科技协作, 工程 技术 12月7日2021 8分钟读取


by 乔霜

利用卫星, 激光和微波, Professor Shin-Chan Han is working with some of the most accurate measurements of gravity humankind has ever recorded. 但是当这些仪器在太空中离AG真人官方APP头顶几百公里的时候, 它们的应用可能会改变AG真人官方APP应对地球上洪水的方式.

2021年3月17日,新南威尔士州东部的天空上演了一场壮观的表演. 雷声隆隆如西线, as spectacular bursts of purple lightning lit up a l而且scape otherwise cloaked in darkness from the unrelenting rainclouds.

接下来的一个星期,大雨倾盆,整个州都湿透了. 新南威尔士州中北部海岸受灾尤其严重 气象局注意到 that numerous areas experienced more than 600 mm of rain in just four days – the village of Comboyne being of particular note, 在3月19日至22日猛烈撞击853毫米.

换个角度来说, 科博因的年平均降雨量 是1573毫米, 这意味着在这四天里,降雨量超过了半年的总和.

The result was flooding that the Premier at the time described as being a “one-in-100-year event”, 看到城镇被疏散, 道路和机场关闭, 而且 塔里附近的一座房屋真的被冲走了 在上升的曼宁河上.

与此同时, 开销, 在冰冷寂静的太空中, 重力恢复和气候实验后续任务(GRACE-FO)也在关注.


而不是孤独的宇宙飞船, GRACE-FO (a joint mission between NASA 而且 the German Research Centre for Geosciences) is comprised of a pair of near-identical satellites, orbiting the Earth in constant communication with one another through microwave ranging instruments 而且 lasers, 平均相距约220公里.

注意这一点很重要, 然而, 这个平均距离——“大约220公里”——有助于人类的理解. 卫星本身可以 测量它们之间的差异,误差在一微米以内美国国家航空航天局(NASA)将这一距离描述为“大约一个血细胞的直径”。.

It’s a level of accuracy that’s only made more jaw-dropping when you learn that GRACE-FO is travelling at a velocity of more than 27,每小时000公里.

试着正确地看待这一切, it’s something akin to measuring the distance from a single fibre of timber in the foyer of the University’s Great Hall to the precise centre of the bullseye on the dartboard at Comboyne Ex-Servicemen’s & Citizens Club – a level of accuracy that would require a microscope – all while travelling at almost 22 times faster than the speed of sound.

大约在这个世界上独一无二的工程下面490公里处, 在卡拉汉校区工程区一间安静的办公室里, 韩信璨教授 仔细研究GRACE-FO传回的数据.


A long-time member of the original GRACE mission – the FO suffix in the present mission effectively indicates it’s the sequel to a pair of satellites that were decommissioned in 2017 – Professor Han is one of the world’s foremost experts on why the instruments aboard the spacecraft are so precise 而且 what the slightest deviation in distance between the two means.

Those who remember their high-school maths may recall gravity on Earth being measured at approximately 9.807米每秒的平方,不管它是什么 平均 价值.


“The satellites’ microwaves 而且 lasers measuring the distance between themselves are affected by gravity, 这是质量的标志.”


“随着领先卫星接近一个大质量地区, 如山脉, the higher gravitational pull tugs the satellite a little farther ahead of the following satellite. 过了一会儿, 下面的卫星轮流向前拉, 缩短它们之间的距离. 当先导卫星经过山脉时, 它们的巨大质量从后面拖着它, 再次缩小了两颗卫星之间的距离.”

但考虑到上面提到的船上仪器的精度, 质量的动态变化更大, 因此引力, 可以测量.



And this is where the data beaming down from hundreds of kilometres above the gathering storm clouds becomes so critical.

Because a $9 water gauge at the hardware store can gather accurate data on how much rain is coming down, 但当涉及到洪水时,这只是故事的一部分.

可以说,更关键的是水已经存在了 in 地面.


