models including the National Center for Atmospheric Research (NCAR)Community Climate models CCM2 and CCM3, the U.K. Met. Office Unified Climate Model, and the fifthgenerationPennsylvania State University–NCAR Mesoscale Model (MM5). The observations include measurements of the mean wind speed and temperature inversion strength and direct measurements of the turbulent fluxes of heat and momentum.A comparison of the calculated and observed fluxes is conducted for conditions in which the surface layeris stably stratified. Based on these comparisons it is found that the simulated friction velocity values are adequate (although slightly larger than the observed turbulent fluxes) under all but the highest bulk Richardson number conditions (greatest static stability). In contrast the magnitude of the calculated sensible heat flux is frequently less than that of the observed sensible heat flux. The use of a larger scalar roughness length for heat compared to that for momentum is found to remove this bias in the calculated sensible heat fluxes. The correlation between the observed and calculated fluxes of heat and momentum is acceptable for the lower bulk Richardson number regimes, but is near zero for the high bulk Richardson number regime. The correlation between the calculated and observed fluxes is in general better for the momentum flux than for the sensible heat flux. The bias in the calculated sensible heat flux could have significant implications for numerical simulations in which the flow is driven by surface processes, and may pose problems for climate-scale simulations. The impact that errors of the observed magnitude have on simulated katabatic winds is explored with a series of twodimensional numerical simulations using MM5. Inferences about the relevance of these findings for climate simulations are also addressedlast_img read more

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Clarkson’s 23 points power Jazz past slumping Hawks, 112-91

first_img FacebookTwitterLinkedInEmailATLANTA (AP) — Jordan Clarkson sank five 3-pointers while scoring 23 points and the Utah Jazz protected the NBA’s best record with a runaway 112-91 win over the Atlanta Hawks.Bojan Bogdanovic had 21 points and Donovan Mitchell added 18 for Utah.Atlanta point guard Trae Young was held out with a bruised calf. Rajon Rondo made his second start of the season. Another starter, forward De’Andre Hunter missed his third consecutive game with a knee injury. John Collins led Atlanta with 17 points. The Hawks suffered their third consecutive loss.Utah led 45-37 at halftime, holding Atlanta to a season lows for points in any half. February 4, 2021 /Sports News – Local Clarkson’s 23 points power Jazz past slumping Hawks, 112-91 Associated Press Written by Tags: Jordan Clarkson/NBA/Utah Jazzlast_img read more

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India reiterates commitment to new solar, wind capacity

first_img FacebookTwitterLinkedInEmailPrint分享Clean Technica:The Indian government has reiterated its commitment to auction large volumes of solar and wind energy capacity in order to achieve the target of 100 gigawatts solar and 60 gigawatts of wind energy capacity operational by 31 March 2022.In a press release issued by the Ministry of New and Renewable Energy (MNRE), the government stated that it plans to auction 60 gigawatts of solar power capacity and 20 gigawatts of wind energy capacity by March 2020 in order to achieve those targets.According to the data released by the Ministry as of 31 October 2018, solar power capacity installed in India stood at just over 25 gigawatts, while an additional 36.6 gigawatts capacity was under construction or auctioned, bringing the total to 61.6 gigawatts. The Ministry hopes that the gap of around 40 gigawatts could be filled through fresh auctions between January 2019 and March 2020. This translates into an average capacity auction of around 2.7 gigawatts every month for the next 15 months.For the wind energy capacity, the figures on 31 October 2018 stood at 35 gigawatts commissioned, and 9.4 gigawatts under construction or auctioned, bring the total to 44.4 gigawatts. The Ministry plans or expects fresh tenders of 20 gigawatts over a period of 15 months through March 2020 to achieve the installed capacity target of 60 gigawatts by March 2022. The monthly average capacity to be auctioned would be around be a manageable 1.4 gigawatts.This is not the first time that the Indian government has issued such a timeline for solar and wind energy auctions to achieve the 2022 targets. The MNRE had the same exercise a year ago, and has failed to keep up with its own timeline.As per the initial timeline, the Ministry had planned for the auction of 13 to 14 gigawatts of wind energy capacity between January 2018 and March 2019. Instead, only 6.9 gigawatts capacity was auctioned between February and September 2018. The Solar Energy Corporation of India, an agency under direct control of the MNRE, had to reduce the size of multiple wind energy tenders, and even had to cancel or postpone some of them.More: India eyes 80 gigawatts of solar & wind tenders by March 2020 India reiterates commitment to new solar, wind capacitylast_img read more

