Interpreting Paleoclimate when Continental Positions are Uncertain: the Effects of Sampling, Modeling and Reconstructing

Parrish 9627771古地理学家和古气候学家在研究古气候方面往往有非常不同的议程，他们不同的方法和兴趣导致了拟议项目旨在解决的古气候研究的循环。这个问题在古生代气候研究中最为严重，当时大陆的位置可能鲜为人知。古气候学家使用了可用的古地理重建，就好像它们独立于古气候数据一样，但实际上，一些大陆的位置至少部分是根据古气候数据确定的。拟议研究的目的是：(1)记录和评价利用古气候数据对大陆进行定位所产生的问题，包括诸如定位的不唯一性以及利用基于纬向气候的概率曲线来定位可能具有非纬向气候的大陆等问题；(2)为在古地理和古气候重建中使用古气候数据建立更严格的抽样程序。为了解决采样问题，即不是指如何收集数据，而是如何编辑数据以用于空间数据，我们将开发一种新的网格系统，更适合于在球体上对数据进行网格划分，而不是经纬度网格，因为纬度网格存在网格单元尺寸不均匀的问题。然后，我们将制定报告古气候指标分布的程序。这将使评估在这类工作中作出的各种假设的稳健性成为可能。最后，我们将应用所发展的方法来解决古生代古地理中的一个长期存在的问题，即晚泥盆世冈瓦那的位置。一个可能的结果是，根据对数据的目标评价，我们将能够裁撤其中一个拟议职位。一个更有可能的结果是，我们将展示必须在哪里收集新的数据，以及必须审查哪些基本假设来解决冲突。该项目的更广泛影响将是加强对古地理重建的严格要求，展示圆形在用于至少部分以古气候指标为基础的古气候模拟古地理重建方面引入的误差，并提出可克服古地理学家和古气候学家的需要之间的基本冲突的程序。

Parrish 9627771 Paleogeographers and paleoclimatologists have tended to have very different agendas in studying paleoclimates, and their differing approaches and interests have led to a circularity in paleoclimatic studies that the proposed project is intended to address. The problem is greatest in studies of climates of the Paleozoic Era, when continental positions are likely to be poorly known. Paleoclimatologists have used available paleogeographic reconstructions as if they were independent of paleoclimatic data, but, in fact, some continental positions are determined at least partly from paleoclimatic data. The purpose of the proposed research is to: (1) document and evaluate the problems that arise from using paleoclimatic data to position continents, including such problems as non-uniquenessof positioning and the use of probability curves based on zonal climates for positioning continents that were likely to have had non-zonal climates: (2) establish more rigorous sampling procedures for the use of paleoclimatic data in both paleogeographic and paleoclimatic reconstruction. To address the problem of sampling, which refers not to how the data are collected but, rather, how they are compiled for use in a spatial fromat, we will develop a new grid system more appropriate for gridding data on a sphere that the latitude-longitude grid, which suffers from uneven grid-cell dimensions. We will then develop procedures for reporting the distribution of paleoclimatic indicators. This will permit evaluation of the robustness of the various assumptions that are made in this type of work. Finally, we will apply the developed methods to a persistent problem in Paleozoic paleogeography, that is, the positions of Gondwana in the Late Devonian. One possible outcome is that we will be able to eliminate one of the proposed positions, based on objectives evaluations of the data. A more likely outcome is that we will show where new data must be collected and which underlying assumptions must be examined to resolve the conflict. The broader implications of this project will be to enforce much more rigor into paleogeographic reconstructions, demonstrate the error introduced by circularity in using for paleoclimatic modeling paleogeographic reconstructions that are based at least in part on paleoclimatic indicators, and suggest procedures that might overcome the basic conflict between the needs of paleogeographers and those of paleoclimatologists.