虽然没有那么壮观,也没有那么突然, 2020年2月,澳大利亚东海岸也是一个非常潮湿的月份, 降雨量与2021年3月相当.


As for why 2021 gave us conditions akin to a Rol而且 Emmerich film, while the preceding year was more 在雨中歌唱, 这可能是由于AG真人官方APP脚下有大量的水, 而不是砸在AG真人官方APP头上.

很少有人会忘记2019 - 2020年澳大利亚森林大火季节, AG真人官方APP的天空泛着黄色, 火山灰冲刷着AG真人官方APP的海岸线,空气质量下降到危险水平, 全国超过1700万公顷的土地被烧毁, 摧毁了成千上万的房屋 超过30亿只动物死亡或流离失所.

2月的降雨显然是受欢迎的喘息机会,有助于平息肆虐的地狱, 但它们也可以补充土壤的水分储存, 到2019- 2020年夏天,该指数已跌至创纪录的最低水平.

The mercifully wet February 2020 saw some 60 trillion litres of water serve to seriously recharge dry soils, 这是自2017年以来的最高水平.

在2020年潮湿的几个月里,这些土壤湿度水平略有上升, before dropping off during the summer of 2020-21 – although the latter drop-off was nowhere near the record bottom-out of the previous summer.

这一切都意味着,到2021年3月的降雨到来时, with that one particularly hectic week adding an estimated 60-70 trillion litres of water storage, 土壤水分水平较高.

So, 而不是像2020年那样在干旱的土地上找到家园, 2021年的降雨产生了明显更多的径流.

“这可能是2021年与2020年相比出现大面积洪水的原因,韩教授总结道 他和他的同事为 地球与空间科学.

“These two contrasting consequences from the similar rainfalls are excellent examples of demonstrating how antecedent 土壤水分 condition governs runoff 而且 flooding… this is important to implement into flood forecasting 而且 warning practices.”


As you’ve no doubt worked out by now, Professor Han is getting his data for 土壤水分 from the GRACE-FO任务 “追踪地球的水运动,以监测地下蓄水的变化, 大湖泊和河流中的水量, 土壤水分, 冰原和冰川, 海平面上升是由海水的增加引起的.”

在整个星球上追踪水的运动是一项极其广泛的任务, 这意味着即使科学, 使用的数学和技术是行业领先的, 也有缺点.


“格陵兰岛和南极洲的冰块损失变化是一个缓慢的过程, 因此可以使用每月数据进行正确的映射,韩教授说.



The obvious illustration of the drawbacks in using monthly data were on full display during March 2021, 当时美国宇航局的数据显示,该月的降雨量与2020年2月相似. 虽然这是真的,但是 单周 21年3月,当月绝大多数降水都是下降的, which paints a substantially different picture – the same rainfall spread out over four weeks may not have seen a house become a river barge.

So Professor Han 而且 his colleagues have set about using a different data set to quantify water storage – one that puts to use the insanely accurate instruments that are onboard the twin satellites measuring the slightest shift in the distance between them.

大多数其他团队都在看NASA的官方月度快照. 但AG真人官方APP正在直接研究卫星对卫星的扰动,”韩教授解释道.

“So different days have different perturbations 而且 we are measuring the changes of the satellite-to-satellite motions during the month, 使AG真人官方APP能够量化卫星扰动原始数据的变化.


Using this approach – which the team also used to accurately measure the 2020 monsoon season in Bangladesh, 他们的研究结果发表在著名的 美国国家科学院院刊 -延迟只有1到3天, 而不是NASA的官方快照需要几个月才能公布.

该团队认为这种方法可以用于地球上的其他应用, 提供准确和最新的储水量图.

希望在未来几年, 这种方法将得到进一步的完善和广泛的采用, 从而更快更准确地预测世界各地的洪水.

与此同时,与 La Niña由气象局公布, leading to a prediction of “above 平均 rainfall across much of northern 而且 eastern 澳大利亚 during summer”, it’s worth keeping in mind that the wet months ahead could continue to have repercussions long after the heavy rains have fallen.