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Australian Open: Federer, Serena favourites to win 2019’s 1st Grand Slam tournament

first_imgNovak Djokovic and Rogerer Federer loom over Melbourne Park for the year’s opening Grand Slam as favourites for the Australian Open as questions remain as to whether one of Generation Next could finally end their stranglehold.The Serbian world number one and his Swiss opponent have won eight of the nine titles on Rod Laver Arena since 2010 and 11 of the last 13 on the bright blue courts in central Melbourne.Both have six titles each, and are seeking to break a three-way tie for the most victories with Australia’s Roy Emerson.While Federer has won the tournament for the last two years – with the 2017 victory at the age of 35 a surprising return after knee surgery in 2016 – Djokovic’s history in Australia and rediscovery of his form midway through last year means the world number one will be the man to beat.The 31-year-old went into a bewildering slump in mid-2016 that only ended when he won Wimbledon last year before he went on to claim his third U.S. Open crown and move to 14 Grand Slam titles, three behind Rafa Nadal.The Spanish world number two, however, is battling another leg injury that forced him out of the Brisbane International last week.While he told local media on Tuesday that he did not feel any pain from his thigh strain, it is apparent that hard courts are putting undue stress on the 32-year-old’s body.He retired in the quarter-finals against Marin Cilic last year in Melbourne and suffered yet another knee injury that forced him out of the U.S. Open semi-finals at Flushing Meadows before he had ankle surgery in November.advertisement Federer, however, continues to defy the odds at 37 and prepared for his title defence with some convincing performances in the Hopman Cup in Perth last week.The 20-times Grand Slam winner’s victories over Greece’s world number 15 Stefanos Tsitsipas and world number four Alexander Zverev prompted the German to playfully quip that he was tired of Federer winning everything.”I mean, you’re 30-whatever. Why? Just why?,” Zverev asked jokingly of Federer at the Hopman Cup trophy presentation.The 21-year-old Zverev appears the most likely of the younger generation of players hoping to end the world’s top three’s domination of Grand Slams, having beaten Federer and Djokovic at the ATP Tour Finals in London last November.While others in ‘Generation Next’ like Austria’s Dominic Thiem and the 22-year-old Russians Karen Khachanov and Daniil Medvedev could cause upsets, it is debateable whether they have can win seven matches over 14 days.Two of the older generation who have shown they do have that ability – Britain’s Andy Murray and Switzerland’s Stan Wawrinka – could be dangerous floaters in the draw as they make their way back from injury-plagued seasons.Murray, a five-time finalist at Melbourne Park, spent most of last year recuperating from hip surgery and looked rusty last week in Brisbane but declared himself pain free.Wawrinka, the 2014 champion, is also coming back from knee surgery and a back injury in the second half of 2018, but typically flies under the radar through Grand Slams and unlikely to have any pressure, which makes him more lethal.WILLIAMS CHASING 24The women’s draw looks more open even with Serena Williams, the most dominant force in the sport, back chasing a 24th grand slam singles title to tie Margaret Court’s all-time record.The American was eight weeks pregnant when she won her 23rd title at Melbourne Park in 2017 and returned to action last year where she reached finals at Wimbledon and the U.S. Open.Williams, who played at the Hopman Cup in Perth, enters the year’s first grand slam ranked 16th but she still remains the favourite in Melbourne even if she lost to Naomi Osaka in the Flushing Meadows final.World number one Simona Halep, with a massive burden off her shoulders, will hope to go one better this year having lost the 2018 final to Caroline Wozniacki.The Romanian, who lost to Ash Barty in the second round of the Sydney International on Wednesday, broke her grand slam duck at the French Open in June last year and finished the season at number one for the second consecutive year. Halep, who is without a coach since Australian Darren Cahill left for family reasons, will expect her back to hold up in competition after a herniated disk curtailed her 2018 season.Wozniacki also has a question mark over her fitness after the 28-year-old Dane revealed her battle with rheumatoid arthritis last October but has since claimed that she has learnt to live with it.advertisementA second Australian Open title will be a perfect birthday gift for world number two Angelique Kerber, who turns 31 in the first week of the tournament.Kerber beat Wiliams in the Wimbledon final to become the first German woman to win the grass court title since Steffi Graf in 1996.She has looked sharp at the Hopman Cup and maintained her 100 percent singles record even though Germany lost to Federer’s Switzerland in the final.Kerber has replaced coach Wim Fissette with 2003 Australian Open finalist Rainer Schuettler and a more aggressive approach could be the hallmark of the new partnership.Also in the mix is the popular Osaka, who stunned Williams in New York.The 21-year-old Japanese, however, had an inconsistent build up to the year’s first grand slam.Osaka suffered a straight set loss to Lesia Tsurenko in the semi-final of the Brisbane International and withdrew from the Sydney International in frustration.Also Read | World No.1 Simona Halep and her coach Darren Cahill part waysAlso Read | Roger Federer warms up to Australian Open by leading Switzerland to Hopman Cup gloryAlso Read | Kei Nishikori survives Daniil Medvedev scare to win Brisbane InternationalAlso Read | Kevin Anderson beats Ivo Karlovic to win Maharashtra Open titlelast_img read more

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