水平方向上的空气对流和复杂的地面状况会导致大气热辐射计算的不确定度增大，目标发射起始段的红外辐射特性测量有助于实现目标识别。因此，研究水平大气透过率和热辐射对目标的高精度红外辐射特性测量具有十分重要的意义。针对以上问题，首先借鉴垂直廓线理论建立了同层大气“水平温度廓线”模型，然后推导了水平方向计算大气透过率和热辐射的公式，并对其进行了实验验证。最后将MODTRAN软件计算和实验测量的大气热辐射结果进行了比较。实验结果表明，传统软件的热辐射计算精度为8.65% ，而本文方法的计算精度为4.91%。该实验说明，在水平方向上，这种算法是正确的。通过公式推导和实验验证说明了该方法的合理性，为水平方向大气透过率和热辐射的计算提供了一种新的思路。

The horizontal air convection and complex ground conditions lead to the uncertainty increasment of the calculation of atmospheric thermal radiation. The measurement of infrared radiation characteristics during the initial part of target launching is helpful for target recognition. Therefore, it is very important to study the atmospheric transmittance and thermal radiation in the horizontal direction to improve the accuracy of the infrared radiation characteristics measurement of the target. Based on the problems mentioned above，the "horizontal temperature profile" model of the same layer atmosphere is established referring to the vertical profile theory firstly. Then the formula of calculating the atmospheric transmittance and thermal radiation in the horizontal direction is deduced, and the experiment verification is carried out. Finally, the results of MODTRAN software calculation and experiment measurement of the atmospheric thermal radiation are compared. The results show that the accuracy of traditional software is 8.65% and the accuracy of the proposed calculation method is 4.91%. The experiment proves that the calculation method is correct in the horizontal direction. The validity of the calculation method is demonstrated by formula derivation and experimental verification. A new idea is provided for the calculation of the atmospheric transmittance and thermal radiation in the horizontal direction.