CAREER: The role of ecosystem management on boundary layer development and precipitation in the Northern Plains

全球气温正在上升，这主要是由于人类活动产生的温室气体对太阳辐射量的影响，这些辐射量被地球表面吸收，而不是被反射回太空。在这一全球背景下，一些区域变冷趋势也是由人类活动造成的，包括那些有利于经济和保护目标的趋势。在北美大平原北部的夏季发现了这些变冷趋势之一。自20世纪70年代以来，在加拿大草原省份的部分地区，夏季最高气温下降了3度以上，降雨量增加了1英寸。这些变化被认为是由于夏季休耕的做法减少了；从20世纪70年代到现在，仅加拿大就失去了大约3500万英亩的休耕地。美国的休耕面积也出现了类似的下降，主要是在北部大平原，但这些变化对美国区域气候的影响迄今尚未得到研究。休耕过去是，现在仍然是在干旱地区广泛实行的，目的是为以后的作物节约用水，但也增加了土壤侵蚀和退化，被认为是不可持续的。生产者也认识到，休耕的节水效益往往被不种植作物的经济损失所抵消。该项目的目标是了解改善土壤保持和可能增加农场收入的农业管理实践如何也有利于现在和未来几十年的气候。作为该项目的一部分，将设计一门实地课程，将蒙大拿大学系统中的部落学院与加强代表性不足的学生的STEM教育联系起来。项目活动还将加强现有的努力，以改善小学一级的课后教育项目。一个跨大学联盟将被设计来协调蒙大拿的大气科学研究活动，包括部落学院。为了了解土地管理对区域气候的作用，有必要了解其影响气候系统的机制，并将这种理解整合到可以预测未来气候动力学的模式中。在有大量休耕的地区，来自陆地表面附近的暖干空气上升，形成一个高而干燥的大气边界层，不太可能经历对流降水。如果有植物存在，更多的水分和更少的热量进入大气，导致一个更潮湿的大气边界层，而不是那么高，这使得云形成对流降水过程更有可能。在该项目中，将测量休耕、草原和作物地表与大气之间的热量和水分交换，并模拟大气边界层的发展、对流降水和区域气候。将在过去三十年中运行模型，以了解管理趋势如何影响气候，并在未来三十年中了解未来土地管理变化如何可能或可能不会继续对抗全球变暖趋势。

Global temperatures are rising, largely due to the effects of greenhouse gases from human activities on the amount of radiation from the Sun that is absorbed at the surface of the Earth instead of being reflected back to space. Within this global context are some regional cooling trends that also result from human activity, including those that are beneficial to economic and conservation objectives. One of these cooling trends has been found in the summer in the northern North American Great Plains. Maximum air temperatures have decreased by over three degrees and rainfall has increased by an inch during summer across parts of the Canadian Prairie Provinces since the 1970s. These changes are thought to be due to a decrease in the practice of keeping farm fields fallow during summer; Canada alone has lost around 35 million acres of fallow from the 1970s to the present. The United States has seen a similar decline in fallow area, largely in the Northern Great Plains, but the effects of these changes on regional climate in the U.S. have not been studied to date. Fallow was, and still is, widely practiced to save water for subsequent crops in dry regions, but also increases soil erosion and degradation and is not considered sustainable. Producers have also realized that the water-savings benefit of fallow is often outweighed by the economic losses of not planting a crop. The goal of this project is to understand how agricultural management practices that improve soil conservation and may increase on-farm income can also be beneficial to climate, both now and over the coming decades. As part of the project, a field course will be designed to link Tribal Colleges in the Montana University System with the goal of enhancing STEM education among underrepresented students. Project activities will also enhance existing efforts to improve after-school educational programs at the grade-school level. An inter-university consortium will be designed to coordinate research activities in the atmospheric sciences across Montana, including Tribal Colleges. To understand the role of land management on regional climate, it is necessary to understand the mechanisms by which it influences the climate system, and to integrate this understanding into models that can predict future climate dynamics. In a region with substantial fallow, warm and dry air from near the land surface rises and creates a high and dry atmospheric boundary layer that is unlikely to experience convective precipitation. If plants are present, more moisture and less heat enters the atmosphere, resulting in a moister atmospheric boundary layer that is not nearly as high, which makes cloud formation convective precipitation processes more likely. In this project, the exchange of heat and water between the surface and atmosphere in fallow, grasslands, and crops will be measured, and atmospheric boundary layer development, convective precipitation, and regional climate modeled. Models will be run over the past three decades to understand how management trends have influenced climate and over the forthcoming three decades to understand how future land management changes may, or may not, continue to counter global warming trends.