Global total precipitable water trends from 1958 to 2021

Authors: WAN, NENGHAN - Kansas State University; LIN, XIAOMAO - Kansas State University; PIELKE SR, ROGER - University Of Colorado; ZENG, XUBIN - University Of Arizona; Nelson, Amanda

Submitted to: Hydrology and Earth System Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/9/2024
Publication Date: 5/15/2024
Citation: Wan, N., Lin, X., Pielke Sr, R.A., Zeng, X., Nelson, A.M. 2024. Global total precipitable water trends from 1958 to 2021. Hydrology and Earth System Sciences. 28(9);2123-2137. https://doi.org/10.5194/hess-28-2123-2024.
DOI: https://doi.org/10.5194/hess-28-2123-2024

Interpretive Summary: This study investigates the trend in global total precipitable water (TPW), surface skin temperature (Ts) and surface air temperature (T2m) from 1958 to 2021 two datasets (ERA5 and JRA-55). TPW trends in most regions of the world are positive, though the magnitude of the positive trends tends to decrease away from the low latitude from 1958 to 2021, and anomalies increase with time. On a global scale, the TPW yielded a rate of 0.16 mm decade-1 for ERA5 and 0.21 mm decade-1 for JRA-55. The significant warming trend of T2m and Ts was shown in almost all regions across global, especially the Arctic where the anomaly temperature increase is three time more than the global average. In addition, the warming over land was larger than over ocean. The TPW trend was positively correlated with surface warming over oceans while the correlation over land is negative. The TPW change response to temperature (Ts and T2m) changes expressed as a ratio of dTPW/dT showed larger variations over oceans than over the land. For the latitude-banded regions, there were two stronger response places located in the southern high-latitude and the tropical over global and ocean.

Technical Abstract: This study investigates the trend in global total precipitable water (TPW), surface skin temperature (Ts) and surface air temperature (T2m) from 1958 to 2021 using ERA5 and JRA-55 reanalysis datasets. We found that TPW trends in most regions of the world are moistening. Larger moistening trends were in tropical land areas from 1958 to 2021. Such moistening trends over large tropical lands, the Indian Ocean, high latitudes in the Northern Hemisphere (NH) were confirmed by the Atmospheric Infrared Sounder (AIRS) satellite and the Integrated Global Radiosonde Archive version 2 (IGRA2) observations. The average global TPW trend ranged from 0.16 and 0.21 mm decade-1 for ERA5 and JRA-55, respectively. We also found that significant warming of T2m and Ts was found in almost all regions especially the Arctic where the temperature anomaly trend (0.55 K decade-1) was three times more than the global average trend (around 0.15 K decade-1). In addition, this warming over land was obviously larger than ocean’s warming. The TPW trend was positively correlated with surface warming over oceans while this correlation over land was negative. The TPW change in response to temperature T2m or Ts changes showed larger variations of 5-11% K-1 over oceans than over land (below 4% K-1 and even negative). In view of global dTPW/dT in the banded-latitudes, two stronger response zones were in the southern high-latitudes and tropical zones, and the dTPW/dT ratios over land were mostly lower than the theoretical ratio of ~7% K-1 in tropical zones.